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CALORIC.
      IN TWO VOLUMES.
         VOL. I. 
" To every form of being ia assigned
 An active principle: howe'er removed
 From sense and observation, it subsists
 In all things, in all natures, in the stars
 Of azure heaven, the unenduring clouds,
 In flower and tree, in every pebbly stone
 That paves the brooks, the stationary rocks,
 The moving waters, and the invisible air.
 *    *    *    *   from link to link
 It circulates, the soul of all the worlds."
                             Wordsworth. 
s»is Hun 3C
CALORIC:
MECHANICAL, CHEMICAL AND VITAL AGENCIES
PHENOMENA  OF  NATURE.


  SAMUEL L. METCALFE, M.D.,
LATE OP TRANSYLVANIA UNIVERSITY.

 VOL. I.
"e[7T"">:--.

C^£-<
      PHll?A DELPHI A:
J. B. LIPPINCOTT  & CCt
          1859. 
 Q
Mire? a

   v.l'
Entered,	according to Act of Congress, in the year 1859, J. B. LIPPINCOTT & CO.,	by
In the Clerk's	Office of the District Court of the United States for the	
	Eastern District of Pennsylvania	
 
*
         PREFACE
TO  THE  FIRST  EDITION.
  In the primitive ages of the world, when men gazed on the
wonders of nature with the freshness of childhood, and before
the vivid information of the senses  had become  obscured  by
fabulous traditions, all their  physical and  metaphysical theo-
ries were founded on the belief that solar fire is the efficient
cause of motion and  life throughout creation.  This belief, so
manifestly the result of observation  and experience, was con-
stantly forced upon their minds with all the evidence of a liv-
ing reality; and" prevailed for thousands of years in  every
quarter of the habitable  globe.  Nor is there  anything so
strikingly obvious to the  unsophisticated common sense of
mankind  as the omnipresent  influence  of the sun, which is
perpetually  exerting a  tranquil, yet  omnipotent  energy,
throughout the air, the ocean and the solid  ground.  He re-
gulates all the phenomena of climate and season, evaporation
and  rain, the  circulation of the  atmosphere, the  flowing of
waters, the transformations  of chemistry, the operations of
vitality, and the revolutions of the heavenly bodies.
  But as the ancients never  explained the laws by which ele-
mentary caloric operates in  the  generation of force and mo-
tion, nor  the manner in which it is  related to electricity and 
vi           PREFACE TO THE FIRST EDITION.
light, thei* speculations have  exerted  little influence on the
physical theories of modern philosophers, who have, strangely
enough, disregarded  nearly all that was most valuable in the
science  of antiquity.  At the present  time, it remains  unde-
cided, whether  caloric is  an exceedingly subtile and active
essence, as maintained by the early Hindoos, Egyptians, Phoe-
nicians,  Chaldeans, Persians and Arabians, as well as the more
enlightened  Greeks  and  Romans; or  whether  it consists in
mere motion and vibration among the particles of ponderable
matter, as supposed by Bacon, Boyle, Hooke, Rumford, Davy,
Young and others.
  One of the most important  modern  discoveries was that of
latent or combined heat, by Dr. Black.  When  he proved by
accurate experiments, that definite measures of caloric  are
required to convert solids into  liquids, and that  the same sub-
tile fluid is obtained from  the  atmosphere  by respiration, he
laid, the  foundation of its true theory.   But as he did not ex-
tend his researches  to its agency in the mechanical,  chemical
and vital phenomena of nature, his labours have not  been fol-
lowed by results corresponding with the magnitude of his dis-
covery,—if we  except the  improvement of the  steam engine
by Watt.
  Nor has any one,  either among the ancients  or  moderns,
ever attempted to give a regular and systematic history of the
mode in which caloric operates in all the molecular and aggre-
gate forces of matter. Mr. Whewell observes, in his late His-
tory of the Inductive Sciences, that  "we have no hypothesis
regarding thermotics, which, being assumed in order to explain
one class of phenomena, has been found to account exactly for
another."   Yet he adds: "it is one of  the cardinal  points on 
PREFACE TO THE FIRST EDITION.
vii
which the doors of physical knowledge must turn,%hich have
hitherto remained closed."
   Within the last hundred years, electricity has been regarded
by many persons as a key by which to  unlock all the  secret
cabinets of nature.  We  have  had electrical  theories of che-
mistry, of life and of the universe.  Yet no one has explained
what electricity is—whether a separate and distinct agent, a
modification of some other exceedingly refined and more com-
prehensive principle, or a mere effect, condition  or  property
of ponderable matter.  The celebrated  Faraday at one time
adopted the simple and rational theory of  Franklin, that it is
a material fluid, definite measures of which belong to each ele-
ment of ponderable matter.  And yet he speaks  of it very
often as if  he  considered it to be a compound fluid.  But
when treating of  its chemical  agency, he represents it  as  "a
modification of the exertion of chemical forces."
   Again,  when  by  following up the discoveries of Oersted,
Davy,  Arago  and Schweigger, who found that electricity is
capable of producing all the phenomena of  magnetic  action on
a small  scale, he succeeded in obtaining an  electric spark from
a permanent  magnet, he  arrived at the conclusion that elec-
tricity and magnetism are identical; except that  in the latter
"the axis of power" is greater  than in the  former.  Yet, as if
not  satisfied with  any of  the foregoing hypotheses, he sug-
gests, at another time, that  electricity  may be resolved into
undulations of an ether;  and, at another time,  that all the
more important electrical phenomena may be resolved into
polarization of the particles of ponderable matter, or what has
been called atomic polarity.  But he does not  explain what he
means  by the axis of power and  electric  polarity;  nor how 
viii          PREFACE TO THE FIRST EDITION.
chemical affinity and  magnetism, which are merely effects or
modes of action, can  be identical with their cause;  nor does
he inform us what the ether is, and what  causes it to vibrate.
Such  have  been the difficulties of this important department
of physical science, that its most distinguished votaries  have
hitherto failed to present us with a consistent theory of elec-
trical  phenomena.   But I hope to make it appear that most of
these  perplexities have arisen  more from defective methods of
inquiry, than from any inherent obscurity of the subject.
  Such is the reverence of mankind for mysteries, that the
majority are always ready to believe what they do not under-
stand; while the most obscure and visionary fancies are often
regarded as profound.   It was long ago remarked*by Longi-
nus, that darkness  is a source of the sublime;  and it must be
admitted that objects are magnified by looming through a fog.
  In all ages of the civilized world, light has been recognized
as a powerful agent in the work of the universe.  As the great
Painter of Nature, it gives to the dome of heaven its azure hue;
to the rainbow its  gorgeous red,  brilliant yellow, refreshing
green and  lovely blue,  shading into  the softer violet.   It is
solar light which touches the morning and evening  clouds with
its  celestial pencil, when they  glow with vivid tints  of ruby,
sapphire and gold.   It  adorns the flowery fields with an end-
less variety of enchanting  colours; while  it is perpetually
modifying  the  taste,  odour  and  other sensible  properties of
different bodies.
  But it is still an unresolved  problem, whether light be a ma-
terial substance, as maintained by  Pythagoras, Democritus
Leucippus, Empedocles,  Plato, Epicurus,  Newton  and Brew-
ster;  or whether it consists in the  mere vibrations of  some 
PREFACE TO THE FIRST EDITION.
IX
unknown ether, as supposed by Descartes, Huyghens, Hooke,
Euler, Young,  Sir  John Herschel, Arago and  others.   Nor
is it yet finally settled  whether white light is composed of
seven  primitive rays, as  supposed by  Newton, or of  only
three fundamental colours,  red, yellow and blue, as maintained,
with many cogent  reasons deduced from experiment, by Sir
David Brewster.   On the  same subject,  the advocates of the
undulatory  or  wave  theory  are equally at  variance among
themselves; for while Huyghens maintained that solar light is
composed of only  two elementary colours, yellow and  blue,
Hooke reduced all its modifications to red and violet; whereas
Young reduced the whole to red, green and violet.
   What  is still more remarkable, neither of the  two  great
rival parties has ever yet attempted to ascertain the relations
of light to caloric  and electricity;  nor in what way they per-
form so many wonderful effects in the moving  drama of the
universe.  But if they be connected in the operations of na-
ture, they must be united in theory.  And it will be a leading
object of the following work to prove, by a careful generaliza-
tion of facts, that caloric and electricity are mutually convert-
ible into each other; consequently, that they are modifications
of one and the same  essence, which is the active principle in
light, and in all the phenomena of nature.
   Since the time of Sir Isaac Newton, it has  been generally
supposed that all the  molecular changes of matter may be re-
ferred  to  attractive and repulsive  forces.  Yet the cause of
attraction and  repulsion  has not  been identified  with  any
known principle capable of demonstration.   The orbits  of
planets, and the times of  their revolutions, have been  mea-
sured with mathematical precision; but  the  cause of  their 
X
PREFACE TO THE FIRST  EDITION.
eternal motion has never been clearly distinguished from pro-
jectile and gravitating forces.   The relative magnitudes of the
particles or atoms of ponderable matter have  been, to a cer-
tain extent, ascertained by the refined analyses of modern
chemistry; yet the cause of chemical affinity is still confounded
with inherent properties, occult qualities and undefined powers.
The composition of plants and  animals has been discovered,
and their intimate structure explored; yet the organizing prin-
ciple  remains  a profound mystery.   What was said by Des-
cartes two hundred  years  ago, is equally true  at the present
day:  "In philosophia  nihil adhuc reperiri, de quo  non in
utramque partem disputatur."   And Mr. Whewell observes in
a very recent  work,  that  "the past  history of man,  of  his
arts,  of  languages, of the  earth, of the solar system, offers a
vast series of problems, of which perhaps  not one  has been
rigorously solved."
   It has been a complaint  of long standing in  the world, that
nature has spread  a veil over the first principles of things,
which man can never hope to remove.  But there is reason to
believe  that all the great  truths of science which are  of  the
highest importance for us to know, are no  less  remarkable  for
simplicity, than for the wide extent of their application; and
that when fully unfolded, they will be  self-evident propositions.
It is true enough, that the  most  familiar phenomena of nature,
when viewed separately, or through the mystical interpretation
of  visionary theorists,  are as  "inscrutable as the scattered
leaves of  the  Sibyl;"  but when traced  to their origin,  the
hidden  meaning of  everything is  gradually  disclosed, and
order springs  from  chaos.  It was  profoundly observed  by
 Sir Edward Bulwer, that " the key to all mystery is the desire 
PREFACE TO THE FIRST EDITION.
xi
to know,"—and that "there is only a single step from a truism
to a great discovery."
  If we are destined  ever to arrive at  a perfect theory of
nature, it must be founded on  a true history of the Grand
Original,  and a  complete knowledge of the Prime  Mover.
Nor is it possible that men should avail themselves fully of the
powers which are in nature, without knowing the cause of these
powers.   It was from the elastic force of the  latent caloric
that belongs to nitre, sulphur and charcoal, that man, uncon-
sciously, obtained the  power of gunpowder; the invention of
which has essentially  modified  the condition of  the  human
race; for it thenceforward secured the uninterrupted progress
of civilization,  which can never  again be arrested  by the in-
cursions of barbarous  hordes, nor the light of knowledge be
extinguished in embryo,  as during the early periods of his-
tory.  It was by discovering that a piece of metal called the
loadstone, when horizontally balanced on a pivot, is constantly
directed to certain points in the polar regions, that commerce
and civilization have been extended to the remotest  parts of
the earth.  But men have yet to learn that the same principle
which directs  the compass-needle to the poles,  guides the
planets in their orbits, and fills them with life.
  It was by seizing the  grand  lever of  nature as a moving
agent, that man was enabled to create the steam engine, which
has  brought about a more important revolution in the condi-
tion of nations, than all the united discoveries of antiquity for
thousands of years.  Nor can there be a reasonable doubt that
a complete knowledge of  the same agent, as it operates  in all
the phenomena of nature, would augment the resources of hap-
piness an hundredfold, dispel the clouds of error which have so 
Xll
PREFACE TO THE FIRST EDITION.
 long hovered over the sciences, and enlarge the empire of man
 over the material world  in an  endless variety of ways.   It is
 animating to think how soon this grand result might be brought
 about, if all the talents  now wasted  on fruitless speculations
 were rightly employed in the study of nature.
   It may be right to inform the reader that  a brief outline of
 the leading views contained in the following  chapters was first
 promulgated by the author  in an essay entitled  "A New
 Theory of  Terrestrial Magnetism,"  published at  New York
 in 1833; and  somewhat  extended in  a series of papers in the
 Knickerbocker Magazine of 1834-5.  The  author  also feels
 it due to himself, and to those friends who have been long ex-
 pecting this work, to  state,  that the first three  books were
 originally intended to be published separately, and were actu-
 ally printed in 1837, the Preliminary Chapter excepted.  But
 as more enlarged views of the subject  opened  to him, he
 clearly perceived that a development of the physiological and
pathological laws of caloric was essential to the completion of
his undertaking; which at that time  he supposed would not
require more than twelve months:—

         "But more advanced, beheld, with  strange surprise,
          New distant scenes of endless science rise."

  The performance of this  task required  a vastly greater
amount of laborious research than he  was prepared to expect,
until he  had proceeded  too far to desist.  In the mean time
he had  the  satisfaction of perceiving that,  with  every addi-
tional knowledge of facts, he was conducted to a more elevated
point of view, and to more comprehensive generalizations; the
 consequence of which has been, that in the Preliminary Chap- 
             PREFACE TO THE FIRST EDITION.          xiii

ter, he has entered more fully into the rationale of geological
and  astronomical  phenomena, than he had ventured to do in
the Second and Third Books.
   In addition to the many difficulties encountered  at every
step, much precious time was lost owing to ill health, by which
the work has been still further and most  painfully delayed, to
the disappointment of the publisher, whose liberality and for-
bearance merit the grateful acknowledgments of the author. 
 
DR.   METCALFE'S   LIFE.
  Samuel L. Metcalfe was born near Winchester, Virginia, on the
21st of September, 1798.  His mother's maiden name was Sittler.
  When  he was quite young, his  parents removed to a farm  in Simp-
sonville, Shelby County, Kentucky.   There, amid the wild beauties  of
nature, he grew up healthy in  body and mind.   At a very early age he
was fond of reading, and made  rapid advances in every branch  of study.
He also,  as quite  a  young boy, exhibited a great taste  for mechanics,
and in his leisure hours amused himself by constructing boats  and toys
for the children.
  It was the intention of his father that he should become a farmer; but
the son had higher aspirations.
  The boy with rosy cheeks and athletic limbs had grown into a thought-
ful youth, who had  gazed on,  and examined with awe, the wonders  of
nature, and longed for that  knowledge  that would explain  to him the
mysteries that surrounded him.  Yet how was  he to obtain the means
necessary for study ?
  At the age of sixteen he was skilled in sacred music, and while pur-
suing his studies in Shelbyville, gave lessons once  a week in singing.
About this  time  he wrote a volume of sacred music.   The thought
occurred to him, that he would  publish this work in some large city, and
that  the profits of  its sale should be appropriated to defray the  expenses
of a  collegiate education.
  He sought his father, and told him of  his plans.  The  father listened
to the enthusiastic youth, but shook his head, saying :—" I cannot con- 
XVI
dr. metcalfe's life.
 sent to so wild a scheme."  A few days after, his father called  him.
 "I have been thinking," said he, "of your request.  I see your heart is
 set upon this journey.   Go, my boy, and may God prosper you."   He
 started for Cincinnati, and there met with a publisher who sympathized
 with the young man, and undertook to bring out the work at his  own
 risk;  and afterwards gave him a sufficient sum to enter College.
   In 1819 he matriculated  in the Transylvania University, Lexington,
 Kentucky; and in 1823 received his diploma as Doctor of Medicine.  In
 the same year he commenced  practice in  New Albany, Indiana.   He
 afterwards removed  to  Mississippi, where  he married, but became a
 widower about four years thereafter.
   For  some  time  his mind had been pondering on the great  subject
 which in after years so completely engrossed his  attention, and  in 1831
 he visited England, in order to procure certain rare and valuable books,
 which he wished to consult in the prosecution of his experiments.   Un-
 fortunately, this valuable library was destroyed by fire during his second
 visit to England.  After his return home, he made a geological tour
 through East Tennessee, North Carolina and Virginia.
   In 1833 he brought out  his work on " Terrestrial Magnetism," which
 was published in New York, and dedicated to  Joseph Delafield, Esq.
 Before this time, he had written and published a brief work  on the
 Indian wars of the West.
   He remained in New York until 1835, occasionally writing articles for
 the Knickerbocker, under the signature of M.  But the small volume he
 had written on "Terrestrial Magnetism" only spurred him on to do more.
 His mind had caught fire on the subject  of Caloric, and he burned with
 desire again to visit  the great British metropolis, there to consult the
vast libraries, and work out his theory.
  In 1835 he again crossed the Atlantic, and took up his abode in Lon-
don.  Those who knew  him there  will  remember  how he worked  on
courageously, unremittingly, for days, months, years, in succession.  His
health was delicate, his means were small, but he felt that his  election
was sure.

  In a letter dated 1838, he says :—
   "Were it not that the prize of my high calling is sure, I should have 
dr. metcalfe's  life.                 xvii
 sunk beneath the protracted labor of thought which my work demanded.
 'Sorrow may endure for a night, but joy cometh in the morning.' "

   Again:—
   "Be not surprised nor discouraged should you find my work attacked
 or abused.   It is impossible it should escape censure, subversive as it is
 of a thousand errors that are interwoven with the interests and reputa-
 tion of men.  But 'truth is mighty, and will prevail.'"
   In 1841 he writes to his brother:—
   "You must not be surprised at the time which I have employed on the
 present work.  Having long since passed the Rubicon, it would be mad-
 ness now for me to think of  anything less  than an absolute conquest of
 the  centre and  capitol of the sciences.  But it is only a small band of
 intellectual heroes, whose minds have been kindled with fire  from  the
 altar of genius, that are capable of understanding the real merit of such
 a conquest!"
   In this trying period of his labours, he was sustained by the sympathy
 of a few kind friends in London.   Their letters to  him (which on his
 death were found among  his papers) prove how much he was beloved.
   In 1843, Dr. Metcalfe's work on  " Caloric" was completed and pub-
 lished by Pickering, London.

   The  following extract is  from  a letter written from  London by  the
 Doctor to his brother in Kentucky:—
   " I have fought the  good fight, I have finished my course,  and  per-
 formed the work which Providence appointed for me to do.  Whatever
 its fate may be, I have already secured a place among the benefactors of
 the human race—a reputation that will go on  increasing  long after I
 shall have ceased to live.
   " Had  I remained at home, I should now, in all probability, be rich,
 and  in an influential position.  But in exchange for those honours, I
 have the gratification to know, that I have added to the stock of know-
ledge ;  and that I shall leave behind me an undying name!"

  On the 25th of April, 1845, he sailed from London in the ship  Brontes,
and arrived in New York on the tenth of June.  His health was much
                                * 
xviii
DR. METCALFE'S  LIFE.
 benefited by the sea voyage.  And now all that he had anticipated was
 realized; he was at home once more; his book was  finished;  friendly
 congratulations greeted him on every side.
  In 1846, Dr. Metcalfe was married to an English lady, with whom he
 became acquainted in London.  In the same year he made arrangements
 with a firm in Philadelphia to re-publish his book; notes which he made
 on the margin of the  London copy are incorporated with the text in the
 present edition; and now the publishers were ready, and the scientific
 world expecting it. But that earnest desire to perfect his work, peculiar
to creative genius, detained him from year to year.  In the mean time his
 health became delicate, and in the spring of 1856 he took cold, and his
 lungs became affected.  As the summer advanced he appeared to revive,
 and expressed a wish to go to the sea-side,  and in July was taken to
 Cape May.   It was his last journey upon earth.  In two weeks from that
time he was buried in the country church-yard on Cape  Island.  He
left a widow and one child, a daughter between eight and  nine years
of age.
                                                         E. M. 
NOTICES  OF  THE   FIRST   EDITION.
  The following extracts are taken from some of the reviews on the
work alluded to in the preceding sketch of Dr. Metcalfe's life:—

    From the London Medical Gazette, May, 1844, pp. 229 and 408.
  " It bears the unquestionable stamp of genius, and carries with it, at
the same time, evidence of learning various and extensive, and of such
laborious research, as can only be successfully achieved by minds of the
noblest order in pursuit of sacred truth."
  " It is a work, the like of which only comes from the press at rare and
distant intervals—a work, indeed, of sublime scope, and, rightly taken,
of the noblest tendency."
  "It is  the spontaneous effusion of a gifted mind, brimful of know-
ledge, and tinctured itself with the hallowed fire of poetry."

  From the New York Journal of Medicine, September, 1845, p. 208.
  "The author appears to us to possess a fine philosophical genius.  His
doctrines and views are so bold and original, so comprehensive in their.
scope, so clearly set  forth, and so supported by facts and reasoning, that
they cannot fail to command the attention of the reader."

     From the New York Journal of Medicine, July, 1846, p. 75.
  " The work resembles the beautiful system of nature which it is desig-
nated to illustrate.   The longer  we examine it, the more beauties do we
find in it.  The author, we believe, is fairly entitled  to the credit of
being the first philosopher who has  discovered a key whereby to unlock
all her secret cabinets of wisdom and wealth." 
XX
NOTICES  OF THE  FIRST  EDITION.
From the Western Journal of Medicine and Surgery, July, 1846, p. 49.
   " If the Doctor succeed in establishing the correctness of hkOheory,
(and we do not oracularly assert that he will not,) he will be one of the
most illustrious benefactors of physical science—if not himself the most
illustrious—that time has produced.   His success, should he achieve it,
will be the solution  of the gordian  knot, to  effect  which many of the
master-geniuses of every  enlightened  era and country have laboured in
vain.  And whether he  succeed  completely or not, he will, by virtue
of what he has already done, occupy a place  among the most eminent
writers of the age."

                  From the same, October 3, p. 19.
   "When estimated as an aggregate, by the value in detail of its inherent
qualities, and by the peculiar nature of certain incidental circumstances
which unite with those qualities  in giving character to it, this cannot fail
to be regarded, by competent judges, as one of the most extraordinary
productions of the kind that has issued from the British press during the
nineteenth century.  Had we said, that has issued from any press during
any century, whose history makes a part of recorded knowledge, it would
not be easy to fasten on us the charge of either  error  or extravagance.
We, at least,  are compelled to think so, after a very careful examination
of the subject.   As an inquiry, we remember no instance in which  the
work  before us has been surpassed on  sundry points in depth and so-
lidity; and we challenge  refutation, when we add, that, in the compass
and grandeur of its outline, it cannot be surpassed."

        From the North American Review, July, 1857, p. 40.
   "We have prefixed to this paper the titles of two essays, published
within the last few years,  and also of a ponderous volume which saw the
light  before either of them, and has  been, or seems  to have been, less
read  than either.  Mr.  Grove's essay has excited  great attention  in
England, and received the honours of translation into the French  lan-
guage.  Dr. Carpenter's  paper, published in the Philosophical Trans-
actions, extended the generalization  of  Mr. Grove into the  domain of
physiology.   Both are brief, and are therefore read. 
NOTICES  OF  THE  FIRST EDITION.
XXI
  "Dr. Metcalfe forgot the motto which he must have often seen quoted
from D'Alembert: 'The author kills himself in spinning out what the
reader kills himself in cutting short.'  Consequently, his book has been
shelved, in spite of its originality and learning.
  " But we must do our countryman the justice to say, that, if there is
anything in the physical theory of vital  actions which has found advo-
cates in  Mr. Newport  and Dr. Carpenter, and which Professor Draper
has  so forcibly illustrated, Dr. Metcalfe has anticipated them  all, in
maintaining that caloric 'is alone, of every form of being, quick or dead,
the active principle,' the same doctrine,  modernized, which, in another
form, was taught by Hippocrates.   And we must be  permitted to ex-
press our astonishment, that a work of such pretensions, published in
London, should be ignored by any English writer of authority, while he
is repeating and developing its leading  ideas, long since given to the
world."                                       ^
 
PUBLISHERS'  NOTICE.
  The present edition contains the emendations of the author up
to the period of his death.  It has, during its passage through the
press, been  submitted to the supervision of a competent editor,
who has revised the text so far as it could be done without essen-
tially changing the sense or language of the author.  An appendix,
also,  has been added, containing some recent facts bearing  upon
the subject-matter of the work, but which  could not have been
introduced into the text without taking what might be considered
an unwarrantable  liberty.
t 
CONTENTS   OF  YOL.  I.
                          BOOK  I.
                   PRELIMINARY  CHAPTER.
                                                         PAGES
A Srxopsis of the Work.........................................................   17-61
                         CHAPTER II.
On the Atomic Constitution of Matter, and the relative Quantities
  of Caloric in different Bodies...............................................  62-116

                         CHAPTER III.
On the Forces of Caloric in Elastic Fluids.—Theory of their Expan-
  sion and Contraction.—Constitution of Liquids.......................  117-154

                          BOOK  II.
                        CHAPTER  I.
Theory of Cohesion, Conduction and Radiation...........................  155-184
                         CHAPTER II.
Chemical Attraction in general................................................
                         CHAPTER III.
Theory of Solution, and of Freezing Mixtures...........................  209-234
                         CHAPTER IV.
Theory of Capillary Attraction, and the connection of Molecular
  with Aggregate Forces of Matter..........................................  235-259 
XXIV
CONTENTS  OF  VOL. I.
                            BOOK III.
                          CHAPTER  I.
                                                               PAGES
 Electricity—Atmospheric, identical with the Caloric which causes
   Evaporation.....................................................................  260-298
                            CHAPTER II.
 Theory of Winds, and their connection with Electrical Phenomena.
   —Rationale of Tornados, Hail-storms, &c..............................  299-322
                           CHAPTER III.
 The Barometer.—Theory of Dew, Mists, Fogs, and  of the Aurora
   Borealis...........................................................................  323-343
                           CHAPTER IV.
 Theory of  Voltaic Electricity, and of  Subterranean or Volcanic
   Forces............................................................................ 344-385

                            CHAPTER V.
 Hypothesis of two Electric Fluids examined.—Relations of Caloric
   and Electricity.......  ......................................................... 386-414

                            BOOK  IY.

                          CHAPTER   I.
 Life—History of  Ancient and Modern Opinions concerning it....... 415-461
                           CHAPTER II.
 Ultimate Elements of Organized Bodies.—Why they unite into Ter-
   nary and Quaternary Compounds, so as to form Living Tissues.__
   Spontaneous Generation.—Theory of Animal Heat, as connected
   with Respiration............................................................ 462-507

                          CHAPTER  III.
 Influence of Respiration on  the Temperature and Vital Energy of
  different Animals.—Cause of the Heart's Action, and of the Ca-
  pillary Circulation,.........................................................  508-599

                          CHAPTER IV.
Theory of Digestion, Sanguification, Coagulation, Secretion, Nutri-
  tion,  Muscular  Motion, Sensation, and of Disease.__Analogies of
  the Macrocosm and Microcosm...................................         5°0-6SO 
CALORIC.
                   BOOK  I.

       PRELIMINARY  CHAPTER,

  " Oh that those who have both time and intellect at command
adequate to the investigation, might, in perfect tranquillity, search
into nature, until they ascertain what quantities of heat are required
to produce every action of matter; that mankind  might then not
only become masters of every kind of knowledge, but of every kind
of power."—Telesius.

  That the reader  may perceive at once the  general
scope and object of the present work,  I shall com-
mence with a brief outline of the leading facts, which
connect the various operations of nature with the fun-
damental laws of caloric.   But as men of science  are
still undecided whether caloric be a material agent, or
the mere effect of motion among the particles of pon-
derable matter, it becomes necessary to  examine  the
evidence on which these opposite views have been
founded.
  Among the most enlightened nations  of antiquity,
elementary Fire was regarded not  only as a most re-
                         2 
18
VIEWS OF THE ANCIENTS.
 fined and spiritual essence of all the elements, but as
 an universal and self-active principle, which they con-
 sidered as identical with existence or being.   It has
 been amply proved by Bryant, Calmet,  and  other
 learned  etymologists,  that the  Greek ezc, and the
 Latin esse, to be, like our words essence and essential,
 were derived from the  Hebrew u'N Esh or Es, the
 fire; and that Vesta, the goddess of that element, had
 her  name  from the Chaldee Knj^K EsJtta or  Esta.
 They have also shown that the word DN Am denoted
 both heat and existence, among the early Egyptians;
 who, believing it to be the cause of motion and organi-
 zation  throughout nature, inscribed it on the  great
 door of one of their temples.
   We are further informed by the learned  and philo-
 sophical Parkhurst, that the sacred mystical letters  lq
 Ie, which were inscribed over the door of the temple
 at Delphi, dedicated to  Apollo, (who was a mythologi-
 cal personation of the  sun or solar fire,) were taken
 from the Hebrew IT Yeh or Yah, signifying existence
 or being,  Nor  is it  unworthy of  notice,  that the
 Greek zoo fire, was derived from  the Hebrew niS pur,
 to break, dissolve, and separate; actions which clearly
imply mechanical and material agency.  So much for
the primitive meaning  of words  employed by the an-
cients to  represent the essential nature of what  is
called heat, but  which I shall generally denominate
caloric,  for  the purpose  of distinguishing the  cause
from the  mere  sensation of  heat.   Let us now ex-
 amine the views which have  been entertained by the
 moderns on this important subject.
   In the  Novum Orgamnn, and in  his Treatise en- 
OPINIONS OF BACON AND  DAVY.
19
titled De Forma Calidi, it  was maintained by Lord
Bacon,  (whose opinion  has been adopted by many
philosophers since  his  day,) that the very essence of
heat is motion, and nothing  else.   In accordance with
this doctrine, Sir H. Davy  observes, in  his Chemical
Philosophy, that "the cause of heat  is motion, and
the laws of its communication are precisely the same
as the laws of the communication of motion."  But in
the Treatise on Life and Death, as also in his Natural
History,  Bacon maintains that " there  is,  in every
tangible body, a spirit  or  body pneumatical, which
fills the pores of all gross bodies:—that it is not some
virtue, or action, or trifle, but  a real and  quantitative
substance, though rare, invisible, and without weight."
Moreover, that this  spirit  or  body pneumatical was
only another name for  what Hippocrates  and other
Greek authors called depfxov heat, is equally manifest
from the fact, that  Bacon represents it as the cause of
evaporation, and of many other effects which are pre-
dicable  of caloric alone. And Sir  Humphrey Davy
observes,  in his Agricidtural Chemistry, that "what-
ever theory we adopt, it is  certain that there is matter
moving  in the space between  us and tlie heavenly bodies,
capable  of communicating heat."   It is therefore evi-
dent, that neither of these  distinguished men can be
fairly ranked as advocates of the immaterial theory;
and that, in reality, they  had  no fixed  or  settled
opinions on the subject.
   The authority of Sir  Isaac Newton has been often
cited in support of the  doctrine  that  caloric is not a
material substance.  But it  is worthy of special notice,
that in  the  latest works of that great man on physical 
20
HYPOTHESIS OF NEWTON.
science, he maintains  the existence of what he calls
"an exceedingly subtile and elastic ethereal substance,
which  is diffused through all places, fills the pores of
gross bodies,  and  forms  a large constituent of their
bulk or volume."   In a  letter addressed to the cele-
brated  Boyle, in 1678, the object of which was to ex-
plain his views of the ether, he  represents it as "the
cause of cohesion, capillary attraction, and of tjie force
by  which  menstruums  pervade  and  dissolve  solid
bodies."  He  adds in another sentence, "I conceive
the atmosphere to be composed of  the particles of all
sorts of bodies  of which  the earth consists, separated
and kept at a distance from one another by the same
active principle*  But if the  ether be the cause of
solution, and of the  elastic force  of the atmosphere,
  * The above views were still further expanded in a scholium at
the close of the second edition of the Principia, published in Vl13;
and in the form of queries, they were reiterated at the close of the
Optics, published in 17H.  In both of these great works, he repre-
sents the ether as the cause of gravity, cohesion, capillary attrac-
tion, solution, elasticity, the emission,  reflection,  refraction,  and
inflection of light.  He also maintained  that the ether is the cause
of animal motion.   Yet he  observes, that he  knows not what the
ether is; and that "we have not that  sufficiency of experiments
which are  requisite to an accurate determination of the laws by
which this subtile spirit operates."  But if Newton had traced the
word ether to its primitive roots,  the discovery of its real meaning
might have modified all his physical investigations, and have given
a totally new aspect to the whole  circle of the Sciences. The truth
is, that a complete Etymological Dictionary would  sweep away
innumerable  misconceptions, errors, and metaphysical subtleties
which have gradually arisen from the revolutions in language, and
the adoption of words  the primitive meaning  of which has not
been understood. 
CALORIC A  MATERIAL  AGENT.
21
it is manifestly identical with caloric.   It is true that
in the  fifth query, toward  the close  of the  Optics,
Newton represents heat as consisting in a vibratory
motion  among the particles of bodies,—and that the
whole theory of the Principia was founded on  the
hypothesis that space is a vacuum; which is certainly
at variance with the foregoing views of the ether.  It
is  also  inconsistent with his doctrine of light, which
he regarded as a  material substance, perpetually flow-
ing from the sun and fixed stars through space.  But
that caloric does not consist in mere motion or vibra-
tion among the particles of ponderable  matter, would
appear from the following considerations:—
  1. That it  may be added to and subtracted from
other bodies,  and measured  with mathematical pre-
cision, as all good thermometers demonstrate:—
  2. That it  augments  the volume of bodies, which
are again reduced in size by its abstraction:—
  3. That it  passes  by radiation through  the most
perfect vacuum that can be  formed by means of the
air-pump, in which it produces  the  same effects on
the thermometer as in the atmosphere :—
  4. That it  exerts mechanical  and  chemical forces
which nothing can restrain,  as in volcanos, the ex-
plosion  of gunpowder  and  other  fulminating com-
pounds :—
  5. That it  operates in a  sensible  manner on  the
nervous  system,  producing  intense pain, and disor-
ganization of the tissues  when in excess:—*
  * The same reasoning on which is founded all belief in the ma-
terial existence of the outward universe applies equally to caloric. 
99
CALORIC A MATERIAL AGENT.
    6.  That  it  modifies the  forms,  properties, and  con-
 ditions  of all other bodies, in  an endless variety of
 ways.*

 No metaphysical sophistry can refute the belief of mankind, that
 whatever operates in a sensible manner upon material organs, must
 be a real  substance; for the obvious reason, that "there can be no
 virtue without substance," as maintained by Newton.   I cannot,
 however,  agree  with  Epicurus,  that nothing exists but  what is
 visible or tangible, since the ultimate atoms of the grossest matter,
 in their separate state, can neither be seen nor touched, owing to
 their extreme minuteness, and yet have a real existence.   It is ob-
 served by an able writer in the Church of England Review, that
 our words thing,  and think, were  derived from  the  Greek  verb
 diyy-ev, to touch; that,is, a thing is what we first touch, and  then
 think upon.  Yet we may think upon the ultimate atoms of matter,
 which  cannot be recognized by any of the  senses until united into
 aggregates.   He adds, that all impressions  on  the senses are re-
 solvable into touch. But there is nothing in nature which operates
 so powerfully on the sense  of  touch as caloric.

          "When Bishop Berkely said there was no matter,
          And proved it—'twas no matter what he said."

 And when men say that caloric is not a substance,  they reject the
 evidence of their  senses, subvert the  foundation of  all  knowledge,
 and pave  the way to  universal skepticism.  Yet I cannot wholly
 agree with Aristotle when  he  says, that those who deny the reality
 of an  external  world, deserve to be chastised rather than confuted.
   * It was first ascertained by Dr. Black, that on mixing a pound
 of water at 112° F. with a pound of  ice  or snow at 32°, the latter
 was melted,  when the temperature of the  mixture  stood  at  32° •
 showing that 140° of caloric had been transferred  to the ice,  and
intimately combined  with  its particles.   Since  then it has  been
found,  as predicted by Black,  that definite  measures of caloric are
required to  convert all other solids  into the liquid and  gaseous
states:—that when a pound  of steam at  212°, is mixed  with 7
pounds of ice at 32°, the latter is converted into water of the same 
OBJECTIONS ANSWERED.
23
   But if caloric were a mere property or quality, how
could  it be taken from one  body  and added  to an-
other?   Or if it augment the volume of other bodies,
must it not itself  have  volume,  occupy space, and
therefore  be a  material  agent?"'   Would it  not  be
mere jargon to  speak of the radiation, reflection, con-
vection, and  conduction of a mere quality, or  imma-
terial  property?  And if caloric were only the effect
of vibratory motion among the particles of ponderable
matter, how could it radiate from  hot bodies without
the simultaneous transition of the vibrating particles?
But it is  certain  that when  iron,  copper, and other
metals are heated to any temperature below the point
of ignition, like boiling water they give  off  caloric
freely, without any sensible loss of ponderable matter.
   It has  been  said, that  "the material theory con-
tains an inherent vice, by assuming the  existence of
a body, which  has  never been  obtained in the sepa-

temperature; showing that 7 X 140, or 980°, are thus transferred
from the steam to the ice, and employed in melting it, without pro-
ducing in it any elevation of temperature.  This is what Black
called the latent heat of water and steam.  It has also been dis-
covered, that a cubic inch of water at 212°, is  expanded to the
dimensions of a cubic foot, or about 1720-fold on passing  into the
gaseous state,—proving that 1719 parts by volume of steam at the
same temperature, are occupied by the  caloric which surrounds its
particles.  The  same fact is still more remarkably illustrated in
hydrogen gas, the volume of which is nine times greater than that
of the same weight of steam, cseteris paribus: so that above 15,000
parts of the space  occupied  by hydrogen  must be filled  by that
subtile form  of matter called heat.
  * We are not however to suppose,  that "extension is the only
essential property of matter," as maintained by Descartes. 
24              OBJECTIONS ANSWERED.
rate form."   But if caloric do not exist in a separate
state while  passing  through a vacuum, all our reason-
ings about it are fallacious and unintelligible.   Nor is
it  possible  to  explain, in a simple and  satisfactory
manner, any single  one of the phenomena ascribed to
it  by all parties,  in accordance with the hypothesis
that it  is identical  with motion, which is manifestly
not  an  agent,  but  merely some  body in the  act of
moving, and always implies the existence of a mover.
The most effectual  method of giving a death-blow to
the vibratory theory of heat, would  be to  show how
soon it  breaks down when applied to the explanation
of facts.
   If this theory were  true, caloric ought to be gene-
rated by all impulses which throw the particles of
bodies into  a state of violent agitation.  But such is
not the  fact;  for if the atmosphere, the ocean, and
the solid strata of the earth, were kept in  a state of
perpetual tremor,  their temperature  would  not  be
materially altered.  The advocates of the immaterial
theory have never  explained what  causes  bodies to
vibrate; nor what keeps the particles of solids, liquids,
and gases, at a distance from each  other while qui-
escent,  or free  from  vibratory  motion*  And  it is
  * It was supposed by Bacon, that the essential nature of heat is
motion, and nothing else,  because it accompanies the motion  of
friction, percussion, combustion, ebullition, violent exercise  &c.
Count Rumford was led to adopt the same opinion from the fol-
lowing experiments: Into a cannon  weighing  113 lbs. and cast
solid, he caused a hole  to be bored 3 7 inches in diameter and 7-2
inches in depth.  Into  this hole he introduced a blunt steel borer
that was made to rub  against the bottom  by horse power, with a 
OBJECTIONS ANSWERED.               25
worthy of special notice, that caloric is disengaged by
pressure, friction, or percussion, only so  long  as bodies
undergo condensation.   For, it has been  proved by the
experiments of Berthollet, Biot, and Pictet, that when
pieces of gold, silver, and copper, of the same size and
shape,  are suddenly  and  forcibly struck,  as when
stamped  in the  process of coining, they were  con-
densed,  and  caloric  evolved, but  more by  the  first
than second blow;  whereas after the third blow, when
they had arrived at  the limit of condensation, there
was  no perceptible increase of temperature.  In the
experiments of Berthollet on copper, the first stroke
raised the temperature 17*3° F., the  second  7*5°, and
force equal to about 10,000 lbs. avoird., the cylinder being turned
at the rate of thirty-two times per minute.   At the expiration of
thirty minutes, when  the cylinder had made 960 revolutions about
its axis, its temperature was found to have risen from 60° to 130° F.
In another experiment, the cylinder was wrapped round with flannel
to prevent the loss of heat, and inclosed in a wooden box contain-
ing 18-77 lbs. of water, which at the beginning was at the tempera-
ture of 60°.   After the experiment had proceeded for an hour, it
was raised to 107°,—in thirty  minutes more, to  142°,—in  two
hours, to 178°,—and  in two hours and a half, to 210°.  At the
close of the experiment, he found that 4145 grains of metallic dust
and scales had been  detached from the bottom of the cylinder by
the rubbing of the borer, or above eight ounces.  And as he found
that the capacity, or  what has been called the specific heat of the
scales, was the same as that of  an equal weight of solid iron, he
arrived at the conclusion, that heat is not a material substance, but
the mere effect of motion. {Philosophical Transactions, 1798.)  But
it will be shown hereafter, that what is  called capacity or specific
heat, is not a measure of the quantity in different  bodies;  and that
this mode of estimating  their latent or combined caloric is fal-
lacious. 
26
OBJECTIONS ANSWERED.
the  third only  1"9°.   [Thomson on  Heat  and  Elec-
tricity, p. 339.)
   In accordance with  these facts,  it is well  known
that the  smith often kindles his furnace by hammer-
ing a piece of iron until it becomes  red  hot; and that
after he  has reduced it to the limit  of condensation, it
becomes cold under the hammer.  I have also found, that
less  heat is  evolved by the  friction  of bodies  in pro-
portion to their hardness,  as when two pieces of rock-
crystal  are rubbed together.  It is  therefore evident,
that caloric is not  generated  de novo, by the  friction
of rubbing dry sticks of wood against each other, the
pressure of wire  drawing, and by rubbing the hands
together;  but that it is merely forced out of the  pores
of bodies, in the same  way  that water  is  disengaged
from the pores of a  sponge by pressure.   And it will
be proved hereafter, that the caloric  which is disen-
gaged by rubbing the hands  together briskly, is resup-
plied by the rapidly circulating blood, which  obtains
it by respiration.*
  * Had Count Rumford been aware of the enormous amount of
caloric which is locked up in a state of combination with all bodies,
even when reduced to the lowest temperature that can be produced,
he would not have maintained that heat is merely the  effect of
motion, because destitute of gravity,  and because of the large
amount of heat evolved by the friction of boring a cannon.  In
fact, Rumford himself  states, that if all the heat which is required
to convert a pound of  ice or snow into the liquid state, were com-
municated to  an  equal weight of gold, the latter would be raised
from 32° F. to the temperature of 2800°; the capacity  of water
for  heat being 20  times greater  than that of gold.  Thus  the
amount of caloric required  to convert snow into  water without
any elevation  of temperature, is 140°, which, when multiplied by 
ALL  BODIES FULL OF CALORIC.
27
   That the particles of  all  bodies are surrounded by
an elastic medium, which prevents their  actual  con-
tact, is evident from their compressibility.   And  that
this medium is caloric  is proved by the facts  already
stated, that it augments  the volume of solids, liquids,
and  gases, which are  again  reduced  to their, former
dimensions by abstracting what was before added; and
by the large  amount of heat that is disengaged by
friction, which is transitive pressure, or by percussion,
 20, gives 2800°; while it is probable, that between 32° and the
 absolute zero of ice, or any other solid body, there is a still greater
 amount of combined heat, had we the power of disengaging it from
 them.  In the experiments of Berthollet, the first stroke on a piece
 of copper coin raised its temperature 17'3°  F., the second blow
 7*5°, and the third only 1-9°.  It is therefore not surprising that
 when a blunt steel borer  was made  to rub against the bottom of a
 hole made in a cannon weighing 113  lbs., and  cast solid, with a
 horse-power equal to 10,000 lbs., the  temperature of the cylinder
 was raised from  60°  to  130°, after it had made 960 revolutions
 about its axis, at the rate of 32 revolutions per minute.  Such ex-
 periments prove  only that caloric  is  disengaged from metals by
 forcing their particles nearer together, since  the effect is not pro-
 duced after they have been brought to the limit of condensation by
 percussion and pressure.
  Among the various and contradictory opinions of Sir Humphrey
 Davy in regard to the nature of heat, he says,  that " Caloric or the
 matter of heat does not exist;" that "it consists in  a vibratory or
 undulatory motion of the particles of bodies round their  axes,
 or in a motion of particles round  each other."  But it is impos-
 sible to reconcile these views with  the experiments of Berthollet;
 Biot, and Pictet, or with  the well-known fact,  (which Davy himself
 admits,) that when "a piece of iron is made red hot by hammering,
it cannot be strongly heated a second time by the same means, unless
previously introduced into a fire."  {Chemical Philosophy, p. 95.) 
28            ALL BODIES FULL OF CALORIC.
which is sudden pressure;  both of which cause con-
densation.   It was estimated by  Sir  Isaac Newton,
that the pores of gold occupy about the same space as
its solid atoms;  and that in water, the  pores are about
forty times  greater than its solid particles.   (Optics,
Book ii. p. 242.)   If  then it be true,  that all bodies
are full of caloric;  that  it occupies 827 parts by vol-
ume of the  atmosphere, and 1719 parts of steam, it
must be obvious that  it constitutes by far the greater
proportion by bulk,  of  the solid globe we inhabit.
And  if when intimately combined with the particles
of ponderable matter, its thermal properties  are dis-
guised or  hidden  from the senses, the same thing  is
true of water and the strong acids, the individual pro-
perties of which are concealed while they are in a state
of chemical union with rocks, salts, &c*
  * The above facts will enable us, in some measure, to compre-
hend the theory of opacity and transparency, the cause of which,
Sir John  Herschel thinks, has never yet been satisfactorily ex-
plained.  For as it is well ascertained  that the particles of the
atmosphere, steam, gases, water, saline and metallic solutions, like
glass,  and  a great variety of  crystalline solids, are arranged in
regular series, at considerable distances from one another, the rays
of light pass through them with slight  interruption, giving rise to
the phenomena of transmission and what is called transparency.
But when the regular arrangement of the  particles of ice, glass,
quartz, and other crystals, is disturbed by unequal pressure, or un-
equal  expansion by caloric, the rays of light  are transmitted im-
perfectly:  and if their symmetrical structure be broken down or
deranged,  as  when they are reduced to powder,  their  power of
transmitting light is  so  far destroyed, that they are  rendered
opaque.  Sir Isaac ^Newton supposed that opacity was owing to
the largeness, and  transparency to the smallness, of the particles
and intervening pores of bodies.  {Optics, B.  ii.  p. 235.)   But 
               GENERAL LAWS OF CALORIC.            29

   Having thus proved that caloric is a material agent,
I now proceed to point out its connection with the laws
of motion, and the widely extended influence it exerts
in all the operations of nature.  The cardinal facts which
connect its agency with the general theory of physics,
may be reduced to the following propositions:—
   1. That the activity or moving power of all bodies is
directly in proportion to  the amount of caloric  around
their particles:—
   2. That all molecular motions,  wliether centrifugal or
centripetal, may  be resolved into the law  by which caloric
repels its own particles, and attracts those of ponderable
matter, with forces  that vary Inversely as the squares of
the distance:—
   3. That the quantity of molecular motion in the world,
whether mechanical, chemical,  or vital, is in proportion
to the mean temperature  of different latitudes,  cseteris
paribus, and diminishes from the equator to the poles:—
   4. That the centrifugal force by which planets are im-
pelled through their orbits, is directly in proportion to the
heating power of the sun, and inversely as the squares of
the distance:—
   5. That caloric is the active principle in light, whether
radiated from the  sun, or generated by ordinary com-
bustion,  friction, percussion, phosphorescence, or the elec-
tric  discharge:—
   6. That every variety of electricity is convertible into
caloric, and the latter again into electricity ; consequently,

many salts, rocks, and metals,  are transparent  when  dissolved in
water and the strong acids, although their particles are much larger
than those of common ink and  many other bodies which are black
and opaque. 
30        CALORIC A  SELF-ACTIVE PRINCIPLE.

that they are modifications of one and the same princi-
ple :—
   7.  That the directive power of the compass-needle di-
minishes from the isothermal equator  to the points of
lowest mean temperature, which are the magnetic poles;
and that all its variations correspond with the variations
of terrestrial -temperature:—
   8.  That the aggregate vltcd energy of animals, and
the development of their organization, are exactly in pro-
portion to the amount  of caloric obtained by respiration,
and combined with their tissues.
   That caloric is a self-active principle, might  natu-
rally be inferred  from the fact, that every change in
the  temperature  of bodies is attended with  motion
among their particles.  It has also the power of mov-
ing from one place to another, and even through the
vacuum  of an air-pump, without any projectile im-
pulse from the particles of ponderable matter; as when
it radiates from hot  bodies.   And that it has the fa-
culty of generating motion among the particles of other
matter, would appear from all the phenomena of na-
ture with which we are best acquainted.
   For example,  under the ordinary  pressure of the
atmosphere, and  at, or a little below the temperature
of 32°, the particles  of water exist in the solid and
apparently fixed  state.    But if 140° of caloric  be
added, their mobility is so far increased that they glide
freely over one another, and assume the  liquid  form.
If more be added, their  activity is still  further aug-
mented by every degree of temperature up to the boil-
ing  point, when the whole is found to be in a  state of
rapid intestine motion. And if at this stage of the ex- 
ATTRACTION AND REPULSION.
31
periment, the water be kept over a furnace until it has
received about 1000° more of caloric, the boiling liquid
is converted into steam, the moving force of which is
exalted  by  every addition  of this active principle,
which has  the power of converting all  other bodies
from solids into liquids, vapours, gases,  and flame, or
incandescent particles.
   Since then it is a fact, that caloric alone gives to the
quiescent  particles  of  ponderable matter powers  of
motion which they do not possess without it, and that
their mobility  is augmented by every  addition, but
diminished by  every abstraction of the  igneous  prin-
ciple—it  follows with  all the clearness  of  absolute
demonstration,  that  in the total absence of caloric, if
such a condition were possible, the universal system
of nature would be a motionless  mass of inert and
chaotic matter.   It  also  follows,  that  everything  in
nature is composed of two descriptions of matter, the
one  essentially active, and the other passive; as main-
tained by the most distinguished sages of antiquity.
   Since the time of  Sir Isaac  Newton, attraction and
repulsion have been generally regarded  as ultimate
principles  of action, for which  no  reason can be as-
signed/11  But if it be a fact, that  the elastic force of
  * After referring to his theory of planetary motion, Newton
observes in his Preface to the Principia—"Many things induce me
to suspect, that all the rest of the phenomena of nature may depend
upon certain forces, by which the particles of bodies, by some
causes hitherto unknown, are mutually impelled toward each other
in regular figures,  or are repelled and recede from one another;
which forces being  unknown, philosophers have hitherto attempted
the investigation of nature in vain."   Sir H. Davy also observes,
that "the various forms of matter, and the changes of these forms, 
g2         ATTRIBUTES OF A PRIMARY CAUSE.

bodies is augmented by every addition, and diminished
by every abstraction  of caloric, it is obvious that the
entire privation of it would destroy the repulsive power
of their particles.   And as we have seen, that without
caloric, they could have no power of  motion, it is evi-
dent that  they could neither approximate nor recede
from  one another; consequently, that both attraction
and repulsion are modified  effects of one and the same
agent.   Moreover, if it can be proved that this agent
is everywhere present—in the  pores of bodies, as  in
the stellary spaces—and cannot be traced to any more
comprehensive  principle—it  must be allowed to pos-
sess  all the attributes of  a  primary physical cause.
For, nothing can merit the title of a vera causa, unless
it be  something which has the power of moving itself,
and of generating motion in other bodies.
  It  is  equally evident, that whatever  the cause  of
attraction and repulsion may be, it must determine all
the phenomena of cohesion, chemical affinity,  crystal-
lization, elasticity,* decomposition, and recombination.

depend upon active powers, such as gravitation, cohesion, calorific
repulsion or heat, chemical attraction, and electrical attraction."
{Chemical Philosophy, p. 67.)   Dr. Arnott further states, that
"attraction  and repulsion are ultimate facts, which  admit of no
explanation in the present state of science." {Elements of Physics.)
And Sir John Herschel adds, that " we have no means of further
analyzing the phenomena of cohesion  and elasticity, but must
regard them, until we see  reasons to the contrary, as ultimate phe-
nomena, referable to the direct agency of an attractive and repul-
sive force."  {Introduction to the  Study of Nat. Philosophy, 8 80.)
  * If the particles of the atmosphere and other bodies were not
surrounded by caloric, there could be no vibrations, (in which heat
has been supposed to consist,) therefore no sound.  And here it is 
          AGENCY OF  CALORIC IN METEOROLOGY.       33

When I come to treat  of the mode in which caloric
produces opposite effects, it will be found that in cer-
tain proportions it causes the particles of ponderable
matter to separate, while in other proportions it forces
them to unite:—that the aggregate force of attraction
by which it tends  to unite with the particles of gross
matter, holds them together, and  maintains the  earth
in the globular form:—in short, that all the phenomena
of  nature may be  referred to the law by which caloric
repels its own particles, and  attracts those  of ponder-
able matter.
   That the quantity of evaporation and rain throughout
the earth is In proportion to the heating poiver of the
sun, caferls paribus, would seem to be a self-evident
proposition.   And it will  be shown  hereafter, from
numerous scientific observations, that the annual ave-
rage amount of rain within the tropics, except in desert
places, is about three times greater than in the middle

worthy of notice, that  the velocity with which sound is propagated
through different media, is directly in proportion to their elasticity,
cseteris paribus.  For example, it travels through the atmosphere
when at the temperature of 32°,  at the rate of 1090 feet per
second;  but when at 62°, it travels 1125  feet per second, or 1275
miles per hour.   It also moves at the rate of 3375 feet per second
through hydrogen gas, which  contains a much larger amount of
caloric around its particles than the same weight of atmospheric
air, or any other gas, as  will be shown hereafter.  In accordance
with the above  facts, it is well known  that sound is  transmitted
more distinctly, and rapidly, through  light and resinous,  or the
more combustible species  of wood, than through such  as are dense,
less elastic, and therefore contain less of the elastic ether termed
caloric.  It also moves with greater velocity through water than
glass, and  more swiftly  through either than  through rocks  and
metals,  if we make allowance for the greater density of the latter.
                            3 
34
EVAPORATION  AND  RAIN.
latitudes;  and  about six  times  greater than  in the
polar regions.  Hence the enormous size of the tropical
rivers, compared  with  those  of the higher  latitudes.
For  example,  it  has been found  that the  Orinoco,
which drains only 400,000 square  miles of  territory,
discharges more water into  the sea than the  Missis-
sippi, which drains  1,350,000 square miles.*

  * By a reference to the  mean annual depth of rain that has been
observed to fall in different  parts of the world, something like an
adequate idea  may be formed  of the stupendous aggregate force
exerted by caloric in the silent process of evaporation.   Owing to
the existing distribution of land  and sea, mountains and  deserts,
the amount varies  greatly  in the  same latitudes.  For example, a
large  proportion of the  area south of the United States,  between
lat. 10° and 30° N.,  consists of  water; whereas  nearly the whole
space from N. lat. 36° to  the equator, is occupied by the continent
of Africa, which lies to the south and southwest  of Europe.   The
consequence of which is, that while the annual fall of rain at Bos-
ton, Xew York, Philadelphia, and Ohio, is from  36 to 39 inches,
and still  more  in  the States farther south, it does not exceed 32
inches in the British  Islands.  And, as it diminishes from the sea
to the interior of continents, the  annual average is about 25 inches
in western France, 22 in eastern  France,  20 in central  Germany,
and 17 in Hungary.  Moreover, as a great part of the aqueous
vapour brought by the south and southwest winds from the ocean,
is prevented from  passing over the temperate latitudes of Europe
and Asia, by the Apennines, the Alps, the  Himalayas, and  other
mountains, precipitation is far more copious south than north of
those immense  barriers.   It has  been found that the annual fall of
rain at the southern  base of the Apennines is 64 inches, but only
26 inches at the northern  base, and 55 inches at  the southern base
of the Alps, but 35 at the  northern.  On the southwest and north-
east sides of the Ghauts, in southern India, the difference is much
greater;  as it is also on the western and eastern sides of the Scan-
dinavian Mountains.
  It has been calculated that the mean annual fall of rain in the 
THEORY OF WINDS.                 35
   If the temperature of the whole earth were reduced
to zero, there could be no fluidity of the ocean, which
would  be  stationary  as the  solid frame-work of the
mountains.  Were it not for the heating power of the
sun, there could be no contractions and  expansions of
the atmosphere,  therefore no winds, nor  fluctuations
of the barometer.   But in the present order of things,
not an atom of the great aerial  ocean is wholly quies-
cent for a single moment of time.  Its tropical portions
tropical zone of America is 115 inches, but only 79 inches in the
same zone of Asia and Africa;  while in the temperate  zone of
North America the estimate has been 39  inches;  and in the same
zone of Europe 34 inches, which is  considerably more than what
has been found in central Asia.   But from  all  the observations
hitherto collated, the average cannot be far from 72 inches through-
out the torrid zone, which embraces an area of 79,169,410 square
miles.  It therefore follows by calculation, that the annual  rains of
the tropics would fill a basin of 89,965-2  square miles in area, and
1760 yards, or one mile, in depth.   Nor can the average be far
from 36 inches in the temperate  zones, which embrace an area of
103,353,140 square miles.  This again, if collected together, would
fill a basin one mile in depth, and 58,723-4 square miles  in area.
In the polar  regions, which embrace an area of 16,421,200  square
miles, the  mean annual amount of rain  may be estimated  at 12
inches,  which if collected into one  mass would fill a lake 3110
square  miles in extent,  and one  mile in depth.   By adding the
above products together, it will be found  that the whole amount of
water that annually falls upon our planet,  would fill a basin  151,723
square  miles  in extent, and one mile in depth.   Lastly, if we divide
this aggregate by  the number of days in  the year, it will be found
that the quantity of water daily converted into vapour, wafted from
the ocean through the atmosphere, and precipitated in the form of
rain, snow, and hail, would make a  lake of one mile in depth and
415 in  area.
   The  proportion of  sea to that of the land, is as 3 20 to  1-00. 
36
FORCES OF CALORIC.
 being constantly expanded  by the influence of a ver-
 tical sun, rise and give place to the denser air of colder
 latitudes;  by which a perpetual circulation is kept up,
 as described in the 1st chapter of Ecclesiastes, v. 0:
 " The wind goeth toward the south, and turneth about
 unto the north: it whirleth about continually, and re-
 turneth again according to its circuits."
   If the earth were of uniform  surface and elevation,
 there would be a gradual diminution  of  temperature
 from the equator to the poles, and the winds would be
 as regular as the movements of the heavenly bodies.
 But owing to the present distribution of land and sea,
 mountains and valleys, plains and woods, the tempe-
 rature of the globe is infinitely diversified, even in the
 same latitudes;  by which the phenomena  are rendered
 proportionally complex.  And as the changes of wea-
ther depend chiefly on the direction  of  winds,  they
 cannot be predicted with  invariable accuracy, without
knowing all the circumstances which modify the tem-
perature of  different  and distant places.  It is  not
 therefore surprising that meteorology has  never been
reduced to the certainty of an exact science.
  Were it possible to compute the aggregate forces of
 caloric in all the mechanical, chemical, and vital trans-
 formations, which are for the most part  unobserved,
 we should  be astonished at the result* But men are

  * It is in the torrid zone that nature  exults in the  plenitude of
her powers in modifying the surface of the earth,—where the forces
of the volcano, the earthquake, and of universal chemistry, are sur-
passed only by those which wheel the planets through their orbits
For example, we are informed by Captain Burnes, that during the
Cutch earthquake of 1819, the Delta of the Indus was  elevated 
VOLCANIC  FORCES.
37
 so  accustomed to the  regular course  of nature, that
 they  are less aroused by the  grandeur of  the sun,
 rising in pomp and might, filling the world with beau-
 tiful creations, and diffusing everywhere the spirit of
 gladness, than by a passing meteor of the night.
   That the whole theory of geological dynamics is in
 some way immediately connected  with  the agency of
 caloric, is now  generally  admitted by philosophers.
 But the  general fact to  which I would  here  invite
 attention is, that the number of volcanos and the forces
 they exert are in proportion to the heating poioer of the
 sun*  For example, among the 270 volcanos now in
 action in different parts of the earth, above 180  are
 confined to the tropical regions.  In the island of Java
 alone, with a surface of 25,000 square  miles, there  are

 about ten feet, over an area of fifty miles in length, and sixteen in
 breadth, in some places.  We also learn from Mr. Lyell's excellent
 work on Geology, that during the shocks of 1822 in South Ame-
 rica, the coast of Chili was raised about four feet, over an area of
 100,000 square miles.  And it  is well known  that  similar move-
 ments are constantly taking place in different parts of the earth, or
 beneath the ocean.
  *  In every point of view, a complete theory of volcanos is of
 fundamental importance: for they regulate the  distribution of land
 and sea, the magnitude and elevation of continents, the diversities
 of temperature in given latitudes, the character of rivers,  and
 modify the direction of winds, which are impeded or deflected by
 mountain ranges.   They are also the great terrestrial laboratories
 in which most of the precious gems are formed,—in  which carbon
 is liquefied, and  by slowly  cooling  under an  immense pressure,
 assumes the crystalline form of that beautiful  ornament, the dia-
 mond, which has been aptly designated as "a lump of light."  Nor
 is it unworthy of notice, that all  the richest gems and metals have
 been found in greatest abundance in the tropical mountains, or among
the materials washed down from them by rains,  rivers, and springs. 
38        RELATIVE HEIGHTS OF THE EARTH.
 43, according to Vander Boom Meseh.  (De Incend'ds
 Mijitilum, Leyden,  1826.)   And there is  nearly the
 same number  in other tropical portions  of the old
 world.  Between latitudes 10° and 15°, in the Pro-
 vinces of Guatimala and Nicaragua in South Ame-
 rica, there are 21;  in Peru, between latitudes 14° and
 20°, there are 16;  while in the tropical islands, and
 around the shores of the Pacific ocean, there are about
 80.  (See Johnstons Physical Atlas.)
   Again; that the subterranean forces by which the
 dry land has been  elevated from beneath  the ocean,
 have in all past ages been in proportion to the heat-
 ing power of the sun, would appear from the relative
 heights of the earth in different latitudes.  Nearly the
 whole of tropical America, for 3000 miles  in length,
 and several  hundred in width, is one great system of
 mountains, separated by plains, which, within the
 tropics, are from  9500 to 12,800 feet above  the sea.
 In lat. l-j° N., Sorato and Illimani tower to elevations
 of 25,400, and 24,350 feet, according to the measure-
 ments of General Pentland.  As we proceed north-
 ward toward Mexico, the loftiest peaks are  those of
 Chuquibamba, Gualatieri, Sahama, Cotopaxi, Sierra,
 ;;n^f/  and  others' Which var^  from  19,000 to
 Z-,000  feet, until  we arrive at the  table-lands of
 Mexico, which, between latitudes 19° and 24° N are
 from 6000 to 8000 feet above the sea.
  As we  advance  through the middle latitudes of
 ^nt /T™; ^ *°ck^ Mountains average  about
 10,000 feet.   And if we except St.. Elias and Mount
Hooker, they rarely exceed 12,000 feet.   Nor do the
table-lands which slope from their base exceed  from 
           RELATIVE HEIGHTS  OF  MOUNTAINS.        39

3000 to 5000:  while it is well known that from lati-
tude 60°, the elevations diminish on to the polar sea.
On the other  side of the equator, the highest moun-
tains  of Chili  are  the  Aconcagua  and  Descabezado,
which, between latitude 32-28°  and 35°  S. rise to ele-
vations of  23,200, and  21,100 feet; from which they
all diminish on to Patagonia,  and thence to  Cape
Horn.*
   If we turn to the old  world, we shall find that there
is not a single mountain chain of the first magnitude
throughout the middle latitudes of  Asia, Europe, New
Holland, nor the islands of the sea:—that the highest
plains of India are from 11,000 to 14,000 feet, while
the Himalayas  rise to  elevations of from  23,000  to
28,000 feet, between the latitudes of 24° and 32° N.:
—that the long chains of the  Altai, which extend
across Europe and Asia, in about the latitude of 50°,
are generally  from 6000 to  8000,  and rarely exceed
15,000 feet:—that the  mountains  of western Europe
also diminish in height  from  the Alps, the Apennines,
and the Pyrenees of the south, to the Carpathians, the
Dofrines, and Urals of the north, which rarely exceed
6000 feet:—that the vast plateaux  of central Asia, be-
tween the Altai and the Thian-shan mountains, in lat.
45° N., are from 3000 to 5000 feet  above the level of
the sea;  while the plains of  Siberia decline gradually
on to the polar ocean:—that in Greenland and Spitz-
bergen the average height of the mountains is  about
5000 feet;  while Hecla  in Iceland is only 4980 feet.
  * It is said that  Captain C. Ross has  recently  discovered in
S. lat. 78° a-mountain 12,400 feet high.   But a few such excep-
tions are too  slight to invalidate the general law. 
40   RELATIVE  HEIGHTS OF MOUNTAINS AND PLAINS.
     If the  mountains of Africa are  less elevated than
  those of southern Asia and tropical America, they are
  far more numerous; while two-thirds of the continent
  south of Sahara seem to be an  enormous pile of ele-
  vated table-lands.   Extending  from  the equator  to
  34° S. and 37J° N. its central plateaux are supported
  by an immense chain  that crosses the continent from
  west to east; between which and  its  southern ex-
  tremity, there  are  three other  parallel  ranges  that
  diminish in  height  on to the Cape of Good Hope.
  The vast plains of Abyssinia and  Nubia are also about
  7000 feet above the ocean, and supported by innume-
  rable mountains of still greater magnitude than those
  of Atlas  in the west:  while the eastern coast is flanked
  by a chain which extends, with few interruptions, from
 north latitude 10° to 32° S.   But it is evident  that
 the elevation  and extent of table-lands, (which are in
 fact widely extended mountains,) afford  a  far more
 accurate  measure of geological forces, than the hei-ht
 of a few  isolated peaks.*
   From the foregoing brief outline we  perceive, that
 nearly all  the highest mountains of the earth  are
 found within  32° of the equator:  and, what is  still
 more important to observe,-^ the average elevation
  * According to Humboldt the mean Estimated height of Eurone
 is 650 feet,  of K  America 750 feet, of  S. America fl 0 e!t  and
 of Asia1150 feet  That of Africa has not been ascertained  no
 ^relative exten  of mountains and plateaux in the different
 But M. Guyot tells us, that those of North  and South America
 embi-ace one-third of its surface;  those  of Africa two-third,  Ind
the  high lands of Asia five-sevenths of  its area;  the elevat d
region between the Himalava and Altai ran^e, vJ-   L™
 long, and 1500 miles broad.'             ** bem* 2400 miIes 
OBSERVATIONS OF SCHROETER.
41
 of the table-lands is about equal to that of tlie mountains
 in the middle latitudes, where, again, the table-lands are
 of nearly the same height as that of the polar mountains.
 The conclusion is therefore irresistible, that the aggre-
 gate force by which mountains, Islands, and  continents
 have been raised, from beneath the ocean, like all the
 chemical  transformations on  the surface of our planet,
 is in proportion to the heating power of the sun, casteris
 paribus.
   And that  the  same law prevails  throughout  the
 planetary system, would  appear not  only from  ana-
 logy, but from a series of  telescopic observations  con-
 tinued for ten years on the surface of Venus, by the
 celebrated Schroeter, who has estimated the height of
 its principal mountains as  varying from 10*84 to 22*05
 miles.  So that after  making due  allowance for the
 uncertainty of such observations, it is probable  that
 he has arrived at an approximation to the truth.   For,
 as Venus is 1*40 times nearer to the sun  than the
 earth, and as the heating power of the  sun is  inversely
 as the squares  of  the distance, Venus  must receive
 more caloric  than a given area of the  earth, in the
 ratio of 1*96, or nearly as 2 to 1, because the square
 of 1*40 is 1*96.   Nor is it  unworthy of notice, that as
 the heating power of the sun is 6"959 times greater at
 Mercury than on the earth, which is 2*638 times far-
 ther from the sun,  the mountains  of Mercury have
 been estimated  at  10*75 miles in  height, and  about
 eight times  higher than those of the earth, compared
 with the magnitude of the two planets.  And as Mars
is 1*494 times farther from the sun than the earth, he
must receive 2*232 times less caloric; which must pro- 
42
PLANETARY INCLINATIONS.
 portionally modify all the conditions  of his  surface.
 In like manner, as Jupiter is 5*157 times farther from
 the sun than the earth, he must receive 26*594 times
 less caloric.   And so on to the extremity of the solar
 system.
   But in  estimating the changes  which  the  surface
 of our planet has undergone  during long geological
 epochs, we must not overlook  the influence of varia-
 tions in the inclination of the earth's axis, in modify-
 ing the mean temperature of different latitudes.  It is
 generally supposed to have been demonstrated theo-
 retically by  Laplace, that the total  variation of the
 planetary inclinations must be comprised within  the
 narrow limits of 3°.  But that, in so vast and compli-
 cated  a problem as  that of perturbation, geometers
 may  have overlooked  some important elements  in
 their calculations, would seem highly probable from
 the limited period  since which accurate observations
 have  been made;  for they admit that the disturbing
 influence of all  the  planets and their satellites upon
 each other is such, that millions of years are required
 to bring about one cycle.
   But if it were wholly impossible to determine the
 exact amount of variation in the planetary inclina-
 tions, during  the countless ages that have past oo-
 logy affords the most conclusive  evidence, that at some
 remote period  of the earth's existence, the  inclination
 of its axis must have been far less than at present- or
 that the equator and poles must have been reversed
 For it has been  discovered that the secondary forma-
tions at Melville Island, and other parts of the polar
regions, are filled with the fossil remains of plants and 
         RELATIONS OF GEOLOGY TO ASTRONOMY.      43

animals  which  could have been produced only in  a
warm climate.   Nor is it possible, that in the present
inclined  state of the earth's axis, tropical plants could
ever have existed in these  high latitudes, for the plain
reason that for several months in the year they are
deprived of solar light and warmth, which  are essen-
tial to vegetation.
   That  this inclination  is now actually diminishing
at the rate of one minute in 126* years, is admitted
by all astronomers.  It therefore  follows,  that if it
should go on decreasing in the same ratio, without
any  oscillations or retrogradations,  it would wholly
vanish in about 177,760 years, when there would be
perpetual spring* throughout the middle latitudes, or
what may be termed a vernal period of the great year.
For although there would be perpetual summer at the
equator,  and a  gradual diminution of temperature on
to the highest  latitudes, there would be no winter.
In short, the days  and  nights  would be everywhere
of the same length, except  immediately  around  the
poles, which would be always  illuminated, and there
would  be no variety of seasons, but an unceasing ver-
dure would everywhere prevail.  That the earth may

  * In  the tenth book of the sublimest song in our language,
Milton represents  the earth  as enjoying  this happy  exemption
from winter, before the fall of man: after which, the Creator
                      "Bid his angels turn askance
          The poles of earth twice ten degrees and more:
          *   *  *   *   *   to bring in change
          Of seasons to each clime;  else had the spring
          Perpetual smiled on earth with verdant flowers.
          These changes in ihe heavens, though slow, produced
          Like change on sea and land." 
44       RELATIONS  OF GEOLOGY TO  ASTRONOMY.
 have frequently passed through such a state, is highly
 probable  from the  fact, that at the present  moment
 the axis of Jupiter has very little if any inclination.
 And  that this  inclination  has an  extensive range of
 variation, would further appear from the fact, that in
 the case of Saturn  it is now 28° 40', while  in that of
 Mars it is 30°  18', according to Sir  John  Herschel.
 There is therefore no obvious reason why the inclina-
 tion of the earth's axis should not go on augmenting
 until it arrives at the same angle.*
   But are w^e not further authorized to conclude, that
 the equator may have gradually shifted to the middle
 and even  the polar latitudes?   This hypothesis would
 enable us to explain the high and uniform temperature
 which prevailed throughout the northern hemisphere when
 the higher latitudes  abounded with tropical plants and
 animals,—a great physical fact which cannot be satis-
 factorily accounted  for in accordance with the theory

  * In reality, it is  more  in accordance with analogy to suppose
 that this variation  may pass through an entire revolution, than
 that it is confined within the narrow limits of 2° or 3°.  Should
 such a revolution go on uniformly at the rate of 48" in a century,
 its completion would require a period of 2,700,000 years,—unless
 interrupted by a conjunction of all the planets; an event which the
 ancients regarded with dread, as the cause of deluges, or some other
 signal catastrophe.  We are informed by Mr. Samuel Davis, that,
 according to the Surya Siddhdnta, the oldest Hindoo work on
 Astronomy,  the obliquity of the  ecliptic was  24°, when it was
 written; which must therefore have been 4000 years before the
 19th century.  {Asiatic  Researches, vol. ii.)   From  the rate at
 which this obliquity has diminished since the  time of Tycho Brache
 Sir  John  Herschel has adopted 48 seconds as the  average in a
century; or 1 minute in 126£ years. 
       FUNDAMENTAL LAWS OF PLANETARY  MOTION.     45

of Laplace.   The truth  is, that his mathematical rea-
sonings were founded on the supposition  that all the
planets move in nearly the  same  plane; whereas it is
now admitted by astronomers, that the  orbit of Pallas
is inclined to the ecliptic at an angle of  34i°, and that
of two satellites of Uranus at an angle of 78° 58'. But
these cosmical bodies  had not been discovered when
this Systeme du Monde was written;  nor had.Geology
then taken its legitimate rank among the Sciences.
   This brings us to the general theory of planetary
motion.   The leading facts of the solar system which
connect  the movements of the heavenly bodies with
the agency and laws of caloric, may be reduced to the
following propositions:—
   1. That the sun  revolves on his axis from west  to
east, in about twenty-five days.
   2. That  planets  revolve  around the sun, satellites
around planets, and all  of  them  upon  their  axes,  in
the same direction  that  the  sun moves  upon his axis.
   3. That the heating power of the sun diminishes  in
proportion as the squares of the distance increase.*

  * For example, as Mercury is 1*888  times nearer to the sun
than Venus, he receives more caloric than Venus, in the ratio of
3-564 to one ; because the square of 1-888 is 3*564.  And as Mer-
cury is 2-638 times nearer to  the sun than the  earth, he receives
6*959 times more caloric, or the  square  of 2638.   For the same
reason, as Mercury is 3-944 times nearer to the sun than Mars, the
latter receives 15-555 times less caloric;  Ceres 25*157 times less;
Jupiter, 185*259 times  less on a given  area; Saturn 625 times
less;  and Uranus 2500 times less.   Or, if we take  our own  planet
as the standard of measure, the heating power of the sun is 2*232
times greater at the earth than at Mars, because he is 1*494 times
farther from the sun; 7*3^1 times  greater than  at Ceres; 26*594 
46
OPPOSITE FORCES OF  CALORIC.
    4.  That the centrifugal force by which  planets  and
 their satellites are impelled  through their orbits dimi-
 nishes in proportion as the squares of the distance from
 the centres of power increase.
    5.  That the centripetal force by which planets are
 impelled toward  the sun, and satellites  toward their
 primaries, diminishes in the  same ratio.
   6.  That by the joint operation of two forces, each
 of which varies inversely as the  squares of  the  dis-
 tance, the celestial  bodies are  impelled through  their
 orbits with velocities  which  vary in  accordance with
 Kepler's third law,  as shown in the following  tables:

                         TABLE I.
                  Mean distance    Periodic times.  Velocities   Diarn-
                  from the sun.     d. h.  m.  s.  per hour.    eters.
 Mercury...................  36,000,000     88  0  0  0  107 100    3 200
 Aen"s......................  68,000,000    224  7  0  0   7!) "27    7*800
 ^irth......................  95,000,000    365  6  0  0   68,093    7'qi"
 *l!irs....................... 142,000,000    687  0  0  0   54,113    4'l89
 Ceres....................... 260,000,000   1681 8  0  0   40 484
 Juflter..................... 41JO,00(.,000   4332 14  0  0   29^08    87(ib'6
 •:a,urn..................... 900,000,000   l07.-,n 5  0  0   21 899    79 000
 \j.™a\..........*;.........1800,000,000   30686 20  0  0   15 356    Ss'oOO
 Dist. of moon from |      no_ ^^                    '         ' "
  the earth............f      23,,000     27 7 43 11     2,271    2,160

 times than at Jupiter ; 89*737 times than at Saturn ; and 358*988
 times greater than  at Uranus.   But as the planets are impelled
 through their orbits by two equal and opposite forces that always
 counteract each other, the velocities do not diminish at the same
 rate as their mean  distances  from  the sun :  for while  Jupiter is
 5-157 times farther from the sun  than  the earth, his velocity is only
 about 2 30 times less.  In  like manner, although Saturn is nearly
 91 times farther from  the sun than the earth, his velocity is only
about three times less  ; and so of all  the other planets, as may be
readily  ascertained by comparing the times  and distances in  the
following Tables, constructed from data furnished by Sir J  Her
schel.  {Treatise on  Astronomy.) 
OPPOSITE FORCES OF  CALORIC.
47
     TABLE II.

SATELLITES OF JUPITER.
                       Mean dist.
First Satellite...................  263,111
Second............................  418,620
Third..............................  667,725
Fourth............................1,174,413
Periodic times.
  d.  h.  m.  Velocities. Diameters.
16
16
13
 3
16
28
14
43
32
38,929
30,860
24,433
18,423
2508
2068
3377
2890
                          TABLE  III.
                     SATELLITES OF SATURN.
                                    Periodic times.
                      Mean dist.     d.   ft.    m.     ' Velocities.
First Satellite..................  132,364      0   22    38        36,750
Second..........................  169.850      1    8    53        32,503
Third............................  208.718      1   21    18        28,949
Fourth...........................  269,350      2   17    45        25,739
Fifth.............................  376,198      4   12    25        21,802
Sixth.............................  872,199     15   22    41        14,320
Seventh.........................2,542,180     79    7    55        8,389-5


   Twelve of the asteroids,*  and the satellites of Ura-

nus, have been omitted, because their  elements have

not yet been fully ascertained.    The third  column in
  *  The discovery of Astua, Hebe,  Iris and  Flora,  Metis and
Diana, Parthenope, Victoria,  and others discovered since  1845,
has augmented the number of the asteroids to fifty-two.
  We are informed by Aristotle, Theophrastus,  Diogenes Lantius,
Cicero, and  Plutarch, that the sun was recognized as the centre of
our system by Pythagoras, who has been supposed by some authors
to have derived  this discovery from the Egyptians.  But as  the
helisantric theory was unknown to Eratosthenes, Possiclonius, and
Ptolemy, (who were the most  celebrated astronomers in Greece,)
as it was to the ancient Hindus, Chinese,  and Hebrews, there is
much reason to doubt  whether it was understood by any of the
ancients except the admirable  Pythagoras, and a small number of
his disciples,  who had  not sufficient  influence to overcome  the
deeply rooted  prejudice of the schools.   It is possible, however,
that Pythagoras may have obtained  a glimpse of this  sublime
theory from some unknown Egyptian Copernicus. 
48             DISCOVERIES OF KEPLER.
 the tables was obtained by multiplying the distances
 by 2; which  gives  the diameter of the  orbits.  On
 multiplying this by 3*1416, and  dividing  the product
 by the periodic times, we get the velocities with a suf-
 ficiently near  approximation  to the truth for our pre-
 sent purpose.
   After the establishment of the true solar system by
 Copernicus,  the  invention of the telescope, and the
 discovery of Jupiter's satellites  by Galileo,  the most
 important advance ever made in  Astronomy was that
 of the immortal Kepler, announced in a work entitled
 "HarmonIce Miu/di," published in  1619.  In that work,
 he demonstrated that " the squares of the periodic times
 of any two planets are to each other, in the same propor-
 tion as the cubes of their  mean  distances  from the sun,"
 —a law which has been found equally true of satel-
 lites and their primaries,—if we except the mutual
 influence they exert upon each other, termed pertur-
 bation.   It  also  led to  the  important discovery of
 Newton, that every particle of matter in  the universe
 attracts every other, according  to the law of the inverse
 square of the distance;—a law which, independent of
 all  hypotheses in regard to the cause of motion, was
 one of the finest generalizations ever made in the sci-
 ence of Nature.*

  * In a letter to Dr. Halley, Sir Isaac Newton himself states,
 that the law of the inverse square of the distance was deduced from
Kepler's theorems.  But it was Galileo  who  first demonstrated,
that in the descent of falling bodies, the spaces  described are as
the squares of the times.  And Sir William Hamilton observes,
 "that the Newtonian theory of astronomy was but  a final gene-
ralization  prepared  by foreign observations, and even  already
enounced." {Ed. Phil. Journal, vol. xxxv. p. 71.) 
NEWTON'S first  law of motion.
49
  In  regard to what is called  Newton's first lav of
motion, various and- opposite opinions  have been en-
tertained.  But whether true or not, it was propounded
by Galileo, long before the time of Newton.   Accord-
ing to this law, as announced in the first book of the
Principia,  "every body perseveres in  its state of rest
or of motion, unless  compelled to change  that  state
by forces impressed thereon."  On this law was founded
his theory of planetary motion, as developed in the
third book, in  which he maintains, that when first
created, the earth and heavenly bodies were projected
into  empty space, by the agency of a primitive im-
pulse, communicated at various distances from  their
centres of gravity; by which their annual and diurnal
revolutions have been ever  since maintained, without
any renewal of the cause.*
  But in all the operations of nature with which we
are best acquainted, force is always expended in pro-
ducing motion; and if not as constantly renewed, is very
soon exhausted.  Nor have we the slightest proof, that
motion is ever generated without the immediate agency
of some active principle.   The power of steam is cre-
ated  by the immediate  agency of caloric, and  ceases
whenever  the active principle  is withdrawn.  The
force with  which a  horse-shoe  magnet of soft iron
holds on to the armature, is generated  by the passage
of an electric  current  through  the wires  which are
coiled around it; but ceases the moment the current
is arrested.  The metallic wire that connects the ex-
  * Newton  observes:  " That the motions of the planets may
subsist an exceeding long time,  it is necessary that the heavens
should be void of all resisting matter."
                         4 
50
views of herschel  and  whewell.
tremities of a voltaic battery, attracts iron filings, and
deflects a magnetic needle in its vicinity, so long as the
electric fluid  is disengaged by chemical action,  but
ceases whenever that action is at an end.  The powers
of digestion, secretion, nutrition, and muscular motion,
are  generated  by  means of an active principle which
obtained  from  the atmosphere   by respiration;  but
cease whenever that important function is  arrested;
as will be shown in subsequent parts of this  work *

  *  In  accordance with the  above views, it is observed  by Sir
John Herschel that, "to say matter has inertia,  is  only to say that
the cause is expended  in producing its  effect, and that the same
cause cannot continue  to produce its effect without  renewal." (Nat.
Philosophy, sect.  234.) And it was humorously argued  by the
author of Knickerbocker, that "as the projectile force  has  long
since ceased to operate, while its antagonist remains in undiminished
potency, the world ought, in  strict propriety, to tumble into the
sun." Nor is this  merely conjecture ; it is now mathematically cer-
tain, that if the centrifugal  force were suspended,  the earth would
reach the sun in about 64£ days, and Mercury in about 15^ days.
Mr. Whewell also observes, in  his Bridgewater Treatise on Astro-
nomy, that "to say motion must continue the same from one instant
to another, because there is nothing to stop it, seems to be taking
refuge in words."  But there is no one force in nature which is not
counteracted by another force.  It is therefore evident that New-
ton's first law of motion does  not apply, as he originally intended,
to the planetary revolutions.  Mr. Whewell is  equally explicit in
renouncing the vacuum of  space: for when treating of the lumi-
niferous ether, he says, "it must not be merely like a material fluid
poured into the vacant spaces  of the material world;  it must affect
the physical, chemical, and vital properties of whatever it touches,
and be the means of communication between planets and systems.''
(Book i. ch. xvii., and book ii. ch. xi.) Yet he observes, in another
chapter, that "in  the  machinery of the universe there  is, so far as
we kuow, no material connection between the parts which act  on
each other." (Book ii. ch. i.) 
ERRORS OF NEWTON.
51
  But if it be true that caloric is perpetually radiated
from the sun and fixed stars into the boundless regions
of space, it must constitute an infinite ocean of ethe-
real essence; consequently, there can be no such thing
as  a  vacuum,  which, as  Aristotle rightly observed,
would destroy all motion.   Nor is  it less obvious, that
if caloric be  a self-active principle, and is everywhere
present, there can be no such condition of matter as
vis inertlop, which literally means the power of not
acting.  And that a single impulse is not competent
to maintain the  unceasing  motion of planets and satel-
lites, is evident from Newton's  own hypothesis, that
they  are impelled or  drawn with an equal force at
right angles  to the direction of the original projection.
Moreover, when Newton referred the centrifugal force
to  the immediate agency of the  Deity,  and that of
gravity to an inherent property of matter, he departed
from that uniformity of nature and of causation, on
which  all true  science is  founded.  To be consistent,
he ought to have referred all physical power to the
immediate agency of  the Deity,  or to the inherent
properties of matter.  Besides, if  a single impulse be
capable of producing the centrifugal force, why should
 not a like impulse be the  cause  of gravity?
    That the  illustrious author of the Principia was not
 ultimately satisfied with the data  on which his theory
 of planetary motion was  founded,  viz. the projectile
 impidse, the  vacuum of space, and the vis insita of mat-
 ter* is plain enough from what  has been already said

   * It might as well be said that animal motion and all the actions
 of  life are the result of a primitive impulse, as that planets are
 maintained in their orbits without the  continual agency of an im- 
52
UNSETTLED VIEWS OF NEWTON.
in the early part of this chapter, concerning his views
of the ether.   But here  again he was unfortunate in
his explanation of  the mode in which it produces the
phenomena of cohesion, capillary attraction, gravita-
tion, &c.   For he supposed that "the ether was more
rare within the bodies of the sun and planets, than in
the celestial spaces  between them; and that its density
increases  perpetually in proportion  as the distances
iucrease from them, thereby causing the  gravity of
those great bodies toward one  another, and of their
parts  toward  each  other, every body endeavouring to
go from the denser parts of the  medium  toward  the
raier."  (Optics, Queries 20, 21.)
   The failure of this hypothesis has  been already ex-
posed by  Mr.  Whewell, who justly observes,  that  the
density of all  radiant matter diminishes with  every
increase of distance from any given  centre.  And it
will be proved hereafter, that the ether is  more dense
within  the pores and around the  particles  of dense
than of light  bodies, in which it is more dense than in
free space.  On  the whole,  it is not very surprising
that Newton's views of the ether have been generally
regarded as chimerical, and insufficient to explain the
leading phenomena of nature; especially as he never
identified it with any known principle.  And when he

pelling principle.   And if we admit that each of the eleven planets
and their fourteen satellites was projected into space by a primitive
impulse, is it not remarkable that the continuous force of that im-
pulse should precisely  correspond with the heating  power of the
sun, and be just  equal to the power of gravity ?  The fact is  that
if the sun were removed from the centre of our system, the revolu-
tions of the different planets would cease, in spite of  the primitive
impulse. 
UNSETTLED VIEWS OF  NEWTON.
53
referred the centripetal forces of matter to its agency,
he  assigned no physical cause of the centrifugal force.
But if the centrifugal force  of planets be directly in
proportion  to the  radiating  power of the solar orb,
caloric must be the cause of this force; for the essen-
tial character of a vera causa is, that the effects it pro-
duces are  a measure of its intensity.*
    Nor is  it  less certain, that if the  caloric which is
perpetually radiated from the  sun be  not annihilated,
it must either accumulate in the planetary spaces, and
thus raise  their mean temperature, or it must return
to  the great fountain from which it emanates.   It also

   * Moreover, as the mean temperature of the earth has remained
the same for long periods of time,  it follows that the planets must
give off by radiation the same amount of  caloric they receive from
the sun.   This  amount must depend  on their superficial  area, and
on their distance from the sun.  It therefore becomes an important
question, how far it may operate in producing  the centrifugal force
of  their satellites, just as the radiating power  of the sun generates
the centrifugal force of the planets themselves.  At the same time
it must be observed, that the motions of the  satellites are subject
to  the  direct influence of the  sun; which,  however, is greatly
diminished by his immense distance, compared to  the nearness of
their primaries.  For, as Sir John Herschel observes, "the greatest
 part of the  sun's attraction, which is common to  both, is exerted
 in  retaining both primary and secondary in  their common orbit
 about himself, and in preventing them from parting company;  the
 small excess of force acting only as a disturbing power."   And he
 states that, according to  the calculations of Newton,  the  mean
 value of this excess, in the case of the moon's disturbance by the
 sun, does not exceed T^ of the principal force which retains the
 moon in its orbit.  (Astronomy, sect. 493.)  It must also diminish,
 relatively, as the magnitude and distance  of planets increase.  Yet
 it is sufficient to give the orbits of their satellites  the character of
 somewhat zigzag circles. 
54
CAUSE OF THE SUN'S MOTION.
follows, that if the vast ethereal tide flow perpetually
toward the sun, with the same force which it exerts in
maintaining the centrifugal power of planets, there is
no good  reason why it should not be the cause of the
centripetal force which maintains them in their orbits.
Thus it would  appear, that the projectile  and gravi-
tating forces of Sir Isaac Newton are owing to one
and  the  same  principle, which  produces  all the con-
tractions and expansions, separations and combinations
of the particles of ponderable matter; as will be proved
in the third chapter of this, and  the  whole of  the
second book.  Nor can there be a rational doubt, that
in the total absence of solar radiation, all the mechani-
cal, chemical, and vital operations of the planets would
be arrested; and that if  the instellary spaces were re-
duced to  absolute zero, there could  be  no motion of the
heavenly  bodies.
  Moreover, if  it be true that there is an  unceasing
circulation of ethereal matter throughout  the  solar
system, it will  account for the revolution of the sun
on his axis; a phenomenon which has never yet been
explained in accordance with  the Newtonian theory;
and  the  knowledge of which is of fundamental  im-
portance to a right understanding of physical astro-
nomy; as it is in the laws which regulate the actions
of the sun, that we must seek for the origin of plane-
tary  motion.  For example, it will be shown  hereafter,
that  the  tendency of caloric to unite with other bodies
is in  proportion to the quantity of matter they contain,
cmterls paribus.   Hence it is that two pounds of water
will  condense just twice as much steam as one pound;
and  that a small fire is quenched by a large quantity 
REVOLUTION  OF THE SUN  ON HIS AXIS.        55
of coal, with which the caloric unites, and thus arrests
the  process of combustion.   We  are therefore author-
ized  to infer, that the aggregate  force by which the
ether of space tends to unite with the  different bodies
of the solar system, is in proportion to  their  mass, and
inversely as the squares  of  the distance*
   If the sun were a perfect sphere, and  not surrounded
with  planets, the ether would  press with equal force
upon all  parts of his surface, and thus maintain him
in a perfectly fixed state.   But as he  is not a perfect

   * By glancing over the Tables, pp. 46-1, it will be observed that
the velocity of planets round  the sun does not depend upon their
magnitudes, but on their distance from him, and that the same law
applies to  their satellites;  which accords  with the  discovery  of
Galileo, that  the velocity with which bodies fall to the earth is the
same,  whether they be large  or  small,  dense  or light, when the
resistance of  the atmosphere  is removed.  But if  the distance of
planets from the  sun were equal,  the velocity of their satellites
would be in proportion  to the magnitude of their primaries, and
inversely as the cubes of the distance.   At the present distance of
the  earth from the sun, the moon revolves around us  at the rate
 of 2168 miles an hour, at the distance of 231,000  miles from  the
 earth.  But if the earth were at the place of Jupiter, and if the
 velocity of satellites diminish in the same ratio as that of their pri-
 maries, on receding from the  sun, the velocity  of the  moon would
 be 2*303 times slower than at present, and only 941 miles an hour.
 It must, however, be observed, that  as  the volume of Jupiter  is
 about  1300  times  that of the earth, his  first satellite, which  is
 263,111 miles from  his centre, moves at the rate  of 37,140 miles
 an hour.   And if his first satellite were only  237,000  miles from
 his  centre, (the distance of the  moon  from the earth,) it would
 move at the rate of 41,200  miles an  hour, and  faster than the
 moon, (if the earth were at the place of Jupiter,) in the  ratio  of
 nearly forty-four to one,—a difference  which must  therefore  be
 owing to the difference between the magnitude of Jupiter and that
 of the earth. 
50
DIURNAL REVOLUTION OF PLANETS.
sphere, and as the pressure of the ether upon him
from every part of the solar system is modified by all
the surrounding planets and  satellites,  it is obvious
that the centripetal force of the ether must vary on
different parts of his  surface, so as  to  give him  a
rotary motion on  his axis,—a result which may be
owing in part to certain actions going on within the
sun himself,  and on which his  radiating power de-
pends.
   The above views will also enable us to explain the
diurnal revolution  of  planets, the elliptical form of
their  orbits, the inclination of their axes, and all the
phenomena of the tides.   In the  first  place, if the
planets were perfectly round, and  not influenced by
each other, both the radiating power of the sun, and
the centripetal pressure of the ether, would be the
same  on all parts of their surface, and they could have
no rotary motion.  Nor could there  be any elongations
of their orbits, which would be  perfect  circles,  if the
centrifugal and centripetal forces by which they are
impelled were always equal and the same.  But as
none  of the  heavenly bodies  are perfectly  spherical,
the solar radiation, like the returning pressure of the
ether, must  operate with  unequal force on  different
parts of their surface, and tend to give them a rotary
motion; the rapidity of which  would seem  to be in
proportion to the difference between  their equatorial
and polar diameters.   In the case of Jupiter, this dif-
ference amounts to 6096 miles, or in the ratio of about
107 to 100.   Accordingly, he revolves upon his  axis
in 9h. 56m., at the rate of  27,400 miles an hour.  The
difference between the equatorial and polar  diameters 
DIURNAL REVOLUTION OF PLANETS.        57
of Saturn is still greater; being above 6700 miles, and
such as to give him the appearance of a parallelogram,
with the four corners rounded off deeply, but not so
much as to bring it to a spheroid, as observed by Sir
W. Herschel in 1805.  The consequence of this de-
viation from the spherical form is, that although nearly
91 times farther from the sun than the earth, his diur-
nal revolution is performed in lOh. 16m., and at the
rate of 24,000 miles  an hour.   But as  the equatorial
diameter of the earth  exceeds the polar only 24 £ miles,
according to Laplace, it requires 24 hours to  perform
its diurnal revolution, while moving round  the sun
with a velocity 2*30 times greater than that of Jupiter.
The diurnal periods of Mercury, Venus, and Mars, are
nearly the same as that of the earth;  corresponding
with the smallness of their deviation from the sphe-
rical form.  In  the  case  of Jupiter, this difference
is as 107 to 100; whereas in  the  earth, it is as 299
to 298.
   There is another circumstance which may have an
equally important  influence on the elliptical form of
the planetary orbits.  For  example, we  learn from the
telescopic  observations  of Sir William  Herschel, that
all parts of the sun are not equally luminous.  He
thinks that one-half of the  sun emits  less light and
heat than  the other;  and that if seen at a very great
 distance, it would appear  like some of  the fixed stars
that have  a periodical variation of lustre.  At times,
there may be seen on his surface spots, (one of which,
on the  29th of March,  1837,  occupied  an area of
3,780,000,000 square miles,) which are so large as to
measure 45,000 miles in  linear diameter, exhibiting 
58       PERPETUAL CIRCULATION OF  CALORIC.
the appearance of a dark, opaque, and solid ground.
It therefore follows, that although the same amount
of caloric is given off by the sun in any given time,
different quantities are  radiated from  different parts
of his surface, so as to augment and diminish, within
certain  limits,  the centrifugal force  of the planets,
causing them to approximate the sun in certain parts
of their orbits, and to recede from him in other parts,
with corresponding accelerations  and  retardations  in
their annual motions, and, perhaps, variations in their
mean annual temperature.  On the other hand, as the
centripetal pressure of the ether on each of them is
modified by the disturbing  influence  of all those be-
yond, this also tends to alter the circular form of the
orbits, and render them more or  less elliptical.   Nor
is it less obvious, that the interference of the moon
must cause  a successive diminution  of gravity  or
ethereal pressure upon the earth, so as to cause a cor-
responding elevation of  the  tides, which are still fur-
ther elevated by  the influence of  the sun when  in
conjunction with the moon.   Thus we perceive  that
as the mean temperature of planets,  (at least of the
earth,) and of the spaces  between them, is uniformly
the  same,  there  must be a perpetual circulation  of
caloric from and to the centre of  the solar system, as
from and to the planets.  We have also found that
the heating power of the sun is just equal to the cen-
trifugal force of planets, and an accurate equation of
the gravitating force; so that whatever is true of the
laws established  by Kepler  and Newton,  must  be
equally true  of the foregoing induction, which has the
additional advantage of assigning a well-known  prin- 
              HEATING POWER OF THE SUN.           59

ciple as the physical cause of the phenomena, and of
thus affording a resting-place for the mind.
   From  all the foregoing  facts  and  observations we
are  authorized to conclude, that caloric is a self-active
principle which is perpetually circulating throughout
the  universe,—from suns  to planets, and back  again
to the great  fountains  from  which it emanates;  in
short, that it is what Homer called
                        " The golden everlasting chain,
   Whose strong embrace holds heaven, and earth, and main."

   That the movements of the heavenly bodies are in
some way immediately dependent on the heating power
of the sun, appears to me almost a self-evident propo-
sition, and was so  regarded by  many of the ancient
sages*   It was also vaguely recognized by Milton,
who represents the  sun as  both eye and soul of this
great, world,—

   *  The agency of caloric in giving rotary motion to a globule of
water or other liquid, is beautifully illustrated by some recent ex-
periments of M. Boutigny.  He found that when a small quantity
of water was placed on a metallic  plate heated to the temperature
of 340° F.  and upwards, it  assumes the spheroidal state,.and re-
mains for some time poised as it were without any visible support,
at a  sensible distance above the surface of  the metal, rolling on its
axis  like a little world in space.  Now whatever the reason may
be, that the caloric radiated from a metal  heated to nearly the
point of redness does not combine with the globule and convert it
rapidly into steam, as at lower temperatures, there can be no doubt
that caloric is the cause of its rotary motion.  And if so, there is
no obvious reason why solar caloric should not be the cause of
planetary motion.  It is supposed by M. Boutigny and other che-
mists, that in such cases the caloric  of the heated metal is nearly
all reflected by the globule, instead of combining with and convert-
ing it into steam, as it does at lower temperatures. 
60
PHYSIOLOGICAL AND PATHOLOGICAL
                  " Toward which the planets
        Turn swift their various motions, or are turn'd
        By his magnetic beam, that gently warms
        The universe, and to each inward part,
        With gentle penetration, though unseen,
        Shoots invisible virtue, e'en to the deep."
                             Paradise Lost, b. iii.
But we cannot expect to comprehend fully the modus
operandi of caloric in any one class  of phenomena,
until we rise high enough to survey the whole field
of knowledge, and to perceive the intimate connection
between all its  various  branches.  It was  truly  ob-
served by  Mr. Hume, that "the  only expedient from
which we  can  hope for  success  in  our philosophical
researches, is to march up  directly to the capital or
centre of the sciences, which being once mastered, we
may everywhere else hope for an easy victory."
   When I come  to treat  of the physiological and
pathological laws  of caloric, it will be found that the
aggregate amount of life on our planet is in  propor-
tion to the  heating power of the sun,  cceteris paribus:—
that  no seed ever  germinates,  and no egg is ever
hatched, without  a  due  supply of warmth:—that as
the thermometer  rises in spring, so does the  sap of
plants; and as the mercury mounts up in summer, the
forces of life augment, but decline in autumn, and are
wholly arrested during  winter:—that as the annual
rings of trees correspond in thickness with  the mean
temperature of  the growing season  in the higher lati-
tudes, and are  always thickest on the  side exposed
to the  sun,—the  germination,  growth, and decay of
plants, constitute  a natural thermometer on a  grand
 scale.  It will also be found, that organized  bodies are 
LAWS OF CALORIC.               61
composed chiefly of those elements which contain the
largest amount  of caloric around their particles; by
which they are  rendered proportionally  active, and
endowed with the faculty of entering into vital com-
binations, so as  to form highly complex tissues:  that
the vital energy of animals, the activity of their func-
tions, and the development of their  organs,  are  in
proportion to  the amount of caloric which circulates
through, and is employed in combining arterial blood
with the solids.   A right understanding of these laws
is of vastly greater importance  than those of Geology,
Astronomy, or even Chemistry.   For until we com-
prehend  the operations of life,  health,  disease, the
modus operandi of medicines and morbific agents, the
healing art can never take its appropriate  rank among
the exact sciences;  nor be rescued from the charge of
mysticism, quackery, and ignorance, of what is essen-
tial to the character of a philosophical physician.  But
as "the strength of a  science is, like that of the old
man's fagot, in  the band," the  candid seeker after
truth is requested to  suspend his judgment until he
shall  have carefully examined the whole of the evi-
dence adduced  in  support  of  the author's peculiar
views. 
CHAPTER II.
          ATOMIC CONSTITUTION OF MATTER.

       "Omnia in mensura, et numero, et pondere."
                              Liber Sapientise, xi. 21.

  Before treating of the relative quantities of caloric
in different bodies,  and of the law by which it  pro-
duces the opposite forces of attraction and repulsion,
combination and separation, contraction  and expan-
sion, I shall present a brief outline of what is known
in regard to the ultimate  constitution of ponderable
matter.  The  doctrine that everything in nature is
arranged  by measure, number, and weight, seems to
have been recognized by the sages of India and Egypt,
long before the time of Pythagoras and  Democritus,
who maintained that all matter is composed of exceed-
ingly small, hard, and unchangeable atoms, that vary
in magnitude;  so arranged and  combined as to  pro-
duce  an  endless  diversity  of mineral, vegetable,  and
animal bodies.
  The same theory was  adopted  by Bacon, Boyle,
Newton, and many other  distinguished modern  phi-
losophers, who very justly conceived that if matter
were  infinitely  divisible, all  species would  be  con-
founded.   And it is obvious that if the elements did
not unite in definite proportions, the laws of chemistry
could not be understood, nor  its results be predicted
       (62) 
•
                VIEWS OF BOSCOVICH.              63

with certainty.  It is equally manifest, that if matter
were infinitely divisible, a finite body must consist of
an infinite number of parts,  which is a contradiction.
It follows, therefore, that matter must consist of ulti-
mate atoms.  In opposition to this simple ard rational
view of the subject, it was maintained by Boscovich,
that the minutest portions of matter consist of mere
mathematical points, without  extension  or solidity, sur-
rounded  by alternate immaterial spheres of attraction
and repulsion; by one of which, the said mathemati-
cal points are drawn together, and by the other kept
asunder, so as to be prevented from touching.
  We  are indebted to the researches of Wenzel, Berg-
man, and Richter, for the discovery that definite pro-
portions of acids and alkalies are required for mutual
saturation; and that many other chemical combina-
tions take place only in fixed ratios.  It was further
maintained by William Higgins  of Dublin, (in a wrork
entitled "A Comparative View of the  Phlogistic and
Antiphlogistic Theories," published in  1789,) that all
compounds are  formed by the  union  of exceedingly
minute atoms, which are surrounded by atmospheres
of caloric; and  that  oxygen unites with nitrogen in
proportions which are even  multiples of the lowest.
But to Dr. John Dalton of Manchester, was reserved
the distinguished honour of reducing the atomic theory
to a systematic form, in a work entitled "Chemical
Philosophy"  published  in 1808-10,—aided  by  the
subsequent  analyses  of Thomson, Berzelius,  Prout,
Gay-Lussac, Dulong,  and many  others.
  The most general law of chemical affinity  as  an-
nounced by Dalton  is, that the  constituents of ponder- 
Q4               THEORY OF  DALTON.

able matter, ivhether simple or compound, arc capable of
combining with each other only  In fixed or definite pro-
portlou* by weight.
  In  a practical point of view, this law has been of
the highest importance to the manufacturing chemist,
independent of its connection with the whole theory
of physical science.
  Passing over the  early and imperfect  analyses of
Dalton, it has been established by the united labours'
of the most accurate experimenters of modern  times,
that water is always composed of 8 parts by weight of
oxygen to 1 of hydrogen; that common salt is always
composed of 36 parts by weight  (in round numbers)
of chlorine to 23 of sodium; that carbonate of lime,
whether in the form of marble, chalk, or stalactites, is
invariably composed of 22 parts by weight of carbonic
acid to 28 of lime, &c.
   It was by thus ascertaining the relative proportions
in which bodies combine chemically by weight, that
Dr. Dalton was led  to  a perfectly  simple method of
deducing the relative weights of their ultimate chemi-
cal atoms.  The theory assumes,  that in all eases the
lowest combining proportion of bodies, whether  simple
or  compound, represents  the weight of its particles;
and that whenever a body combines with another in
two or more proportions, the larger is an even multiple
by some whole number of the  smaller, as 2 to 1, 3 to 1,
4 to 1, &c.; fractional  parts seldom occurring in well-
 ascertained cases.
   By inspecting  the following Table, it will be seen
 that the smallest combining ratio of oxygen is 8, com-
 pared with hydrogen as unity; and that when it com- 
CHEMICAL SYMBOLS.               65
bines with other elements in larger proportions, they
are 16, 24, 32, 40, or some multiple of eight.  Chlorine
combines with  mercury  in  the ratio of 36, as in
chloride of mercury, (calomel,) or of 72, as in the bi-
chloride of mercury, (corrosive sublimate,)  and so of
carbon, hydrogen and other elements.
   I have adopted the atomic numbers employed by
the majority of British chemists in preference to those
of Berzelius, chiefly with a view of avoiding the incon-
venience of fractions.   I have also chosen  hydrogen
as a standard of comparison for the same reason.  Ber-
zelius has selected oxygen 100*00 as  a standard, on
account of its great abundance, and the vast variety
of combinations which  it forms;  while Thomson and
Ure have employed oxygen as unity, by which hydro-
gen is rendered eight times less, or 0-125: carbon 0'75,
sulphur  two, mercury 25 or 12i, chlorine 4*5, and so
on; both of which are unavoidably attended with frac-
tions that are difficult to remember.
  Dr. Wollaston  employed the term chemical  equiva-
lent, and Sir Humphrey Davy combining proportion, to
denote the atom of Dalton.   I shall generally use the
term atom, or particle, as indicating the smallest che-
mical divisions  of bodies;  and molecule, as a small
assemblage of atoms.
  Berzelius represents the different elementary  bodies
by  the initial letters of their  Latin names.  Thus, O.
denotes oxygen, H. hydrogen, N. nitrogen, S. sulphur,
P. phosphorus, CI. chlorine, Br. bromine, I. iodine, F.
fluorine, C. carbon, Au. gold,  Hg. mercury, Ag.  silver,
Cu. copper, Pt. platinum, Sn. tin, Pb. lead, Zn. zinc, Si.
silicium, Se. selenium, As. arsenic, Fe. iron, Mn. man-
                        5 
66
CHEMICAL SYMBOLS.
ganese,  Al. aluminum, Mg. magnesium, Ca. calcium,
Ba. barium, L. lithium, Na. sodium, K. potassium,  (or
kalium,) which are the most important.
   The number of atoms in each element  of a com-
pound is indicated by figures, as in the following for-
mula'.   N05, represents one atom of nitrogen and five
of oxygen, as in nitric acid:  while sulphuric acid, which
is composed of three atoms of oxygen and one of sulphur,
is denoted by S03.   He has in many cases introduced
symbols of still more  remarkable  brevity and conve-
nience.  For example, the number of oxygen atoms
in a compound is  designated by dots placed over the
letter, which indicates  the element with which it com-
bines.  Thus, the  composition of water is represented
by the symbol,  H; carbonic oxide by C;  carbonic acid
by C; protoxide of nitrogen by N; binoxide of nitro-
gen by N; nitrous acid by N; and nitric acid by  N.
This is  a  most important  improvement of chemical
symbols, when  we reflect that oxygen enters into the
composition of  nearly all compound bodies.
  Berzelius represents the number of sulphur atoms
by commas.  Thus  H indicates sulphuretted hydro-
gen; and  H, bisulphuretted hydrogen, &c.   He also
denotes  various compounds by the initial letters of
their names.   Aq. represents water; Cy. cyanogen;
Ni. nitrate of potass; Am.  ammonia, &c.   It is some-
times convenient to denote two atoms of an element by
a dash under its symbol.  Thus Fe, denotes two atoms
of iron and three of oxygen, as in the peroxide of iron. 
ATOMIC WEIGHTS.                     67
                  TABLE OF ATOMIC  WEIGHTS,
       AND OF THE SYMBOLS BY WHICH THEY ABE BEPEESENTED.
Parts by weight.        Parts by weight.
  8 Oxyg. combine with   1 H. to  form......H   9 parts by weight of water.
 16 02......................   1H.................H  17 Binoxide of hydrogen.
  8 0 ......................   6C..................C  14 Carbonic oxide.
 16 02 ......................   6C..................C  22 Carbonic acid.
 16 0.......................  16 S...................S  32 Sulphurous acid.
 24 03 ......................  16 S...................S  40 Sulphuric acid.
  8 0  .....................  14 N..................N  22 Protoxide of nitrogen.
 16 02......................  14 N..................N  30 Binoxide of    do.
 24 03 ......................  14 N..................N  38 Hyponitrous acid.
 32 04......................  UN..................N  46 Nitrous      do.
 40 0- ......................  14 N..................N  54 Nitric       do.
  8 0 ......................  36 CI................CI  44 Hypochlorous acid.
 32 04......................  36 CI................CI  68 Hypochloric  do.
 40 05 ......................  36 CI................CI  76 Chloric acid.
  8 0 .....................  40 K.................K  48 Potassa.
  8 0 ......................  24Na...............Na  32 Soda.
  8 0 ......................  20 Ca...............Ca  28 Lime.
 24 03 ......................   8 Si................Si  32 Silex, silicic acid.
  8 0 ......................  64 Cu...............Cu  72 Protoxide of copper.
 16 02 ......................  64 Cu...............Cu  80 Binoxide of   do.
  8 0 ......................200 Hg..............Hg 208 Protoxide of mercury.
 16 02...................... 200  Hg..............Hg 216 Binoxide of    do.
  8 0 ......................110 Ag..............Ag 118 Protoxide of silver.
 24 Os......................  32 P..................P  56 Phosphorous acid.
  8 0 ......................  28 Mn...............Mn  36 Protoxide of manganese.
  8 0.......................  28 Fe...............Fe  36 Protoxide of iron.
 24 03 ......................  56 Fe2..............Fe  80 Peroxide of iron.
  8 0 ......................  12 Mg.............Mg  20 Magnesia. 
68                     ATOMIC  WEIGHTS.
Parts by weight.        Parts by weight.
  8 0  ......................   14A1...............Al  22 Alumina.
 24 0.......................   12 C.................C2  36 Oxalic acid.
 36 CI ......................   1H...............HC1  37 Hydrochloric acid.
126 1  ......................   1H................HI 127 Hydriodic acid.
 16 S ......................   1H..................H  17 Sulphuretted hydrogen.
 32 S2 ......................   1H..................H  33 Bisulphuretted hydrogen.
  6C ......................   2 H2...............CH2   8 Light carburetted do.
 12 C2......................   2 H2.............CJI,  14 Olefiant gas.
 12 C2......................   14 N...............C2N  26 Cyanogen.
 36 CI......................  24 Na............NaCl „GO Chloride of sodium.
 24 C4......................   4H...............C4H4  28 Etherine (En).
 36 C6 ......................   3 II...............C6H3  39 Bicarburet of hydrogen.
 36 C6......................   5H...............C6H5  41 Naphtha.
 60 C10......................   4H..............C10H4  64 Naphthalin.
 90 C15......................   4H..............C15H4  94 Paranapthalin.
 14 N-■-■.*.'....................   3  11................NH3  17 Ammonia.
  8 0......................lOOAu.............AuO 108 Protoxide of gold.
  8 0...........„.-........ 104  Pb.............PbO 112 Protoxide of lead.
  8 0 .....................,  96  Tt..............PtO 104 Protoxide of platinum.
 24 0 ......................  72  Bi................Bi 80 Oxide of bismuth.

 26 Cy......■;..............*.   1  H..............HCy  27 Hydrocyanic acid.
 26 Cy......................   8 0.................Cy 34 Cyanic acid.
 26 Cy......................  40 S................CyS  66 Sulphocyanic acid.
 26 Cy.......................  36 CI.............CyCl 72 Chlorocyanic acid.
 14 C2H2....................   9Aq...........C4H5H 23 Alcohol.
 28 C4H4....................   9Aq...........C4H4H 37 Ether.
 22 C.......................  17NH3............NH3C  39 Carbonate  of ammonia.
 44 C,......................  48 K................KC, 92 Bicarb, of  potassa.
 54 N ...........*'..........  48K................KN  102 Nitrate of potassa.
 37 C1H.......•.............  17  NH3........NH3HC1 54 Muriate of ammonia. 
ATOMIC WEIGHTS.
69
Parts by weight.      Parts by weight.
 37 C1H..................... 28 En..........EnHCl  65 Muriatic ether.
 40 S ...................... 32 Na.............NaS  72 Sulphate of soda.
 40 S ...................... 20 Mg.............MgS  60 Sulphate of magnesia.
  The lowest numbers in the first two columns of the
above table down  to oxide of bismuth,  represent the
atomic weights of  simple bodies, or multiples of them;
while the  numbers of the third column, including all
those from hydrocyanic acid in the first  and second
columns, denote the weights of compound particles or
molecules.
  The recent progress of chemical  science has led to
the discovery of some apparent exceptions to the law
of multiples.  The following examples  have been in-
dicated  by Dr. Turner.  The peroxide of iron is com-
posed of  12 parts oxygen to  28 of iron.   Oxygen
combines with manganese in the same  ratio, forming
a sesquioxide, from the Latin word sesqui, one  and a
half.
  This  difficulty has  been evaded by supposing that
two equivalents  or atoms of one substance  unite with
three, five, or more atoms of another—that if one atom
of iron  unite with one of oxygen, and  another com-
pound be formed  of  two atoms of iron to  three of
oxygen, the latter  would be in  the proportions of one
and one-and-a-half, and so of other like cases.
  When one atom of oxygen unites with two of lead,
they form a ternary atom of what is termed a dinoxide,
or a suboxide.   Dr. Turner lays it  down as a general
rule, that when  a metal forms two oxides, the oxygen
of which is in the ratio of one to one-and-a-half, the
first  is usually the protoxide, and the second a com-
pound of two atoms or equivalents of the metal to 
70
ATOMIC WEIGHTS.
 three of oxygen, as in the oxides of iron, nickel and
 chromium.
   It is highly probable, that a more accurate and re-
 fined mode of analysis  will  prove  hereafter that
 several of the present  atomic  numbers do not  repre-
 sent the  true weights of the atoms.  But it is also
 probable, that in  nearly  all cases  where  this is not
 so, they represent either multiples  or  submultiples of
 them.
   There  are  other exceptions  to  the law,  that all
 bodies combine chemically in fixed or definite propor-
 tions by weight.  Many of the metals unite with each
 other in all proportions when converted into the liquid
 state by heat, or electricity, forming alloys.
   Water  combines with alcohol, and with the strong
 acids in unlimited proportions; and it will be shown,
 further on, that the ratios in which sugar, numerous
 salts, oily, resinous  and gelatinous substances,  unite
 with water by chemical solution, are determined by
 the temperature of the water, solubility of the bodies,
 &c.  But in all such cases, the affinity is comparatively
 weak,  and the changes of properties consequent on
 combination inconsiderable.

                THEORY OF VOLUMES.

  In the year 1805, Gay-Lussac and Humboldt proved
by numerous experiments, that water is always  com-
posed of two measures by volume of hydrogen to one
of oxygen, as had been previously shown by Higgins.
By following up the investigation, Gay-Lussac found,
that many other gases, both simple and  compound, 
THEORY OF VOLUMES.
71
unite with each other in very simple ratios by volume;
that one volume of A unites with one, two, three, or
more volumes of B; and that the bulk of the resulting
compounds always bears a very simple and definite ratio
to that of its constituents, or to that of one of them.*
   This lawr has been extended by Dr. Prout and others
to vapours, and even to the supposed vapours of bodies
which do  not  exist  in the  elastic form, except when
united  with the  permanent gases.  For example,  if
carbon  be burnt  in  100 cubic  inches of oxygen gas,
(the weight  of which is 34*60 grains,)  an equal vo-
lume of carbonic acid is formed,  (which weighs 47*26
grains;) showing that 12*66 grains of carbon  have
been  dissolved  and chemically  united with 100 cubic
inches of oxygen, and thus converted  into the elastic
state; and that two atoms of oxygen have united che-
mically with one of carbon.   In this way it was found,
that  the specific gravity of  carbon  vapour  is  "416,
compared  with oxygen  1*111,  as determined experi-
mentally by Dr. Thomson.-j-  It was  also  found that
  * Memoires D'Arcueil, 1809, tome ii.
  f Mitscherlich has maintained recently, that the specific gravity
of carbon vapour is double "the estimate of Prout.  He observes,
that as it cannot be determined by direct experiment, it ought to
be deduced from  analogy—for example, if carbonic acid consisted
of equal volumes of carbon vapour and oxygen, he maintains that
they ought to  combine without any condensation, because in  all
other cases, when equal volumes  of gaseous bodies unite chemi-
cally, there is no contraction, as  in binoxide of nitrogen, hydro-
chloric acid, hydriodic  acid, kc.   He thinks that condensation
never takes place, unless the combining volumes are unequal;
therefore, that carbonic acid is composed of  one volume of oxygen
to half a volume of carbon vapour, (the specific gravity of which 
72
THEORY OF VOLUMES.
 when sulphur is chemically combined with oxygen by
 combustion, an  equal  volume  of sulphurous acid is
 formed, the specific gravity of  which is 2*222, or just
 double that of oxygen: therefore it is  evident, that
 100 cubic inches of sulphur vapour, as it exists in sul-
 phurous  acid, are of the same weight as 100  cubic
 inches  of oxygen.  Such facts led to a new mode of
 ascertaining the  atomic  weight of bodies,  and shed
 much additional  light on the ultimate constitution of
 matter.   For example, if sulphurous acid be composed
 of two atoms of oxygen  to one of sulphur, it follows,
 that the atom of sulphur  must be just 16 times that of
 hydrogen, and double that of oxygen.
   By  pursuing  this  method  of investigation, Dr.
 Thomson arrived  at the conclusion, that carbon, oxy-
 gen and  sulphur, are  even  multiples of hydrogen
 without fractions;  (Records of Science, March, 1836;)
 whereas Berzelius makes the atomic weight of carbon
 0-7643S;  that of sulphur 2*01165;  and sulphurous
 acid 4-01l6o, compared with oxygen 100.
   Without pretending to decide which of these illus-
 trious experimenters has approximated most nearly
 to the truth, it would appear from all the  lights of
 modern analysis, that when the  atomic numbers  shall
 have been ascertained with perfect accuracy, they will
 be found  to constitute very simple ratios.  It is ob-
 vious, that if the atomic weight  of carbon is six times
that of hydrogen,  oxygen eight, and sulphur 16, the

would be *832, instead of *416, or 12  times that of hydrogen )
But it is not very material whether we regard the specific gravity
of carbon vapour as six or twelve times  that of hydrogen, as either
number is in accordance with the law of multiple ratios 
THEORY OF VOLUMES.
73
above and many other equivalent numbers of Berzelius
cannot be correct; which is also the case with those of
Dr. Turner, who has adopted most of them. Whether
this be true or not, the simplity of the atomic theory,
as proposed  by Dalton, and improved by later che-
mists, has  been  greatly diminished  by the number of
decimals which Berzelius has affixed to  his  atomic
weights.   I concur most fully with Professor Forbes,
in the hope that philosophers may dismiss that super-
fluity of decimal places which has been recently intro-
duced into several branches of physical science.  They
have already tended to shake the confidence of some,
as to the soundness of the atomic theory.
   The important discovery of Gay-Lussac has been so
far extended and verified by the  united researches of
modern chemists, that it may be regarded as an estab-
lished law, that  all gaseous bodies combine with  each
other in definite proportions  by volume, and in accord-
ance with the law of multiples.
   The following table will  show the connection be-
tween the specific gravity of gaseous bodies and their
atomic weights.   The first  column of figures repre-
sents their specific gravities, compared with common
air as a  standard, deduced from  the  experiments of
Thomson, Prout, Berzelius, Dulong, Gay-Lussac, Ure,
Dumas and Mitscherlich, under the ordinary pressure
of the atmosphere, and at the temperature of 60° F.
with the exception of phosphorus, sulphur,  arsenic,
and such other bodies as require higher temperatures
to convert  them into the gaseous state.  The second
column  exhibits the number of grains in  100 cubic
inches; while the  third column gives the relation of 
74
SPECIFIC GRAVITY  OF GASES.
  their  specific  gravity  to  that of hydrogen  as  unity;
  and is obtained  by dividing the numbers in  the  first
  column by the specific gravity of hydrogen.

                                             No. of grains in   Sp. gr. corn-
    Gases and vapours.          Specific gravities.        100 cubic      pared with
                                               inches.      hydrogen.
 Atmospheric air.....................   1-000  ..............   3101............    15
 Chlorine ..............................   2-500  CI............  7620............    36
 Iodine vapour........................   8-716  1.............  265*70............   126
 Bromine do.........................   5-555  Br........... 16929............    80
 Carbon vapour......................    -416 C............  12-68............    6
 Carburetted hydrogen.............    -555 CH2..........  17-30............    8
 Olefiantgas...........................    -981 C2H2.........  29-90............   14
 Etherinevapour.....................  1-963 C4H4.........  61-13............   28
 Carbonic oxide.......................    -972 CO or C.....  29-02............   14
 Carbonic acid........................  1-527 C............  47-26............   22
 Aqueous vapour.....................   -625 H............  19-05............     9
 Alcohol vapour......................  1-620 C4H602......  49-37............    23
 Ether    do.....................   2-570 C4H50...!....  79-67............    37
 Cyanogen..............................  -j.g^ CN..........  5(J.47............    2g
 Sulphurous acid.....................   2-222 S...        67-7^           <lo
 Sulphuric acid.......................   2-777 S............  84-72............    40
 Protoxide of nitrogen.............   1-527 N............  47-21;.........      22
 Nitrousacid..........................    3-19 N............  98-80............    46
 Nitric   d0...........................    3-75 N............ H6-14............    64
 Hydrogen gas........................ 0-0690 H............... 2-13...           1
 Phosphuretted hydrogen.........   1-185 PH....       36-""l
Nitr°Sen Sas.........................    -972 N...............30-16............    14

Ammonia .............................    -590 NH3.............18-19...,          8-5
Hydrochloric acid..................   1-270 HC1............39-36...          i8 5
Hydrocyanic do..................    -942 C,NH............29-30............    13,3
Binoxide of nitrogen...............   1-041 \...............32.13 
SPECIFIC GRAVITY  OF  GASES.
75
                                   No. of grains in   Sp. gr. com-
   Gases and vapours.         Specific gravities.    100 cubic    pared with
                                     inches.     hydrogen.
Hydriodic acid.......................  4-409 HI..................................   63-5
Hydrobromic acid..................  2-812 HBr...............................   40-5
Mercury vapour.....................  6-944 Hg........................ .........  100
Protochloride of  mercury ........  8-204 HgCl..............................  118-5
Bichloride of     do.........  9-431 HgCl2..............................  136
Bromide of      do.........  9*665 HgBr.................................  140

Oxygen................................  1111 O................34-60............   16
Phosphorous vapour...............  4-444 P...................................   64
Arsenic vapour...................... 10-625 As..................................  150
Sulphur  do.......................  6-666 S...................................   96

   By comparing the  numbers in  the third column of
the table, down to nitrogen, with the atomic weights
in the preceding table, page 67, it will be found that
they  are identical; or, that the  specific gravity of the
gases  and vapours in the  upper  department of the
table corresponds  with  their atomic weights, as de-
duced from the analyses of compound  bodies.   From
which it follows, that  equal volumes contain  equal
numbers of atoms.
   This however is not the case  with the next class of
gaseous bodies; for it will be observed, that from  am-
monia down  to bromide of mercury, the atomic weights
in the third  column are just half  of what they ought
to be, were the atom  and the volume the same;  that
is, allowing  the atomic weights in the first table to
be the true ones.
   It will also be observed, that the specific gravity of
oxygen is 16 times that of hydrogen, while its atomic
weight is only eight;  showing that its specific gravity 
 76        COMBINATION OF GASES BY VOLUME.
 is double  its atomic weight  as exhibited in  the first
 table.   The difference is still  greater between  the
 specific gravity of phosphorous vapour and its atomic
 weight,  in the ratio of two  to one,  or of 64 to  32.
 The same is true of arsenic vapour, its specific gravity
 being 150 times  that of  hydrogen,  and  its atomic
 weight only 75; while the specific gravity of sulphur
 vapour is six times its atomic weight, the former being
 96, and the latter 16.
   The following table will illustrate  the nature and
importance of the facts on which the theory of volumes
is  founded, and their connection with  the atomic con-
stitution of matter:—
Vols, or cubic inches.    Cubic inches.
 200 H. combine......100 O. to form
 300 H  do.......100 N. to form
 200 H.  do.......100 C. vapour.
 200 H.  do.......200 C.  do.
 400 H.  do.......400 C.  do.
 300 H.  do.......600 C.  do.  .
 500 II.  do.......600 C.  do.
1000 Car. vapour......400 H...........
1500 C.  do.......400 H...........
 200 Nit. vapour......100 Oxygen....
 200 N.  do.......300 O ............
 200 N.  do.......400 O ...........
 200 N.  do.......500 O............
 100 C.vapourdo......200 O............
 200 C. do.  do......100 N ............
 400 Car. oxide........400 H............
 100 Olefiantgas......100 Aq. vap ....
 200   do.......100 Aq. do.....
Vols.
	200 of Aqueous vapour.
	200 Ammonia.
CH,	100 Light Carbur. hyd.
.C2H2	100 Olefiant gas.
En.	100 Etherine vapour.
.C6H3	100 Bicarburet of hydr.
■C6H5	100 Naptha vapour.
O, H	100 Napthalin vapour.
•v'10la4	
•C.-H	100 Paranapthalin do.
•VJ15il4	
NO	200 Protoxide of nitr.
N	200 Hyponitrous acid.
.N	200 Nitrous acid.
N	200 Nitric acid.
C	200 Carbonic acid.
C2N	200 Cyanogen.
W	Hydrous acetic acid.
C4H502	100 Alcohol vapour.
C*H50	100 Ethereal vapour.
 
COMBINATION  OF GASES BY VOLUME.        , i
Vols, or cubic inches.		Cubic inches.		Vols.
100 Chlorine	rln	....100 H.........	........HC1	200 Hydrochloric acid.
		....100 O .........	........c	200 Carbonic oiide.
100 I do.		....100 H.........	........HI	200 Hydriodic acid.
100 Cy..........		....100 H.............	.........HCy	200 Hydrocyanic acid.
100 Cy.......		....100 CI..........	........CyCl	200 Cyanuret of chlorine.
100 Cy.......		....100 I..........	........Cyl	200 Cyanuret of iodine.
200 N ........		....200 O..........	,. ., N	400 Binoxide of nitr.
25 P.........		....100 H..........	........HP	100 Phosphuretted hyd.
16 Sulphur	vap.	....100 H..........	.......HS	100 Sulphuretted do.
16 S.	do ,	....200 O..........	........S	200 Sulphurous acid.
16 S.	do	....300 O..........	.......s	200 Sulphuric acid.
   By glancing over the above table, we perceive that
the aggregate volume of the eighteen first gases  and
vapours, down  to ether, is  reduced during chemical
combination from 3 to 2, 4 to 2, 3 to 1, 4 to 1, (as in
defiant gas;) from 8 to 1, as in etherine; from 9 to 1,
in Faraday's bicarburet of hydrogen; from 11 to 1, in
naptha vapour;  from 14 and 19 to 1, as  in napthalin
and paranapthalin; in all of which, the specific gravity
and atomic weight coincide.
   The next class of gases and vapours, in the second
department of the table, unite chemically without  any
change of volume, such as chlorine and  hydrogen, to
form  hydrochloric  acid  gas,  the  specific gravity of
which is a mean of its  constituents;  and so of the
other six gases and  vapours, including binoxide of
nitrogen;  in  all of which the specific gravity repre-
sents  only one-half of their atomic weights.
   It will also be observed, that the volume of phos-
phorous vapour is augmented from 25 to 100, on uniting 
78      CONTRACTION AND EXPANSION OF GASES.
 with hydrogen, and that of sulphur from 16 to 100, as
 in sulphuretted hydrogen, sulphurous acid, &c.
    Here is a most important series of phenomena that
 have never been explained:—1. Why the specific gra-
 vity of gaseous bodies does not always correspond with
 their atomic weights, except  in  accordance with the
 law of multiple or submultiple ratios:—2.  Why many
 gases unite chemically with contraction of volume and
 diminution of elastic force:—3. others without con-
 traction:—4. and some with expansion of volume, as
 the vapours of sulphur, phosphorus, &c.
   It will be shown  in  the  next chapter, that all the
 phenomena of contraction, expansion, and the elastic
 force of gaseous  bodies, depend on their relations  to
 caloric,  which surrounds every  atom  of ponderable
 matter,  and, by  its  transition from one body to an-
 other, determines all the chemical or physical changes
 which they undergo; that the elastic  force of hydro-
 gen, oxygen and nitrogen, (which depends on the rela-
 tive proportions of caloric and ponderable matter  of
 which they are composed,) is so great, that no degree
 of force, except that of chemical  attraction, has been
 adequate to condense them perfectly into the liquid
 form; but that on uniting chemically with each other
 and with carbon, phosphorus, sulphur  and various
 other bodies, they are deprived of their elastic force

 Zlovk  manJ CaSGS With°Ut  ^  diseiWme"t of
  The following  observations will show at once how
chemical affinity modifies the specific gravity and elas-
tic force of gases.  It has been seen that the specific
gravity of chlorine is 36 times  that of hydro-en   Its 
          WHY GASES CONTRACT AND EXPAND.        79

elastic force is also small, as  it may be condensed by
a pressure equal to four atmospheres, or even by cold
without pressure.  But when  100 cubic inches of chlo-
rine unite chemically with 100 cubic inches of hydro-
gen, (the elastic force of which is immense,) they form
200 cubic inches  of hydrochloric  acid gas, the elastic
force of which is equal  to the pressure of 40 atmo-
spheres at the temperature of 50°.  During this com-
bination, the  larger atoms of chlorine receive from
those of hydrogen a definite ratio of caloric, by which
the elasticity of the hydrogen is diminished, and that
of  the chlorine increased.   At the same  time,  the
atoms of chlorine are removed farther from each other,
causing an alteration of specific gravity in the result-
ing compound.  In like manner,  when one volume of
iodine vapour, the specific gravity of which is 8*75,
unites chemically with an equal volume of hydrogen,
the specific gravity of the resulting compound is dimin-
ished to 4*385; and so of the  rest, together with many
other like combinations not set down in the table.
   The volume of phosphorous, arsenic  and sulphur
vapours is still further  augmented  on uniting with
hydrogen  and other permanent gases.   The  specific
gravity of these vapours, as deduced from the experi-
ments of Dumas  and Mitscherlich, (who  converted
them  into  the  gaseous  state  by  heat,)  is 4*444,
10-025, and 6*666, {see table, page  74;) but when phos-
phorous vapour unites with  hydrogen, its volume is
augmented  fourfold; that is, from 25 to 100, as in
phosphuretted hydrogen.  Sulphur vapour is expanded
still more  on uniting with hydrogen, viz. from 16 to
100,  as in  sulphuretted  hydrogen, as before stated. 
80        RELATIONS OF ATOMS TO VOLUMES.
 Now it must be remembered that the vapours of phos-
 phorus,  sulphur, mercury and arsenic, have little or
 no elasticity, unless at high temperatures; from which
 it follows, that their volume and elastic force are aug-
 mented  on uniting with hydrogen, by acquiring from
 it a sufficient amount of caloric to produce  the effect.
 These views will be more fully expanded when I come
 to treat of the attractive and repulsive forces of caloric.
   When thus investigated in connection with the cause
 which moves atoms, and the law by which they are
 united and separated, the atomic theory embraces  the
 whole science of nature.  But until the mutual rela-
 tions of ethereal and ponderable matter shall be better
 understood, the  theory  of  atoms, and consequently
 that of chemistry, must remain involved in profound
 obscurity; a lifeless mass of phenomena, for which no
 satisfactory reason can be assigned.
  In regard to several  bodies termed elementary, che-
 mists have not yet been able  to determine whether
 we  have  obtained their true atomic weights, or only
 multiples or  submultiples of them.  At one time, it
 was  supposed by Ampere and Dumas, that equal vo-
 lumes of all gases and vapours, simple or compound,
 contain exactly the same number of atoms.   In order
 to sustain this hypothesis, so beautiful from its sim-
 plicity, Dumas  imagined that  when  chlorine unites
 chemically with  hydrogen to form hydrochloric acid
gas, their atoms  undergo a division, by which two
atoms of the acid are formed out of one of each of  its
elements.  It is needless to insist, that these hypotheses
have not  been found in  accordance with established
facts. 
           RELATIONS OF ATOMS TO VOLUMES.         81

  That equal volumes of all gases contain equal num-
bers of atoms was inferred, first, from the circumstance
that all  gaseous bodies are equally expanded by the
same  additions of caloric,  the pressure being equal:
and secondly, from the supposed fact, (which has been
termed the law of Mariotte,) that the volume of any
gas whatsoever, diminishes in proportion to the pres-
sure exerted  upon it, the temperature being equal. It
was maintained, that if the number of atoms in each
gas were not the same, the diminution of volume under
the same pressure ought also to vary.  Recent experi-
ments performed by OErsted and Despretz, have proved
that this is actually the case;  that the volume of sul-
phurous  acid, cyanogen, ammonia  and  sulphuretted
hydrogen,  diminishes much  more rapidly under an
equally increasing pressure, than oxygen and nitrogen,
as in common air; consequently, that the law of Ma-
riotte is not true when applied to gases indiscrimi-
nately; but only  to such as have the same  degree of
elastic force.   Despretz regards the above  deviation
from the law of Mariotte, as referable to some unknown
Jaw which regidates the constitution of gases.
  When I  come to treat of the  causes which  modify
the elastic  force of gases, it will be shown that  their
volume and compressibility are determined by  their
relations to caloric, and  not by the number of atoms
in a given volume.
  Berzelius maintains in a recent work,  entitled Pes
Proportions Ghimiques, that the atomic weights of sim-
ple bodies are represented by their specific gravity in
the gaseous state: from which it wTould follow, that
the atomic  weight of hydrogen is one-sixteenth that of
                        6 
82      ABSOLUTE WEIGHTS OF ATOMS DOUBTFUL.
  oxygen, instead of one-eighth, corresponding with the
  difference between their specific gravities.  And as it
  was found  that water is always  composed of two
  volumes of hydrogen to one of oxygen, it was inferred
  by Davy, Berzelius, Prout and  others, that water  is
  compounded of two atoms hydrogen to one of oxygen.
    In like manner, when it was  found that  the pro-
  toxide of nitrogen is composed of two volumes nitro-
  gen  and one of oxygen, it was  inferred that it is a
  compound of two  atoms nitrogen to  one of oxygen.
  In accordance with this view, Berzelius and many of
 the continental  chemists regard the hydrogen atom of
 Dalton, and  the  nitrogen atom of Thomson,  Turner
 Brande and other British authors, as double atoms, or
 multiples of their real weights.  But if it be true, that
 the only combining proportions on which we can de-
 pend, are such  as the  most accurate  experimenters
 have found them to enter by weight into the  composi-
 tion of compound  bodies,  we are not  authorized to
 adopt the numbers  of Berzelius, until verified  by new
 and more accurate methods of analysis.   At the same
 time, I am free to confess, that the great degree of elastic
 force ln nitrogen, favours  the opinion of Berzelius,
 that its atomic weight is seven, compared with hydro-
 gen, instead of 14.  It cannot, however, be supported
 on the ground that equal volumes of gases and vapours

 hat while the atomic weight of ammonia is  17 times
that of  hydrogen, its specific gravity is only 8*5- that
tl,e atomic weight of hydrochloric acid  is 37, but ita

gases.   It i.s also evident, that whenever the  specific 
MINUTENESS OF ATOMS.
83
gravity of gases does not correspond with their atomic
weights, they vary according to the  law of multiples
or submultiples, which renders the theory of volumes
nearly as simple as if the atom and  the volume were
always the same.
   It is exceedingly difficult, if not wholly impossible,
to explain the foregoing phenomena  of chemical com-
binations, without adopting  the theory  of Newton,
Tliggins and Dalton, that the elements of ponderable
matter are composed of ultimate atoms, which, how-
ever minute they may be, must have both extension
and weight.  If they were mere meithematlcal ptolnts,
or mere centres of force, wltliout extension, as maintained
by Leibnitz,  Boscovich, Kant,  Ecloy  and  Faraday,
they  could not  possibly form extended  and  massy
aggregates.*   That ponderable matter consists of in-
calculably small particles or atoms, is evident from all
the phenomena  of solution,  the diffusion of  odours,
and the minuteness of organized animalcules.  Accord-
ing to the observations  of Ehrenberg, a single grain of
silex  has  been found to contain  187,000,000 animal-
cules in  the  fossil state.   Verily, the revelations  of
Science require faith as well as reason.
   * In a paper published in the  London and Edinburgh Phil.
 Magazine, for 1845, Faraday maintains that "the modern theory
 of atoms is at best an assumption."  " To my mind," says he, "the
 nucleus vanishes, and the  substance consists of the powers."  He
 adds: " gravitation is a certain property of matter, dependent on
 a certain force, and it is this force which constitutes the mattery
 Moreover, as Kant resolved heat, electricity and light, into the
forces of attraction and repulsion, Faraday has further resolved
 them into the polarity of forces. 
81
MINUTENESS OF ATOMS.
   The phenomena of crystallization are not less as-
tonishing.  When a drop of solution of muriate of am-
monia is magnified by an oxy-hydrogen microscope, it
is seen  to  shoot  into many hundred thousand  small
crystals, (each of which must contain at least as many
ultimate atoms,) which  coalesce into one symmetrical
solid crystal; yet are they all governed and arranged
by number, measure and weight.  An ultimate particle
of lead, which is 104 times greater than an atom of
hydrogen,  is  estimated  by  Dr.  Thomson  as  only
3iwoob>i>tn °f a gram-  ^et, if the  Igneous ether which
surrounds these molecules be a material agent, its
particles must  be inconceivably smaller.  We can no
more  measure  the  ultimate  minuteness of this spi-
ritual and  fiery essence than we can comprehend the
infinitude of space and duration.   We are less amazed
on contemplating the vast cycles  of geology and as-
tronomy, than  by attempting  to follow nature in her
smallest  proportions.   We know  not  the absolute
weights of atoms, but we  know from the preceding
facts, especially those on which the law of multiples is
founded,  that they  vary in size.   We know not the
forms of  ultimate atoms, nor whether they are all of
the same density; but as all bodies in the liquid state
are disposed to assume a round form, we may conclude
that they are spherical, and that the various forms of
crystalline  bodies  are  determined  by the modes in
which their particles are grouped and arranged. 
LATENT CALORIC  IN DIFFERENT BODIES.      85
RELATIVE  QUANTITIES OF  CALORIC IN DIFFERENT BODIES.

   This is one of the most difficult problems in Phy-
sical Science, the very elements of which have yet to
be unfolded.  If it be true, that  the whole material
world is composed of particles or atoms which vary in
size, and  that they are  surrounded by an active and
ethereal  principle, which is  immediately  connected
with all their properties and changes, it is obviously
an object of primary importance to ascertain the rela-
tive proportions  of each, and  the laws of their ope-
ration upon each other.   Without  hoping fully  to
develope a subject which has hitherto baffled so many
able men, I shall endeavour to show, that the methods
which have been employed for the purpose of estimat-
ing the constituent caloric of bodies are fallacious; the
application  of which,  to  the phenomena of combus-
tion, respiration,  evaporation and solution, has been
a constant source of error.
   It has been known ever since the time of Dr. Black,
that different quantities of caloric  are required to pro-
duce the  same temperature, in equal weights or vo-
lumes of different bodies; that one pound of water re-
quires about double the quantity of caloric to raise its
temperature  50°  or 100°, that one pound of oil does;
and  that on cooling an  equal number of degrees, w^ater
gives out  twice as much  caloric as an equal weight  of
oil: from which it was inferred, that the same difference
existed between the latent caloric  of oil  and water  at
all temperatures,  down  to  their  absolute  zeros; in
other words, that the whole amount of caloric in water
is double that of  oil. 
86      LATENT CALORIC IN  DIFFERENT BODIES.
    This  difference  of capacity  for caloric, as it was
  termed  by Dr. Black  and  his disciples, which was
  found to exist between all other bodies, has  been re-
  garded by Crawford, Kirwan, Lavoisier and Laplace,
  Leslie and Dalton, as a measure of the relative quan-
  tities of caloric which is chemically  combined  with
  them, and has been generally termed specific heat. But
  it is now universally conceded, that the whole subject
  is involved in profound obscurity, and that nearly all
  the experiments connected with specific heat are at
  variance with each other, which alone is a sufficient
  proof that the truth has not yet been fully ascer-
  tained.
    According  to the  above  mode  of  deducing the
 amount of caloric in bodies, water should contain more
 than an equal weight of any other known liquid or
 solid, as it gives out a larger quantity on cooling an
 equal number of degrees.  If capacity or specific  heat
 were a true criterion of what they contain, the latent
 caloric of ether, alcohol, oils, wood, coal, and all those
 bodies which  are known  to be the most combustible,
 would be comparatively low.   But this idea is refuted
 by the amount of hydrogen that  enters  into the com-
 position of such bodies; and by the fact that hydrogen
 gives out more caloric, during  combustion, than an
 equal  weight  of any other known substance   Ever
 since the  first discovery of hydrogen, it has been re-
 garded as an  exceedingly igneous substance    The
older chemists termed it inflammable  air  At  one
time, Kirwan  maintained that it was  identical with
the phlogiston of Stah], which was in  realitv the  un-
discovered latent heat of Black. 
            LATENT CALORIC  OF HYDROGEN.          87

  These vague hypotheses were  superseded  by the
more  definite views of the  celebrated Lavoisier, who
proved  that hydrogen is composed of a ponderable
base, united with an igneous fluid, which he termed
caloric,  and which may be separated from each other
by chemical action.
  According to the experiments of Dr. Dalton, caloric
enough  is given out during the combustion of one pound
of hydrogen gas to melt 320 lbs. of ice. According to
Crawford, 480 lbs. of ice are melted by the heat given
out during the combustion of one pound of hydrogen;
which Dr. Thomson thinks  is about as far beyond the
truth as Dalton's  estimate falls short; and that about-
400 pounds may be regarded as the mean quantity of
ice that will be melted during the combustion of one
pound of hydrogen.  If then we admit with Dr. Black,
that 140° of caloric are required  to  melt one pound
of ice, 56,000° of heat must be given out during the
combustion of  one pound of hydrogen.
  It must however be observed, that during the pro-
cess, two volumes of hydrogen combine chemically with
one of oxygen; or that one atom of oxygen combines
with one of hydrogen; and as the atomic weight of
oxygen  is eight times  that of hydrogen, eight pounds
of oxygen must unite with one of hydrogen, making
nine pounds of water.   From which it is evident, that
a certain proportion  of the  caloric disengaged, is
afforded by the oxygen; for we find that the volume
and elastic force  of both gases  are  destroyed on  as-
suming  the liquid form.
  If the volume of water were diminished in the same
ratio at  all temperatures, by the abstraction of caloric, 
S8      IMPORTANCE OF OXYGEN AND HYDROGEN.
 we might arrive at a proximate estimate of the abso-
 lute quantity of caloric which it contains.  For  ex-
 ample, it is known that water is diminished about one
 twenty-second of its volume on reducing its tempera-
 ture 180°, viz., from 212° to 32°.  If then it be assumed
 that the pores of water are 20  times greater than its
 solid atoms,  (and  Newton supposed that  they were
 double this estimate,) it would require the abstraction
 of 3600°, to deprive it  of all  its caloric, provided the
 volume continued to diminish in the same ratio. But
 as it has been found that below the freezing point of
 mercury,  its volume contracts  in a greater  ratio than
 at higher temperatures, it  is probable that the same
 thing may be true of other  bodies.
   When we consider the vast abundance and import-
 ance of oxygen and hydrogen  in the economy  of
 nature, it becomes obvious,  that a correct mode of as-
 certaining the relative quantities of caloric which they
 contain would throw new light on all the relations of
 ethereal and ponderable matter.  All the  waters  of
 the earth are composed of  oxygen and  hydrogen,  in
 the proportions  of  eight to one by weight.  When
 converted into vapour  by solar caloric,  and diffused
 through the  atmosphere, water is connected with all
 the  phenomena of  meteorology.   As a mechanical
 agent,  running  water is perpetually wearing down
 mountains, hills  and elevated plains, and transporting
 them to valleys, lakes and seas.
   As a chemical agent, water is slowly but constantly
dissolving rocks, salts and  metals, which  are again
precipitated in the crystalline or solid state.  It forms
a large proportion of all  animal and vegetable bodies; 
          EXPERIMENTS OF DULONG AND PETIT.       89

also, of many salts  and rocks.   As a  constituent of
the, atmosphere, oxygen is  indispensable to all  the
phenomena of  vitality.  It enters largely  into  the
composition of nearly all acids, alkalies, native ores
or metallic bases; and constitutes about one-fourth of
the earth's crust.
   The  importance  of  carbon  is not  less manifest;
forming, as it  does, the basis  of all organic matter.
In combination with hydrogen, it constitutes the prin-
cipal portion of the food by which we  are nourished,
and of the fuel by which we  are warmed and kept
alive during winter.  According to the  analysis of
Gay-Lussac, and of Dr. Prout, it forms  about one-half
of lignin,  or perfectly  dried woody fibre.  It is  the
chief ingredient in those immense  subterranean forests
of ancient vegetation, termed fossil coal;  and which,
perhaps, exceed in quantity an hundred  fold, all  the
trees  and  plants that now cover the surface  of  our
planet.
   After  all attempts to  ascertain the specific heat of
bodies had proved discordant and fallacious, a series
of experiments was  undertaken by MM.  Dulong and
Petit, the object of which was to discover what rela-
tion existed between the atomic  weights of various
bodies and their capacities for caloric.  The result of
their  researches was, that the specific heat  of  water
was nearly three times that of sulphur  and several of
the metals, in which it was about one-half less than
in some other elements; four times less than in others
again, such as phosphorus and iodine; while in carbon
it was nearly six times less than in water, or as 0*169
to 1*000.   They also found that  there was no uniform 
90
EXPERIMENTS OF THOMSON.
 relation  between  the  quantities  of caloric  evolved
 during the  combustion of different bodies, and the
 specific heat of their resulting  products, the capacity
 of which was  often the same before as after the pro-
 cess.  Yet they maintained that the atoms ofedt simple
 bodies have the same specific heat, because when  they
 vary, it is in multiple or submultiple r/itios, or nearly
 so; and that the atomic  equivalents of all bodies which
 do not accord  with this assumed  law, ought  to  be
 altered and  made  to agree with it. (Ann. de Chlm. et
 de Phys. tome x.)
   The recent  efforts of Dr.  Thomson  to  verify the
 hypothesis of  Dulong and Petit, have not  been suc-
 cessful, as will appear from the  following table, repre-
 senting the atomic weights of twenty-six simple sub-
 stances, (compared with oxygen as unity,)  their spe-
cific heat, and  the resulting  product.   He observes,
that '-'if  the specific  heat of bodies multiplied  into
their atomic weights  be a constant quantity, it will
follow that every simple atom is surrounded with the
same quantity of heat."  (Records  of Science, April,
1S36.)                                           l   '
   „ ,                  Atomic weight.  Specific heat.  Product.
   Carbon..............              n.7-     „„,„
   „.,.      ..............................  ° <°     0-257    0-192
   Silicon.................             i        _ in_
   .,        ...........................  1        0*187    0-187
   Aluminum ............            1,9c     n-irr.
   n         ............................  1 25     0-150    0187
   &:::::=...................;,       ™    •*»
   »,„  •      ........................... 45       0-827    0-372
   fT107ne................................... 10        0-472    0-437
   ^dr°gen................................. 0-125     3-293    0-412
   iTr.................................. W5     °-269    0-472
   Sulphur ..........              o
   A   .    .............................. 2        0-188    0-376
   Arsenic............              A ~,.
   Antimony......  ........................ ^     ™81    °™
   Tellurium........  ........................ !        °/°47    9^6
   Iron.....      ......................... *        0091    0364
         .................................. 3-°       0-110    0-385 
EXPERIMENTS OF THOMSON.
91
                        Atomic weight.  Specific heat. Product.
   Nickel......................................  3-625.    0-103     0-375
   Zinc........................................  4-125     0-927     0-383
   Lead....................................... 13        0029     0-377
   Tin..........................................  7-25      0057     0370
   Copper.....................................  4        0-095     0-376
   Bismuth...................................  9        0040     0-360
   Mercury..'................................. 12-5      0-029     0-362
   Gold........................................ 12-5      0-029     0-373
   Platinum................................. 12        0 310     0-372
   Cobalt......................................  3-25      0-150     0487
   Phosphorus...............................  2        0-385     0-770
   Silver....................................... 13-75      0-056     0-770
   Iodine...................................... 15-75      0-89     0-401
             Mean of the whole.....................................0-375

   Dr. Thomson maintains, that if the atoms of car-
bon, silicon and aluminum  were doubled, and those of
phosphorus and silver reduced one-half, their specific
heat would be  about the  same  as  the  mean of the
whole;  and that the other deviations from this ave-
rage ought  to be referred to inaccurate experiments.
But  if, for the sake of  argument, we admit his asser-
tion, it would follow that an equivalent of water con-
tains 5*85 times more caloric than one of carbon, sili-
con,  or aluminum; 4*76  times  more than  an atom of
oxygen;  above two and  a  half times  more than one
of hydrogen, nitrogen, iodine, or cobalt;  about 40 per
cent, more than one of phosphorus or silver; for the
specific heat of water is 1*125 when multiplied by its
atomic weight.  And that capacity is no measure of
the  relative quantities of caloric in different bodies,
would appear from the experiments of  Haycraft, De
la Rive and Marcet, who found that equal volumes of
all gases are equally heated and cooled by equal addi-
tions and subtractions of caloric. 
92          EXPERIMENTS  OF DULONG AND HESS
   The following experiments of Dulong and Hess, per-
formed with a view of  ascertaining the relative quan-
tities of caloric evolved during the combustion of seve-
ral gaseous bodies and  a few metals, will  be  found
more instructive.
                                  /.  •           Grammes of
        Substances employed.         ' om\c com~      water raised
                                   VOSltlOTla       -| ,-,    .   T
                                  r            1° centigrade.
   1 Litre of Hydrogen...................................................  3,102
   1   "    Light carburetted Hydrogen.... CH2.................  9,587
   1   "    Olefiantgas......................... C2H2................. 15,338
   1   "    Carbonic oxide..................... CO.....................  3,130
   1   "    Cyanogen.......................... NC2................... 12,269
   1   "    Alcohol vapour..................... C4H602.............. 14,375
   1   "    Ether vapour....................... C,H50...............  32,254
   1   "    Turpentine vapour................ C10H8................. 70,607
   Carbon vapour equal to 1 litre in the gaseous state............   7,858
1 Litre of Oxygen gas with Iron....................................  6 216
Tin....................................  6,508
Antimony............................  5,552
Zinc...................................  7,577
Cobalt.................................  5 721
Nickel..................................  5^333
              Mean of the six metals.............................  g 151

   To these may be added the results of M. Despretz,
who  found, that during  the combustion of one pound
of  different  substances,  caloric enough  was evolved
to raise the following quantities of water from 32°  to
212°  F.

         Substances employed.                     r,    . .
    iv, .f tt ■,                                Quantities of water.
    lo.or Hydrogen.................                         J
       "   Charcoal from wood..!1!!.".!"!.T.!!.''.'.'.'.............. 23U-4 lbs.
       "   Olive oil...........
       „   w           ...........................................   90
       "   wax...........................
       "   Ether.........................................................   °"
       "   Pure charcoal...................
       "   Alcohol..........          ..........................   78
                       .........................................   67-5 
ON THE COMBUSTION OF  GASES.
93
       Substances employed.                 Quantities of water.
   1 lb. of Bituminous coal........................................... 60 lbs.
   1   "  Baked wood................................................ 36
   1   "  Wood with 20 per cent, water........................ 27
   1   "  Turf.mean................................................. 27

  From the table of Dulong and Hess we perceive,
that during the combination of one atom of oxygen
with two of hydrogen  and one of carbon, as  in light
carburetted hydrogen,  about  three times more caloric
is evolved, than by the  combustion of the same volume
of pure hydrogen; and that one atom of carbon vapour,
as it exists  In carbonic  oxide, gives out almost precisely
the same amount of heat as an equal volume of hydrogen.
It would also appear from the same table, that during
the chemical union of oxygen with the above metals,
and its conversion into the state of solid oxides, about
twice as much caloric is evolved as by the same bulk
of hydrogen.  So that if nearly the whole is afforded
by the oxygen, it would be about eight times less than
is given out by the  same weight of hydrogen, corre-
sponding with  the difference between their atomic
weights;  for hydrogen is sixteen times  lighter than
oxygen: from which it would follow, that during the
combination of oxygen with carbon and hydrogen, the
atom of each gives out the same quantity of  heat.
  We further perceive, that  during the  combination
of oxygen with two equivalents of carbon, and two of
hydrogen, as in the combustion of olefiant gas, above
four  times as much caloric is  evolved as by the union
of one atom of oxygen with one of hydrogen; and
that, although the coincidence is less  exact  between
the quantities of heat evolved and the atomic consti- 
94
THE REFRACTIVE POWER OF BODIES
tution of the remaining compound gases, it is  suffi-
ciently so to prove that hydrogen  and carbon contain
more caloric around their atoms than an equal weight
of oxygen; and that equal volumes of the  gases  do
not  afford  the same  quantities of caloric.   It must,
however, be admitted, that the results of Despretz are
at variance with those  of  Dulong  and Hess, as  he
found that alcohol, ether, and other compounds of car-
bon  and hydrogen, afforded  much  less caloric than in
the gaseous state.
  Let us next inquire whether the power of bodies to
refract light may not afford a measure of the relative
quantities of caloric  around their particles.   It was
suggested by Newton, at the close of both the Optics
and  Principia, that the  power of bodies to reflect, re-
fract and inflect light, is in proportion to the  quantity
of ether that covers their surface and surrounds their
particles;  which ether he also  regarded as the cause
of cohesion,  elasticity,  solution, capillary attraction
and  gravitation. For example,  he  found that in spirit
of wine, spirit of turpentine, olive oil, linseed  oil, cam-
phor and amber, which are highly inflammable bodies,
the power of refracting light was  two or three times
greater, in respect to their densities, than  in salts,
rocks, or any other  stony  concretes, which  are  less
combustible:  and as  it was higher in the  diamond
than in any other body which  he  tried, he arrived at
the conclusion that it was a sulphureous or unctuous
body coagulated, and would be found  inflammable.
(Optics, Book ii., pp.  240 and 200.)
  That there is at least a  nucleus  of truth in  this
hypothesis of Newton, would appear from the nume- 
      A MEASURE OF THEIR CONSTITUENT CALORIC.    9-5

rous experiments of Brewster, Wdlaston, Biot, Arago
and  Dulong, who  have found  that in phosphorus and
sulphur, as in all  those  bodies  which  are  composed
chiefly of hydrogen and  carbon, with various propor-
tions of oxygen and nitrogen,  the power of  refracting
light is much greater in proportion .to  their specific
gravities, than in any other bodies;  and we have the
most decisive proof that they contain proportionally
more caloric around their particles, as might naturally
have been inferred from all the phenomena of their
combustion,  volatility, and  tendency to  assume  the
gaseous state.   But, so far  as  I am informed, no  one
has  attempted to ascertain what  relation  exists be-
tween the latent caloric of  bodies and their refractive
powers, except my friend Mr. Dyar, whose views on
the  subject,  if ever carried out, have not been  pub-
lished.
   The most important experiments on the refractive
power of  gaseous  substances  with  which  I am ac-
quainted, are those of M. Dulong, published  in  the
Annates de Chlmie et de Physique, xxxi. 154; as in
the following table, which  represents their refractive
power and specific gravity, at the same temperature
and  pressure of the atmosphere,—to which I have
added their atomic composition.

                      TABLE I.
                      Refractive Power.
   Atmospheric air...................... 1-000  .....
        Oxygen....................... -924  .....
        Hydrogen....................  -470  .....
        Nitrogen..................... 1-020  .....
   Deutoxide of Nitrogen............. 1-030  N02
   Protoxide of Nitrogen............. 1*710  NO.
Specific Gravity.
....... 1-000
....... 1-026
......  -685
.......  -976
....... 1-039
....... 1-527 
96
EXPERIMENTS OF DULONG,  AND THE
                    Refractive Power.         Specific Gravity.
Carbonic Oxide...................... l*ir>7 C0 .......................   •)T-
Carbonio Acid........................ 1-626 C02....................... 1*524
Marsh Gas............................ 1*504 CH2........................555
OlefiantGas........................... 2-302 C2H2.....................  -980
Hydrocyanic Acid................... 1*531 NC2H....................  *944
Hydrochloric Acid.................. 1527 HC1...................... 1*245
Ammonia............................. 1*309 NH3.....................  -691
Chlorine............!............'...... 2-623 .......................... 2-470
Cyanogen.............................. 2-832 NC2....................... 1.818
Sulphuretted Hydrogen............ 2-187 HS....................... 1*178
Sulphurous Acid..................... 2-260 S02...................... 2-247
Hydrochloric Ether................. 3-720 C4H5C1................... 2-234
Phosgene Gas........................ 3-936 CO.C1.................... 3-442
Sulphuret of Carbon............... 5-110 CS2....................... 2-644
Ether.................................... 5-197 C,H50.................... 2-580
  From the above table we perceive, that there is no
uniform relation between the refractive power of gases
and what is called their specific heat, as admitted by
M. Dulong; while it is equally obvious,  that it is not
in proportion to their  specific gravity, nor to the size
of their particles.   It will be observed, however, that
the refractive  power of oxygen  is  nearly double that
of hydrogen, which is sixteen times  lighter: it there-
fore follows, that if their refractive powers be a mea-
sure of their  latent caloric, hydrogen must contain
about eight times more than an equal weight of oxy-
gen ; corresponding with  the difference between their
atomic  weights and  the relative quantities of caloric
they evolve during the process of  combustion.   It is
much to be regretted that we have  no means of ascer-
taining the  refractive power of carbon, separately, in
the gaseous state.  But as it is about three times higher
in carburetted hydrogen, and four times greater in de-
fiant gas than in simple hydrogen, we are  authorized to 
      AND THE CONCLUSIONS TO WHICH THEY LEAD.    97

conclude, that a pound of hydrogen contains six times
more caloric than the same weight of carbon;  or that
the  particles of each are  associated with the same
quantities of caloric.
   And as  the  refractive power  of nitrogen  is 2*17
times that of hydrogen, the specific gravity of which
is fourteen times less than that of nitrogen, it follows
that hydrogen  must contain 6*45 times more caloric
around its  particles than the same weight of nitrogen.
Nor can there be a rational doubt, that if the experi-
ments were rigidly  accurate, the refractive power of
hydrogen would be  just eight  times that of oxygen,
and seven times that of nitrogen;  consequently, that
the  true atomic weight of nitrogen is seven compared
with hydrogen, as maintained by Dalton and Berzelius,
instead of 14, as supposed by the majority of chemists.
And if such  be the fact, it follows, that hydrogen, car-
bon, nitrogen and oxygen,  (which are by far the most
important of all the elements, because the most active,
and because they are the principal constituents of or-
ganized  bodies,) contain the same  amount of caloric
around their chemical atoms.*

   *  There is, therefore, reason to believe, that when the refractive
power of all bodies shall be  rightly ascertained, we shall have a
more certain method of determining their atomic equivalents, many
of which are acknowledged to be doubtful; and that we shall be
able  to correct errors in regard  to the chemical composition of
bodies, that have arisen from imperfect analyses.   It must, how-
ever, be admitted, that in the present state of science, the refrac-
tive power of compound gases, liquids and  solids, does not always
correspond with that of  their constituents in the separate state; a
circumstance which may be owing in part to imperfect experiments,
and partly to the fact, that during nearly all chemical combinations
                          7 
98             EXPERIMENTS OF  BREWSTER.

  A still  more direct and cogent proof that  the re-
fractive power of bodies is in proportion to the amount
of caloric around their particles is, that it is higher in
water than in  ice, higher  in fluid than in solid sul-
phur,  as it is in all those  bodies which  are composed
chiefly of carbon and hydrogen, such as alcohol, ether,
the volatile and fixed  oils, than in water, the  specific
gravity of which is greater, as will be seen from the
following table, taken chiefly  from the experiments of
Sir David Brewster.   It will also be  seen, that  it is
higher in the  diamond, which consists of pure  carbon,
(condensed by an immense pressure,) than in any other
solid body, if we except phosphorus and sulphur, both
of which are highly inflammable, and afford very large
quantities of  caloric by combustion.

                         TABLE II.
REPRESENTING THE REFltACTIVE POWER AND SPECIFIC GRAVITY OF  DIFFERENT
        CLASSES  OF BODIES IN THE LIQUID AND SOLID STATES.
                             Refractive Power.  Specific  Gravity.
     Water......................................... 1-335          1-000
     Ice............................................. 1-307           -950
     Alcohol..........................'............. 1-372           -794
     Ether......................................... 1-358           -700
and decompositions, caloric is either absorbed or given out, as will
be shown hereafter.  But as we have found that in hydrogen, car-
bon and  oxygen, it coincides so nearly with the quantities  of caloric
they give out during combustion; and is nearly the same  in several
compound gases, when reduced from the refractive power of their
elements, the subject is one that merits the most careful investiga-
tion.   For if there be no uniform ratio between the refractive power
of bodies and their specific gravities, while in the best-ascertained
cases it accords with the quantities of caloric they afford by com-
bustion, it is difficult to resist the conclusion that caloric is the cause
of refraction, as it is of attraction and repulsion. 
EXPERIMENTS OF BREWSTER.
99
                                  Refractive Power.   Specific Gravity.
      Melted Beeswax...........................  1-450             -960
        "   Spermaceti........................  1-470             -940
      Oil of Lavender............................  1-457             -877
        "   Caraway.............................  1-491             -940
        "   Turpentine..........................  1-475             -890
        "   Camphor.............................  1-487             -988
        "   Lemon................................  1-481             -847
        "   Olives.................................  1-470             -910
      Castor Oil....................................  1-490             -969
      Melted Sugar...............................  1-555            1-500
      Gum..........................................  1-554            1-400
      Acetic Acid................................  1-396            1-062
      Malic Acid..................................  1-395            1-090
      Nitrous Acid.,..............................  1-396            1-450
      Nitric Acid..................................  1-406            1-480
      Sulphuric Acid.............................  1-440            1-840
      Phosphoric Acid...........................  1-544            2-687
      Rock Salt....................................  1-557            2-600
      Quartz........................................  1-548            2-600
      Garnet.......................................  1-515            4-000
      Calc Spar....................................  1-665            2-700
      Arragonite...................................  1.693            2-800
      Sapphire, blue..............................  1-794            4-200
      Arsenic.......................................  1-811            5-900
      Calomel.......................................  1-970            7-200
      Carbonate of Lead........................  2084            6-400
      Sulphur, native.............................  2-038            2033
              melted............................  2-148            1-990
      Phosphorus.................................  2-224            1-770
      Diamond.....................................  2-470            3 591
      Chromate of Lead......................... 2-926            6-000
      Mercury.....................................  5-000*          13-500

   * The refractive  power of mercury was determined by M. Arago
from its power of reflecting light.  But  it was supposed by Newton
that both refraction and reflection are owing to the same cause, and
that the one is a measure of the other.   Should this hypothesis be
well founded, we have an easy method of ascertaining the refractive
power of solid and opaque bodies.  That M. Arago has very closely
approximated  the truth in regard to mercury, would appear from
the high refractive  power of calomel, as determined by Brewster.
And that it is nearly the same in lead as in mercury, would appear 
100    THEORY  OF ISOMORPHISM  AND  DIMORPHISM.

   It has been recently discovered by the researches of
chemists, that  many bodies composed of different ele-
ments, the  atoms or particles  of which vary in size,
exhibit the same crystalline form, as in the  phenomena
of Isomorphism, from lao^, equal, and ftoptpy,  shape.*   It
has  been also ascertained that other bodies composed
of the same elements of ponderable matter  in the same
from the high refractive power of its compounds, as in the car-
bonate and chromate of lead; while it is well known that  gold,
platinum, silver, iron, tin, zinc and other dense  metals, reflect a
much  larger proportion of light  (when smoothly polished) than
the same surface of rocks, gems, glass, or the lighter metals; and
the latter  more than water, alcohol, ether or the oils.  It would,
therefore, appear that the  denser  metals contain from two to four
times  more caloric around their  particles  than an equal bulk of
water, but very much less  than an equal weight of water, sulphur,
phosphorus, or any of the compounds of  oxygen, carbon, hydrogen
and nitrogen.
   * In regard to the rationale of isomorphism, Mitscherlich laid
it  down as a law, that "the  same number  of  atoms combined in
the same way, produce the same  crystalline form, which is deter-
mined  by the number and position of the atoms, independent of
their chemical nature."  According to this view, the arseniate and
phosphate of soda,  the protoxides of iron, zinc, copper, nickel,
manganese and some other salts, are of the  same form, because
composed  of the same number of particles arranged in the same
manner.  But the  atomic weight of arsenic acid is one hundred and
fifteen, and of phosphoric acid, seventy-two. The seleniate of soda
is also identical in  form with the sulphate of soda, although the
atomic weight of selenic acid is  sixty-four, and that  of sulphuric
acid, forty.  It is  therefore not easy to comprehend why they pro-
duce  the same form on uniting with soda,  without supposing that
sulphuric acid contains a larger amount of caloric, around its par-
ticles,  the  volume of which  would be  thus increased, so  as to
approximate the magnitude of those of the selenic acid. 
OBSERVATIONS OF SCORESBY.
101
proportions, assume totally different crystalline forms,
as in the phenomena of dimorphism.
   For example, it was found by Scoresby, that in the
arctic  regions  water  congeals in an  almost  endless
variety of geometrical figures, of which he enumerates
five classes; the lamellar, the stelliform, (which is the
most general, and occurs chiefly when the temperature
is near 32°;) the regular hexagon, which becomes thin-
and diminishes in size as the cold increases; aggrega-
tions of  hexagons, which occur chiefly at low  tempe-
ratures; and lastly, combined ions of hexagons with spines
or radii.  (Arctic Regions, vol. i. p. 432.)  It is also re-
lated by Dr. Daniel Clark, that on one occasion at St.
Petersburg, when  the temperature of the air was five
degrees below the freezing point, every particle of snow
which  he examined consisted of a wheel or star, with
six equal rays,  bounded by circumferences of equal
diameters.   They all had the same number  of rays
branching from the centre; and were about the size of
a pea divided into two equal parts.  (Travels  in Russia.)
When  this subject is better understood, it will be found
that those  crystals of snow which are found  at the
same time, in  still weather, and  at the same  tempe-
rature, have generally the same form; but when pro-
duced  at different times, and at different temperatures,
they exhibit different  forms;  of which Koenitz  thinks
there are several hundred; and many of which  he has
observed that  were not figured by Scoresby. (Meteor-
ology, p. 131.)    It is therefore  clear, that the form of
crystals depends on the arrangement of their particles,
and not on their essential nature.  But if it be a fact
that  caloric  Is the agent which regulates the distance 
102
OBSERVATIONS  OF SCORESBY.
of atoms or particles from  one another, and causes all
their movements, whether of union or separation, it must
obviously determine the various modes of their arrange-
ment, whether in the solid,  liquid or gaseous states.  And
as the  atomic composition of water  in  every state is
the same, it is impossible  to comprehend why it should
assume various crystalline forms, as observed by Kep-
ler, Cassini and Scoresby, without admitting that its
particles are  surrounded with different quantities of
caloric, on assuming these different forms.*

  * The various crystalline forms are now generally arranged in
six divisions or systems, as in the following classification by Gustav
Rose:  1. The cubic  or tessular.   2. The square prismatic, (in
which the  lateral edges, like  the terminal planes, are parallel.)
3  The rhombohedric.  4.  The right prismatic.  5.  The oblique
prismatic.   6. The doubly oblique  prismatic.
  In all crystalline bodies the form is angular, and the arrangement
of their particles rectilinear.   In those of which all the sides and
angles are alike, the expansion by caloric is equal in all directions,
as in the cube, the regular octohedron, and the rhomboidal dodeca-
hedron ; and the refraction of  light  is single, when they are of uni-
form temperature and density, as it is in the  transparent gases,
vapours, liquids and glass.  But in the square prismatic and rhom-
bohedric classes, the expansion by caloric is dissimilar in two direc-
tions ; while in the  right prismatic,  the oblique prismatic, and the
doubly oblique prismatic, it is  dissimilar in three directions.  And
when  a ray of light is made to pass through any of these bodies,
or through  glass unequally cooled,  and solids of unequal density,
whether from unequal temperature  or  pressure, it is refracted in
two different pencils,  more or less inclined to one another, accord-
ing to the molecular arrangement of the body, and the direction in
which the pencil is  incident; thus producing all the phenomena of
double refraction, which also occurs when it passes through resins,
gums, jellies, horn, shells, bones, elastic  integuments and animal
lenses.  Whenever a  ray of light is  thus divided, one of the trans- 
CAUSE OF DIMORPHISM.
103
  It has been also discovered  by Rose, that  at the
temperature of  50°,  carbonate  of lime assumes the
form of rhombohedric crystals, as in calc spar; whereas,
at the temperature of 150°, it takes the cubic form, as
in arragonite, the composition of which is the same.
And when rhombic crystals of calc spar are heated to
212°, they are changed to the cubic form, without any
change in its chemical composition,—if we except the
addition of caloric, which is the cause of all molecular
aggregations, and therefore the creator of forms.  Cor-
responding with the foregoing facts, Mitscherlich has
shown  that the mutual  inclination of the crystalline
planes in calc  spar is altered eight and a half minutes
of a degree between the temperature of 32° and 212°;
while in other cases it  varies nearly 1° in different spe-
cimens of  the same  salt.   For a full account of his
discoveries, see Ann. de Ohim. et  de  Phys., tome xiv.
172;  xix. 350;  xxiv.  264, 355.
   In accordance with  the above facts, it has been dis-
covered that  on crystallizing  from  solution  in the
bisulphuret of carbon, or oil of turpentine, at  tempe-
ratures below 100°, sulphur  assumes  the  octohedric

mitted rays is said to be polarized; that is, its properties  are  so
far changed that it is incapable of undergoing reflection or refrac-
tion, except at certain  angles ;  or of transmission through  trans-
parent bodies, except  in particular positions.   For example,  a
plate of tourmaline permits the ray to be transmitted in one posi-
tion, but in a position  perpendicular to that  it arrests and stifles
it, because in these two rectangular directions its  particles are
differently arranged.   It is therefore manifest that all the phe-
nomena of crystallization, the  reflection, refraction, double refrac-
tion, polarization, and doubtless the diffraction of light, are imme-
diately connected with the theory of caloric. 
104      NUMBER  OF THE  PRIMITIVE ELEMENTS.

form, with rhombic bases; but that when melted by
itself and allowed to cool slowly, it takes the form of
an oblique rhombic prism on solidifying at 230°.  (Gra-
hanis Elements of Chemistry, p. 189.)  It has also been
ascertained that  pure  carbon occurs in  the form of
regular  octohedrons, as in the diamond, but in six-
sided plates  in  graphite.   And Professor Johnston
has recently shown that there is a large  class of bodies
composed of the same  elements in the same  propor-
tions, which crystallize in two, if not more primitive
forms.  But since the time of Dr. Black,  chemists have
attended so little  to the agency of caloric in the vari-
ous transformations of matter, that they have scarcely
ranked  it among their elements, although it consti-
tutes by far the largest proportion  by volume of solid
bodies.
  Among the most civilized nations of  antiquity, it
was  supposed  that everything  in nature  is composed
of four  primitive elements, which they termed  earth,
water, air and fire; to which Aristotle  added a fifth.
But  the tendency of modern science has been  to in-
crease the number, until it has  extended to sixty-two,
all of which are regarded as simple, because chemists
have not yet been able to resolve them into fewer ele-
ments.  There is  reason, however, to believe that none
of our chemical atoms and elements are perfectly sim-
ple, if we except caloric, which also exists in a great
variety of states, as will be shown hereafter; and that
it is  only in the  subtilized form of light that we can
hope to discover  the ultimate constitution of ponder-
able  matter.*

  * For example, if it be true that all the reputed elements are 
        LIGHT IDENTICAL WITH  PONDERABLE MATTER.   105

    In  accordance with  the hypothesis  advanced  by
 Newton in one of his  Optical Queries, that light and

 convertible into  light, and that light is decomposable into  seven
 primitive rays by prismatic refraction, as maintained by Newton, or
 into  only three fundamental  colours, when analyzed by absorbent
 transparent  media, as maintained by Brewster, it will follow that
 what we call simple bodies are composed of one, two, three or more
 of the  primitive  elements which constitute white light.  Now it is
 worthy of remark, that hydrogen is the  most elastic of all gaseous
 bodies, and  affords  during combustion an almost perfectly blue
 light; while, according  to the experiments of Newton, the blue
 rays  are more refrangible than  any others except  the violet, which
 is not a simple colour according to Brewster, but composed chiefly
 of blue, with small  proportions of yellow and  red; which he re-
 gards as the three primitive rays, and the elements of all compound
 colours.   It  is therefore  probable that the blue and violet rays are
 more refrangible  than the others, for the same reason that hydro-
 gen,  of which they are formed, is the  most elastic of all known
 bodies,  viz. because it contains more  caloric around  its particles in
 proportion to their  size.  And it was  supposed  by Newton that
 the atoms  of light diminish  in  size from the red to the violet ex-
 tremity of the spectrum.  Again, as sulphur burns with a blue, and
 iodine with a violet light, (which contains small  proportions of the
 other rays,) they  may be  composed chiefly of hydrogen, with some
 other base or bases;  and cannot be otherwise decomposed than by
 expanding them into the subtile form of  light. On the other hand,
 during the combustion and ignition of potassium, strontium, lithium,
 sodium  and magnesium,  they afford chiefly red light, with  small
 proportions of the other coloured  rays;  therefore must all be
 composed principally of one element, the primitive atoms of which
 are red, while those of hydrogen (which is the basis of sulphur,
 iodine, and perhaps  some other bodies,) are blue.  Chloride of
 sodium  also  affords an  orange-coloured light; while in that of
 chlorine, silver, copper and some  other  bodies, there is a predo-
 minance  of greenish rays; so  that  if green light be composed
chiefly of yellow  and blue, as maintained  by Brewster, all bodies
that burn with a  green light  must be compounds of two or  more 
10G   LIGHT IDENTICAL WITH PONDERABLE MATTER.
 common  matter are  mutually convertible into  each
 other, it has  been recently maintained  by Sir David
 Brewster, that " the particles of light are Identical with
 the ultimate atoms of bodies, and that there is a specific
 affinity between definite atoms and definite rays, though
 we  do not  understand its nature."*  (Transactions of
 the Brit. Association, vol. i. p. 231.)  He  also observes
 in another work, that " when a portion of light enters
 a body, and is never again seen, we are entitled to say
 that it is  detained by some power exerted over it by
 the  particles of the body; that it enters into chemical
 combination with them, and produces the various che-
 mical effects by which their colours are changed, and
 the  juices of plants elaborated,"—to which  he  adds,
 " It  is not easy to allow that such effects  are produced
 by undulations of an ethereal medium.  (Optics, chap.
 xxxiv.)
  That every description of  ponderable  matter is ac-
 tually convertible  into light  by a  sufficiently intense
 heat, or by electricity, will appear  from the following
 undeniable facts:—
  1.  That the quantity of light generated by ordinary
 combustion, friction or percussion, is  always in  pro-

 primitive elements; while others, again, which afford different pro-
 portions of all the coloured rays of the spectrum, are still more
 complex.
  * A similar doctrine seems to have prevailed among the ancients,
for the sceptre of the Egyptian Pthah was painted with four colours,
which were attributed to the four elements.  Plutarch also says,
that Pythagoras maintained the existence of four primitive colours,
and that Zeno regarded colours as the first configuration of mat-
ter; while, according to Plato, they are produced by the reflection
of light from bodies to our eyes. (De Placet. Philosophorum.) 
        CALORIC THE ACTIVE PRINCIPLE  IN  LIGHT.     107

portion to the rapidity with which ponderable matter
is ignited and volatilized.
  2.  That the colour of light  thus produced  always
depends on the species of matter employed.
  3.  That the electric  spark, like that produced by
the collision of flint and steel, consists of exceedingly
minute portions of ponderable matter in a  state of in-
candescence, as will be shown hereafter by the decisive
and beautiful experiments of Fusinieri.
  4.   That  when the  electric fluid is  transmitted
through the vacuum of  an air-pump, little or no light
is produced, as proved by the experiments of De Luc,
and afterwards by those of Sir H. Davy.
  5.  That the most intense heat of  a voltaic  battery
never produces any light, except when  acting  on pon-
derable matter; consequently, that light and heat are
not identical,* as maintained  by some  modern theo-
  * That caloric is a constituent of light, (as it  is of all  other
bodies,) and is the active principle in  its generation, is evident
from the fact, that the most refractory gems and metals are trans-
formed into luminous incandescent particles by a sufficiently intense
heat, definite measures of  which are required to produce the effect
on different  species of matter.  It has also been proved by the ex-
periments of Hulme, Dessaignes, Macartney and others, that every
species of phosphorescence is promoted (for a time) by moderate
heat, and always extinguished by the coldness of freezing mixtures;
while  others have  found that the light of luminiferous insects  is
much  greater in vessels of oxygen gas than in common air.   But
that  caloric is  a  distinct  essence, and may exist  independent  of
light,  is manifest from the  fact, that  it converts solids into liquids,
vapours and gases, in the midst of perfect darkness; while it radi-
ates from the earth during night, as it does from  boiling liquids
and other hot bodies, without being attended with any light. 
108         CHEMICAL AGENCIES OF LIGnT.
  rists; and that  neither of them is generated  by the
  mere vibrations  of an ethereal medium.
    In accordance with the foregoing facts, it has been
  found that each of the primitive rays produces specific
  changes of colour  in  different  bodies; that the blue
  and  violet rays  of the spectrum change the white
 chloride of silver to a dark-violet hue;  whereas the
 red rays change it to a rose colour; and that the same
 change of colour is produced on  the protochloride of
 lead  and the  oxide of mercury, when moistened  and
 exposed to the red  rays of the spectrum, as in the ex-
 periments of  Scheele, Sennebier, Davy and Seebeck:
 —that a piece of white paper stained  yellow  with a
 solution  of guiacum in alcohol, was turned green in
 five minutes  by  exposure  to  sunshine, but remained
 unaltered for  several months in the dark; and that
 when the yellow paper was made green by exposure
 to the violet rays, its original colour was  restored by
 exposure  to the  red  rays of the spectrum, as  shown
 by the experiments of Wollaston.
   The chemical agency of light is still more strikingly
 illustrated in the production of those accurate pictorial
 delineations of objects termed Daguerreotypes,  which
 are formed by the  immediate influence of the  regal
 sun.   Moreover, that there is "a  specific affinity  be-
tween definite atoms  and definite rays,"  is evident
from  the  fact, that  bodies  repel and  reflect certain
rays,  while they attract and absorb others.  For ex-
ample, it was  found  by Sir David Brewster, that red
transparent solutions and  glasses permitted the red
rays of the spectrum to pass freely through them, but 
DECOMPOSITION  OF  LIGHT.
109
absorbed and obliterated the other rays;* that  blue
media  permitted  rajs  of the  same  colour to  pass
through them, but absorbed the other rays;  and  that
green  media absorbed the rays at both extremities of
the  spectrum,  but the  red most  where  it verges to
blue, and  the violet  most where  it verges  to yellow.
Nor is it more remarkable, that bodies should  absorb
one or more primitive  rays,  and reflect or  transmit
others, than that certain elements of ponderable  mat-
ter should  have an elective  affinity for some, and an
antipathy for other elements;  the rationale of which
is doubtless  the same  in both cases, and  must be
sought in the fact, that as the  different rays of light
are of different temperatures, so  are the elements of
ponderable matter associated with different quantities
of caloric.   And it will be found hereafter, that no
chemical union of bodies ever takes place without the
  * If in our cathedrals, colleges and other public buildings, were
judiciously placed a few windows composed of perfectly red, yellow
and blue glasses, (to which might be added combinations of these
colours,)  the mind would be elevated, refined and instructed, on
beholding such a vivid display of all that is most beautiful in light,
when thus decomposed, and reduced to its primitive elements.  The
effect would also be much improved by arranging the colours so as
to produce an imitation of the rainbow; to which might be added
other appropriate symbols, and  even inscriptions, written in letters
of light.  Never shall the author forget  the emotions of delight
and admiration he experienced on first looking at the sky through
a fine ruby  glass,—when it presented the appearance of  a vast
dome of lurid flame; and the whole face of the earth, as if by en-
chantment, was  suddenly dyed of a gorgeous crimson  hue.  We
little think how  cheaply some of the highest pleasures of existence
may be purchased. 
110          CHEMICAL UNION OF BODIES.
 transition of caloric from one to the other, attended,
 in most cases, with a change of temperature.
   But if the ultimate atoms of  ponderable matter be
 identical with those of light, and the latter consist of
 seven  primitive rajs, as supposed  by Newton, it fol-
 lows that the sixty-two elements enumerated by che-
 mists are not simple bodies, but compounds of two or
 more primitive elements, as before suggested; or, that
 if light consist  of only  three primitive rays, united
 with caloric, everything  in nature must be composed
 of four elements.   Nor  is it possible to admit with
 Newton, that the  blue and  indigo are distinct primi-
 tive rays;  while it is certain that all the known varie-
 ties of colour may be produced by combinations of red,
 yellow  and blue; which, as Brewster has shown, over-
 lap each other, and reach quite across the spectrum.
  What then becomes of the enormous quantities of
 light perpetually radiated  throughout  the solar sys-
 tem?   This is doubtless one of  the most curious, im-
 portant and  comprehensive  problems  in  the whole
 range of physics, and deserves the profoundest atten-
 tion of philosophers.   One  thing is  certain, that if
 light be matter, it cannot be annihilated, any more
 than the  great  fountains from which it  emanates;
 that whatever falls upon the  earth, and is not reflected
 or radiated from it into surrounding space, must com-
 bine with, and become  a constituent portion of its sur-
face; that certain  rays produce  specific chemical and
vital effects; while  the  various powers of different
bodies  to decompose white light by absorption, trans-
mission, reflection,  refraction and polarization, cause
 an endless diversity of colours.   Light, then, is not 
COSMICAL  PHENOMENA OF LIGHT.
Ill
only a revelation of all that is grand and beautiful in
the outward universe, but the agent by which all its
operations are carried  on.  It is  therefore probable,
that when fully  understood, it will enable us to  ex-
plain whatever is  now mysterious in  the  ultimate
mechanism and laws of nature.
   And if "the particles of light be identical with  the
ultimate  atoms of  ponderable matter,"  the question
naturally arises, whether all the planets  and satellites
of our system may not be so many masses of embodied
light, which is first aggregated into nebulae, and then
into comets, that go on gradually augmenting in size,
by constant additions of light, until, after enormous
periods of time, (compared with which our geological
epochs are mere fractions,) they arrive  at maturity,
or until,  by the expenditure of his substance, the  sun
is so far  reduced in magnitude, that the  centrifugal
power of his rays becomes inferior to the  centripetal
pressure  of the surrounding ether—when they would
gradually approach, and finally in succession fall into
the  sun?  In short, whether the ponderable matter
of  the sun and  fixed stars  is not  perpetually  ex-
panded by caloric into the subtile form of light, which
is as constantly reconverted into the matter of planets
and satellites.
   This theory enables us to answer the important
question, "What becomes of light?" while  it affords
a more intelligible explanation of the manner in which
cosmical  bodies are generated  and finally destroyed,
than any merely metaphysical  hypothesis—unless by
metaphysics we understand the universal Science of 
112          COSMICAL PHENOMENA OF  LIGHT.
Ontology,,  or of whatever  exists.*   It also  enables us
to comprehend why the  distances of the planets from
   *  The periodical creation, destruction  and reorganization  of
 worlds, was a fundamental doctrine of the ancient Hindu cosmogo-
 nists, who maintained that they are all emanations from the eternal
 Brahm, and that after enormous periods of time they return to the
 primitive source of their existence.  But the mighty Brahm was
 a personation of the entire  universe, in its two-fold character of
 spirit and matter, or nature  active and passive.  In the Vidds, the
 eternal Brahm is represented as perpetually sacrificing a portion
 of his immensity in the formation of worlds, which  he  creates and
 recreates  for the purpose of  multiplying  happiness.   According to
 this ancient theory, the universal Brahm comprehends the innu-
 merable fixed stars or suns that throng the infinitude of space, and
 from which  proceed myriads of  planetary systems in endless suc-
 cession.   In the Rich  Vidd, the solar orb  is invoked as  "the god-
 head from whom all proceed, and to whom all must return;"  as
 we are  informed by Sir William Jones.  In regard to what is said
 in the Puranas, concerning the sleep of Brahma, during which the
 universe, after having existed for countless ages, fades away into
 an invisible  state, and again  emerges into being when he awakes—
 it must be viewed as the dream of oriental transcendentalism, or as
 an allegorical account of those cosmical revolutions described by
 Sallust, who tells us that in the course of certain vast periods, the
 whole  universe undergoes mutations which are equivalent to the
 entire destruction of worlds, and the formation of others from their
 ruins.  (De Diis et Mund., c.  vii., xvii.)  The same doctrine (which
 is in actual  accordance with all known  analogies in nature) may
 be found in the third book of Seneca's Natural Questions.
   We are further informed  by Diogenes Lanteus, that  according
to Herachtus, all things were originally formed from  fire, which, in
its ordinary state of flame,  is light.  And  we read in the  first
chapter of Genesis, that light was created  before the earth or the
sun, moon and stars.   The fact is, that in all the ancient cosmogo-
nies, light is represented as  the  first of created  things.   Among
the Egyptian sages, it was the first-begotten of  Osiris  and Ms,
who were personations of spirit and  matter, or of the active  prin- 
C0SMICAL AGENCY OF  LIGHT.
113
each other  augment in  nearly  definite  ratios, from
Mercury to  Uranus; why they increase in magnitude
(if we except Mars and  the asteroids) from Mercury
to  Jupiter;  and why their  equatorial exceeds their
polar diameters.  For example, it  is  probable  that if
light obey the same laAvs as other  projectile bodies, a
much larger proportion of what is radiated from  the
sun would lose  its  original force and velocity at  the
distance of  Jupiter,  Saturn  and Uranus, than at that
of any one of the  planets  nearer to the sun; so that
a  corresponding amount of luminous matter would be
aggregated into comets, which  may successively  fall
into those great masses  and  their satellites,—in the
same way that  many thousand  meteoric  stones, and
ciple in nature, and the passive matter out of which everything
was formed.  In the Orphic Hymns, light is called Ttpwroyovoq, or
first-begotten of the ether and chaos, which the ancients universally
regarded as the origin of all things.  Nor is it more  difficult to
comprehend the generation of worlds from the matter of light,
than their creation out of nothing—a doctrine which involves the
incredible supposition, that during the whole eternity that preceded
the act of creation, the Deity existed alone in the vast solitude of
his own immensity unemployed.  It is far more in accordance with
the attributes of infinite wisdom and goodness that belong to the
author of the universe, to suppose that he  has been  always em-
ployed in the creation of worlds, and  the diffusion of happiness,
than  that he should have commenced at some finite period, or, as
the Brahmans tell us, that he should suffer them all to fade away,
fall into a periodical state of practical nonentity.   As to Laplace's
theory, that the  planets of our system were formed by a gradual
contraction of the sun's atmosphere, there is no assignable reason
why the sun should have thrown off such an atmosphere at one
time  rather  than at another.   Nor would such  an  atmosphere, if
aggregated, form the smallest satellite of our system.
                            8 
114     RADICAL DEFECTS OF THE  AVAVE THEORY.
  showers of stones, have fallen from unknown  heights
  upon our planet, since the historical era,—a fact which
  clearly demonstrates that the earth has been augmenting
  in six, Independently of the  constant additions  of mat-
  ter it receives from the sun in the form of light.  And
  as it is equally evident  that the tropical portion of
  planets receives much greater quantities of light from
  the sun than the middle and polar latitudes, this fact
  affords  a more  satisfactory reason  for their equatorial
  protuberances than the prevalent theory, which refers
  them to the rapid  diurnal motion of their equatorial
  zones.
    If the  foregoing views  be well founded,  it follows
 that light, in connection with caloric, which  is the ac-
 tive  principle  in its generation, and  always forms a
 constituent portion of it, is the primitive basis of all
 material existence,—or the physical Ens cntlum; con-
 sequently cannot be resolved  into the  mere vibrations
 of an ethereal medium, as maintained by many distin-
 guished mathematicians of the present age
   That  the vibratory theory  of light is not a true re-
 presentation of  nature, would further appear from the
 following considerations:__
   1.  That it does not  explain what the ether is, nor
 what causes it to vibrate.
   2.  That light is propagated in straight lines, and
 will not  pass through a bent tube; whereas vibrations
 move around interposing bodies, which  obstruct the
 passage of  light, as maintained by Newton

rntt Tllf1thi!+Wre the°ry d0GS not exPlain the  gene-
ra ion of light  by combustion, ignition, friction and
peicussion; how it is connected Avith caloric and elec 
        RADICAL DEFECTS OF THE WAVE THEORY.     115

tricity; nor why ponderable matter is essential to its
production.
  4. That it  does  not explain the decomposition  of
light by prismatic  refraction, absorption  and trans-
mission ; nor  how it modifies the chemical and vital
properties of ponderable matter;  Avhile  "it leaves the
Avhole subject of colours, both in  opaque and trans-
parent bodies, involved in profound obscurity."  (Whe-
well.)
   5. That in  adopting the theory of undulations,  "we
are called on for acts of faith, and  certain admissions
must be made at every step," as acknowledged by Sir
John Herschel, who is certainly one of its ablest advo-
cates.
  6. That as  the different colours of light depend on
the species of  ponderable matter employed in its gene-
ration, they cannot  be  resolved into different numbers
of ethereal vibrations.
  7. That when a sunbeam impinges  on objects, it
produces  mechanical,  chemical  and vital changes;
causes pain and inflammation of the eyes; alters the
colour,  taste,  odour and other sensible properties  of
bodies; effects which cannot be  reconciled with the
hypothesis that light is not a material substance.
  The radical defects of the wave theory have been
disguised by an imposing array of  algebraical formulae;
Avhile the most important facts connected with its his-
tory have been overlooked, or intentionally neglected;
and  that  it is exceeding difficult  to understand,  is
admitted by Mr. Whewell.  In short, the amount of
mathematical  reasoning brought  to its support, would
seem to be inversely as the number of facts on which 
116     RADICAL DEFECTS OF THE WAVE THEORY".
it is based:  for the ATeiy existence of the ether is as-
sumed; Avhile its Aibrations are made longitudinal or
transverse, just as the phenomena may require.  And
it might as  Avell be  said that  the first  mover in the
steam engine is motion, as  that light consists  merely
in the vibratory motions of an  ether. 
CHAPTER  III.
 ON  THE LAW BY WHICH  CALORIC PRODUCES THE  OPPO-
   SITE  FORCES   OF  ATTRACTION  AND REPULSION,  CON-
   TRACTION AND EXPANSION.

   " That alone is true philosophy which repeats the words of the
 universe with fidelity, and is written, as it were, by dictation of the
 universe."—Bacon.

   The doctrine  that everything in nature is composed
 of tAvo descriptions of matter, the  one essentially ac-
 tive  and ethereal, the other  passive and motionless,
 Avas recognized  by the most acute and profound  sages
 of antiquity in  every quarter of the civilized world.
 But  notAvithstanding  they all  regarded  elementary
 caloric as the prime mover, they seem to have  over-
 looked the law  by which it repels its  own particles,
 and  tends to combine Avith those of  ponderable matter,
 with forces that vary inversely  as  the  squares of the
 distance, so as to produce all the centrifugal and cen-
 tripetal  forces of nature.   The  same observation ap-
 plies equally to  Bacon, Descartes, Newton and other
 modern  philosophers, who,  although they sometimes
 referred all the operations of nature to what they called
 a .spirit or pneumatical body, a  materia subtil Is, a subtile
ether, &c, they  never identified it with any known
principle, nor explained how it causes both attraction
and repulsion, union and separation.
                                          (117) 
118        CALORIC A  SELF-ACTIVE PRINCIPLE.
  Why then does caloric repel its own  particles, and
attract  those  of ponderable  matter, with forces  that
vary  inversely as the  squares of the  distance?   To
this primary and leading question I answer, that ca-
loric repels  its own  particles because they are of the
same nature, and attracts those of ponderable matter
because they are of  a totally different nature;  that in
every variety of state  caloric is  an essentially active
principle, and incomparably more refined than  any
description of ponderable matter, even when expanded
into the subtile  form of light;  for it  permeates the
most dense  and opaque bodies, which  are wholly im-
pervious  to light.   And that the forces  of  caloric
diminish  in proportion as the  squares of the distance
augment, is obvious from  the fact, that all ethereal
emanations are necessarily diffused in the same ratio,
on  radiating from any  given  centre.*
   That atoms of the same nature  repel one another,
and attract those of a  different nature, would  appear
from the best-known  phenomena  of  chemistry and
physical optics.  For example,  it  has been long  known
that  similarity of properties among the elements of
ponderable  matter causes them to repel each other, as
if by a mutual antipathy; but that diversity  of pro-
perties is favourable to chemical  combination.  We
  * It would  therefore seem to follow, that there must be a limit
to  the diffusion of caloric; that  it is not infinitely subtile  and
divisible ; but  that there must be a definite number of particles in
any given quantity of it.  It is only by its extension throughout
illimitable space that it can be  regarded as infinite; for we shall
find that, while it governs all the  operations of the material uni-
verse, it is itself governed by invariable and necessarily fixed laws. 
   RELATIONS OF CALORIC AND PONDERABLE MATTER.   H9

 have also found that transparent media transmit rays
 of light of their own  colour, but  attract and absorb
 those of different colours.
    That  caloric is a self-active principle  has been al-
 ready shown by its power  of moving itself, and  of
 giving motion to other bodies, the activity of which is
 augmented by every addition, and diminished by every
 abstraction of  heat;  proving, that if the particles of
 ponderable matter could be wholly deprived of caloric,
 they Avould be passive and motionless.   At the  same
 time it is highly probable, that if universal space were
 filled Avith caloric alone, (without any ponderable mat-
 ter,) it Avould also be inactive, and constitute a bound-
 less ocean of poAverless or quiescent ether, because it
 would then have nothing on which to act.   And  Ave
 shall find that, however inactive of itself, ponderable
 matter has certain properties by which it  modifies and
 controls  the  actions of caloric, both of which are go-
 verned by  immutable  laws that  have their origin in
 the mutual relations and specific  properties of each.
   I now  proceed to show, that all the expansions and
 contractions of gaseous bodies depend on the relative pro-
portions of cedorlc and ponderable matter of which they
 are composed.  For example, the atoms of hydrogen
 are smaller, and contain a larger  amount of caloric
 around them, in proportion to their size, than those of
 any other gas;  the  consequence of which is, that its
 elastic force is such, that no mechanical pressure hith-
 erto employed has been sufficient to condense it into
the liquid form.*  And  it was found by Perkins,  that
  * Under the pressure of the atmosphere, and at the temperature
of  60°, hydrogen is 15,480 times lighter  than water, the pores of 
121)           CONTRACTION AND EXPANSION

atmospheric air  (which is  composed  of oxygen and
nitrogen in  a state of mechanical mixture) may  be
submitted  to a  pressure  equal  to 1200  atmospheres,
without being perfectly condensed into the liquid form.
(PhilosophIced Transactions, 1826.)
   But Avhen three volumes of hydrogen  unite chemi-
cally Avith  one  of nitrogen, they contract  into two
volumes of  ammonia, the elastic force of which is  so
far diminished that it may be condensed into the liquid
which are 40 times  larger than its solid particles, according to
Newton.  It is therefore evident, that the pores of hydrogen exceed
the diameters of its particles several thousand times, and, perhaps,
to the same extent, that  the  spaces between the different planets
exceed their mean diameters.  What, then, is the cause of the stu-
pendous force by which the particles of hydrogen are kept at such
comparatively great distances from one another ? Is it some virtue,
property, or  condition termed polarity?  Or is it owing to the
existence of certain hypothetical immaterial spheres of repulsion
around its particles ?  Is it possible that masses, and the atoms of
which they are composed, are capable of acting upon each other at
comparatively great  distances without an  intervening medium ?
That the volume of gaseous bodies is augmented by every addition
of caloric, has been proved by the experiments of Gay-Lussac, who
found that 1000 cubic inches of common air were expanded to 1375
cubic inches by raising its temperature from  32° to 212°. It was
further ascertained by Dulong and Petit, that the same law of ex-
pansion is true of atmospheric air and hydrogen, up to the tempe-
rature of 680° ;  from which they concluded, that it was true of all
gases, and at all temperatures. (Ann. de Chim.  et Phys., vii.  120.)
Dr. Dalton also found that the elastic force of  steam was equal to
the weight of the atmosphere at 212°, but was equal  to  the pres-
sure of six atmospheres when raised to 320°.   And we learn from
the experiments of Perkins, that when water  is confined in very
strong vessels, it expands with a force equal  to the  pressure of 20
atmospheres when raised to the temperature of  419°. 
OF GASEOUS  BODIES.
121
state by a pressure equal to 6*5 atmospheres, or by cold
alone at the temperature  of 46° below 0° F.  And
when iavo volumes of nitrogen combine with one of
oxygen, the elastic force of the resulting compound gas
is so far diminished, that it may be liquefied by a pres-
sure equal to 44  atmospheres  at the temperature of
82°, as first shown by the experiments of Sir H. Davy;
or by a pressure  equal  to 50 atmospheres at the tem-
perature of 45°, according to Faraday.  What then is
the  rationale of  these curious phenomena?  Is  the
sphere of repulsion in the elementary gases exchanged
for one of attraction as they  unite chemically, with
contraction of  volume  and diminution of elasticity?
Or  how  many immaterial and imaginary spheres of
attraction  and  repulsion are required to explain the
phenomena of solidity, liquidity and vapourization ?
The summary answer to these queries is, that "the self-
repulsive power of caloric is counteracted and diminished-
by its affinity for ponderable matter, by which the ethe-
real atmospheres are drawn into a smaller compass.  The
reduction of volume and  elastic force are  referable
Avholly to this one cause.
  Perhaps the  principle cannot be  better illustrated
than by a consideration of  the  statical and dynamical
changes that are produced  on hydrogen and  chlorine,
by their mutual action upon each other.
  We have seen,  that the specific gravity and atomic
AAreight of chlorine are 36, compared  with hydrogen as
one; and that the elastic force of hydrogen is immense.
It has  been also  shoAvn by Faraday, that  the elastic
force of chlorine is so Ioav that  it may be liquefied by 
 122         EXPANSION AND CONTRACTION

 a pressure equal to four  atmospheres at the tempera-
 ture of 60° F.
   But when one volume  of chlorine is made to unite
 Avith one of hydrogen, they form two volumes of hydro-
 chloric acid gas, the specific gravity of which is 18o;
 or a mean between that  of its constituents.  During
 this combination, the hydrogen loses the greater part
 of its elastic force, while that of the chlorine is greatly
 augmented.  That is, a definite proportion  of  caloric
 passes from the smaller atoms of hydrogen to the larger
 atoms of chlorine, by ivhlch  the latter are  removed far-
 ther from  one another.   Nay more,  it  is by virtue of
 this  transfer of caloric that  the atoms of  hydrogen are
forced  Into chemical union  with those of  chlorine, and
 their separate Individuality destroyed.   In other Avords,
 all the above changes, including  that  by Avhich the
 gases are  united and identified, are referable Avholly to
 the transition of caloric from the one to  the other.
   It will  be shown hereafter, that  no chemical  combi-
 nation of any one body with another ever takes place,
 without a simultaneous passage of caloric or electricity
 from one to the other; that if  water and  other liquids
 could exist as such without caloric,  (which is  impos-
 sible,)  they could not combine with  salts, metals and
 rocks; and that the diminution of  bulk which attends
 the  combination of liquids with solids, is owing to the
 same law which determines the reduction of volume
 and elastic force of gases and vapours.  The most
 simple illustration of combination  effected  by  the at-
 traction of caloric  for ponderable  matter,  is that by
 which steam  is condensed by water or  ice, and inti-
 mately combined with their particles.  When a certain 
OF GASEOUS  BODIES.
123
proportion of steam is mixed with cold water, its vol-
ume and elastic force are destroyed by the same attrac-
tion of  caloric  for ponderable  matter which causes
liquids to combine Avith, and dissolve solids, or which
causes gases to  combine chemically, with contraction
of A^olume and diminution of elastic force.
   There is no limit to the application of this doctrine
in the phenomena of chemistry.
   If a piece of  ice be introduced into a vessel full of
ammoniacal gas, the latter disappears rapidly, and the
ice is melted, forming a chemical solution of ammonia.
Now it is obvious, on a moment's reflection, that the
volume and  elasticity of  the ammoniacal gas are de-
stroyed  by the  transfer  of caloric from one to  the
other.   It is equally true, that the ammonia is che-
mically combined with the ice by the same attraction,
as will  be  proved when I come to treat of chemical
solutions.  Again, if one  volume of hydrochloric acid
be mixed with one volume of ammoniacal gas, they may
be made to combine rapidly with evolution of  much
heat, when they lose the gaseous or elastic state, mak-
ing a solid crystalline salt, (sal ammoniac,) of a cubical
or octohedral form.   The atomic weight of the acid is
37, and  that of the alkali 17.  (See Table of Atomic
 Weights, p. 67.)
   In this case, there is an attraction of caloric for the
larger particles  of the acid, by which those of the am-
monia are forced into chemical combination with them,
forming compound  particles of  still  larger size, the
weight of Avhich  is 54, compared  with hydrogen as
unity.
   Thus it is evident that the repulsive power of caloric, 
 124         CONTRACTION AND EXPANSION

 on which the volume and elastic force of gases depend,
 is counteracted and diminished by its affinity for pon-
 derable  matter, and that this attraction augments in a
 certain  ratio as the size of the particles increases, until
 it wholly predominates over  the repulsive force.   The
 atoms of hydrogen, nitrogen, oxygen and light carbu-
 retted hydrogen, have a large amount of caloric around
 them in proportion to their size; the consequence of
 which is, that the thermo-repulsive force  greatly pre-
 dominates.  But when they are made to combine with
 each other  chemically, or with carbon,  phosphorus,
 sulphur, chlorine, &c, making gases of greater specific
gravity  and atomic weight, their elastic force is dimi-
nished, even in cases where little or no caloric is  given
out, as in the combinations of nitrogen and hydrogen,
nitrogen and oxygen, nitrogen and  carbon, with nu-
merous  others, formed of these and  of sulphur, phos-
phorus,  &c.
   It has long been a matter  of controversy whether
the oxygen and nitrogen of the atmosphere exist in a
state of mechanical mixture, as maintained  by Dr.
Dalton,  or in  a state of chemical combination.  Dr.
 Thomson has recently maintained  that it  is composed
of 80 parts nitrogen to 20  of  oxygen, constituting
definite  proportions by volume;  therefore, that it is a
chemical compound.  (Records of  Science, vol.  iii. p.
 184.)   This hypothesis does not accord with the best-
established facts connected with the theory of volumes.
For example, in all the combinations of oxygen and
nitrogen that are  known to be chemical, there is a re-
duction  of volume and elasticity, except in the case of
 the binoxide, which is composed  of equal volumes of 
OF GASEOUS BODIES.
125
each.  Besides, it would seem to be a general law, that,
whenever unequal volumes of gases unite chemically,
there is a diminution of their aggregate volume.  This
view is supported by the facts presented in Table III.,
page 76; while it is evident from the foregoing details,
that all such chemical combinations are attended with
a reduction of elasticity.  But the volume and elastic
force of oxygen and nitrogen, as they exist in atmo-
spheric air, are the same as when in a separate state,
which would  seem  to  demonstrate, that air is a me-
chanical mixture, and  not a chemical  combination.
   The elastic force of light carburetted  hydrogen is
less than that of simple hydrogen.   When Mr. Per-
kins submitted it to mechanical pressure, he found
that it began  to liquefy under a force equal to the
weight of  40  atmospheres;  and that under  a  pres-
sure of 1200 atmospheres it was  perfectly condensed
into the  liquid form.   Being composed of tAvo atoms
hydrogen to one of carbon, its specific gravity and
atomic weight are to hydrogen in the ratio of eight to
one.
  When iavo  atoms or volumes of carbon unite with
two of hydrogen, they form  bicarburetted hydrogen,
(olefiant gas,) the specific gravity and atomic weight
of which are  14, compared  with  hydrogen as unity.
During this combination, the four volumes of hydro-
gen and carbon contract into one volume, the elastic
force of which is much less  than  that of  carburetted
hydrogen;  yet we have seen from the experiments of
Dulong and Hess, that equal volumes of  carburetted
hydrogen give out  three, and olefiant gas five times
more caloric than simple hydrogen; while the vapours 
126
CONTRACTION AND EXPANSION
of ether and  turpentine  afford from ten to twenty
times more.  Why then is their elastic force so much
less at the same temperature?  The  only answer to
this question is, that  the  repulsive force of caloric is
counteracted by its attraction for the  larger particles
of the compound gases by which their elements are
chemically united,  producing definite  contraction of
volume.   If such were not the case, their elastic force
Avould be greater than that of hydrogen, in proportion
to the greater amount of caloric they contain.
   This inference is rigorous;  and it is so important in
its bearing upon the whole  science of chemistry and
physics, that I have dwelt upon it even at the hazard
of repetition, with a hope that by presenting  the ope-
ration of the  same  principle in  different points of
view, it  might be rendered  clear and intelligible to
the most ordinary capacity.   It explains why the ex-
pansive force of steam  is greater, other things being
equal, in proportion as the quantity of water employed
in its generation is less; a thorough comprehension of
Avhich is destined to effect an immense saving of fuel.
   The law by which  the  repulsive force of caloric is
counteracted by its affinity for  ponderable matter, is
still more strikingly illustrated  by  the changes which
are produced in the statical and dynamical properties
of hydrogen and sulphur, oxygen and nitrogen, chlo-
rine and nitrogen, with  some others.
   It  was before noticed  that the  specific gravity of
sulphur vapour, as determined by the  experiments of
Mitscherlich,  is 6-666,  which is about 96 times the
specific gravity of hydrogen gas;  and it requires a
temperature of about 640°  F. to  maintain it  in the 
OF GASEOUS BODIES.
127
gaseous form, when not united with other bodies.  But
if brought into  contact with hydrogen  gas, or if sul-
phur be volatilized in contact with hydrogen, they both
undergo remarkable changes.
   In the  first place,  16 parts  by Aveight of sulphur
combine chemically with one  of hydrogen, forming
hydrosulphuric acid, (sulphuretted hydrogen,) the spe-
cific gravity of which is 17 times  that of hydrogen,
and its elastic force comparatively low.   The particles
of sulphur, which are 16 times larger  than those of
hydrogen, receive from the latter gas a portion of the
ether that encompassed its  atoms,'by which they are
intimately united.
   During this process, the particles of sulphur acquire
a much greater  repulsive force, and are removed so
much  farther  from each other, that they occupy six
times  the volume which they did in the form of va-
pour, before combining with the hydrogen.
   The elastic force of the  hydrogen is so far dimi-
nished by uniting with sulphur,  atom to atom, that
sulphuretted hydrogen may be  liquefied by a pressure
equal to 17 atmospheres, at the  temperature of 50°,
according  to the experiments  of Faraday.   It was
afterwards discovered by Davy, that when  reduced to
the temperature of 3° F., the  elastic force of its va-
pour Avas equal to the pressure of only 14 atmospheres.
   When two atoms of sulphur 32,  combine with one
atom of hydrogen, the resulting compound is a broAvn-
ish yellow and dense liquid, (specific gravity 1*769,)
somewhat acid, of an oily and  tenacious consistence.
If submitted to very low temperatures, its specific
gravity and cohesion are still further augmented, Avhen 
128          CONTRACTION AND EXPANSION

it becomes an exceedingly firm  solid, like butter, tal-
low  and innumerable  other  fluids  and  semifluids
under  the  same circumstances.   When  an atom of
sulphur 16, combines with  two atoms of oxygen 16;
or when sulphur vapour combines Avith  oxygen, the
elasticity of the latter is nearly destroyed; Avhile the
atoms of sulphur are removed farther from each other,
and acquire a degree of elasticity at the expense of the
oxygen:  for  the specific gravity of  the  sulphurous
acid thus formed is only 2*222, which is just one-third
of 6*666, that of the sulphur vapour, in agreement
with the law of multiples, which may be traced in all
the contractions and expansions that gaseous bodies
undergo during combination and decomposition.
  According to the experiments of Faraday, sulphur-
ous acid  may be liquefied by a pressure equal to two
atmospheres, at the temperature of 45°; and by cold
without  pressure, according  to  the  experiments  of
Bussy and others.  It must be observed, however, that
during the combinations of oxygen  and sulphur, a
portion of caloric is given out, as in the union of  oxy-
gen and  hydrogen to form  aqueous vapour; which is
one cause of the diminished elasticity in  sulphurous
and sulphuric acids.
  The same  order of phenomena wdiich  marks the
union of sulphur and hydrogen, is  exhibited  during
the combination of  phosphorus, iodine, bromine, sele-
nium, tellurium, &c, in  the state of vapour, Avith hy-
drogen and other permanent gases.   The volume and
elasticity of these  dense vapours are augmented by
receiving from the lighter gases a portion of the prin-
ciple on which their volume, &c. depend, during the
very act of combining. 
OF GASEOUS  BODIES.
129
   The specific gravity of phosphorous vapour is 4*444,
at the temperature of 550° F.; or about 64 times the
specific gravity of  hydrogen.   But when it combines
with hydrogen, it becomes highly elastic, and its par-
ticles occupy four times their former space, as in phos-
phuretted hydrogen,  the  specific gravity of which is
only 17 times that of hydrogen.
   The specific graAaty of iodine vapour is 8*75 at the
temperature of 347°  F.   When it unites with hydro-
gen, atom to atom, (that is, in the ratio of  126 by
weight to one of  hydrogen,) hydriodic acid is formed,
the specific gravity of Avhich is  4*386, or about one-
half that of  iodine  vapour, in  accordance with the
law of multiples  as shoAvn in  hydrochloric acid, am-
monia, &c.
   The same principle applies to  the A^arious combina-
tions of hydrogen with the vapours of bromine, cyano-
gen, arsenic and  mercury, as in its combinations with
the vapours of sulphur, iodine, &c.  (See Table III., of
the preceding Chapter.)
   When three, four or  five volumes  of oxygen com-
bine with two of nitrogen, the  aggregate bulk and
elastic force  of the resulting compounds diminish with
every additional  dose of oxygen.  Nitrous acid may
be liquefied  by moderate degrees of cold without pres-
sure.   Yet it contains  nearly  if not quite as much
caloric as the oxygen  and nitrogen of which it is com-
posed, 'when in  a separate  state.  It was long ago
observed by Higgins,  that during the combinations of
oxygen with nitrogen, no caloric is  given out; and
that during  the union of nitric acid with potassa, very
little heat is disengaged.
                         9 
130
PHILOSOPHY OF
   That such is really the case would  appear from the
immense quantity and  intensity of the  heat evolved
by the deflagration of nitrate of potassa Avith charcoal
and  sulphur, as in gunpowder and other deflagrating
mixtures formed of nitre, phosphorus, naphtha, tur-
pentine and various combustibles.   It  is  generally
known, that during their combustion with nitre, nearly
as much caloric is given out, even in vacuo, as when
they are burnt in atmospheric oxygen; which proves
that a large amount of  caloric is concentrated around
the  particles of the nitric acid of the saltpetre, and
set at liberty during its decomposition.

      PHILOSOPHY OF EXPLOSION  OR DETONATION.

   Immediately connected with  the foregoing theory,
is the rationale of  explosion;  a  phenomenon which
has never been explained, and has been often adduced
as an argument against the materiality of caloric.   It
has  been  supposed that the quantity of heat given
out  during explosion, and that which is requisite to
convert gunpoAvder into the gaseous state, could  not
have existed in a state of combination with its par-
ticles.
   This error has arisen from not attending to the law
by which  caloric is  concentrated around  the atoms of
ponderable matter, with a force that increases in pro-
portion to the augmentation of their size, other things
being equal; and  by which its  self-repulsive force is
counteracted.   I have  shown that the elastic force of
nitrogen is equal  to a pressure of 1200  atmospheres;
but  that when five volumes of oxygen are combined 
EXPLOSION OR  DETONATION.
131
Avith two of nitrogen, they contract  into two volumes
of  nitric acid, without any  material loss of caloric;
and that when five atoms of oxygen 40, unite with an
atom of nitrogen 14, they form compound molecules of
nitric acid, the weight of which is 54, compared with
hydrogen  one:  from which, and the foregoing facts,
Ave are bound to infer, that the  repulsive force of  the
ether which surrounded the atoms of oxygen and ni-
trogen, is counteracted  and nearly vanquished  by the
attraction of caloric for the larger particles of the com-
pound.*
   By referring to Table I. page 67,  we perceive that
the  atomic weight of potassa  is 48, compared with
hydrogen as unity.   One atom  of nitric acid 54, com-
bines Avith one of potassa 48, making compound mole-
cules of nitrate of potassa, the weight of which is 102;
and the attraction of caloric for Avhich, so much  ex-
ceeds its idio-repulsive force,  that they are aggregated
into a crystalline solid of a prismatic form.  Let us then
  * It was before  observed that when two volumes of hydrogen
combine with one of oxygen to form water, an immense quantity of
caloric is disengaged, and  that the  aeriform state is merged into
the  liquid  state.  But as  the combinations of oxygen and nitro-
gen retain  nearly the same amount of caloric as their constituents,
they also retain the gaseous form at  ordinary temperatures, though
their aggregate bulk and  elasticity  are greatly diminished.  This
fact is very remarkable; for the particles of nitric acid  are larger
than those  of water in the ratio of 54 to nine; or six to one.  It
is difficult to conceive why  they retain the elastic state, unless they
retain around them a large amount of  the same ethereal principle
which belongs to their elementary constituents; whereas  oxygen
and hydrogen give out a large proportion  of  it on combining to
form water. 
132
PHILOSOPHY OF
examine the composition of gunpowder.  It consists of
one atom of nitre 102, one of sulphur 16, and three
of carbon 18, in a state of intimate mixture.  When
perfectly dry, and heat is applied, the nitre is decom-
posed into its original constituents, Avith a tremendous
force of explosion, which  is owing principally to the
elastic force of the nitrogen, on being released from its
combination with the oxygen and potassa of the nitre.
During this rapid process, two atoms of oxygen  com-
bine with one of sulphur, making sulphurous  acid
gas; while the other three atoms of oxygen that ex-
isted in the nitric acid, combine with three atoms of
carbon;  forming carbonic oxide and carbonic  acid.
But as the elastic force of these gases is comparatively
Ioav, the explosive action must depend chiefly on the
sudden expansion of nitrogen on assuming the gaseous
state.   The whole is  nothing  but  an instantaneous
combustion of sulphur and charcoal, accompanied by
the disengagement of  heat and light as in ordinary
combustion, and by the sudden liberation of nitrogen,
which,  in  the separate state, exerts an elastic  force
equal to a pressure of  16,800 lbs. to the square  inch.
The force is also greatly increased by the caloric given
out during the formation of carbonic  oxide, carbonic
acid and sulphurous acid.
   This is a most instructive exemplification of the law
by which caloric exerts two opposite  forces; the one
or the  other prevailing according  to circumstances.
At ordinary temperatures, the compound  particles of
nitre, sulphur and carbon retain caloric around  them
with a greater force than that by which it repels its
own particles; but  Avhen they are decomposed and 
EXPLOSION  OR  DETONATION.
133
subdivided into smaller particles, the repulsive force of
their ethereal constituent acquires the ascendency.
  The same principle applies to all fulminating com-
pounds, whether solid, liquid or aeriform, as chlorate
of potassa; fulminating mercury, gold, silver, platinum,
&c.; iodide and chloride of nitrogen, protoxide and
peroxide of chlorine, and some other detonating com-
pounds, all of which are attended Avith expansion of
volume and disengagement  of heat during their de-
composition.
  Chlorate of potassa is  composed of chloric acid and
potassa.  When triturated with sulphur, phosphorus or
charcoal, it forms a deflagrating compound.  In  the
ratio of three parts of the chlorate to one of sulphur,
it explodes violently when  gently heated, or struck
Avith  a hammer.  If  two grains  of the chlorate  be
mixed Avith one of phosphorus,  in a bit of paper, and
struck Avith a hammer upon an anvil, there is a vio-
lent explosion.  The chloric acid is decomposed in all
such cases; the  chlorine unites  with the combustible,
and the oxygen being liberated expands with a force
proportional to  its elasticity in  the gaseous state, for
the same  reason that nitrogen expands Avhen sepa-
rated from the nitre of gunpoAvder.
  It is by  contemplating the elastic force of caloric in
oxygen and nitrogen, Avhile in the state  of simple
gases, that we are enabled to appreciate the stupendous
force of attraction by which it is concentrated around
the molecules of ponderable matter.  If Ave take the
experimental result of Rumford, that 15 grains of gun-
poAvder expand Avhen ignited, Avith  a force equal to
the pressure of 400,000 lbs. or 200 tons Aveight, it fol- 
134
PHILOSOPHY OF
lows from a simple calculation, that the elastic force
of caloric in one pound of gunpowder, is equal to the
pressure of 102,400 tons weight.  This enormous force
is restrained by the attraction of caloric for the mole-
cules  of gunpowder  and all detonating compounds
that contain  nitrogen, until decomposed, when it ex-
pands with an energy far surpassing the most elastic
steam, for the same reason that the oxygen of chlo-
rates expands Avith irresistible violence when decom-
posed.
  Of all the  detonating compounds, chloride of nitro-
gen affords the most simple and striking example of
the opposite effects exerted by caloric  under different
circumstances.  It is composed of three  volumes of
chlorine  to two of nitrogen, which, on uniting,  con-
dense into a  volatile, oily liquid, the specific  gravity
of Avhich is 1*6.   While its elements  are united, the
elastic  force of the caloric  in nitrogen is restrained
by the greater force with which it combines with the
atoms of chlorine.  These two opposite forces are so
nearly balanced,  that  by adding a small amount of
caloric to the chloride it is  decomposed, the nitrogen
expanding with  its accustomed force when reduced
to the separate state.   The chlorine also assumes the
gaseous state, with evolution of heat and light.   The
chloride may be decomposed by the volatile oils, naph-
tha, phosphorus and various other combustibles, which
unite with chlorine, when it explodes as when heated
to 212° F.
  Euchlorine, (chlorochloric acid,) peroxide of chlorine
and deutoxide of hydrogen, also expand with explosion
and evolution of heat and light on being decomposed, 
COMBUSTION AND DEFLAGRATION.
135
because the affinity of caloric for their particles is dimi-
nished by reducing their size.   The more completely
ponderable  matter is  divided, the less tendency has
caloric to concentrate around its particles.  Hence, the
quantity of caloric given out during ordinary combus-
tion, other things being equal, is in proportion as the
decomposition is complete.  When coal or wood is but
partially  decomposed,  gross  vapours  are  formed, con-
stituting smoke, the particles of which are much larger
than those of flame, and which retain and carry off a
considerable amount of the  caloric that  is given out
by radiation when the combustion is perfect.
   The whole theory of combustion is founded on the
\Tarious degrees of force with  which caloric attracts
the particles of ponderable matter under  different cir-
cumstances.  It is more concentrated around the atoms
of dense, than of light  gases and vapours;  and greatly
more so around the larger compound particles of liquids
and  solids.   In short, all the absorptions of caloric by
Avhich  it  combines Avith and becomes latent in  pon-
derable matter, result from this  affinity;  Avhile  the
escape of caloric during combustion or deflagration, re-
sults from the diminution  of that affinity;  for  the
same reason  that the volume and elastic  force of hy-
drogen  and nitrogen greatly augment on the decom-
position of ammonia.
   There  is  nothing  more   clearly  demonstrable  in
science, than that all  the caloric  evolved during the
decomposition of  ponderable matter,  whether solid,
liquid  or gaseous, is only a liberation of what  ay as
previously concentrated  around the atoms of the ma-
terials  employed.   When the  particles of solids  are 
136
PHILOSOPHY OF
separated and  subdivided by friction  or collision, a
portion of their concentrated caloric  is disengaged,
producing incandescent sparks, or streams of fire.
  A machine is exhibited at the Hall of Practical
Science in London, Avhich illustrates  the manner in
Avhich  solid bodies may be reduced to a state of in-
candescence by mechanical friction.  A circular plate
of soft iron is  made  to revolve  at the rate of 5000
times per minute, Avhen  the  hardest  steel on being
applied to its edge is cut through  rapidly, and reduced
to inconceivably small particles,  which are expanded
by the  caloric thus liberated, into a shower of metallic
flame  and sparks.   This kind  of  ignition proceeds
equally Avell in A^acuo as in the atmosphere.
  Mr.  Brande  observes, in  the  last  edition  of his
Manual of Chemistry, page 390, that the existence of
nitrogen  in nearly  all  the  powerfully  detonating
bodies, is a singular  fact;  and  that explosion  must
remain unexplained until we ascertain the cause of
the detonating power of such compounds.  He  also
adds, that  at present  the phenomena are at variance
with the usual  explanation of the  evolution of heat and
light during combustion, which have been supposed to be
the result of union and condensation, instead of expan-
sion and  decjomposltlon.
  The truth is, that in a large majority of cases, com-
bustion, as well as explosion, is  attended Avith expan-
sion  of  the  materials  employed.   Lavoisier, who
maintained that gaseous  oxygen was  the source of
heat and light  in all cases of combustion, supposed
that it was always condensed on  combining with com-
bustibles.  This  partial vieAv of  the subject has been 
            COMBUSTION AND DEFLAGRATION.        137

incorporated with so many works on Chemistry and
Natural Philosophy, that it has become a very general
opinion, that oxygen is the only supporter of combus-
tion, and the source of heat and light, instead of the
bodies Avith which it unites.
   We have already seen, that during the combination
of oxygen with  hydrogen, they are both condensed
into the liquid state;  which condensation is attended
Avith the evolution  of caloric and light.   But a large
proportion of the caloric thus  given out is disengaged
from the hydrogen, which is therefore as much  a sup-
porter of combustion as the oxygen.
   Oxygen  is  also condensed, and even solidified  on
combining with metals during their combustion in it,
by which  they are converted into oxides.   In such
cases, it is doubtless  the principal source of caloric.
It is hoAvever not the only supporter of metallic com-
bustion ;  for cyanogen, chlorine, bromine, iodine, sul-
phur, phosphorus, and some other solid bodies,  unite
rapidly with metals when  they are heated together,
Avith evolution of heat and flame.
   The combustion of carbon, sulphur and phosphorus
in oxygen gas, is attended with intense heat; yet they
are greatly expanded without any condensation of the
oxygen:  for the carbonic, sulphurous and phosphoric
acids produced, have the same volume as that of the
oxygen.
   During  the combustion of  ether,  alcohol, oils,
resins, Avood,  coal  and  other  inflammable bodies in
oxygen, the volume of the gaseous products exceeds
that of the oxygen; yet the process is attended with
the production  of  immense  quantities of heat and
light. 
138
PHILOSOPHY OF
  There is a mixture prepared at the Military Aca-
demy at Woolwich, called the Carcass composition,
that burns  Avith great violence  someAvhat like the
detonating  compounds, Avhich  cannot be quenched
Avith Avater, and has been supposed to resemble the
Greek fire.
  I  am  indebted  to  Dr. Faraday for  the following
mode of preparing it:—
                                          lb.  oz.
     Nitrate of potassa............................................... 6    4
     Sulphur............................................................. 2    8
     Powdered antimony............................................. 0   10
     Powdered resin................................................... 1   14
     Tallow.............................................................. 0   10
     Venice turpentine................................................ 0   10
  The resin,  tallow and turpentine,  are  melted to-
gether.   The sulphur and nitre are then added, being
kept hot all the time and well stirred about.  The
poAvdered antimony is then added and worked well in
it, when it may be formed into the shape required.
  The  combustion of this mixture is truly terrific,
and the quantity of heat evolved enormous.   It also
goes on in vacuo as well as in the air, which is true of
all deflagrating and detonating compounds.  All such
combustions are attended throughout  with expansion
of the  burning bodies instead of condensation.
  The explosive power of gunpowder may be lessened
by  augmenting the proportions of charcoal and sul-
phur.   Fuses, which burn with a gradual or continu-
ous deflagration, are composed in the ratio of
                                          lb.   oz.
     Nitre................................................................. 4    4
     Sulphur............................................................. 1    0
     Common gunpowder ground into meal..................... 1   12 
            COMBUSTION AND DEFLAGRATION.        139

   From the foregoing facts and observations, we per-
 ceive how partial  and erroneous is the prevalent no-
 tion, that under all circumstances caloric is a repulsive
 agent.   We find that the caloric of explosion, like that
 of ordinary combustion, is only a  liberation of  what
 was previously concentrated  around  the particles of
 ponderable matter, and diffused during its dissolution.
   Such is  the beautiful simplicity of nature, that a
 clear comprehension of the law by which the molecules
 of a salt are aggregated  and dissolved, affords a minia-
 ture representation of the mechanism by which all the
 phenomena of nature are carried on, from that of plane-
 tary motion to the no less important  transformations
 of chemistry.
   It has been shown, that  cold, or the abstraction of
 caloric, produces the same effect on gases as mechanical
 pressure; that is, it diminishes their volumes, and con-
 denses  them into liquids or solids; which is effected
 by lessening the ratio of ethereal or elastic matter,
 Avhile the quantity of ponderable matter remains the
 same.   If we suppose that the repulsive force of this
 ether in hydrogen is equal to  the weight of 2000 at-
 mospheres, it must combine with the atoms of sulphur
 and other bodies with a still greater force, for Ave have
 seen that Avhen one  atom of  sulphur combines  with
 one of hydrogen, the resulting compound, sulphuretted
 hydrogen, may be liquefied by a pressure equal to 17
 atmospheres at 60° F.; and the bisulphuretted hydro-
gen  becomes liquid, or semi-solid,  without  any pres-
sure.
   By the affinity of caloric  for ponderable matter its
atoms  are  approximated and  held together: by its 
140
CONSTITUTION OF LIQUIDS.
elastic or self-repelling  property, it separates them
from  each  other, as in vapourization,  explosion  and
all decompositions.   The fact that Philosophers have
overlooked this affinity by Avhich caloric is concen-
trated around  the  particles of liquids  and solids, re-
soh^es the problem of contradictions  by which  the
theory of caloric has been so long perplexed, and ex-
plains Avhy many have  doubted its  materiality; why
the phenomena of combustion, explosion, cohesion  and
chemical affinity have not been understood.
  Thus Ave perceive, that caloric is the cause of repul-
sion in steam and all gases; in vapourization, combus-
tion, and the expansive force of detonating compounds:
and that this elastic force is counteracted and dimi-
nished, or A^anquished  by its affinity for inert matter.
This  doctrine throws a  clear and full light on all the
poAvers, motions, combinations and  decompositions of
the elements by which we are surrounded and  sus-
tained; and, when  perfectly unfolded in all  its rela-
tions, will  be found to  furnish a simple and rational
interpretation of innumerable phenomena that have
never been fully explained.

              CONSTITUTION OF LIQUIDS.

   It  has been  shown  in the preceding chapter,  that
there is an intimate relation between the elastic force
of gases, and the proportions of ether which surround
their atoms; that hydrogen contains a larger amount
of caloric, in proportion to the quantity of ponderable
matter, than any other known body, and possesses  a
corresponding  degree  of expansive force;  but  that 
CONSTITUTION  OF  LIQUIDS.
141
when it unites chemically Avith oxygen, it gives out a
large proportion of caloric, by Avhich  its volume  and
elasticity are diminished.  It has also been shown that,
other things being equal, the elastic force of all gase-
ous  bodies  is in proportion to the  amount of caloric
Avhich is  combined with any given quantity of  pon-
derable matter.
   I iioav  proceed  to shoAV,  that the  lightest and most
volatile  liquids are composed of elements Avhich con-
tain  the  largest  proportion of caloric  around their
atoms.   I am not aAvare that any one has attempted
to explain Avhy liquids differ so greatly in their vola-
tility: Newton referred  it  to their smallness; Boyle
supposed that their tenacity Avas owing to the gross-
ness  of their particles,* Avhich are nearly the same.
But it is  now Avell known that the proximate atoms of
Avater are less than those of alcohol, ether and various
other liquids that are more elastic and volatile at the
same temperatures.   The atoms of  nitrous and nitric
acids, of  sulphuretted and phosphuretted hydrogen, of
chlorine,  hydrochloric acid  and many  other  gaseous
bodies, are larger than those of carbon, sulphur, phos-
phorus,  silicium, calcium, &c.   Yet  the former are
much more volatile and elastic than the latter.  The
atoms of etherine, sulphurous acid,  muriatic ether,
(Avhich is composed of etherine and hydrochloric acid,)
  * Lucretius observes that light passes through scraped horn,
which wine and water will not do, because the particles  of the
latter are too large; but that water and wine percolate strainers
more readily than oils, because the latter are composed of larger
particles, or of particles that are  hooked.  (De Naturd Rerum,
Book II.) 
142            CONSTITUTION OF LIQUIDS.
protoxide of  chlorine, &c,  are larger than  those  of
water or  hydrocyanic  acid, the elasticity of  Avhich is
much inferior.
  Such facts prove conclusively, that the elastic force
of gases and  liquids is not determined alone by the
size of their proximate particles, but by their  relations
to a self-repelling fluid.
  There  is a class of  liquids  which  are composed
chiefly of hydrogen and carbon, that  seem to form a
connecting link between gases and more fixed bodies.
They are generally much lighter than  water, and ex-
ceedingly volatile.   Such are etherine, spirit of  gum
elastic and naphtha.  Ether, alcohol, pyro-acetic spirit,
acetic ether, and most of the essential  oils, which are
composed of carbon and hydrogen united with small
proportions of oxygen, are lighter  than  water,  and
some of them highly volatile.   There  are also a few
combinations  of hydrogen and carbon  Avith nitrogen,
chlorine and  even  iodine, that are very volatile, as
nitrous ether, hydrocyanic acid, muriatic and hydriodic
ethers.  There cannot be a doubt that all such liquids
owe their volatility to the same cause which determines
the elastic force of gases.  For we find, that etherine,
the lightest of them all, boils or expands rapidly into
the gaseous state, under the pressure of the atmosphere,
beloAv 32°. Common ether boils at 96°, muriatic ether
at 60°,  nitrous ether at 60°, acetic ether at 105°, and
alcohol  at 173°.*  But when the pressure of the atr

  * With a view of ascertaining  how far the  rationale of such
phenomena had  occupied the attention of philosophers, I took an
opportunity of asking a distinguished  professor of  chemistry why
ether and alcohol were more volatile than water: to which he re- 
               CONSTITUTION OF LIQUIDS.           143

mosphere is removed, as under an exhausted receiver,
the elastic force of the  caloric which  surrounds their
particles expands  them rapidly into  vapour at 145°
below their boiling points under the pressure of the
atmosphere.   In all  such cases, liquids  are  expanded
into the gaseous state, by the elastic force of their con-
stituent caloric, Avhich is thus diffused and carried off,
by Avhich intense cold  is  produced.   In vacuo, pure
ether is rapidly expanded into vapour at —46°, alco-
hol at 28°, and water at  67°; from which  it  follows,
that they are all elastic fluids like gases, but in a less
degree; and that if their elasticity were not restrained
by the pressure of the atmosphere, they would boil at
ordinary temperatures, until the  process were checked
by the pressure of their own atmospheres.
   By reference to a  subsequent  table, it will  be seen
that ether is composed of five atoms of hydrogen, four
of carbon,  and  one of  oxygen;  and  that  alcohol is
composed of the same substance, united with one par-
ticle of Avater.   Hence the  difference between their
specific gravities and boiling points; the specific gravity
of pure ether being  about *700, and  that  of alcohol
■794, compared Avith water 1000, which congeals at 32°
F.; Avhile ether and alcohol  are exceedingly  difficult
to congeal.*
plied that he did not know, unless it were owing to the smallness
of their cohesion.  And Dr. Young tells us,  that " the weakness
of cohesion in fluids is owing to the mobility of their particles."
(Lectures on Nat. Philos., vol.  i., p. 620.)  The truth is, that our
books abound with such definitions.
  * It has been said that alcohol was frozen by Hutton; and
Fourcroy supposed that he had frozen ether at  —46°.  But neither
Thenard nor Bussy were able to congeal it: from which it is pro- 
J44            CONSTITUTION OF  LIQUIDS.

  That light and volatile liquids contain more caloric
than Avater and some others which are more dense and
tenaeious, might be inferred from the large amount of
hydrogen Avhich  they contain,  and from  their highly
combustible property.
  It has been often stated gravely by chemical writers,
that cold results from evaporation,  because  vapours
have a greater capacity for caloric than the liquids from
which they are formed.   But this does not explain hoAv
liquids are  converted into vapour.   The  coldness re-
sults from the elastic force of their constituent caloric,
by which they are  expanded over a larger space; yet
Avithout its being separated  from their particles and
radiated, as during combustion.
  When an open vessel of Avater is placed over a fire,
its temperature never rises above 212° F., hoAvever hot
the fire  may be; because at  212°, the  elastic force of
caloric in Avater overcomes the pressure of the atmo-
sphere, and expands it into steam, the bulk of which
is 1720  times that of water.  But when Avater is en-
closed in a strong vessel like  Papin's digester, and pre-
vented from expanding into  steam, its  temperature
rises to  500° or  more.  If a vessel  could be obtained
strong enough, water might be made red hot; and if
again permitted to expand, its temperature would ira-
bable, as observed by Mr. Brande, that the ether employed by
Fourcroy was not pure.  It is now certain, however, from the ex-
periments of Thilorier, that both may be congealed.
  When alcohol  and water are mixed, they combine chemically
with diminution of their aggregate volume and disengagement of
heat.   Proof spirit is composed of about equal weights of each,
the specific gravity of which should be *916. 
CONSTITUTION  OF  LIQUIDS.            145
mediately fall in proportion to the diffusion;  and so of
all other vapours.
  The production of cold during the exhaustion of a
receiver, as reported by Leslie and Dalton, is referable
to the same cause, and not  to an increase of capacity
for caloric in rarefied air, as they supposed.  That is,
a large proportion of caloric is carried off in combina-
tion with the  air which is pumped  out;  so  that Avhat
remains  is. greatly diffused by virtue of its elasticity,
producing  a corresponding reduction of temperature.
When carbonic  acid, ammonia, cyanogen, chlorine and
other elastic fluids are  converted into the  liquid  or
solid state by  pressure,  a still  greater reduction of
temperature results from  their sudden expansion on
removing the  pressure.
  M. Thilorier has recently invented an apparatus by
which he can  form large quantities of liquid carbonic
acid, the rapid expansion of which, when released
from pressure, causes a reduction of temperature equal
to 164°  below the freezing  point of water, by which
the liquid  carbonic acid  is converted into Avhite  solid
lumps.   When  alcohol was  poured upon them, it was
immediately converted into a hard, brittle ice;  while
ether was congealed  to  the consistence of sodden
snoAv.*   M. Bussy has also congealed alcohol (sp. gr.
■850) by the evaporation of liquid sulphurous acid in
\racuo. (Ann.  de Chim. for May, 1824.)

  * Carbonic acid is procured in  the liquid state by adding to-
gether in a close strong iron vessel, two pounds bicarbonate of
soda, three pints of water at  100° and eight ounces of sulphuric
acid.
                         10 
146
CONSTITUTION OF LIQUIDS.
   When ether is dropped  upon the hand, the caloric
 of the living  body expands it into Aapour, and is car-
 ried off in an  invisible  form,  causing coldness.  In
 the  same  way, the caloric of the solar rays is con-
 tinually expanding the Avater of the earth into vapour,
 and diffusing  it through the  atmosphere, (to be given
 out  in  colder regions,) by which the sultry  heats of
 summer are diminished.
   That all odoriferous emanations consist of extremely
 minute particles of bodies diffused through the atmo-
 sphere  by caloric, need scarcely be mentioned; being
 obvious from  the fact, that at very low temperatures
 they are not produced.  Excessive cold puts a stop to
 all Arolatilization and decomposition of matter.
   That the numerous facts connected with the consti-
 tution of different  liquids may be the  more readily
 understood, I  have  presented them in a tabular form.
   The first column of the first table  exhibits the for-
 mula1 of the  various  compound liquids; the second
 represents  their united  equivalents, compared with
 hydrogen as unity.   The  third column gives  the spe-
 cific gravity of the liquids, compared with water 1000,
 —and the fourth, their boiling  points.   The  remain-
 ing numbers give the relative proportions of their con-
 stituents in the 100 parts  by weight,  as derived from
 the best  analyses of modern chemists.   By inspecting
 the first  table, it appears that all the  most spirituous
 and volatile liquids contain large proportions of hydro-
gen and  carbon; most of which are lighter than water,
 and boil  at lower temperatures. 
CONSTITUTION  OF LIQUIDS.                147
                              TABLE  I.

Representing the Atomic Constitution, Specific Gravity and Boiling
               Points  of various Volatile Liquids, &c.
Etherine..........
Sp. of caoutch...
Mur. ether.......
Nitrous ether__
Acetic  ether.....
Ess. of lemon....
Ilydrocy. acid...
Kther..............
Naphtha..........
Bicarb, of hyd...
Paraffine.........
Pyro-acetic sp...
Pyroxilic spirit.
Hydriod. ether..
Hydrocy. ether-
Alcohol ...........
Bisul. of carb....
Chi. of sulphur..
Chl.ofnitr.......
Iodide  of nitr....
C,H4
CH
C4H-C1
C4H5N04
C8H804
C5H4
C2HN
C4H50

C6H3
C24H25
C3H30
C2H30
C4H5I
C4H5Cy
C4H602
cs2
S2C1
NC13
NL
 N. acid, concen. NHO
 Mu. acid, cone... HClAq6
 Hydriodic acid.. HI
 Acetic acid......;C4H404
 Cyanic acid......'CyO
|Sul. cyan. acid.. CyS,
I Perchloric acid.. C107

 Sul. acid, cone... SHO
 Water............. HO
 28

 65
 70
 88
 34
 27
 37
 36
 39
129
 29
 23
154
 55
 46
 38
 68
122
392
63 1
91 1
Relative Proportions by Weight in
         100 Parts.
127
 60
 34
 59
 92

 49
  9
627
640
874
880

847
705
700
75U
850
870
792
804
92
700
794
272
687
6
5
2
7
062

022
6

845
000
0.	
32° 85	15
.... 85	71
60° 36	9
70°,32	00
105° 54	55
.... 188	1
80°! 44	4
96°if>4	87
100°
180°
120°
132°
150°
148°
180°
173°
102°
280°
212°
184°
112°
260°
217c
392c

620c
212°
   H.
14-25
14-29
 7-7
 6-67
 9-09
11-9
 3-7
13-51
12-25
66	33-33
02	14-98
08	10-33
17	13-05
60	3-15
•5	9-1
17	13-51
79	84-21 S
94 S	47-06 CI
5 CI	
41	
N	1-58
48C1	7-69
•211	•79
	6-66
5	41-10
8Cy	54-2 S
13C1	
6S	1-7
	11-9
55-4 CI.
42-67
'36-36
21-62
27-59
34-78
81-251

34-32
76-20
53-83

53-32


60-87

73-7
38-1 
148
CONSTITUTION  OF  LIQUIDS.
                             TABLE  II.

Representing the ultimate Constitution of the Volatile  and Fixed
   Oils, with some other Compounds,—their Specific Gravity, Boil-
   ing Point, &c.
Camphene........
Oil of Anise......
 "  Peppermint.
 "  Lavender.....
 "  Rosemary...
 "  Camphor....
 "  Caraway ....
 "  Juniper......
 "  Cinnamon..,
 "  Sassafras....
Benzule.. ........
Naphthalin......
Paranaphthal....
Creosote..........
Petrolene.........
Oil of bitr.  aim.
 "  Cloves........
 "  Spermaceti..
Hogslard.........
Tallow.............
Castor Oil........
Linseed Oil......
Olive Oil.........
Resin.............
Beeswax.........
Camphor.........
Sugar.............
Gum...............
Starch ............
Gluten............
Lignin............
Blood.............
Flesh..............
Protein............
Cln H
C14|H9
C-20 H,
   0
h;, o
Hw  0

H]00
H„J0
C12jHin'0

C48'HwO
CiB|HMQ0
= 9 1  c
105
 64
 94
109
128
106
173
 76
171
162
162

162
535
535
537
860
985
920
877
890
988
940
911
350
094
037

043
988
Relative Proportions by Weight in
         100 Parts.
       C.      H.     O.
312° 881   j 11-0
 ... -,81-4   | 7-98  10-62
 ...  77-3   ,12-6   10-1
397°   ...   !   ...
365°'   ...   |   ...
     '9-28   10-36  10-36
410° 89-00
572°   ...
397° 72-42
536°, 88-5
     79-50
     70-02
     79-5
     79-098
     78-996
     74-000
     76-01
     77-21
     75-94
     80-60
600°
400
42-1
43-75
43-75
57-7
43-75
11-00

 8-12
11-5
 5-5G
 7-42
11-6
11-146
11-700!  9-304
10-29  15-71
14-46

14-88
22-56
 8-9
 9-756
11-35
13-36
10-71
11-47

 0-"i
 6*77
 6-77
 7-8
 6-77
 12-63
 942
 13-33
 7-93

|-51 5
[49-68
 49-68
 22 00
 49-68
14 
COHESION OF LIQUIDS.
149
   Naphtha is composed of five  atoms hydrogen  and
six of carbon, or of 87*75 parts by weight of carbon,
to 12*25  of hydrogen in the 100.  It is also more
dense than etherine, and less volatile.  Hence it would
seem, that the elasticity of etherine  exceeds  that of
naphtha, for the same reason that the elastic force of
olefiant gas is greater than that of etherine;  or that
the elasticity of hydrogen exceeds that of olefiant gas.
   It has been found,  that several of the essential oils
are hydrocarbons, as the essence of turpentine, lemons,
copaiva, bergamot and camphene, or camphogen;  but
that most of them are composed of hydrogen and car-
bon, united Avith oxygen; or  that they are oxides of
hydrocarbons, as they  have been termed by Dumas.
   The oil of mustard contains sulphur and nitrogen;
the oil of  bitter almonds also contains some nitrogen,
according to Liebig  and  Wohler.   When perfectly
pure, it is composed of one equivalent of benzoxyl and
one of hydrogen, the  proximate  molecule  of which is
106.  But the molecular  Aveights of the volatile oils
have  not  been accurately ascertained, owing to the
fact, that  they do not combine Avith bases  without de-
composition.   They are of a pungent  aromatic taste
and  odour;  and many of them  pass into the form of
vapour at the temperature of boiling water; but some
of them require a much greater  heat.   Dumas ob-
serves, that their density is  proportional to the quan-
tity of oxygen they contain.
   The specific gravity and  chemical constitution of
the fixed oils are nearly the  same;  yet they require a
temperature of about 600° F. to volatilize them.  Why,
then,  it may be naturally inquired,  if they  consist 
150             COHESION OF LIQUIDS.
chiefly of carbon  and  hydrogen, is their cohesion
greater than that  of ether, alcohol, water and  the
essential oils ?   The following facts may tend to throw
some degree of light on this question.
  By ad\erting to the  second table, it will be found
that camphene, or  camphogen,  is  composed of C10H8,
united into one compound particle, the  weight of
which is 68, compared  with hydrogen: whereas,  the
essence  of  lemon  is composed of  C5H4,  making a
proximate particle equal  to 34,  or  one-half that of
camphene.  The consequence  of which  is, that  the
latter is much more  volatile than the former, though
their  specific  gravities  are  nearly the same.   Cam-
phene requires a temperature of  312° F. to make it
boil, while the essence of lemon is highly volatile like
naphtha.  Camphene is the principal ingredient in oil
of turpentine and  camphor, both of  which  are oxides
of camphene.   Common camphor is  composed of  one
equivalent of camphene to one of oxygen.   There is
also an artificial camphor, composed of  hydrochloric
acid one  equivalent, united with one of camphene;
while three  equivalents of water and one of camphene
make the hydrate of camphene;  and five atoms oxy-
gen to one of camphene, camphoric  acid.  Petrolene,
which is  obtained from petroleum by distillation, is,
according to Boussingault,  composed of carbon  and
hydrogen in the same  proportions as camphene;  but
its  proximate particle  being just double  that of cam-
phene, corresponding with the difference between the
specific gravity of their vapours, it possesses the  con-
sistence of a fixed  oil, requiring a temperature of 536°
F. to convert it into vapour.  The product (asphaltine) 
COHESION OF LIQUIDS.
151
 which remains after the distillation, is still more tena-
 cious.
   Naphthalin  is composed of C10H4  united into one
 equivalent 64.   It is a highly tenacious liquid, requir-
 ing a temperature of 400° for its volatilization.
   According to Dumas and Laurent, there is a combi-
 nation of carbon and hydrogen in the ratio of  C15H4
 (equivalent 94) which has been called paranaphthaldn.
 It is one of the last products  from the distillation of
 coal-tar, and is less  volatile than naphthalin.   The
 atomic  weight  of sulphuric acid is  40, and  that  of
 naphthalin  64.   When two equivalents of the former
 unite with two  of  the latter, the compound equivalent
 is 208 of sulphonaphthalic acid, (according to  Fara-
 day,) forming a hard and  brittle solid, that is soluble
 in water, alcohol and oils.
   Naphthalin also forms a dense and tenacious com-
 pound with  chlorine.  With cyanogen, sulphur, iodine,
 bromine, &c, it forms dense semi-liquids, the cohesion
 of AAhich augments  in proportion to the  increased
 magnitude of their compound equivalents.
   From the molecular constitution of camphene, oil
 of turpentine, cloves, peppermint, anise,  naphthalin,
 &c, there can scarcely be  a doubt that their cohesion,
 and  that  of the fixed oils, is greatly modified, if not
 Avholly determined, by the number and relative pro-
 portions of elementary atoms AArhich combine into com-
 plex molecules of larger size.  Hence,  etherine  is  more
 Arolatile than naphtha, and the latter  than camphene.
Camphene is more vnlatile than  naphthalin, and the
latter than paranaphthalin, although they are all com-
posed of carbon and hydrogen.   The equivalent of 
152
COHESION OF  LIQUIDS.
camphene exceeds that of naphthalin, while the latter
is less volatile; but this is owing to the fact, that cam-
phene contains just double the ratio of hydrogen.
  By looking over the preceding  tables, Ave  perceive
that the most volatile  liquids are composed largely of
hydrogen and of other elastic gases; such as hydro-
chloric ether, nitrous ether, acetic  ether, hydrocyanic
and hydriodic ethers, chloride of nitrogen, nitric acid,
(anhydrous,) pyroacetic spirit, &c.; all of which expand
into  the gaseous state at temperatures below  212°  F.,
notwithstanding their proximate equivalents are large.
But it was also  shown, that carbon, phosphorus, sul-
phur, iodine, bromine, and even arsenic, may be con-
verted into permanent gases by combining chemically
with hydrogen;  that they receive from it a portion of
caloric by  Avhich their elastic force is increased, and
that of the hydrogen  diminished; that their volume
and  elasticity decrease  in  proportion to the size of
their proximate particles, until they assume the liquid
or solid form.   The most singular circumstance con-
nected Avith this subject  is, that carbon should not be
elastic at all temperatures, like oxygen, nitrogen,  hy-
drogen and their combinations.  Considering the large
amount of caloric evolved during its combustion, there
is  something  very  mysterious about  the fixedness of
charcoal at high temperatures.
   The whole theory of distillation and sublimation is
founded on the different degrees of volatility  in  the
various ingredients of solid and liquid bodies, from the
rectification of the ethers, alcohol and the volatile oils,
to the distillation of coal, by Avhich its carbon,  hydro-
gen and oxygen are volatilized in a state of carburetted 
COHESION  OF LIQUIDS.
153
hydrogen, olefiant gas, carbonic oxide, &c, as in coal-
gas.
   That the proximate molecules of tlie fixed oils, such
as olive oil, castor oil, spermaceti, lard, tallow, &c, are
larger than those of  the volatile  oils, would  appear
from a variety of considerations:—
   1.  They are generally opaque, and many of them
obtained by expression from the seeds of plants;  from
which it  is probable that they contain a mixture of
gross particles, united with more volatile particles; and
that they differ from essential oils  in a manner some-
what analogous to the difference between smoke, Avhich
is composed of gross vapours, and the pure gases, Avhich
are transparent and invisible.
   2.  In its ordinary state of impurity, oil of turpen-
tine volatilizes slowly at 300° F.,  when  a limpid oil
passes over.   At 360° it boils; but on losing its essen-
tial oil, it becomes more tenacious, and requires a tem-
perature of 500° F. to make it boil; thus, passing from
the state of a volatile to that of a fixed oil.
   The oil of anise is composed of 10 atoms carbon,
six of hydrogen and one of oxygen, making its proxi-
mate atom equal to 74;  Avhile the  oil of peppermint
consists of C10H10O, making its compound equivalent
78 :  so that in their atomic construction they resemble
naphthalin, forming a medium between the more vola-
tile oil of lemons, and those termed fixed.
  According to  Dumas, the oil of  cloves is composed
of 20 atoms  carbon,  to 13 of hydrogen and  five of
oxygen, making  its  proximate atom 173.  It is ac-
cordingly  very difficult to volatilize, like the fixed oils; 
154
COHESION OF LIQUIDS.
from Avhich it is probable, that their atomic  constitu-
tion is similar, and determines their tenacity.
  When the volatile  oils are exposed to the atmo-
sphere, they absorb oxygen, by AAdiich they become re-
sinous and concrete.   The oil of turpentine is thus
converted into rosin.   By absorbing oxygen, the fixed
oils become rancid; and  much more rapidly in Avarm
than  cold weather;  during  Avhich process,  carbonic
acid is produced, and heat evolved, as in fermentation.
Hence, the spontaneous  combustion of cotton goods
which have imbibed oily matter.  Again, the mole-
cular  equivalent of starch, sugar and gum, is  162, 171
and 162; while  that of the animal tissues is 535, ac-
cording to  the  lowest estimates.  Hence, the great
tenacity  of muscular  fibre,   of  tendons,  ligaments,
membranes, and the difficulty of volatilizing them; as
in the case  of starch, sugar and gum. 
BOOK  II.
                  CHAPTER I.

ON THE AGENCY OF CALORIC IN THE  COHESION OF SOLIDS.

  " Among learned men, it is no unusual or unheard-of arrogance,
wilfully to reject opinions which they cannot shake."—Bacon.

  It was long since observed by Lord Bacon, that the
most  important facts connected with the fundamental
constitution of nature had been quite  overlooked; such
as "the cause of  heat  and light, weight and density,
hardness and  softness,  solidity and fluidity, fermenta-
tion and putrefaction, germination and organization"
(Novum Orgcunum.)
  Although more than two  centuries have elapsed
since  Bacon pointed out the radical defects of science,
and the true mode of its regeneration, scarcely one of
the above problems has been resolved in a satisfactory
manner.   Philosophers are still as much  divided  in
regard to  the nature of heat and light as they were in
the time of Bacon, Galileo and Boyle;  or the still more
remote period of Plato and Aristotle.
  Sir Isaac NeAvton devoted many years to the inves-
                                         (155) 
156
COHESION OF  SOLIDS.
ligation  of light, and really  accomplished much  to-
ward an elucidation of its physical properties;  but
without ever having inquired into its connection with
heat, or its Avonderful  agency in the Avork of  the uni-
verse.
  The same  illustrious author resolved the cohesion
of solids and the tendency  of heavy bodies toward
the centre of the earth into  the  same  law Avhich de-
termines the  aggregation of planets, and their revolu-
tions around the sun; but he did not identify the cause
of uniAersal  attraction Avith  any known  agent.   In
short, he did not distinctly  unfold the fundamental
principle of action in  nature—of expansion and con-
traction, density and lightness, hardness and softness,
solidity and  fluidity, chemical union and decomposi-
tion.   There is nothing more remarkable in the  his-
tory of science, than that the phenomena of attraction
should have been so far unfolded and generalized, with-
out any definite knoAvledge of their cause.  It  Avould
seem that one of the first inquiries of the  philosopher
ought  to be,  what is the agent or cause  of force, by
Avhich the atoms of matter  are  held together?  and
that the most natural answer Avould be,  that  Avhich
surrounds and fills the spaces betAveen them.
  It can no longer be disguised, that in regard  to the
cause of cohesion, capillary attraction and  gravitation,
Sir Isaac Newton has expressed himself with so much
ambiguity  as to leave his followers in great  doubt
whether he had any  settled  opinion on  the subject.
In  the third book  of the Principia, he  maintained
that universal space is a vacuum; or that  it Is void of
all  sensible matter, and that  the ultimate  particles of 
COHESION OF SOLIDS.
157
bodies are endowed with  inherent forces, or powers of
attraction and repulsion*
   That he aftenvards renounced the vacuum of space
and the self-motive power of atoms, is evident from the
scholium  which he added to the second edition of the
Principia, his letter  to Boyle,  and from the  Avhole
tenor of the  Opticks; in each of which he maintains
the  existence of an  exceedingly subtile,  active  and
elastic ether, as  pervading  universal  space  and the
pores of all bodies.
   Considering  the almost  unbounded  influence of
Newton's authority on nearly all subjects connected
with the science of nature, it  is  important  that his
real opinions  should be distinctly understood.  I shall,
therefore, proceed to prove, by his oavii words, that he
did not regard attraction as an ultimate law of nature,
resulting  from  the inherent properties of  atoms.   In
addition  to  the passages before quoted, in  the first
chapter of this Avork, he observes in the advertise-
ment to the  second edition of the Opticks: "to show
that I do not take gravity for an essential  property of
bodies,  I  ha\re  added  one  question  concerning  its
cause, choosing to propose it by way of question, be-
cause I am not satisfied about  it for want of experi-
ments."
  * Such, however, is the blinding influence of custom and au-
thority, that men who have never found any difficulty in admitting
Sir I. Newton's inherent powers of attraction and repulsion, are
yet startled at the inherent powers of caloric, or the doctrine that
it is a self-active principle.   The self-motive power of spirit was
beautifully symbolized by the Greeks, who represented  Psyche
standing on a car which moved itself. 
158
COHESION OF  SOLIDS.
  The same view is still further expanded in the third
book of the Optlel-s, page 365.  After observing that
"all matter, even light, seems to be composed of ex-
ceedingly small, hard and unchangeable atoms, which
in the densest bodies touch only in a few points," he
adds: "how they can stick together so firmly as they
do Avithout the assistance of something  which causes
thein to be attracted or pressed toward one another, is
very difficult to conceive."*   He remarks, in another
passage,page 369, "there are agents in nature capable
of causing the particles of matter to stick together by
very strong attractions, and  that it is the business of
experimental philosophy to find them out."  Yet it is
an  undoubted fact, that nearly  all the  most distin-
guished followers of  Newton have represented him as
teaching, that the sun operates upon the  planets with-
out any intervening mechanical  medium;  and that
the matter of which planets is composed is held  to-
gether by virtue of inherent power, or  innate forces,
Avhich  Newton expressly says  that he could not con-
ceive.
  Again: in  a letter to Dr. Bentley, he says:  " You
sometimes speak of gravity as essential to matter.
Pray do not ascribe  that notion to me;  for the cause
of gravity is what I  do  not pretend to know, and
therefore  would  take more  time to consider."  (Page
20.)  He adds,   in  another letter: "That gravity
should be innate, inherent  and essential to matter, so
that one  body may  act upon  another at a distance
  *  The same idea was advanced  about 2000 years ago by Plato,
who observes in the  Timseus, that "it is impossible for two things
alone to cohere, without the intervention of a third." 
DOCTRINE OF THE ANCIENTS.
159
through a vacuum, Avithout the mediation of anything
else, by and through which their action and force may
be comreyed from one to another, is to me so great an
absurdity, that I believe no man who has in philoso-
phical matters a competent faculty of thinking, can
eA^er fall into it."  (Third letter to Bentley, page 26.)
   It was truly observed by Bacon, that " the  doctrines
of great and original minds are often degenerated and
embased by time;  that while the lighter parts of their
labours float down the stream of time, the weightier
and more  valuable  frequently sink into oblivion."*
This remark applies with great force to the miscon-
ception and perversion of the ancient systems of phi-
losophy, the most important features of which are but
vaguely and imperfectly comprehended by the mo-
derns.  When Greece was  the centre  of light and
civilization to the whole world, nearly  all  her most
distinguished sages  maintained the existence of  an
igneous  principle, which extended throughout  the
universe.   This powerful and omnipresent agent was
regarded by them as the life of nature, and  the cause
of all concord and discord, (by which they  evidently
meant attraction  and repulsion,) by virtue of which
the celestial bodies were preserved in their respective
 courses, and connected  as by an  invisible everlasting
 chain; and without which there could be no genera-
 tion or dissolution of bodies.
    Such Avere the opinions of Pythagoras, Parmenides,
 Democritus, Heraclitus, Plato and many  others.  Hip-
 pocrates termed it "a strong but invisible fire which
* Advancement of Learning. 
160
DOCTRINE OF THE ANCIENTS.
 rules all things Avithout noise, and is neA^er in repose;
 which  actuates and animates  the Avhole system of
 nature."  Here is  a definition  of heat  in  accordance
 with the discoveries of Dr. Black, but still more com-
 prehensive and important.
   Like the ancient Greek philosophers, Bacon reduced
 all matter to two classes, active and passive;  the  first
 of which he  describes as  rare, invisible and without
 weight,  though a real and  quantitative  substance, per-
 vading and filling the pores of all gross bodies.  I have
 already shown that this active  spirit, to which Bacon
 referred all the motions and transformation of matter,
 is only  another name for caloric.  (See page 19.)  But
 if this pneumatical body be the cause of all the changes
 of living and  dead  matter, it must be the cause of at-
 traction as Avell as repulsion;  of decomposition  and
 recombination.
   In his treatise  on the  Wisdom of  the Ancients,
 Bacon further maintains that the attraction of matter
 was  typified, among the early Greek philosophers and
 poets, by  the  elder  Cupid,  or principle  of  love; that
 it was  the primitive cause of  force, or the moving
 power of elementary atoms, which formed and organ-
ized  the universe of things out of chaos.  He adds,
 by way of commentary on this  ancient  allegory, that
 "there  is doubtless a primary  and universal law of
nature, which  regulates the circular revolutions of the
celestial bodies, and to which are owing all contraction
and expansion of matterT
  In the  third book of his treatise on  the Advance-
ment of Learning, he says, that whoever shall  atten-
tively observe the  appetences of matter, shall receive 
          HYPOTHESES OF BACON AND NEWTON.      161

clear information  concerning celestial objects  from
things which are constantly seen around us; and that
it is  the object of science not only to ascertain the
number, situations and periodic motions of the hea-
'venly bodies, but the physical cause of their mutual
action upon  each other, which he terms living astro-
nomy, to distinguish it from  that which is vulgar and
empirical.
   It  was also maintained by Newton, that all the
phenomena of nature are resolvable into  attraction
and repulsion, which he referred to the agency of  an
all-pervading ethereal substance, capable of  contraction
and dilatation.  But, as it is now demonstrable, that
caloric alone  is the cause of expansion and  the elastic
force  of gases, Arapours  and volatile  liquids, there can
no longer be the shadoAV of a doubt that it is identical
with  the ether of Newton, the pneumatical power of
Bacon and the universal igneous principle of the an-
cient Greek  philosophers.  Nor is it possible to deny
that  Newton has represented this principle  as the
proximate cause of cohesion, capillary attraction, che-
mical  affinity and  of  universal  gravitation;  all  of
which he viewed as modified effects of one and the
same agent.   But OAving to the vague and imperfect
account Avhich he gave of it, philosophers  have even
doubted the reality of its existence, and treated it as
a  chimera of the  author's imagination, invented for
the purpose of sustaining his theory of nature.   The
consequence  of which has been,  that the law of gra-
vitation  has  been regarded as a comprehensive gene-
ralization of  phenomena, for which no definite reason
can be assigned; while the great and noble science of-
                        11 
\Q2          NEAVTON,  BLACK AND BUFFON.

chemistry, which, in a practical point of view, is far
more  important than  astronomy,  consists of an im-
mense collection of facts and experiments, the con-
nection of Avhich Avith the phenomena of heat, light,
electricity, cohesion, capillary attraction  and gravita-
tion, has never been distmctly understood, nor reduced
to fundamental laws.
   Had Newton  discovered  the  simple laAV by which
the ether  produces  the opposite effects of contraction
and expansion,  he  would probably have traced its
agency in the phenomena of combustion,  solution,
vaporization and all the molecular changes of matter.
Or, had Dr. Black and his successors fully compre-
hended that  universal law of caloric by which  it
attracts ponderable matter with a force that augments
in proportion as bodies are deprived of it, they would
have found  that it is  as  capable,  under such circum-
stances, of becoming a powerful bond of cohesion, as
it  is,  under other circumstances,  of dissolving  their
union, and  of converting them into elastic fluids.
But they have all  overlooked the  force of attraction,
by which  this subtile fluid is concentrated around the
particles  of rude matter,  and thus rendered latent;
and by which its self-repulsive force is counteracted.
   Not being able  to  comprehend how one and the
same agent could produce both attraction  and repul-
sion, Buffon maintained that the  powers  of nature,
which are known to us, may be reduced to two:  tlwi
which causes weight, and that which causes heat; that to
the power of attraction, joined to the cause of heat,
may be referred all the phenomena of living and dead
matter.  Still the cause of attraction  remained unex- 
              DALTON,  DAVY AND NEWTON.           163

plained.   Had Buffon advanced but one step farther,
he would have resolved  all the forces of nature  into
one and  the same cause.
  Since  the  discovery of latent heat by Dr. Black,
philosophers have Adewed it as the antagonist of  that
universal force by which all things are held together.
When treating of liquids, Dr. Dalton observes,  that
they must be  considered as bodies under the control
of tAvo most powerful agents, attraction and repulsion,
the last of Avhich he refers to caloric.  Sir H. Davy
also observes,  that  heat, or the power of repulsion,
may be considered as the antagonist of cohesion; the
one tending to separate, and the other to unite the
particles of bodies.   (Chemical Philosophy, page  30.)
Still the important  question recurs, what is the cause
of attraction ?  Newton says, it is an effect of some un-
known ethereal agent, and  that it is  the business of
philosophy to find it out.
  What, then, is  the  internal constitution of matter?
Are the pores of  bodies void of all substance? or are
they pervaded by subtile and active matter?  If so,
what  is  it, and what are the laws by which it  ope-
rates?  It is quite certain, that until  these important
queries are resolved,  the science of nature can never
be established on the solid basis *of fixed  principles,
but must  remain, as  heretofore, imperfect  and vacil-
lating.*

  * it was  supposed by  Epicurus and his followers,  that  "the
atoms  of fluids were  smooth and spherical, by which  they  were
enabled to glide  freely  over each other; but  that the atoms of
solids were hooked,"  as if their forms could change on passing
from the liquid to the solid state.  He also maintained that the 
164
LAPLACE AND MORVEAU.
   It requires no extended series of argument to prove,
that whatever the cause may be which moves atoms, must
also be the cause which moves the  largest bodies, for the
simple  and obvious  reason that they are  made up  of
atoms.   If it be true, that cohesion, capillary attrac-
tion and chemical  affinity, be only modifications  of
gravity, as maintained  by NeAvton, Laplace,  Buffon,
Morveau and other philosophers, it follows, that the
whole theory of nature,  whether mechanical, chemical
or physiological, is resolvable  into that of atoms, and
the cause  by which they are  attracted and repelled,
united and separated.   If Ave  are capable of discover-
ing the cause Avhich holds together the particles of a
pebble, or  crystal of ice, Ave are  also  capable of com-
prehending the cause which binds all things together
by gravity. Newton expressly affirms, that " the drops
of fluids affect a round form by the mutual attraction
of their parts, as the earth affects a round form by the
mutual attraction of its parts by gravity."  (Opticks,
book iii. page 370.)
   It is self-evident, that if the particles  of bodies be
not endowed with inherent  powers of motion, they

pores of bodies were void of all matter.  (De Naturd Rerum,
book ii.)  Others have supposed that the particles of bodies are
glued together by an immaterial cement, as bricks are held together
by mortar. (Baxter on the Immateriality of the Soul.)  The Rev.
W. Jones referred cohesion to the pressure of a cold ether, from
the fact that liquids are converted into  solids by cold.   Ampere,
Berzelius  and some other modern philosophers have maintained
that the atoms of bodies are endowed with electric polarity, or that
their opposite sides are in different states of electricity; while the
great body of chemists regard the whole subject as involved in pro-
found obscurity. 
CAUSE OF COHESION.
165
must be impelled by some other agent; that is, they
must act upon each other at a distance, without  the
agency of imy physical tie, or by some intervening
medium.   Thus it will be found, that the primary ob-
ject of science is to ascertain the cause Avhich moves
atoms,  and the mode  in Avhich it produces  so  many
and diversified effects;  that chemistry and natural
philosophy are only different branches of one great
science, Avhich cannot be studied separately from each
other, without departing from the unity and simplicity
of nature, all the operations of Avhich are governed by
the same code of physical  laws, from the aggregation
of crystals to that of suns, planets and their satellites.
   I  have shown, in the foregoing  chapters,  that  the
atoms of all bodies are surrounded Avith subtile and
active matter, Avithout Avhich they could neither  ap-
proximate  nor recede from each other; consequently,
Avould be  passive and motionless; that the various
forces, movements and changes of form Avhich bodies
undergo, are determined by the relative proportions of
ethereal and ponderable matter of which they are com-
posed;  that Avhen the active principle predominates,
they are decomposed, or expanded into gases, vapours,
or even flame, Avhich is luminous ether; but that when
the ratio of ponderable matter predominates, the at-
traction of caloric for  the  latter counteracts  its self-
repulsiAre force; by which gases are chemically united
into vapours, Avith contraction of volume and diminu-
tion of elasticity, or condensed into liquids  and solids.
  Perhaps the most fruitful source of error in plrysics
has been partial and limited vieAvs of nature; and  the
confounding of phenomena or effects Avith the  cause 
166
CAUSE OF SOLIDITY.
which produces them.  Some modern writers on natu-
ral philosophy speak of gravitation as though it Avere
" the animating principle  of  nature."  In the fifth vo-
lume of the Cabinet Cydopedla, we are told  that, "all
the great changes and revolutions of the bodies which
compose our system can be traced to, or derived from,
this principle."  And Professor Bonnycastle observes:
" The single principle of gravitation pervades the Avhole
universe, and puts every spring and wheel in motion."
*  * *  "From this active, invisible  and invigorating
agent, proceeds all  that order,  harmony, beauty and
variety, Avhich so eminently distinguish the Avorks of
creation." (Astronomy, p.  184, 8th ed.)   But if gravi-
tation were a  universal principle of  action in nature,
it ought to explain  the phenomena of solution, repul-
sion, evaporation, the expansive force of gases and ful-
minating compounds; in short, it ought to account for
all  the operations of chemistry, geology and meteor-
ology; Avhich is  not the  fact.  It therefore follows,
that there must be a principle of action in nature ulte-
rior to that of gravitation, as admitted by NeAvton.
  It might as Avell  be said that repulsion is the ani-
mating principle  of nature,  as  the  general  attraction
termed gravitation.  The true state of the case is,
that both attraction and repulsion  are  subordinate,
though universal effects of an  all-pervading principle
that surrounds every particle of matter in  the uni-
verse;  to which  may be  referred the phenomena of
heat,  electricity,  light, evaporation  and combustion,
together  with  all the  diversified transformations of
matter.
  It Avas by confounding  the external world with the 
             BERKELEY, LEIBNITZ AND KANT.        167

 impressions  Avhich it  produces  on the senses,  that
 Berkeley was led to resolve  the universe  of matter
 into  mind or spirit.  What can we make of the mo-
 nads of Leibnitz,—without parts, extension, figure or
 divisibility,—the essential  properties of which are,
 nevertheless, perception and  appetite?  The  mathe-
 matical theory of Boscovich, before noticed, is equally
 beyond the  power of human  comprehension.  In the
 same  spirit  of metaphysical subtlety, the  celebrated
 Kant denied the existence of ultimate  atoms, by as-
 suming that they Avere without extension or solidity;
 while he resolved heat, light, electricity and magnet-
 ism into the power of attraction and  repulsion, as if
 such  poAvers could exist without  substance.   Not less
 obscure is the modern doctrine which resolves light,
 heat  and electricity into vibrations of  some unknown
 hypothetical ether.  Who can grapple with such sha-
 dowy and unsubstantial data?
   It is an exceedingly partial and superficial view of
 caloric to regard it merely as the cause  of temperature,
 fluidity, vaporization, decomposition, &c.; for it is self-
 evident that if the attraction of caloric for metals, ice
 and other bodies  augments in proportion as they are
 deprived of it, it must be an  attractive as well  as a
 repulsive agent—an  ethereal  bond of cohesion, the
 force  of Avhich Agarics according to the relatiA^e propor-
 tions  of caloric and ponderable matter.  Every altera-
 tion in  these proportions produces a  change  in the
 mechanical,  chemical,  and  even  Arital properties  of
 bodies.
   That the force with which caloric combines ivlth, and
is concentrated around the particles of ponderable matter. 
168
RATIONALE OF COHESION.
augments  In proportion as they arc deprived of It, may
be regarded as a fundamental axiom, derived from the
general experience of mankind;  and it is founded on
a law of nature which connects all the phenomena of
molecular attractions with the theory of latent caloric.
Without the recognition of this important truth, it is
impossible to comprehend  the most familiar pheno-
mena of every-day life—why, for example, the  atmo-
sphere abstracts from animal  bodies their vital heat,
Avith a  rapidity proportional to  the reduction  of its
temperature;  or Avhy caloric is rendered a latent con-
stituent of all matter.  The attraction of ice for caloric
exceeds that  of Avater,( because it contains less of it
than Avater;  the  consequence of Avhich  is,  that  the
particles of Avater are drawn closer together, and  main-
tained in  the solid form with a corresponding force of
cohesion.  If it be objected  that Avater expands during
congelation, it may be answered that its particles are
arranged  in  series, forming angles of 60° and  120°,
making large pores or cavities.   Were it not for this,
the volume  of ice and  other crystalline  bodies Avould
diminish on assuming  the  solid form.   That the vo-
lume of ice is actually reduced, and its cohesion greatly
augmented  by the abstraction of caloric, is evident
from the  large fissures found in bodies of ice after an
excessive  frost, and from the rocky firmness which it
exhibits.*  Were it possible to reduce the temperature
of ice 1000°, the attraction of caloric  for it would be

  * In fact, M. Brunner has recently proved by experiment, that
when the temperature of ice is reduced  from 32° V. to 4° F., its
specific gravity is considerably augmented.  (Silliman>s Journal,
Jan. 1846, p. lit.) 
RATIONALE OF COHESION.
169
immense; while there would be a corresponding aug-
mentation of its density and cohesion.
  If the atoms of gold, silver, copper, iron, lead, tin
and  other  metals, be  surrounded Avith caloric alone,
and if it have a definite degree of attraction for each,
it must hold them together with a corresponding force
of cohesion.   Or if the atoms of oxygen, hydrogen
and  carbon,  of vegetable matter, be  surrounded with
caloric, and nothing else, it must be the cause of their
contraction and  expansion, of their chemical union
and  decomposition, unless  the atoms  be endowed Avith
inherent poAvers of attraction and repulsion; which is
hypothetical and contrary to all analogy.
   Should it be maintained, that electricity is a con-
stituent of all  bodies, I answer, that electricity, as it
exists in a state of combination Avith the particles of
ponderable matter is identical a\ ith latent caloric.  For
the  proofs of this  identity, the reader is referred  to
the next book, where it will be demonstrated that solar
caloric is the  basis of lightning; and that under all
circumstances, hoAvever various  the  phenomena  of
electricity, they are only modified effects of the same
agent Avhich produces evaporation and solution.
   The general recognition of this important truth will
banish from the science of nature an immense mass of
hypothetical speculation, and much of that complexity
which has hitherto baffled every attempt to explain, in
a satisfactory manner, the connection of heat and elec-
tricity Avith cohesion and  chemical affinity.   The ab-
surdity of  supposing that the  atoms of  bodies  are
surrounded  with two distinct ethereal agents, one of
which draAvs  them together,  while the other repels 
170
THEORY OF COHESION.
them asunder, is too obvious to require a serious refu-
tation.
  By the attraction of  caloric for ponderable matter, It
unites and holds together all things; by Its self-repulsive
agency, it sep>arates and expands all tilings.
  To Avhatever portion of nature's Avide domain avc
turn our attention, Ave recognize the operation of this
universal laAv.  Hence it is, to use the significant lan-
guage of Bacon, that  " heat and cold are nature's two
hands;"  Avhich is  a general though vague enunciation
of the above laAv:  for  it is certain, that in a philo-
sophical  sense, the Avords heat and cold  are only rela-
tive terms, Avhich  indicate different proportions of the
same ethereal agent.
  It is because the attraction of caloric for solids ex-
ceeds that of liquids, that their cohesion is greater than
that of liquids.   It is  because the  attraction of caloric
for mercury is greater than for Avater, that  the parti-
cles of the former are  held together with a greater
force of cohesion.   When reduced to the temperature
of —39°, this cohesion is so far augmented that it
assumes the  solid  form,  and acquires the poAver of at-
tracting  other bodies, the temperature  of which is
higher.  When the hand is applied to frozen mercury,
it is also held with great force, as iron is attracted by
a poAverful magnet when charged by a voltaic battery.
It is therefore highly probable, that if the temperature
of mercury were  reduced  —100°, it would  abstract
from animal bodies their vital  heat Avith a force and
rapidity resembling an  electric shock; and that if it
were possible to reduce its temperature a thousand de-
grees below zero, the attraction of caloric for it  Avould 
THEORY OF COHESION.
171
surpass all  means of computation;  Avhile its cohesion
and density would be proportionally augmented.*
   It is owing to the attraction of caloric for  gravitat-
ing matter, that Avhen the hand is applied to iron, cop-
per, gold, silver and other  dense metals  at very low
temperatures, it adheres fast, and cannot be disengaged
without lacerating the skin; or that when a portion of
melted zinc is poured  upon a solid  plate of the same
metal, there is a rush  of  caloric from the liquid to the
solid, by Avhich their particles are forced together; that
when Avater is  poured upon a block of ice  15° or  20°
belovv zero, it is immediately converted into the solid
state, and  incorporated Avith the ice by virtue of  the
same force which causes  universal attraction.
   * It is because caloric has a stronger attraction for iron, copper,
 gold, silver, platinum and  other dense metals, than for silks, furs,
 down, woollens, resins, bitumens, sulphur, coal, iodine, bromine, dry
 wood, potassium, sodium, with innumerable other light bodies, that
 they abstract it more rapidly from warm-blooded animals, and con-
 sequently feel colder to the touch.  It is because caloric has a pow-
 erful attraction for the dense metals, that it is concentrated and
 held around their  particles with immense force, and cannot be dis-
 engaged from them, even in small proportions,  without the  appli-
 cation of  great mechanical  pressure.  Accordingly, we find that
 they are good conductors  of caloric, and  cohere together with a
 corresponding force of aggregation.   Their cohesion and conduct-
 ing power are also augmented in proportion to their condensation
 by  pressure, as in wire drawing; from which it follows, cseteris
paribus, that their affinity for caloric, on which their cohesion and
 conducting power depend,  increases with their density and loss of
 caloric.  It is equally true of all other bodies, without a single
 exception, that their cohesion and conducting power are determined
 by the relative degrees of their attraction  for  caloric, which aug-
 ments in proportion as they are deprived of it. 
172
THEORY OF COHESION.
  It is by the attraction of caloric for ponderable mat-
ter that it combines Avith different bodies and produces
their liquidity; it is also by virtue of the same attrac-
tion, that liquids are enabled to dissolve and combine
with other bodies.   Philosophers have generally as-
sumed,  that  cohesion  is the antagonist  of  chemical
affinity, and that they are produced by different causes.
But  the most obvious phenomena  of nature demon-
strate that they  are produced  by one  and the same
cause, and that all molecular combinations result from
the attraction of  caloric for other matter.  The only
difference between cohesion and chemical attraction is,
that the one  is exerted betAveen  homogeneous atoms,
and  the other between  heterogeneous atoms, which
van- in  size, and in the degrees of  their affinity for
caloric.   It  is owing  to  the attraction of caloric for
ponderable matter, that Avhen a piece of tin is laid on
a portion of melted lead, the tin is dissolved,  and its
particles intimately blended with  those  of the lead.
In all such  cases, it is undeniable that the atoms of
the liquid  are forced  to  combine with those of the
solid, by the  agency of caloric alone; for the obvious
reason, that no other agent has been employed to  pro-
duce the effect.
  It is in this way that all metallic alloys are formed.
If six drachms of solid  zinc be brought in contact with
an ounce of melted copper, there is a transition of
caloric from the one to the other, by which the particles
of zinc  are transported from their original place, and
intimately combined with  those of the copper, by the
same power  which unites the  atoms of individual
metals.   The fact is, that  all the elements of nature 
THEORY OF COHESION.
173
may be united  by fusing them  together, and again
separated by larger proportions of the same agent.  If
a mass of granite or basalt were  plunged into a caul-
dron of burning lava, they Avould be intimately incor-
porated throughout by the transition of caloric from
the lava to the solid rock.  It is  scarcely necessary to
add, that the various materials of  which all volcanic
rocks are formed, are thus united and held together,
by the same cause which maintains the  solidity and
cohesion of the earth.
   The art of plating bars of iron, copper, &c, with
gold, silver,  zinc, tin  and  other metals,  is founded
wholly on the cementing poAver of caloric, Avhich forces
them together, by what may be termed chemical cohe-
sion, to distinguish it from the aggregation of simple
bodies.   Plates of gold are made to unite Avith bars of
iron and other metals, by being pressed together and
placed in a stove or furnace.
   When bars or plates of iron  are thoroughly cleaned
and polished until quite bright, and immersed in melted
tin, they are soon covered over with a thin white coat;
or if a slip of copper be perfectly cleaned and polished,
then heated, and  rubbed over Avith a piece of tin, a
portion of the latter metal combines with the copper,
giving it a silvery  coat, which adheres to it for the
same reason that the hand adheres to frozen mercury,
or other  metals, when reduced  to very low tempera-
tures.
   The common mode of tinning copper vessels, is to
make the surface bright by scraping and Avashing them
Avith a solution of hydrochlorate of ammonia.   They
are  then Avarmed, when the tin is melted and poured 
174
THEORY OF COHESION.
 into them, by Avhich it incorporates with CA'ery part of
 their surfaces, and Avhen cold remains firmly united.
 In the same Avay, iron vessels are coated with zinc.  It
 is Avell  known that silex cannot be made to combine
 with potassa or soda to form glass without the agency
 of heat, Avhich is  equally essential to the Avelding  of
 iron and to  the soldering of other metals.   The ad-
 hesive  property of wax, gum, sugar, &c, when  in a
 state of fusion by caloric, is equally familiar  to every
 one.
  The truth  is, that all the internal and external  pro-
 perties  of bodies,  whether mechanical  or chemical,
 such as hardness and  softness, density and lightness,
 tenacity and firmness, volatility and  combustibility,
 are determined by their relations to caloric.
  It is Avell known to spinners and weavers,  that the
 fibres of cotton,  wool, flos-silk and  flax, are brittle
 during  cold weather, and that if their rooms are not
 kept at a proper  temperature,  their threads  often
 break.    On the other  hand, some of the most brittle
 substances in nature,  such as glass, may be spun into
 thread almost as fine  as that of the silk-worm, when
 in a state of  fusion by heat;  while butter, lard  and
 many other  substances that  are soft and tenacious
 Avhen warm, become hard and brittle at very low tem-
 peratures.  The same  is true of iron and some  other
metals,  which become  brittle  like glass or ice during
excessively cold  weather.  The rationale of this Avill
 appear from the general fact already established, that
the  attraction of caloric for bodies  augments in pro-
portion  as they are  deprived of it; the consequence of
Avhich is, that it is more concentrated  around their 
THEORY OF COHESION.
175
particles, which  cohere  with a corresponding force,
producing great hardness;  but Avhen by a blow, or any
sudden force, they are removed in  the slightest degree
from their place, the cohesion is broken, and they fly
asunder.   In the state of liquids,  their particles glide
freely  over each other, without losing their hold, as
one magnet glides over another.   This is the case with
all the malleable metals, and with the tenacious oils,
gums,  glue, &c. until reduced to very low temperatures,
when  they all become more or less brittle like ice.  It
is OAving to the augmented cohesion  and hardness of
very cold iron that it will not bend, but snaps asunder,
—that is, its particles refuse to glide over each other;
Avhile, at higher temperatures,  the greater  extent of
the igneous atmospheres that surround them holds on
to them at greater  distances, though with  less force,
causing toughness or tenacity.
   When tAVO pieces of lead, tin, zinc or any other soft
metal, are  pressed  together with sufficient firmness,
their atoms are  brought within the range of this at-
tractive medium.   The same is  true  of the  hardest
substances, when softened  by  heat.   Even polished
plates of glass, marble, wood and many other bodies,
Avhen brought into close  apposition, cohere, but  still
 better when fused together by heat.
   It was  before  stated that the ethers, alcohol  and
 many other liquids, have no cohesion whatever at or-
 dinary temperatures;  and  when released from the
 pressure of the atmosphere, are expanded into vapours
 by the repulsive power of their latent caloric.  They
 are accordingly  very bad  conductors, like  silks, wool-
 lens, furs and other light bodies, that are full of ca- 
176
THEORY OF COHESION.
loric.  Yet  by a sufficient reduction of temperature,
their attraction for the igneous principle is so far aug-
mented, that their particles are drawn closer toward
each other, and bound together in the solid form; and
if their temperature could be reduced 1000° F. there
is every reason  to  believe that their cohesion Avould
equal that of salts, rocks, or even the denser metals.
  From all the foregoing facts  and arguments it  is
evident, that attraction  and repulsion, hardness and
softness, solidity and  liquidity, density and  lightness,
are not essential conditions of bodies, but depend on
the relative proportions of ethereal and  ponderable
matter of which they are composed; that  the most
elastic gas may be reduced to the liquid form by the
abstraction of caloric, and again converted into a firm
solid, the  particles of  which would cling together with
a force proportional  to their augmented  affinity for
caloric.  On the other hand, it is equally evident, that
by adding a sufficient quantity of the same  principle
to the  densest  metals, their  attraction for it is dimi-
nished, when they are  expanded  into the gaseous
state, and their cohesion destroyed.
  Having met with  a few  individuals who  cannot
readily conceive how  a self-repulsive agent can operate
as a bond of cohesion  between the particles of common
matter, it may be  proper to  show, by a few familiar
examples, that the force with which liquids hold to-
gether the particles of solid bodies, is not in proportion
to the attraction of their own particles for each other,
but in  proportion to their affinity for the solids.
  It is Avell knoAvn that at ordinary temperatures of
the atmosphere, the particles of water cohere Avith very 
THEORY OF COHESION.
177
slight force, if not deprived of air.   It is also known,
that when granite,  lime, clay and marble, together
with all other rocky and earthy bodies, are reduced to
the condition of a perfectly dry and impalpable powT-
der, their particles glide freely over one  another, hav-
ing little or no attraction for each other.  On adding to
this powder a due proportion of water, they are found
to unite together by a very strong attraction, forming
dense and highly tenacious mortar.  The  less water
such ingredients contain, the stronger is their attrac-
tion for it.  Hence it is, that  the cohesion of mortar
augments in proportion  as it is deprived of Avater by
drying; or that when  the earth has been parched by
a long drought, it attracts and absorbs more rapidly a
shower  of rain, than  Avhen in a moist  state, in  the
same way that all bodies  absorb caloric Avith a force
and rapidity in proportion as  they are deprived of it.
In like manner, the cohesion of mortar  is  diminished
by  adding to it  larger proportions of water, in  the
same manner that the cohesion of ice, metals and other
bodies, is  lessened by increasing their temperatures;
that is, by altering the relative proportions of caloric
and ponderable matter.
  Innumerable liquids might be mentioned, the atoms
of which  have no cohesion among themselves, which,
nevertheless, operate as a bond  of union  among  the
particles of various other solids Avhen in the state of
powder.   It is  by virtue of the affinity between wheat
flour and water, that they form a cohesive dough;
and so  of a thousand other  bodies, the particles of
which have little attraction for  each other, without
the medium of a liquid; but if caloric be  indispensable
                         12 
178
THEORY OF CONDUCTION.
to fluidity, it must be the ultimate and efficient cause
of attraction between liquids  and  solids.   It is the
caloric of melted wax, glue, paste, gum, molasses, &c,
by Avhich they are enabled to combine with and hold
together the particles of solid bodies,  for  the  same
reason that the  caloric  of  melted  metals, rocks, &c.
enables them to combine with solids, and to hold  them
together.   If sulphate of lime be reduced to the state
of powder, its particles have scarcely any cohesion for
each other; but if converted into mortar by the ad-
mixture of water, they  cohere into a rocky cement,
the firmness of which is in proportion to the force of
attraction between the water and the lime.
   In fine, the more  profoundly we scrutinize the ope-
rations of nature, the more evident it becomes, that
all the modifications of force by which the particles of
bodies are united, depend on the agency of a self-repul-
sive ether.  It is therefore ridiculous to maintain, that
an agent  which repels its own particles, cannot hold
together the particles of other bodies.

        THEORY OF CONDUCTION AND  RADIATION.

   The most  general  and  well-established fact con-
nected with conduction is, that all the lightest bodies
in nature are  bad conductors of caloric and electricity;
such as furs, eider down, silks, woollens, cottons, resins,
lac, bitumens, phosphorus, dry wood, &c. among solids;
and ether, alcohol, oils and water among liquids; while
gases  are still worse conductors;  whereas, the densest
known bodies are good conductors, such as gold, silver,
copper, iron,  zinc,  tin, lead, &c.  Next to  the  pure 
THEORY OF CONDUCTION.
179
metals  in conducting power,  are  rocks, gems,  flint-
glass, porcelain and the denser liquids, as solutions of
the  acids and alkalies.   Owing to their extreme fusi-
bility, it is difficult to determine the conducting power
of potassium  and sodium;  but it is certain that they
are bad conductors of caloric, and probably worse than
water, in proportion to the difference between  their
specific gravities.
  It has also been proved in  the preceding chapter, that
all the  lightest known bodies are composed  of  large
proportions of caloric, (which repels its own particles,)
compared with the quantity of ponderable matter.
   The atoms  of gases being surrounded by extensive
atmospheres of caloric, are  therefore bad conductors.
It Avas  found by  Sir  Humphrey Davy,  that when
metals,  such  as mercury,  tin and arsenic, are con-
verted into the gaseous state, they become, like other
gases, non-conductors of electricity.   (Works, vol. ii.
p. 22.)  The  same thing is true,  though in a less de-
gree, of all the lighter liquids and solids.
  On the other hand, the atoms of the  metals which
contain less caloric around them in proportion to their
size, and being closer together, attract and  conduct it
from one to the other,  with different degrees of ra-
pidity;  modified by the arrangement  of their atoms,
and  perhaps by other circumstances not yet fully un-
derstood.   It  is, doubtless,  owing to  the crystalline
structure of ice, that it  is a worse conductor of elec-
tricity than water.   May it not be owing to the same
cause that glass, resins, sulphur and some other bodies
are better conductors of electricity in the liquid  than
in the solid state? 
180
THEORY OF CONDUCTION.
   That the conducting poAver of all bodies augments in
proportion as they are deprived of caloric, other things
being equal,  may be regarded as absolutely certain.
   The  conducting power of metals  is increased in pro-
portion to their condensation by pressure, for the same
reason  that it is augmented by a reduction of tempera-
ture,—that is,  owing to the loss of a portion of tlieir
heat. Caloric has a stronger attraction for pure metals
than for  their  oxides,  chlorides,  fluorides, bromides
and iodides;  their specific gravity, cohesion and con-
ducting power  are also greater.*
   The  connection of this subject with the philosophy
of radiation is exceedingly important, and seems never
to haAre been rightly understood.   It was ascertained
by a great variety of experiments performed by Dr.
Wells,  Avith  a  view of  explaining the production of

  * Lord Bacon observes, in the Second Book of the Novum Or-
ganum, that it should be inquired why metals and stones feel colder
to the living body than the fur of animals,  silks, woollens, feathers,
wood, &c;  whether the latter contain more inherent heat than the
former;  and if  so, whether it be owing to their oily nature, or to
the air which they contain.  Dr. Thomson thinks that it is owing
to the air within their pores; while the great mass of writers on
Chemistry and  Physics, resolve  the  whole mystery by telling us,
that they are bad conductors of caloric, which is  the very thing
to be explained.  The hypothesis of Dr. Thomson  is so far from
affording a solution of the difficulty, that he does not explain why
air is a bad  conductor.  The simple matter of fact is, that all those
articles of clothing which retain the caloric of the body most effect-
ually, contain a large amount of the  igneous principle,  and are
therefore bad conductors.  For the same reason, they are highly
combustible; and, when submitted to friction, afford abundance of
the electric  ether; on which account, they have been called elec-
trics. 
THEORY OF RADIATION.
181
dew.   He found that eider down, wool, cotton, grass,
the leaves of trees and all vegetable substances, parted
with their caloric more rapidly by radiation, than rocks
and metals;  that while  dew collected in large quan-
tities on the former, during  clear nights, there  was
generally little  or none on the latter.   But no one
seems  to have suspected, that the  radiating power of
bodies was determined by their latent caloric, or  that
it was even modified by  their attraction for it.
  It was supposed by Prevost, whose opinion has been
adopted  by a majority of writers  on Chemistry and
Natural  Philosophy, that  the tendency of all  bodies
to an  equilibrium of temperature, is owing  to  a per-
petual exchange of caloric from one to the other by
radiation.  But it is evident from the foregoing facts,
that the  motions of caloric by which it passes  out of
one body into another, are owing to its attraction for
ponderable matter, as well as to its self-repulsive  or
radiating poAver.  When a hot body is placed  in vacuo,
and at a distance from other  bodies, it  parts with
caloric by  radiation alone,  Avith a rapidity propor-
tional to temperature.  When placed  in atmospheric
air, it loses the same quantity of caloric by radiation,
while an additional portion is abstracted  by the con-
tiguous particles of air.
  It is generally stated,  that  bodies cool about twice
as fast in air as  in vacuo.  Count Rumford found  that
a thermometer  cooled from 212° F. to 32°, in  vacuo,
       in.......10 m.   5 sec.
       in air......     7      3
         Avater.....1      5
         mercury ....     0     36 
182
THEORY OF RADIATION.
But if it be true that all bodies attract and absorb
caloric aa ith a force and rapidity in proportion as they
are deprived of it, it is obvious that in air, —50°, the
thermometer Avould sink much more  rapidly.   It  is
equally obvious, that when placed in water, mercury
and other dense liquids, the effect is produced wholly
by the attraction of  caloric for  them,  and Avithout
radiation.
   It was  before stated, that caloric has  but little atr
traction  for the  metallic oxides,  compared  with the
pure metals; and that their cohesion, specific gravity
and conducting power are accordingly small.  The ex-
periments of Leslie prove  that their radiating power
is much  greater.   He found that  while the  radiating
power of clean lead was only 19, it  rose to 45 when
tarnished by oxidation;  that the radiating  power of
plumbago was  75, and that of red lead 80.   He also
discovered, that  while the radiating power of  gold,
silver, copper and polished tin was  only 12, that of
croAvn-glass was 90, sealing-wax 95, resin 96, writing-
paper 98, and lamp-black 100.
   In short,  all light  bodies, which are full of latent
fire, and  therefore bad conductors, are proportionally
good radiators; while the  denser metals, which con-
tain less of  it,  hold on to it for a longer time, under
the  same circumstances.   But as their  affinity for
caloric diminishes in  proportion as they acquire more
of it, they also radiate freely at very high  tempera-
tures.  On the other hand, if the  dense metals could
be reduced 1000° below zero,  they would attract and
conduct it with a force and velocity like lightning.
   The more  careful and reliable  experiments of Dr. 
THEORY OF RADIATION.
183
A. D. Bache and of J. Brocklisby, have proved that
colour alone exerts no influence upon the radiating
power of a surface.
  It has been long known that metallic vessels, such
as tea-urns, retain their temperature much longer than
vessels  of stone, earthenware, wood, &c, Avhich have
less affinity for caloric than metals;  and that the same
metallic vessels  retain their temperature longer when
highly polished  than when rough.  The latter effect
would seem to be owing to the closer proximity of the
particles composing a smoother surface; for it has been
found, that  when wood is reduced to  sawdust, it  ra-
diates more  rapidly than in the solid state; that locks
of wool, cotton,  flos-silk, &c, radiate better than the
same materials when spun and woven,  by which their
fibres are brought closer together.  So when the par-
ticles of a metallic surface are brought near to each
other, they  have a stronger  affinity for caloric than
Avhen more  distant, and thus prevent it  from flying
off,  for  the  same reason that the cohesion and con-
ducting power of metals are augmented by condensa-
tion, as in  wire drawing.  Melloni found that the
radiating power of  metals was impaired by polishing
their outer layers, which  are thus  condensed by the
pressure used, and that cast silver  radiates one-third
more than hammered silver, which is more dense; the
polish of surface being the same.   Is it not owing to
the same cause,  that electricity escapes more rapidly
from  rough  surfaces which  consist of innumerable
points,  than from  such as are smooth and  highly
polished ?
  Connected Avith  this subject  is another fact, that 
184
THEORY OF RADIATION.
has  never been explained, and which may appear at
variance Avith the above theory of radiation, until duly
considered.  It has  been ascertained by  Leslie and
other experimenters, that the reflecting power of bodies
is Inversely as their  radiating power; and that their
power  of absorbing caloric is proportional  to their ra-
diating power.
   It was discovered  by Newton, that the  surfaces of
glass and polished marble are covered over by an invisi-
ble and repulsive medium, which prevents tlieir actual
contact,  even when pressed  together with  great force.
It is doubtless owing to this elastic and repulsive
ether,  Avhich adheres to polished  metals by  a still
stronger attraction, that when Avater is  poured upon
them,  it glides  over, without wetting  or  touching
them;  and that steel needles' are enabled to float on
the  surface of water, notwithstanding their greater
specific gravity.  It is this thermo-electric ether Avhich
prevents  polished metals from absorbing caloric, and
causes it to rebound from their surfaces by reflection;
while  light bodies, and metals that are  rough or un-
even, which contain less of the repulsive medium over
their surfaces, absorb more and reflect less  caloric. 
CHAPTER  II.
             CHEMICAL  ATTRACTION.

  "Of the great  and comprehensive laws, which rule over the
widest provinces of natural phenomena, few have yet been dis-
closed to us."—Whewell.

  Whether in  a practical or philosophical point of
view, a perfect theory of chemistry would be  of far
higher importance than that of universal gravitation;
for it Avould lead to a knowledge of all the properties
of the elements by which Ave  are  surrounded, and of
their application to the extension of human happiness.
Yet  there never was a period in the history of science,
when greater uncertainty prevailed in regard to  the
primary cause of chemical action, than at the present
time.  The celebrated (Erstedt regards the science of
chemistry as in  the same condition now, that mechani-
cal philosophy was in the age of Galileo, Descartes,
Huygens and Newton; and he maintains that no gene-
ral principle has been discovered which governs all
affinities.  (Snr  YIdentite des Forces Chimlques et filec-
trlques.)
  Notwithstanding the recent progress of atomic che-
mistry, Dr. Prout observes, that this  great science "is
founded  solely  on experience, for the phenomena of
which Ave can assign no reason."  (Bridgewater Ti-eatise,
                                         (185) 
186             CHEMICAL ATTRACTION.

p. 29.) On the same subject, the language of Professor
WheAvell is  still more emphatic and precise.  In the
concluding  chapter  of his  Treatise  on Astronomy, he
states, that  "no one has pointed out any common fea-
ture between  chemical affinity and the attractions of which
ire hwiv the  exact effects; and that we arc still more pro-
foundly ignorant of th e vital principle."  Lord Brougham
also observes, in his Natural Theology, that  " we know
little or nothing of the minute motions by which the
particles of  matter are arranged, when bodies act che-
mically on each other." (Vol. i. p. 373.) Lastly, Liebig
says:  "the  ultimate  causes of combinations and de-
compositions are chemical forces, and these  differ from
all other forces, inasmuch as we perceive their exist-
ence only by their manifestations when bodies  come
into  immediate contact Avith  each other."  (Letters on
Chemistry, p. 32.)   Alas ! if this be a true representa-
tion  of the actual state of human knowledge, is it
not high time  that men should  awake from  their
lethargy, and observe more  attentively all the circum-
stances connected  with chemical action?  It was pro-
foundly  observed  by  Bacon, that "in  all generation
and transformation of bodies, we shoidd inquire what is
added, what remains and what is lost,—what  is united
and what is separated,—what hinders, what commands
and what gives the motion."  (Novum Organum.)
   This is the true character of the inductive philoso-
phy;  careful observation, rigid analysis, the  rejection
of all  hypotheses  and the  undue authority of distin-
guished  names, must  ultimately lead to the solution
of all physical mysteries.   It is doubtless an object of
great practical importance to know the proportions in 
                CHEMICAL ATTRACTION.             187

which the elements of ponderable matter unite to form
water, alcohol, ether, acids, alkalies, salts, rocks, &c.;
but it is still more important to know Avhat the agent
is, by Avhich they are brought together and maintained
in a state of intimate combination.
   That the ancients regarded fire as the  great agent
in all the transformations of  nature, would appear
from the etymology of the word  chemistry, which,
like the Greek xyueca, Chemeia, was deriAed from the
Oriental HD'D, Chime,  signifying Heat, according to
the learned Parkhurst.   But Sir William Drummond
quotes a passage from Zosimus, of Panopolis in Egypt,
who states, on the authority of the Hermoic books,
that the art Chemeia took its name from the  word
Chema.  (Orlgines, vol. ii. p. 264.)   Noav it is remark-
able,  that this Avord was employed, with slight dia-
lectical variations,  by  se\reral  of the  most ancient
Oriental nations, to represent  Heat.   By the Egyp-
tians it was called DPI,  Khem, or Ham with the aspi-
rate.   By the Chaldeans and Hebrews it Avas called
("Olf, Kheme, or chema, signifying the solar Fire, which
the Arabians  called hama.  In fact, the word hama,
Heat, has been traced  in the  old  Pahlivi language,
which has been regarded by competent authorities as
the mother of the  Sanskrit, the  Zeud of Persia, the
ancient Kouwen of China, and  some  other Asiatic
tongues. Nor is it unAvorthy of notice, that the name
of Brahma Avas derived from the Sanskrit bra, to create,
and hma, or homa;  signifying the creative Fire.
  The proximate agency of caloric in chemical affinity
might  have been long  since recognized, but for the
difficulty of comprehending how a self-repulsive agent 
188
CHEMICAL ATTRACTION.
could become  a cause of attraction.   But  it is self-
evident, that if a globule of ice be composed of oxjgen,
hydrogen and  caloric; and if there be  an attraction
between  the particles of ice and caloric, they must be
held together with  a force equal to that attraction;
and so  of all other bodies.   Besides, if it  Avere de-
monstrated, that some other  ethereal agent, such as
electricity, surrounds the particles of ice, it must have
an attraction for them like caloric, or it could not be-
come a bond of union.  It therefore  follows, that in
either case, the effect  results  from one  and the same
fundamental law, which involves an identity, or unity
of causation.   In addition to Avhat was before stated,
page 177,  the  following facts will  further  illustrate
the manner in which a self-repulsive agent becomes a
bond of union  between  the particles of inert matter,
Avhich have no inherent affinity for each other.
  It is Avell known, that the particles of ether, alcohol
and many other volatile liquids, repel each other with
such force, that when  the  pressure of the atmosphere
is removed, they fly asunder,  and assume the form of
elastic vapours, thus presenting the character of an
idio-repulsive agent.   It is also  knoAvn that when the
particles of resin,  charcoal   and hundreds of other
bodies, are reduced to the state of an impalpable pow-
der, like the dust of our roads  after a long drought,
they have little or no attraction for each other;  but
that if they be brought into  contact with the above
volatile liquids, they cohere with considerable force.
Why?  Undoubtedly  because there is  a mutual at-
traction between the liquids and powders, which coun- 
CHEMICAL ATTRACTION.
189
teracts the repulsive force of the liquids, and prevents
them from flying off in the form of vapour.
  It has been long knoAvn that platinum when reduced
to the form of a black powder, absorbs about 800 times
its  volume of oxygen gas,  which is thus condensed
around its molecules.  During this process, the caloric
Avhich maintains the oxygen in the gaseous state  must
be giA^en out, yet so gradually that no sensible eleva-
tion of  temperature is  observed.  When  a jet of
hydrogen gas is  thrown upon the poAvdered platinum,
it combines Avith the oxygen condensed in the interior
of the mass, by which water is  generated,  and heat
evolved, until  the  hydrogen is  inflamed,  and the
platinum  made  red hot.  If the jet of  hydrogen be
interrupted, the pores of the platinum become im-
mediately filled again with oxygen; showing that this
absorption of gases  by porous solids is  greatly aug-
mented by  caloric.   We are further authorized to
conclude, that the  latent caloric of oxygen is the
cause of its primary combination with, and condensa-
tion around, the  molecules  of  platinum: for Avhen
raised to the temperature of 572° F., poAvdered  glass
possesses the same property of absorbing and condensing
oxygen as spongy platinum at ordinary temperatures
of the atmosphere.  In fact, there is a large class of
metals, Avhich,  Avhen  reduced to a state of minute
division, combine rapidly Avith  oxygen at ordinary
temperatures: such  as iron, nickel, cobalt,  uranium,
lead, &c.  When iron is  in mass, it has but little ten-
dency to oxidation:  but Avhen  firmly  pulverized, it
cannot  be brought  in contact with atmospheric air 
190
CHEMICAL ATTRACTION.
 Avithout  becoming  red hot, and converted  into  an
 oxide.
   If the particles of dust had  no cohesion for  each
 other whatever, they would represent the condition of
 ultimate atoms Avholly deprived of caloric, which could
 neither approximate nor recede from each other.  At
 the temperature of 67° F. water is an  elastic fluid in
 vacuo; but if  a thin film of water be placed between
 tAvo  plates of  glass in an  exhausted  receiver,  they
 cohere together, because the water is  more strongly
 attracted by the glass, than repelled by its OAvn par-
. ticles.   However imperfect  such illustrations may be,
 they are sufficient to prove that a self-repulsive agent
 may become a bond of attraction to other bodies.  But
 the fact which must forever set  this question at rest
 is, that the attraction of all bodies  for caloric  aug-
 ments, cceterls paribus, in proportion  as they are de-
 prived of it, and that their  cohesion  augments in the
 same ratio.
   To those philosophers who have regarded electricity
 as the  proximate cause of molecular attraction, it  may
 be somewhat surprising  that I have  proceeded so far
 without  an examination  of the facts  on  which  the
 electro-chemical theory was founded.
   To this  I answer, that no  general law of electric
 action  has  ever yet been pointed  out  capable of ex-
 plaining  all the phenomena of molecular forces;  in
 short, that nearly all the leading facts, connected with
 the theory of electricity, are involved  in the utmost
 obscurity and uncertainty.
   I have shown that  caloric is  a universal and inde-
 pendent  agent, which  may be everywhere recognized 
CHEMICAL ATTRACTION.
191
as a source of power and motion—of contraction and
expansion—of solution and  recombination;  and that
it is a  principle of action in all the  proceedings of
nature.
   But, in regard to electricity, we are  not  informed
by those Avho assign it as the cause of chemical action,
Avhether it  be  a material agent which  may be added
to, and  subtracted from ponderable matter, or a mere
effect resulting from  the inherent properties of com-
mon matter.  The electro-chemical theory of Sir Hum-
phrey Davy Avas founded on the well-known fact, that
Avhen bodies are in different  states of electricity, they •
attract  each other.   Starting from  this point, he as-
sumed,  first, the existence of two electric  fluids, each
of which has  an  attraction for the other, and repul-
sion of its  own  particles; secondly, that all  bodies
Avhich combine chemically, are in opposite states of
electricity.   Finding  that the atoms of oxygen, chlo-
rine, fluorine, iodine  and bromine, were attracted by
the  positive pole of  the voltaic battery,  he inferred
that they were combined with negative  electricity;
while all those bodies that were attracted to the nega-
tive extremity of the battery, were supposed to  be
electro-positive; and that in consequence of the attrac-
tion existing between such bodies, they rushed into a
state of chemical  combination, when the  two electri-
cities assumed the form of light, or fire.  (Phil. Trans-
actions for 1806.)
   It would be an irksome task to detail all  the objec-
tions that might be urged against this ingenious hypo-
thesis.   That  it Avas  not understood by Sir H. Davy
himself, is  manifest from the fact, that, in  the same 
192
CHEMICAL ATTRACTION.
Lecture, he  asks the question, " May not the  remote
cause of electrical energy be identical with chemical
affinity, and an essential property  of matter?"  He
also  observes, in his Chemical Philosophy, that "elec-
tricity seems  to result from the general powers  and
agencies of matter."  How  is it possible to reconcile
or comprehend such vague and contradictory views?
   Had  not  this distinguished chemist attached him-
self  in early life to the hypothesis,  that " caloric  was
a mere effect," instead of being  an  all-pervading  and
sufficient cause of motion, his OAvn experiments Avould
have led him to perceive that caloric and electricity
are mutually convertible into each  other;  for he  Avas
among the first to demonstrate that electricity is capa-
ble of producing the same  effects which  are usually
ascribed to  caloric.   By means  of  a wire, connected
Avith the poles of a battery, he caused Avater and other
liquids to boil.
   Let us examine  briefly  some of  the  consequences
which flow  from the hypothesis that caloric results
from the combination of two electric fluids, admitting
for the present, (what has never been  established,)
that electricity consists of two  mutually attractive
fluids.
   The hypothesis assumes  in the first place, that all
the  elements of ponderable matter are reducible to
two classes, one of which is united Avith positive, and
the other with negative electricity; the mutual attrac-
tion and combination of which produce the  pheno-
mena of heat, and the chemical union of bodies.  But
it is self-evident, that if heat result from the union of
two electric fluids, all simple bodies must  be without 
CHEMICAL ATTRACTION.
193
caloric, until they unite chemically, which is contrary
to matter of fact; for it has been proved in the pre-
ceding part of this work, that all bodies are composed
of cedorlc and ponderable matter; a fact which cannot
be predicated of electricity, unless we  admit, that, in
its latent or combined state, it  is identical with the
omnipresent igneous principle.   It is  impossible to
imagine  anything  more  at variance with common
sense and the universal experience of  mankind, than
the supposition  that caloric is  the offspring of elec-
tricity ; or that an universal agent should be the effect
of any other power which is not universal.
  Another  objection to the electro-chemical theory
arises from the fact, that bodies which are assumed to
be in the same electric state, unite chemically.
  For example, oxygen combines with chlorine, iodine
and bromine, making chloric, iodic  and bromic acids;
while sulphur, phosphorus, carbon, hydrogen and the
metals, which are considered to be in an opposite state
of electricity from the above elements, combine chemi-
cally  with each other as well as with oxygen, chlo-
rine, &c.   Besides, it is not true that oxygen, chlorine,
iodine and bromine, are uniformly in the same electric
state; for it is very Avell known that when chloric
acid is decomposed, its elements  are conveyed to diffe-
rent  poles of the battery;  that Avhen sulphurous and
sulphuric acids are decomposed  by the pile, sulphur
goes to the negative pole; but that when sulphuretted
hydrogen is decomposed, sulphur goes  to the opposite
pole;  that Avhen  carbon, selenium,  arsenic and tellu-
rium  are united  with oxygen, they are positive, but
negative  with  hydrogen;  proving that bodies are
                        13 
194
CHEMICAL ATTRACTION.
neither essentially  positive nor negative, and  that
they vary in this  respect according to circumstances;
consequently, that all classifications of bodies founded
on their electric polarities are fallacious.
  Dr. Thomson obsen^es, that " if chemical  affinity
were merely the result of different states of electricity,
bodies could not remain united  unless these different
electrical states were permanent.  But if the positive
and negative electricities  combine and fly off in the
form of fire, there must be an end  of the different
electrical  states which  caused them  to  unite, and of
course the  union must cease, which is  contrary to
matter of fact."   (Thomson on  Heat  and Electricity,
p. 335.)
  A still more fatal objection to the  electro-chemical
theory is, that it  affords no explanation  Avhatever of
cohesion or simple aggregation;  whereas I have shoAvn
that the particles  of homogeneous bodies are held to-
gether by the same cause which maintains the chemical
union of heterogeneous elements; that the particles of
copper are held together by the same agent that causes
it to combine with zinc and other metals:  but avIio has
ever maintained that the atoms of homogeneous bodies
are in different states of electricity?
  It is not surprising that M. Becquerel,  Avho follows
Davy and Berzelius in referring chemical attraction to
electricity, should have admitted that cohesion  is a
stumbling block (la pierre  d'achoppement) in the way
of every attempt hitherto made to connect the theory
of chemistry with that  of electricity.   (T)~aite tfftlec-
tricite et du Magnetlsme, torn. iii. p. 369.)
  Those who regard caloric and electricity as distinct 
CHEMICAL ATTRACTION.
195
agents, and the latter as the cause of chemical affinity,
make caloric the cause of repulsion.   Nothing could
be more absurd  than such  partial and contradictory
views of nature.   Has it not been known, ever since
electricity was first  studied as a  science, that  it pos-
sesses the power of repulsion as  well as caloric?   I
have  also proved that the effects of caloric are not
limited to its self-repulsive agency; that it has an uni-
versal attraction for ponderable matter, and repulsion
of its own particles, by virtue of Avhich it binds bodies
together, or tears them asunder, according  as  it per-
vades them  in greater or less proportions; and it will
be shown hereafter, that all the motive powers of elec-
tricity, whether of high  or low tension, are  governed
by the same fundamental laAv;  that all the most pow-
erful  displays  of electric action  are only  modified
effects of that principle  or essence which warms  in
the life-giving solar beams, and preserves the universe
in a state of unceasing motion.
  It is because philosophers have not sufficiently ex-
amined the  relations of  heat and electricity, and the
laAv by which they  are  connected with ponderable
matter, that almost  every department of Physics has
become involved in profound obscurity.   It is self-evi-
dent,  that if electricity be a bond of union between
the particles of bodies, it must have  an attraction for
them; a circumstance which has been overlooked  by
Davy, Berzelius, Ampere and  their followers.   Dr.
Thomson observes, that "with respect to the  unknown
link which  unites  electricity to  atoms, and keeps  it
united with them, Ave are quite in the dark."   (Inor-
ganic Chemistry, vol. i. p. 40.) 
196
CHEMICAL ATTRACTION.
   Never can the science of chemistry be  reduced to
the  simplicity of  established  principles,  until  men
shall recognize the relations of  caloric and electricity,
and the universal law by which they are connected
with ponderable  matter.
   When a bar of iron  is charged Avith the  electric
ether, it attracts  iron filings,  Avhich  collect around it
in large bunches, each particle  clinging to  the others,
like bees suspended from the branch of a  tree.   But
if electricity be a self-repulsive  agent, it must have a
still stronger attraction for the  particles of iron, or it
could not become a temporary bond of union between
them;  and that  it is the true  cause of magnetic air
traction in soft  iron, is obvious  from the fact,  that
when it is Avithdrawn the attraction is destroyed.
   At the  same time, it  is equally evident that elec-
tricity is not the  generic principle of action in nature.
If so, it ought to be everywhere present under all cir-
cumstances ;  but  so far is this from being  the fact, that
in its most copious and  concentrated form, (that of
lightning,) its manifestations  are  only occasional  and
momentary.   Besides, if electricity were  the prime
mover,  it ought to be the cause  of fluidity, evapora-
tion, vapourization and those expansions of the atmo-
sphere on which  all its circulations depend.  It is  true
that when sufficiently concentrated,  it  produces the
same phenomena which  are  universally ascribed to
caloric; that  is,  it raises the temperature of bodies,
converts solids into liquids, vapours and gases;  ignites
combustibles,  and  produces the  chemical union of
bodies.
   If then there be any truth in the great fundamental 
        IDENTITY OF CALORIC WITH ELECTRICITY.     197

axiom, that the same effects must be referred to the same
cause, it is clear that electricity is only a modification
of the omnipresent  igneous principle.   This identity
is  indicated  by the fact, that when a current of the
electric fluid  is made to combine with metals, until
they are melted or ignited, its properties  are  so  far
changed, that it no longer produces a shock, but in all
respects  exhibits the  same phenomena which  result
from the heat of combustion.   Dr. Hare attributes the
explosive power of gunpowder and other fulminating
mixtures  to electricity, which is wholly unintelligible
on the supposition  that  caloric and the electric fluid
are distinct agents;  for it is certain that the expansive
force of all such compounds is owing to their sudden
conversion into gases, and that gases are expanded by
caloric as certainly as that the elastic force of steam
is  due to the same  agent.
   A thousand facts might be adduced to prove the
radical identity of caloric and electricity. Those light
and highly combustible bodies which afford the largest
amount of caloric by friction, such as furs, silks, wool-
lens, resins, sulphur, &c. also afford the largest propor-
tions of electricity during the same process, and there-
fore have been termed electrics.  Moreover, the strong
acids, which  give out the most heat  during chemical
action, afford the  largest supply of electricity Avhen
acting on the metallic plates of a voltaic battery.
   Again,  those  bodies for which  caloric has the
strongest attraction, such as metals, conduct it most
freely.  The same is true of electricity.  Hence it is
that both caloric and electricity disappear most rapidly
when in  the vicinity of good conductors,  being at- 
198
CHEMICAL ATTRACTION.
tracted by them and incorporated with their substance.
It is thus that flashes of lightning are absorbed by the
earth and  rendered latent.   Or, if a light feather be
charged Avith electricity, and suspended in the still air
of a room, at equal distances  from sticks of resin, sul-
phur, glass  and metals, it will approach the  latter in
preference  to the former, cceteris paribus, with a force
and  rapidity that varies inversely as the  squares of
the distance.
   If it  be  true that caloric  and  electricity  be only
modifications of the same  agent, the  electro-chemical
theory becomes intelligible,  and may be  reconciled
with the chemical agency of caloric.  For example,
those bodies which have  the strongest tendency to
unite chemically with each  other,  are said to be in
opposite  states of electricity.   It is also certain,  that
the same bodies which contain different quantities of
caloric, are most disposed to unite chemically; while
those which have nearly the  same relations to caloric
have  little attraction for each other, such  as sulphur
and phosphorus, potassium and sodium; the reason of
which is, that a transition of  caloric from one body to
another is indispensable to all chemical combinations.
   Every chemist knows, that he cannot carry on his
distillations, separations and  recombinations, without
the agency of  heat.  But, regarding  this as an  inci-
dental circumstance,  he resorts to  the agency of elec-
tricity for a solution of the  problem, Avithout inquiring
into the  source of this mysterious agent, or whether it
could have any existence independent of the igneous
principle.
   The controlling agency of caloric in the phenomena 
            CAUSE OF CHEMICAL  ATTRACTION.         199

of chemistry, may be traced in all the decompositions
and recombinations that  are  perpetually  going on
throughout nature.  The truth of this proposition is
attested by the vast amount of chemical action within
the  torrid  zone, and  within the temperate latitudes
during summer; while in the regions of perpetual con-
gelation there  is no chemical  transformation.  It is
well known,  that animal and vegetable matter may be
preserved Avithout alteration for unlimited periods of
time, in conservatories of ice or snoAv.*  It is therefore
obvious, that if the earth could be wholly deprived of
solar caloric, all its  chemical motions and changes
Avould  cease.  It was admitted  by  Dr. Black,  that
"heat Is indispensable  to chemical action, by overcoming
the cohesion of  bodies,  and thus enabling them  to exert
their attractive powers."   But I have  proved that  the
agency of caloric is not  confined  to  the mere separa-
tion of bodies; that  the same agent Avhich  expands

  * Nothing could more  clearly illustrate this fact, than the ac-
count of a huge elephant (or mammoth)  discovered in the midst
of a large mass of ice on the shore of the frozen ocean, near the
mouth of the river Lena in Siberia;  where it must have remained
for thousands of years, as it belonged to an extinct species.  When
first discovered, in 1799, by a Tonguiese fisherman, the carcass was
perfectly fresh and entire, parts of which were given by the neigh-
bouring Jackouts to their dogs; while the remainder was devoured
by wild beasts, after its disengagement from the ice, when its skin,
bones and teeth were removed to Petersburg.  Its neck was co-
vered with a long  mane, and the rest of its body with black hairs
and a reddish fur or wool.  The tusks were  nine feet long, and
weighed 350 pounds.  For further particulars in regard to this
curious discovery, see Cuvier's account, extracted from the  Me-
moirs of the Petersburg Academy, and quoted by Bertrand in his
Revolutions of the Globe. 
200        CAUSE OF CHEMICAL ATTRACTION.

them into vapours and  gases, causes  them  to  unite
chemically Avith each other, to form neAV compounds,
in obedience to the same law by Avhich liquids are
enabled to dissolve and unite  chemically with solids;
that is, by the attraction of caloric  for ponderable
matter.
  The most extraordinary fact  connected  Avith the
history of modern science is, that while cedorlc is con-
stantly employed in all  the operations of chemistry,
and  the  arts of everyday use, several distinguished
modern philosophers  have  refused it  a separate nu-
merical station among the elements; treating it  as an
incidental  or subordinate effect of those  powers and
changes of which it is the primary and efficient cause.
  When Count Rumford and Sir H.  Davy supposed
that heat was motion, they mistook  the effect for the
cause; for I have shown that all the contractions and
expansions of bodies, whether solid, liquid or gaseous,
result  from their  various relations  to caloric.  If a
portion of alcohol or  water be put into a  Florence
flask, their particles remain comparatively tranquil;
but when placed over a burning  lamp, a rapid  intes-
tine  motion begins, and augments in proportion to the
increase of temperature, until they  are driven off in
the form of steam.  Nothing, however, could be more
absurd, than to confound the motion  of ebullition Avith
its cause, which is evidently something derived  from
the lamp;  for when the source of heat is removed, the
ebullition and vapourization cease.
  When Lavoisier pointed out the  extensive agency
of oxygen in  combustion and fermentation, he  over-
looked the still more important fact,  that the chemical 
WHAT IS PHLOGISTON?
201
power of all bodies is augmented by every addition of
caloric; and when Davy observed, that combustion
was  the solution of bodies  in  oxygen gas, he over-
looked the fact, that all  gaseous bodies are solutions
of ponderable  matter in caloric, without which they
could not dissolve  and combine chemically with other
bodies.
   It was maintained by Beccher and Stahl, that all
bodies contained within them an exceedingly subtile,
elastic and active  principle, which  they termed phlo-
giston, and which was  disengaged during the process
of combustion, producing the phenomena of heat and
light, or fire.   Many and long were  the  disputes of
philosophers  concerning the  nature  of  phlogiston.
While many maintained that it was  a material sub-
stance,  Lavoisier is supposed to have demonstrated
that it was only an imaginary something, invented for
the purpose of explaining the mystery of combustion.
That Stahl regarded phlogiston as the cause of heat
and  inflammation, is evident from the etymology of
the Avord, which signifies heat or fire.
   From what  is reported of Dr. Black's  unpublished
Lectures on Respiration,  it  would seem that he con-
founded phlogiston with the carbon secreted from the
lungs;  for he  maintained,  that a  portion  of  atmo-
spheric air unites  Avith phlogiston  in the  lungs,  and
that animal heat was disengaged during the process.
(Leslie on Animal  Heat.)
   The celebrated Scheele supposed that heat Avas com-
posed  of phlogiston and  empyreal air, (oxygen,)  and
that light was composed of phlogiston and heat: while
Kinvan  supposed  that phlogiston was identical with 
202       LAVOISIER'S THEORY OF COMBUSTION.

inflammable air,  (hydrogen.)   Such  were  the vague
and contradictory opinions of philosophers in regard
to the nature of heat, light and phlogiskni,  during a
great part of the preceding century.
   After the discovery of latent heat by Dr. Black, and
of oxygen by Priestley, the theory of Stahl Avas gra-
dually  superseded  by  that  of Lavoisier.   This  cele-
brated  chemist maintained  that oxygen consisted of
caloric  and  light, united with a ponderable base, and
that during every case of combustion  this base com-
bined with the burning body, by which its volume was
diminished; while  the caloric and light of the oxygen
were given out in the form of fire.
   It is scarcely necessary to add, that this theory Avas
also found to be exceedingly defective and erroneous
in nearly all its essential conditions; that atmospheric
oxygen is not  indispensable  to the process of combus-
tion, nor the  exclusive source of  caloric  and light;
that all bodies contain definite quantities of caloric in
a latent or combined state, and may be expanded into
flame or light by a  sufficient  quantity of the same
principle.*   He was equally mistaken in supposing

  * When carbon, sulphur, phosphorus, boron and the metals are
heated in vacuo, they  become luminous without the  agency of
oxygen.   Another decisive proof that  oxygen is not the only
source of light is, that the colour of the flame varies according to
the nature of the combustible.  Hydrogen affords a bluish light;
potassium and many other bodies, burn with a red light.  Hence it
is, that bituminous coal burns with a bluish light when  only partially
ignited, because the hydrogen alone is volatilized, while its carbon
remains fixed.  Hence also it is, that around the bottom of a candle
flame, where the heat is not sufficient to ignite the carbon, there is
always a circle of bluish light, which proceeds from the combustion 
Lavoisier's theory of  combustion.       203
that the  condensation of oxygen was always neces-
sary to combustion.
  It is doubtless true, that during the chemical union
of gaseous oxygen  with metals, its volume is greatly
diminished, and  a large amount of heat  disengaged,
by which the metals are expanded into the luminous
state when the  process is rapid.  But it is  equally
certain,  that  the combustion of other bodies is at-
tended Avith expansion instead of contraction of the
combining materials, as illustrated in the third chapter,
Avhen  treating of explosion  and deflagration.  It is
here worthy of special attention, that while Lavoisier
pointed  out  the vast abundance and importance  of
oxygen  in combustion, respiration,  acidification and
fermentation, he did not explain the cause of oxida-
tion, which is indispensable to a theory of combustion.
  Nearly all the phenomena of chemistry may be re-
ferred to combustion and solution.   Fermentation, re-
spiration and  putrefaction, are slow  combustions,  to
which caloric  is equally essential,  as to every  case
of solution, liquefaction and Arapourization.  It is  well
knoAvn to every practical chemist, that water is gene-
rated by combustion; that nitrogen, carbon,  sulphur,
phosphorus, selenium, chlorine, iodine, boron, arsenic

of hydrogen.  When potassium  is thrown  upon water, it enters
into a state of vivid combustion; the water is decomposed, and
the metal expanded  into red light.  At the same time, a portion
of the hydrogen thus decomposed, unites with the potassium, pro-
ducing a beautiful purple and rose coloured flame;  that is, the blue
and red colours on combining produce a reddish purple.   Query,—
May  not all the diversities in the colours of heterogeneous light
resulting from combustion be thus accounted  for in a very simple
manner? 
204        CALORIC THE  CAUSE OF OXIDATION.

and  some  other  bodies, have no  affinity for oxygen
at very low temperatures;  but that when caloric is
added in sufficient quantities, a rapid oxidation takes
place, as in ordinary combustion, by which acids are
generated—that  when  potassium, sodium,  barium,
lithium,  calcium,  magnesium  and  strontium,  are
heated  in  atmospheric  air,  they  combine  rapidly
with its oxygen, forming alkalies;  that Avhen alumi-
num, glucinum, yttrium, thorinum and zirconium, are
heated Avith oxygen gas, new compounds are generated,
termed earthy bases;  and that when the other metals
are exposed to a high temperature, they are converted
into acids or metallic oxides.
   At the temperature of 32° F., oxygen has no per-
ceptible  attraction for  iron.   Hence it is, that in the
polar regions, and during excessive winters in the mid-
dle latitudes, metals are not corroded by oxidation, but
speedily acquire a coating of rust in tropical climates.*
The process of oxidation augments with every addition
of caloric up to the fusing point.   It is therefore pre-
posterous  to maintain, that  the attraction of metals
for oxygen is owing to  some inherent property of their
particles, or that caloric operates  merely by overcom-
ing their cohesion, and thus enabling their  chemical
forces to come  into play.   So powerful is the attraction
of iron for oxygen when raised to a white heat, that
  * If a piece of cold polished iron be inserted into fluid mercury,
there is little or no attraction exerted between them;  but if the
iron be made red hot before immersion, it acquires  a  coating of
mercury, which adheres firmly.  Even gold, which adheres to mer-
cury at common temperatures, attracts it still more powerfully
when heated, and so of other metals. 
          CALORIC THE CAUSE OF  OXIDATION.       205

it takes it from potassium, Avhich, at ordinary temper-
atures, is the most easily oxidized of all the metals. As
the attraction of potassium for oxygen is known to be
augmented by every increase of temperature, there is
every reason to believe  that its latent  caloric  is the
primary and efficient cause of the chemical force by
which it is enabled to decompose  water, or even ice;
and that if its temperature could be sufficiently re-
duced, its affinity for oxygen would be destroyed.
   In accordance  with this view of the subject, it is
Avell known that phosphorus, sulphur  and the most
combustible compounds of hydrogen and carbon have
no affinity for oxygen  at very reduced  temperatures,
but attract it rapidly when assisted by heat.  It would
therefore be a waste of time to multiply proofs that
caloric is the cause of oxidation.   There is hardly a
substance in nature with which oxygen may  not  be
made to unite under the influence of heat.
   Finding  it impossible to overlook the  agency  of
caloric in chemical affinities, Sir H. Davy maintained
that "it gav-e freedom of motion  to the particles of
bodies, and exalted their electrical energies."  (Phil.
 Ti-ansactions, Nov.  1806.)
   It is also observed by Berzelius, that  "a  great num-
ber of bodies seem to possess  but feeble affinities at
ordinary temperatures of  the  atmosphere,  which  ac-
quire very active powers of attraction when raised to
high temperatures."  (Des Proportions  Chimiques, p.
 57.)
   This illustrious chemist might have added, that the
chemical power of all bodies is  exalted by every addi-
tion of caloric, and diminished by its abstraction.  All 
»
206             LIGHT OF COMBUSTION.

the destructions and  regenerations of matter may be
referred to that laAv of caloric by which it repels its
own particles, and  attracts those of ponderable mat-
ter.   By its self-repulsive  property, caloric dissolves,
expands and decomposes all things; by its affinity for
ponderable matter  it contracts, unites and holds to-
gether all  things;  thus  causing the centrifugal and
centripetal forces of nature.   By the agency of heat,
chlorine, fluorine, iodine and  bromine,  are  made to
combine with sulphur, phosphorus, metals, &c. by which
new compounds are generated, termed chlorides, fluo-
rides, iodides and bromides.   When carbon, sulphur,
phosphorus and other bodies are heated with metals,
they are converted into carburets, sulphurets and phos-
phurets.   By the agency of solar heat the oxygen of
the atmosphere is made to combine with  the elements
of dead animal and vegetable matter,  Avhich are thus
constantly  undergoing a slow combustion or  dissolu-
tion during summer, by which new combinations  are
formed.
  It has been said that iron and other metals may be
kept  in a  state of ignition for unlimited periods of
time  without any  loss of  their substance.  Nothing
could be more unfounded.  The truth is, that the in-
candescence or luminosity of all bodies, caleris paribus,
is in proportion to temperature; while they are vola
tilized and dissipated in the same ratio.   When iron
is raised to a red heat, the oxygen of the air combines
with it, as  in cases  of ordinary combustion, by which
the process is kept up; but if they are heated in vacuo,
the ignition ceases when the heat is withdrawn, because
there is no oxidation. 
LIGHT OF COMBUSTION.
207
   It is necessary to distinguish the quantity of light
produced by  combustion from  its intensity.   When
lime, magnesia and many other fixed bodies are sub-
mitted to the high temperature of an oxy-hydrogen
blow-pipe, they are slowly dissipated, with  the disen-
gagement of a most dazzling and intense light, but in
small quantity;  whereas, if ether, alcohol, naphtha,
wax, tallow, oils, resins, phosphorus, sulphur, cotton,
paper,  silk and many other inflammable compounds,
are submitted to one-third of the  above temperature,
a far greater quantity of light is produced, but of much
less intensity: yet Dr. Lardner observes: " there is rea-
son to believe that all bodies begin to be  luminous
when heated, at the same temperature."  (Treatise on
Heat, p. 24.)  On the other hand, when charcoal is ex-
posed to the concentrated heat of a large voltaic bat-
tery, it is expanded  into  light,  which in  splendour
almost rivals that of the solar beams; yet not in such
great quantity as during the process of  ordinary com-
bustion, by which more carbon is ignited.  The con-
centrated heat of a forge while  acting upon iron  and
other metals that are difficult to  volatilize, creates a
light so intense, that it strikes upon the eye-balls  like
finely comminuted sand.   But the same  degree of heat
acting upon an equal weight of oil, wood or bituminous
coal, Avould  produce one hundred  times the quantity
of light, though of much less intensity.
   That modification of light  termed phosphorescence,
is  generally the  result of a slow combustion.   Being •
produced at very  low temperatures, it is both small in
quantity, and of low intensity. 
208
GENERAL CONCLUSIONS.
  From  all the  preceding  facts and observations it
would appear,—
  1. That the heat of combustion  results from  the
disengagement of that principle which holds the par-
ticles of  bodies together; and that what is called the
polarity of atoms, or the electro-positive and negative
conditions of matter, depend upon its plus and minus
relations to caloric.
  2. That the attraction of caloric for ponderable mat-
ter  is modified by every chemical change which  the
latter undergoes, whether of combination  or decom-
position,  contraction or expansion.
  3. That the light of combustion  or flame, results
from  the ultimate division of ponderable matter by
caloric, which is diffused in  all directions by radiation
with extreme velocity; and that without the volatili-
zation of combustible  matter, there  could be no arti-
ficial light. 
CHAPTER  III.
             CHEMICAL  SOLUTION.

  "Veniet tempus quo  posteri  nostri apperta nos nescisse mi-
renter. "—Seneca.

  Could we take in at one view the whole system of
nature, we should behold, throughout, one vast theatre
of solution and crystallization, of decomposition and
recombination.  We should  perceive, that the  atmo-
sphere always contains an  immense quantity of water
diffused through it in  a state of invisible transparent
vapour, until it meets with colder  currents of  air,
when it is condensed  and precipitated in the form of
rain, snow or hail, by the abstraction of its solvent
principle. All lakes, rivers and springs contain greater
or less proportions of the rocks, salts  and metals, that
compose the crust  of  the  earth  through which they
pass, in a state of  chemical solution;  that are carried
down by running water  and  deposited  on   different
parts of the great "ocean floor."
  We should  observe many  thousand  hot  springs,
issuing from the sides  of mountains and from the bot-
tom of the  sea, charged with  enormous quantities of
earthy and metallic bodies in solution; which are pre-
cipitated  as  they  cool down,  forming new  strata of
rocks and earthy deposits.
                         14              (209) 
210
CHEMICAL  SOLUTION.
   Could  Ave  look  through the  earth  as through a
great crystal, and  behold  all  its  molecular  motions
and changes, as we do the formation of a salt by the
aid  of  an  oxy-hydrogen  microscope,  we should  be
transported Avith  admiration of a scene  at  once so
grand, simple and  beautiful.   The exquisite mechan-
ism by  Avhich crystals are  generated, is carried on by
the regular arrangement of atoms in series and aggre-
gates, the forms of which are determined  by the most
exact mathematical laws, by the adjustment of atoms,
far too small to be  discerned with  the  most powerful
microscope.   During the crystallization of a drop of
muriate of ammonia,  magnified  three million  times,
and reflected on a large white ground, many thousand
small crystals are seen  shooting in every direction as
the solution evaporates, which  coalesce and form one
solid crystal.   Still  more admirable  is  the process of
organization by which the  particles of  Avater, air, car-
bonic acid, ammonia, &c.  are  converted  into plants
and animals, endoAved with irritability, sensibility and
the power of attracting nourishment for their support;
Avhile solution  or fluidity is  essential  to  every vital
process.*  <

  * A complete history of the Mississippi river would afford an
instructive  example of  the power of water in slowly dissolving
rocks and transporting them to distant regions.  Receiving, as it
does, many large tributaries, that are fed  by a thousand smaller
streams, which drain more than a million square miles of territory,
they  pass through  every variety of  rocky strata.  Some of its
largest tributaries, such as the Ohio, Missouri, Kentucky, Cumber-
land  and Tennessee rivers, meander  through extensive regions,
based on secondary limestone, which extends, with occasional inter-
ruptions, from Alabama to the Falls of Niagara; and varying from 
CALORIC THE  UNIVERSAL SOLVENT.         211
   That caloric is the universal solvent of nature is evi-
dent from the fact, that it converts all solid  bodies Into
liquids and gases or vapours, which are reconverted Into
solids by Its abstraction.  It is equally clear, that if caloric
be the cause of all liquidity and vapourization, it must
be the menstruum by  which  liquids and elastic fluids
are enabled to dissolve other bodies.
   The most  remarkable facts  connected with solution,
may be reduced  to the following propositions:—

500 to 2000 feet in  depth.   Through these immense beds of an-
cient  limestone, they have furrowed channels from 200 to 500 feet
deep.  By their chemical solvent power, hundreds of  subterranean
caverns have been gradually formed in the long lapse  of ages, with
all those beautiful calcareous crystals termed stalactites, with which
many of them are so gorgeously decorated.  All valleys  and river
beds are slowly formed by the chemical and mechanical  agency of
running water.  Many springs also contain in solution large quan-
tities of carbonate of iron, which, as well as lime, makes  a cement
that binds into solid masses  the beds of loose sand  through which
they pass, forming sandstone.   Were we to follow out this subject
in a geological  point of  view, we should  find that a great portion
of the solid materials that have been thus removed from the numer-
ous valleys drained  by the  Mississippi, have been transported to
the Gulf of  Mexico, which it is slowly filling up; while the rest is
conveyed by the Gulf Stream  into the wide Atlantic  to form new
rocks, after having travelled thousands of miles in a state of invisi-
ble solution.  The amount of soil, gravel and sand which are washed
down from mountains, hills and plains into the valleys during floods
of rain is enormous.   A  large proportion of Louisiana, which con-
tains  about 48,000 square miles, is composed of vegetable mould,
pebbles, gravel, sand and clay that  have been  conveyed by this
great river into the Gulf of  Mexico.   Immense masses of floating
trees are also deposited on its banks and  islands and at its mouth,
which are covered by sand  and clay, where they  will  be gradually
converted  into beds of coal.  Thus it is that'everything  in nature
is in a state of perpetual transition and revolution. 
212        CALORIC  THE UNIVERSAL SOLVENT.

  1.  That  all  fluids  are chemical combinations  of
caloric Avith ponderable matter.  Water is composed
of oxygen,  hydrogen  and caloric;  sulphuric acid  of
oxygen, sulphur, water and  caloric, and  so of  other
liquids, the elements  of Avhich are chemically com-
bined Avith it in definite proportions:
  2. That no solution of a solid in a fluid e\Ter takes
place, without a transition of caloric from the solvent
to the sol vend:
  3. That the solvent power of water and  other men-
strua is exalted by caloric  and diminished by its ab-
straction :
  4.  That  the  solutions of animal, vegetable and
mineral  substances in water and  other liquids, are
strictly chemical combinations.
  These propositions  being  admitted, it folloAvs, ac-
cording to  the  most rigid  principles of logic, that  if
caloric be  the cause of solution, it must also be the
cause  of chemical attraction,  by which salts,  rocks
and metals  are held in a state of intimate combination
with liquid menstrua.
  It may be objected, that caloric is not the universal
sohent of nature, because lime and magnesia are more
soluble in water at 60° F. than at 212°.   But if it be
true that lime and magnesia, like all other bodies, are
dissolved in unlimited proportions by hot springs, such
exceptions disappear, and therefore cannot invalidate
the  general fact.
   It is stated by  Mr. Lyell, to Avhom the science  of
geology is very largely indebted, that the warm springs
which supply the  baths of San  Filippo, near Rome,
contain in  solution so large a quantity  of calcareous 
HOT SPRINGS.
213
and magnesian rocks, that they have been knoAvn to
deposit in a pond a mass thirty feet thick  in  twenty
years. (Principles of Geology, vol. i. p. 204.)
   Mr. Lyell seems to suppose that the carbonic acid
contained  in  hot springs, is the chief cause of their
solvent power.  But it is well known  that sulphate
of lime and many other rocks, are dissolved by hot
springs Avithout the aid of carbonic acid.  It is there-
fore evident, that the solubility of lime  and magnesia
is augmented  by heat, as certainly as  that the fusi-
bility of all other rocks and metals is augmented by it.
It is highly probable, that the carbonic acid found in
hot springs, has been driven off from a state of com-
bination Avith lime by the agency  of intense heat.
Few geologists are  aware 1ioav large  a proportion of
the calcareous, magnesian  and  silicious rocks distri-
buted over our planet, have been deposited from hot
springs.   Mr. Lyell has shown, that A^arious parts of
Italy and  Sicily are covered over by  strata of lime-
stone thus formed, several hundred feet deep in many
places.
   It is impossible to have enlarged views of chemical
science, if  Ave confine  our observations to the petty
operations of  an artificial  laboratory.    Those who do
so tell us that  silex is insoluble, or nearly so, in Avater.
But those who look to the great laboratory of subter-
ranean chemical action, where the heat is far more
intense than  man can produce, will find that silex is
there dissolved as copiously as sugar in  boiling Avater;
and that  it is deposited  in vast quantities  by hot
springs, such  as the geysers  of Iceland, the valle das
furnas of  St.  Michael  and innumerable others that 
214
SILICIOUS PETRIFACTIONS.
 issue from volcanic regions, forming opal, chalcedony
 and various  silicious gems.
   The  flinty deposits  found  in  the chalk-beds of
 Europe have doubtless been derived from submarine
 hot springs.   Many of the marine fossils found in the
 chalk are composed of silica,—a fact Avhich cannot be
 otherwise accounted for.*

   *  It  is related by Mr. Barrow, in his Visit to Iceland in  1834,
 that the streams which proceed from the geysers of Iceland deposit
 a white silicious rock, of a close compact texture, resembling  white
 marble.  This is an exceedingly interesting  and important fact to
 the geologist.  The author was  once greatly embarrassed on finding
 beautiful strata  of perfectly white silicious rocks, which had been
 obviously deposited from water, inclosed between masses of basalt,
 greenstone and  other volcanic  rocks in the mountains of North
 Carolina, more than 4000 feet  above the  ocean level.   As all the
 other portions of those mountains consisted of granite, gneiss, por-
 phyry and other igneous rocks which had  been  elevated by subter-
 ranean heat, the  existence of the white sedimentary rocks remained
 a mystery, until the agency  of hot springs was investigated.
  The geysers rise up through volcanic rocks, in  an island where
 the eruptions of  lava are so enormous as to fill up  gorges  many
 hundred feet deep and two hundred feet wide.   When not confined
 in narrow valleys, they expand  into broad lakes  of melted  rocks
 that  vary in thickness.   Were  such eruptions to  cover the white
 silicious strata deposited by the geysers, (as they undoubtedly have
 done, and will do again,) they would be inclosed between igneous
 rocks, like the snow-white flinty strata in the mountains of North
 Carolina.   All  animal  and vegetable petrifactions  composed of
 silex have been doubtless formed in waters holding this mineral in
 solution, from the most minute  animalcules  and  delicate  moss
 agates, to the  largest fragments of silicified wood.  Mr. Barrow
 states, that on the margins of the numerous little  streams in the
neighbourhood  of the great geyser, every  description of wood,
bones, the horns of animals, and even  paper,  worsted  stockings,
handkerchiefs, &c. were found in a silicified state. 
SALINE SOLUTIONS.
215
   It is  stated  by Gay-Lussac, that the  solubility ot
sulphate of soda in water, is augmented by every ad-
dition of  temperature  from  32° to 91*4°,  and then
diminishes up  to 212° F.  (Ann. de Chim. et de Phys.
xi. 296.)
   It has been also said, that chloride of sodium (com-
mon salt)  is not more soluble in water at 212° than at
60.°  Whatever may be the cause of such anomalies,
they do not afford  the slightest proof that caloric is
not the solvent, for  this plain reason, that when  a
solution of common salt is exposed to great cold, it is
precipitated and the Avater becomes nearly fresh; that
is, when the agent which  held it in a state of chemical
combination  with  the water is withdraAvn,  it  falls
down; which clearly proves that the chemical attrac-
tion of water for the salt is owing to its caloric.  Hence
it is, that sea water is deprived of nearly all its salt by
congelation, as demonstrated experimentally by Danes
Barrington,—a fact which the author has seen verified
on a large scale.   In the  month of  January, 1834,
when the  Bay  of New York was frozen over, the ice
that covered it  was found to be  but slightly brackish.
It is therefore evident, that if the ocean could be frozen

  The steam emitted from volcanos is charged with a great variety
of rocks, salts and metals in a state of solution, which are deposited
in the crystalline form as the solutions cool down.   When melted
silex cools under the pressure of a mass of lava, making rock crys-
tal, a portion of steam is sometimes inclosed within its centre and
condensed into water, where it remains for unlimited periods of
time.  All geodes are probably formed by the cooling down of
lava, that contained steam  or other gaseous fluids within their inte-
rior, which, escaping by percolation, if the rocks be porous, had
left their centres hollow. 
216
OBJECTIONS ANSWERED.
throughout, it Avould not be capable of holding its salt
in a state of chemical  combination, but that it would
fall to the bottom, constituting a solid stratum, varying
in thickness with the depth of the ocean.  Dr. Turner
states, that common salt dissolves in twice and a half
its own Aveight of water at 60°; from  Avhich, and the
preceding facts, it follows, that if the ocean were satu-
rated Avith salt and afterwards frozen, it Avould deposit
a stratum more than one-third its depth.
   It is likeAvise obvious, that the tropical  ocean  must
contain more salt in suspension than  the  Polar seas,
especially during winter, and in the  vicinity of ice-
bergs or other frozen masses.*
   If it be maintained that caloric is  not  the solvent
of sulphate of soda, lime and magnesia, because they
are  more soluble in Avater at 60°  than at  212°, the
same mode of reasoning would  prove that  caloric is
not  the solvent of sulphur, which is well knoAvn to be
perfectly liquid at 230° F., but becomes viscid at 300°,
and continues so up to 400°.  In reply to such objec-
tions,  it may be stated  in   the  first  place, that no
chemical union ever takes place  until one at least of
the  combining bodies is reduced to the fluid state,- and
that caloric is essential to all fluidity: secondly, that
the  chemical force by which water is enabled to dis-
  * It can hardly be denied, that sugar is chemically combined
with cider by the agency of caloric ;  for it is well known that dur-
ing the congelation of sweet cider, its sugar falls down, and may
be found at the bottom of the vessel which contains it, in the state
of a highly concentrated syrup.  But if  afterwards exposed to
warmth, it is again taken up and recombined with its watery sol-
vent, which thus acquires its original properties. 
BERZELIUS AND DR. ARNOTT.
217
solve and combine with animal, vegetable and mineral
substances, is exalted by every addition of tempera-
ture, in a thousand cases for one exception.   And I
have shown  that  the  above examples afford no real
exceptions to the principle, but  confirm it; that sul-
phate of soda and common salt are far more soluble in
water at 60° than at 32°; that lime and magnesia are
perfectly soluble in  hot springs, Avhich owe their sol-
vent power to intense subterranean heat.
  Berzelius supposes that the greater solubility of lime
and  magnesia in cold  than  boiling water, is owing to
a portion of carbonic acid that is almost always found
combined with cold water;  but Avhich is driven off at
a high temperature.   Whether this be regarded as a
true explanation of the fact or not, it is generally ad-
mitted by chemists, that carbonic acid augments their
solubility in water.   This  however does not fully
resolve  the problem, since  the solubility of sulphate
of soda increases A\dth  the  temperature  from 32° to
91*5° F., and then diminishes slightly, up to 212°.*
  Dr. Arnott admits, that  the solution of a solid in
any gas or fluid menstruum  is merely another mode of
melting it by heat; and that the menstruum itself is
fluid only because of the heat Avhich it contains. (Ele-
ments of Physics, vol. ii. p. 47.)
  This is a true statement as far as it goes;  and it is
highly probable, that if this philosopher had renounced
the  inherent  attractive properties of atoms, as  Newton
did on second thoughts, he would not have added the
  * M Lassaigne has recently shown that water saturated with
carbonic acid dissolves more carbonate  of lime at 50° F. than at
32°.  (Journ. de Ch. Med., Fevrier, 1847.) 
218
INFUSIONS  MADE BY CALORIC.
 following  sentence.  "A  menstruum  dissolves other
 bodies, merely because its attraction for them brings
 their particles into union Avith the heat AAThich already
 exists in it."   Why then  should water at 212° exert
 a stronger  attraction for salts than Avater at 32°? Why
 should hot water ascend  through porous solids and
 capillary tubes more rapidly  than cold water?  Why
 should boiling water dissolve  18 times  more nitrate of
 potassa than ice-cold water? and 20 times more chlo-
 rate of potassa?  Why should  boiling Avater  attract
 and dissolve, or combine chemically with the aromatic
 constituents of tea, coffee  and a thousand other vege-
 table products, more rapidly than cold water, if caloric
 be not the  combining agent ?  or Avhy are the chemical
 affinities of all bodies modified by every addition and
 subtraction of caloric, if it be not the ruling principle
 of action in all solutions?
  That caloric is  the  medium by Avhich Avater is en-
 abled  to combine chemically  Avith salts, will  appear
from another view of the subject.  For example, those
salts for which caloinc has the greatest affinity, have also
the strongest extraction for water.   The  consequence  of
which is, that they absorb it from the atmosphere, pro-
ducing what is termed their deliquescence;  and when
dissolved in water they absorb  its caloric, by Avhich
cold is produced.
  It is likewise OAving to the powerful  attraction  of
caloric for  such salts, that when  dissolved  in water
they are so difficult to  congeal;  that is, they require
an intense  degree of cold to abstract from them that
portion of  caloric which maintains them in a state  of
chemical combination  with water.  When I come  to 
CONGEALING POINT OF SOLUTIONS.         219
treat of freezing  mixtures, it will  be seen  that solu-
tions of potassa and chloride of lime, formed by mix-
ing them with snow, remain liquid at 82° and 83° below
the freezing point of water.
   The same thing is true of many other salts, though
to a less extent.  It is oAving to the attraction of caloric
for common salt,  that sea water will not freeze at 32°,
but requires a further reduction of temperature to pro-
duce the effect, when it gives up a portion  of its heat
and the salt falls down.   When 30 per cent, of com-
mon  salt is dissolved in water, its freezing point is re-
duced to 0°.  Moreover, the cohesion of  the solution
is so  far augmented, that its boiling point is raised to
224° F.
   In like manner, all those salts for which caloric has
a strong attraction, and therefore produce cold during
their solution, elevate its boiling point; such as nitrate
of potassa, nitrate of soda, acetate of soda, tartrate of
potassa, muriate of ammonia and many others.*
   Dr. Lardner  states, that  the solution of a salt  in

  * It is owing to the affinity of caloric for sulphate  of soda, that
when  dissolved in  hot water, and tightly corked up in a phial, it
cools  down without  crystallizing, if kept perfectly still.   But  if
shaken, a portion of the caloric which held it in a state of combi-
nation with the water is disengaged, when the phial becomes warm,
and the solution crystallizes.  If the cork be  withdrawn, the same
effect is produced, owing to the mechanical pressure of the atmo-
sphere, which forces  out of the solution a portion of its caloric.
By inserting  into it a piece of ice, or any salt that has an affinity
for caloric, crystallization is produced, for the same reason that all
other fluids are congealed by the abstraction of their caloric.   It
has been said that a film of oil retards the crystallization, which is
no doubt the fact,  because it is a bad conductor  of caloric, and
therefore prevents its ready escape. 
220
COHESION OF SOLUTIONS.
water  diminishes the cohesive force  of the liquid, and
therefore  lowers  its freezing point.  (Treatise on Heat,
p. 194.)
   The fact however is just the reverse, for a saturated
solution of chloride of calcium  in Avater requires 42°
more caloric to OArercome its cohesion than pure water;
that is, it requires  a temperature of 264° F. to make
it boil.  In other words, the particles  of water, which
are held in a state of chemical union Avith the salt by
caloric, have a stronger attraction for the particles of
chloride of  calcium than for each other;  therefore
they cannot be separated  and driven off in the form
of vapour without an augmentation of temperature.
   From the preceding facts and observations we are
brought to the general conclusion, that the deliques-
cence of salts, the production of cold  during their so-
lution  in  water, the low temperatures at which they
congeal and the high temperatures at which they boil,
are all determined  by their relations to caloric, which
holds them in a  state of chemical  combination with
water.

           THEORY  OF FREEZING MIXTURES.

   It was before stated that no solution of a solid in a
liquid ever takes  place without  a transition  of caloric
from the  solvent to the sol vend.   The truth of this
proposition is strikingly illustrated by the phenomena
of freezing mixtures.
   When water is congealed into snow or ice, caloric
has a stronger affinity for it than in the liquid state.
Hence it  is that  Avhen a pound of water, at the tern- 
THEORY OF FREEZING MIXTURES.
221
 perature of 172° F. is mixed with a pound of ice  or
 snow, the latter is dissolved, and the mixture brought
 to the temperature of 32°; proving that 140° of caloric
 have passed from  the water to the snow, and  inti-
 mately combined with it during the process of lique-
 faction.
   But there are many salts which abstract caloric from
 snoAv, by which they are dissolved, or chemically com-
 bined with  the snow.   Such is the affinity of caloric
 for common salt, that when mixed with its own Aveight
• of  snow, both  at the temperature of 32°, there is a
 transition of  caloric from the  snow to the salt, by
 which they  are intimately united, and the temperature
 of  the  mixture reduced 41°.  Again, so powerful is
 the attraction  of caloric for chloride of calcium  that
 when three parts  of the  latter are  pulverized  and
 mixed with tAvo of snow, both at 32°, the temperature
 and congealing point of the mixture are reduced —50°:
 and if four parts potassa be mixed with three of snow,
 the temperature falls —51°, or 83° in all.  But if two
 parts chloride of calcium and one of snow be reduced
 to —9°, and put into the solution of snow and  salt,
 the temperature and freezing point of this new mix-
 ture are reduced to —74°.
   That there  is a transition  of caloric from snow to
 such salts, is evident from the  fact, that if the chlo-
 ride of sodium and snow be  cooled to —9°, and then
 mixed  together, no  solution or further reduction of
 temperature takes  place; and that if chloride of cal-
 cium and snoAv be cooled from 32° to —50° before they
 are mixed,  no chemical solution, nor  change  of  tern- 
 222        THEORY OF FREEZING MIXTURES.

 perature occurs, because  there  is no transition of ca-
 loric from one to the other.
   Many other salts have the power of absorbing ca-
 loric from water, acids and from snow,  such as nitrate
 of potassa, nitrate of soda, hydrochlorate of ammonia,
 chloride of zinc, sulphate of soda, &c.   If nitrate of
 ammonia be pulverized and mixed with its OAvn weight
 of water, at 50° F. the  temperature is reduced 46°;
 that is, doAvn to 4°, which is 28°  below the freezing
 point of water;  and if the same quantity of carbonate
 of soda be added, the temperature is reduced to —7°,
 or  39°  beloAv 32°.   If then  such  salts can abstract
 caloric from liquids at 4°, and even below zero, it fol-
 lows a fortiori, that they can take it from snow at 32°.
   Dr. Turner observes, that when  salt and snow are
 mixed, the salt  causes the snow to melt  by reason of
 its  affinity for water.  But if the  snow  and salt  be
 cooled down to  —9°, there is no attraction between
 them, and therefore no solution  nor reduction of tem-
 perature.   Nor  is  it a fact, as stated by Dr. Thomson,
 that every mixture which generates cold, contains a
 considerable quantity of water in the solid  state; for
 hydrochlorate of ammonia contains none, and the ni-
 trate of ammonia only 1 i per cent.   So of many other
 salts.   The truth is, that all freezing mixtures are
 dissolved by caloric as certainly as that  snow is dis-
 solved by boiling water;  for the simple and sufficient
 reason,  that  caloric is  indispensable  to  all fluidity,
 without which there can be no chemical combination.
 " Corpora non agunt, nisi  sint soluta."  When snow is
dissolved in  the strong acids, there is a rapid transi-
tion of caloric from the acids to the snow,  by which 
THEORY OF FREEZING  MIXTURES.         223
they are  chemically combined,  with  a reduction  of
temperature,  as in  the solutions  of ice or  salts  in
water.   If eight parts of snow be dissolved in five of
hydrochloric  acid, the temperature of the mixture is
reduced 59°;  and  if seven parts of snow be dissolved
in four parts  of diluted nitric acid, the mixture falls
to  62°.   The same effects  are  produced by mixing
pulverized salts with the strong  acids.*
   After having  proved  that caloric is the universal
solvent of nature,  and that solution is strictly a che-
mical process, it would  be needless to insist that the
strong acids owe all their  chemical properties  to the
heat Avhich  is combined with their  atoms.   Like all
other liquids, they are solidified  by the abstraction of
caloric, and when frozen, their burning caustic proper-
ties are  greatly impaired,  together with their powers
of combining  with other bodies.*]-   This view agrees
Avith the  etymology of  the word caustic, which was

  *  It is said that the best of all freezing mixtures is one com-
posed of four  ounces carbonate of ammonia, four ounces  subcar-
bonate of soda, and four ounces of water.   This mixture will con-
vert ten ounces of water, contained in a tin vessel, into ice.
  f  When this subject shall have been more fully investigated, it
will be found that the melting point of tin, bismuth and lead, when
united into an alloy, is reduced for the same reason that the melting
point of chloride of sodium, chloride  of calcium, potassa and other
salts, is lowered  on mixing them with snow.  This would appear
from the fact, that when 217 grains of lead, 118 of tin, and 284 of
bismuth, are finely powdered and mixed with 1617 grains of mer-
cury, the temperature of the mass falls from 64° to 18° F.,—proving
that there is a transition of caloric from one to the other; which is
true, in fact, of all chemical changes.   Besides, when three parts
lead, two of tin,  and five of bismuth,  are pulverized and mixed to-
gether, they melt at 197° F. 
224              PROUT  AND LLOYD.
derived from  the Greek noun *autn<; cans is, Heat, or
from the verb  xauaw causo, I will burn.
  It may  be regarded as a fundamental axiom in sci-
ence, that the laws of nature are uniform throughout
all her diversified changes and revolutions.  Whatever
hypothesis is opposed to this great principle, should be
at once rejected as unsound.
  Some modern philosophers, of high reputation, have
taken a different view of this important  subject.   In
his  late Bridgewater Treatise,  Dr. Prout observes, that
" the world itself before arriving at its present condi-
tion, has  not  only undergone a progressive series of
different states, but in these different states, different
laws of nature have prevailed." (Book I. Section 4.)
  It is also maintained  by the Rev. Mr. Lloyd, that
" the forces by which the world was brought into its
present form, were originally far more energetic, before
the appetences of matter for  matter had been so ex-
tensively satisfied.  Shall we expect (he adds) to find
the same  activity in a neutral salt, as in its separate
elements before chemical combination?" (Transactions
of the British Association for 1835.)
  In answer to such hypotheses, it may be affirmed,
that the aggregate amount of force and motion in the
universe never varies; and that if the laws of nature
were not   alwaj7s the same, there could be no  esta-
blished principles of science.   Old things pass away,
and all things become new,  but the  properties  and
laAvs of the primitive elements never change.  Mem-
phis and  Thebes, Nineveh and Babylon, Balbec and
Jerusalem, with their  gorgeous palaces and solemn
temples, have passed into other forms of existence— 
          ALL ROCKS FORMED FROM SOLUTION.      225

yea, the " everlasting  mountains" have silently moul-
dered  into  ruins, and been transported  to other re-
gions; but  nature retains forever the same youthful
energy as in the morning of creation.   The "sun him-
self may waste  aAvay, grow dim with age," and pass
into other modes of existence; still, there is not the
slightest evidence that  the  primitive constituents of
matter ever change.
   If then it be true that caloric is indispensable to the
existence of gaseous oxygen, and  to its  combination
with other bodies, as in combustion, fermentation and
putrefaction—to the generation of Avater, and its power
of uniting with salts,  it must be equally essential to
the generation of acids,  and to their chemical combi-
nation with the alkaline, earthy and metallic  oxides,
as in the formation of salts and rocks.
   It is quite evident, that all solid bodies have  been
formed from a state of  chemical  solution.   Volcanic
rocks have been formed  from a state of fusion by sub-
terranean caloric; while sedimentary rocks have been
formed from a state of solution in water; and I have
proved that the  solvent power of  water is owing
wholly to caloric; since  those bodies which are inso-
luble in cold or even boiling water, become so at still
higher temperatures.
   It was observed by Lord  Bacon, that  "we  should
inquire how far infusions may be made, by the help of
attractions."   The truth is, that all infusions, like the
solutions of salts in Avater, are obtained by the attrac-
tive agency of caloric.   The familiar process of draw-
ing teas depends simply on the attractive power of
                        15 
226       SOLUTION, A CASE OF ATTRACTION.

heat, to Avhich Ave owe all our infusions, medicinal ex-
tracts, emulsions, &c.  The superior cleansing property
of hot over cold water, is owing to its povver of com-
bining chemically with the various  impurities that
adhere to clothing, &c.   It is also known that metals
are deprived  of their drossy combinations, and thus
purified  by the agency  of heat.  Hence, among the
nations of antiquity, it was  regarded as the type of
purity; a term derived from the Greek word m>p, sig-
nifying heat or fire.  Cold water has no attraction for
tallow, butter and other oily substances; but the cook
understands practically, that when water is raised to
a boiling temperature, it  will  extract  and combine
with the gelatinous and  oleaginous ingredients of ani-
mal bodies, making soups  and gravies;  which proves
that the combining power is not in the water, but re-
sults from the agency of heat.
  The chemical power of water is so far exalted by
caloric, that when  raised to  the temperature of 400°,
as in Papin's  digester, it dissolves nearly all  animal
matters,  together with the oily and  resinous portions
of wood, which are but  slightly soluble  in  boiling
water.
  Caloric enables water to  combine with salts and the
various ingredients of organic compounds, for the same
reason that it enables  atmospheric oxygen to unite
with wood, coal and all  other combustibles, including
the metals; and for the same reason that it enables
melted metals to dissolve and unite with solid metals.
  All solutions of salts  in water, or  metals in acids,
are the results of an attraction between the solvent
and the solvend.  But if this attraction augment with 
           VAST FORCE OF THIS  ATTRACTION.        227

every addition of caloric, it cannot be an inherent pro-
perty in the atoms of the menstruum.
   Nothing could more  strikingly illustrate the im-
mense aggregate force of chemical attraction than the
phenomena of solution.  For example, it is well known
that when sugar or salts are dissolved in  water, and
metals  in  acids, the liquids undergo very little  aug-
mentation of volume; consequently, their density must
be greatly increased.  But it is evident1 from the ex-
periments of Perkins, that a mechanical pressure equal
to 2000 atmospheres, is not capable of  reducing water
more than one-twelfth of its volume, if so much. What
then must be the force of attraction  by Avhich salts
and metals are united during the  process of chemical
solution ?   By the transition of caloric from liquids  to
solids,  the latter are dissolved and chemically united,
Avith diminution of volume, for the same reason  that
the bulk  and elastic force of  gases are lessened on
combining chemically.
   The force of chemical attraction is equally  evident
from the manner in which it overcomes the cohesion
of solid bodies.   The attraction of nitric acid for the
atoms  of silver, copper and iron, must exceed that of
their cohesion; for it tears them asunder, but in an
almost imperceptible manner, and atom by atom.
   It Avas  before shown, that when tin, lead,  copper,
silver and other metals, are converted  into the liquid
state by heat,  their power of combining  with each
other is greatly  augmented;   and that whenever a
melted  metal  unites  with a solid metal,  there  is a
transition of caloric from the one to the other.
  In like manner, when mercury,  gold, silver, &c. are 
228         CHEMICAL FORCE OF THE ACIDS.

converted into vapour,  under plates  of copper, iron
and other solid bodies, there is a transition of caloric
from the former to the latter, by which the particles of
metallic vapour  are transported  to,  and  intimately
combined  Avith the  solids, for the same reason that
melted tin unites chemically Avith copper and iron ves-
sels when poured into them,  as in the process of tin-
ning;  or for the  same reason that aqueous vapour is
attracted by cold bodies, and  combined with them in
the  form  of dew or frost;  that is, by virtue  of an
attraction of their caloric  for  bodies that contain less
of it.
   But if the attractive power of all bodies be  modi-
fied by every change in their  relations to caloric, it is
unphilosophical to refer the effect to electricity, unless
it be a modification of caloric; and still  more  so to
confound attraction with the innate properties of gross
matter.
   That  the  strong  acids owe  their  activity and che-
mical properties to caloric, is evident from  the follow-
ing facts:
   1. They all become solid by the  abstraction of ca-
loric, Avhen their burning caustic properties are greatly
diminished,  together with their  power of dissolving
other solid bodies.*
  * Since the London edition of this work was published, M. de
Mareska has found by experiment, that at__112° F., sulphuric
acid no longer reddens litmus, and does not act upon the alkalies,
the carbonates, iodide of potassium, nor chlorate of potassa.  He
also found that  bromine, iodine and sulphur, combine with liquid
chlorine at —90° F.; that when powdered antimony is put  into
liquid chlorine at the same temperature, they combine with evolu- 
CHEMICAL  FORCE OF THE ACIDS.         229
  2.  Their power of dissolving metals is greatly aug-
mented by raising their temperature.
  Concentrated sulphuric  acid acts  very feebly  on
iron,  until made boiling hot.   Copper is dissolved ra-
pidly by sulphuric  acid when  raised to the boiling
point.  Lead, which is not affected by sulphuric acid
when cold, is readily dissolved by it at  212° F.   Its
solution in nitric and  acetic acids  is also greatly aug-
mented  by raising their temperature.  But it would
not be philosophical to maintain that an agent wrhich
is indispensable to all fluidity, and which increases the
sohTent power of acids, is different from the primary
and efficient cause of solution.*
  3.  When  the earthy, alkaline and metallic oxides
are dissolved in the acids, they are chemically united
with  them, and thus  maintained in a state  of  trans-
parent  solution, like salts  in  Avater, in opposition to
their specific  gravity;  and  may  be  crystallized  by
evaporation or by cold.
  When  salts, rocks and many metals, are converted
into the liquid  form, whether by the  direct agency of
caloric alone, or by means  of  a chemical menstruum,

tion of heat (and light?).  But that if dry chlorine gas be brought
in contact with antimony placed in a tube, and the latter be inserted
in solid carbonic acid, (which congeals at —148° F.,) no action is
produced. (Silliman's Journal, March, 1846, p. 256.)
  * The first part of the process by which metals are dissolved in
the  strong acids, is decidedly one of combustion.  For example,
when nitric acid is poured upon plates of iron, copper, &c. a por-
tion of its oxygen unites chemically  with them, by which they are
converted into oxides, with disengagement of heat, (as when poured
on volatile 'oils, and other inflammable bodies,) after which, they
are dissolved like salts in water. 
230
, CRYSTALLIZATION
their particles arrange themselves in regular series, at
various angles, forming symmetrical aggregates, that
cohere in definite forms  as  they cool  doAvn.  When
sulphur,  iodine,  camphor, benzoic  acid, with  many
other simple and compound bodies, are converted into
the gaseous state, they also crystallize in regular forms
on  cooling down, like solutions  of salts in water, or
metals in acids.
  From  some recent experiments performed by M.
Bequerel  and Mr. Cross, it  has been  supposed that
electricity is the agent by which crystals  are aggre-
gated.  But if electricity be regarded as  a distinct
agent, sul generis, and the  only cause of crystalliza-
tion, why do water  and other  liquids assume  the
solid and symmetrical form on merely  reducing their
temperatures?   There can be no doubt, that Avhen a
current of voltaic electricity is directed for days, weeks
and months, upon  salts  and  rocks, as  in the experi-
ments of Mr. Cross, it decomposes and transports their
elements to the extremities of the battery, Avhere they
will assume the  crystalline  form.  But it is equally
certain, that crystallization is constantly going on in
the laboratory of nature,  where no electric  action can
be detected by the most delicate  tests.   The  whole of
this problem is resolvable into one of still  higher im-
portance and generality; that is, whether  electricity
be only a modification of that universal principle of
action, which I have  endeavoured to show, is capable
of producing all  the contractions  and expansions of
matter.
  As yet, philosophers are  but partially acquainted
with the circumstances which determine the numerous 
MODIFIED BY TEMPERATURE.
231
 diversities in the forms of the same  substance: why,
 for example, there should  be above 600  modifica-
 tions in the crystalline arrangement of carbonate of
 lime ?   But it has  been ascertained  by the recent re-
 searches of Mitscherlich and Haidinger, that various
 proportions of water unite with many substances at
 different temperatures, during the process of crystalli-
 zation, producing a corresponding diversity of forms;
 that seleniate of zinc unites with three different por-
 tions of water, and assumes three  different forms,
 according as its temperature is cold, lukewarm, or hot;
 and so of other solutions.  They also found that mode-
 rate degrees  of temperature, such as  that of the solar
 rays, produced a decided change in the molecular ar-
 rangement of solid  crystals.   It is equally certain that
 the crystalline  form of snow  and  many other  bodies,
 varies  according to the temperature at which they
 become solid, and depends on the different quantities
 of caloric around  their particles, the arrangement of
 which is thus modified. (See  page 101.)
   When it  shall  be  clearly explained why sugar,
 gums, starch, gelatine,  albumen and many salts,  are
 more soluble in water than in alcohol;  why sulphur,
 phosphorus,  resins, &c. are more soluble in alcohol
 than in wrater;  Avhy some  bodies are soluble in ether
 and oils that are insoluble in other liquids;  why one
 acid dissolves metals which another will not; and Avhy
 some metals  are more  soluble in diluted than in con-
 centrated acids;  the obscurities of  chemical science
 will rapidly disappear.   Again, why are resins soluble
in the fixed  oils; the latter  in  the volatile oils; and
both of  them in ether?  Is it not because there is a 
232
ELECTIVE AFFINITIES.
transition of caloric from the smaller particles of the
latter, to  the larger particles of the former, just as
there is from the particles of snow and powdered  ice
to those of common salt and other freezing mixtures?
Why do the volatile oils  have a pungent taste, and
redden the skin, Avhile the fixed oils are nearly insipid,
inodorous, and do not heat the skin?  Is it because
the former contain little or no oxygen, and therefore
when diffused  over the skin, tongue  or olfactories,
undergo  a slow combustion; whereas the fixed oils
require to be decomposed by  a  higher temperature
before the carbon and hydrogen can  unite with atmo-
spheric oxygen?  Certain  it is, that the volatile oils,
like ether and alcohol, take fire at much lower tem-
peratures than resins or  fixed oils.
   That caloric is the universal solvent, without which
liquids could not'combine  chemically with solids;  Ave
must endeavour to resolve the remaining difficulties,
by carefully investigating the circumstances which de-
termine the relative attractions of caloric for different
bodies, and its transition from one to another.
   BetAveen  water in the  state of ice, and tallow, or
oils, there is no affinity whatever.  But when water is
raised to  the  boiling point, it unites readily with all
oleaginous substances; and at still higher temperatures
dissolves  resins, and various other bodies.   The solu-
bility of  sulphur  and phosphorus in alcohol  is also
augmented by raising its temperature.
   All solutions and precipitations are owing to the tran-
sition of  caloric from one  bejdy to another.   What is
termed elective affinity is OAving to the stronger attrac-
tion of one body for caloric  than another.    By  the 
             ELECTIONS AND  PRECIPITATIONS.        233

solvent power of caloric in nitric acid, it is enabled to
combine chemically with silver, the particles of which
are diffused  equally throughout the menstruum, mak-
ing a transparent solution of nitrate of silver.  But if
a portion of mercury be poured  into the solution, the
silver  is  precipitated as the  mercury dissolves.  It
therefore folloAvs, that if the caloric of nitric acid en-
abled  it to dissolve  and combine with  the  silver, it
must have a still stronger  attraction for the  particles
of mercury, or it would not desert the atoms of  silver
for them;  in short, that  the silver is separated from
its  combination with the  acid by an abstraction of
caloric, for the same reason  that salts dissolved in
water  are precipitated by a reduction of temperature.
  The same principle must apply to all other elections
and precipitations, modified, however, by circumstances
Avhich require a careful investigation.
  Lead precipitates mercury, and copper lead, which
is again thrown down from a  state of combination
with  nitric  acid by  iron;  all of which changes are
attended with transitions of caloric from the solvent
to the sol vend.
  The art of coating metals with other metals by pre-
cipitation, is founded on  the above laAv, such as gild-
ing, silvering, tinning, &c.  If a plate  of copper or
iron be immersed  in a solution of nitrate of mercury,
a coating of the latter metal is precipitated on them,
for the same reason that aqueous vapour is precipitated
on  cold  bodies, and coheres to them in the form of
frost or ice.   If nitrate of silver be dissolved in water
and a  plate of clean copper be inserted into  the solu-
tion, a beautiful coating of shVer  is precipitated on the 
234     CALORIC  THE CAUSE OF ALL  AFFINITIES.

copper;  or, if a  polished  iron  rod  be immersed in a
solution of  chloride of  gold,  the latter  is  precipi-
tated on it in the metallic form, for  the same reason
that melted tin,  zinc, bismuth,  silver, &c. are attracted
by solid metals and thus chemically united with them,
as in the process of plating.  Hence it follows, that if
caloric  be indispensable  to  the solution of metals in
acids, their precipitation must be owing  to its abstrac-
tion by the solid metals.
  From a general view of the  preceding facts and ob-
servations, it is evident that caloric is the cause of all
oxidation; that  water and the strong acids are gene-
rated by its  agency and  chemically  united with the
earthy, alkaline  and metallic oxides, forming  salts and
rocks: in  short, that combustion, fermentation and so-
lution are modified effects of the same cause.*

  * Mulder observes, that at  temperatures from 59°  to 67° F.,
when  yeast  is added to  sugar, fermentation is brought on, by
which alcohol and carbonic acid are  produced.  But when made
to ferment at temperatures from 97°  to 104°, other  products  are
formed.  He further states, that a definite temperature  is required
to convert alcohol into oxide of ethyl  and water  by means of sul-
phuric acid,  which at other temperatures converts starch into gum
and sugar; that one portion of caloric causes three, and another
portion five equivalents of oxygen to unite  with the  same sub-
stance, forming phosphorous and phosphoric acids. He also main-
tains that the influence of caloric may be traced in nearly all cata-
lytic phenomena; that the commencement of decomposition in
yeast is attributable  to a determinate  catalyzing  temperature; in
fine, that "Heat is  the pulse  of life  in the chemical  changes of
bodies, and  has thus an unlimited influence  upon their chemical
combinations." (Chemistry of Veget. and An. Physiol, pp. 34, 43,
44,  45, 46.)  He  observes in another place, that "the primary
source of all chemical action must be referred  to temperature." 
CHAPTER  IV.
             CAPILLARY ATTRACTION.

          That very law which moulds a tear,
            And bids it trickle from its source,
          That law preserves the earth a sphere,
            And guides the planets in their course.
                                      Rogers.

   Considered in all  its relations and bearings, capil-
lary attraction is one of the most important processes
in nature, being immediately connected  with all the
changes and  modifications of both  living and  dead
matter.   It is the force by which solids and liquids
are drawn and held together, which causes  plates of
glass, Avood, metal, &c. to adhere with some force to
the surface of Avater  and other liquids, Avhen laid flat
upon them.  It is  by the force of  capillary attraction
that the waters of  the earth are conveyed through its
crust in opposition to  that  of gravity;  for  Avater is
much lighter than the earthy and rocky strata through
Avhich it descends; and has been found at the greatest
depths to Avhich miners have penetrated, forming sub-
terraneous streams, which greatly augment after heavy
rains.  During this transudation of water through the
earth, it dissohres and combines chemically with a por-
tion of its mineral ingredients; after which, it is forced
                                         (235) 
236
CAPILLARY ATTRACTION.
to the surface by hydrostatic pressure,  (on  meeting
with an  obstruction to its horizontal  progress,) form-
ing innumerable springs and fountains of delicious
Avater.
  It is owing to the  attraction  of liquids for solids
that the  dust of our roads, which, Avhen dry, has little
or no  cohesion, becomes so tenacious after rain; or
that a rope,  when moistened Avith Avater,  contracts
Avith  great  force.   The combination  of tannin with
leather, and colouring  matter with clothing, are  due
to a modification of the same power that enables  Ava-
ter to combine with salts, or to permeate porous rocks.
  Several distinguished  philosophers  have  recently
conjectured, that a discoArery of the cause which de-
termines the rise of liquids  through porous solids  and
capillary tubes, would  unfold the  latent principle of
action in all molecular changes,  Avhether chemical or
Arital.  The  trunks, stems, leaves  and flowers of all the
trees  and plants that adorn  the earth, are composed
throughout  of exceedingly  small capillary tubes  and
cells, that attract  liquid nourishment from  the earth
and convert it into their own substance, by the same
power which  causes the combination of other solids
and liquids.  And so of all animals.   Every muscle,
gland, nerve, bone and blood-vessel is composed of im-
perceptibly  small capillary  tubes, through which  the
blood  is  circulated by the  same power which causes
universal attraction.
   The subject of  capillary attraction has been labo-
riously investigated by many of the most distinguished
votaries  of  science for the last 150 years, but Avithout
any attempt to explain the cause of the phenomena; 
CAPILLARY ATTRACTION.
237
if we except a single suggestion of Newton, contained
in his letter to Boyle, concerning the ether.   He there
refers capillarity to the same agent which causes men-
strua to  dissolve  solids,—a most  important hint,  for
Avhich his successors have not given him due credit.
It must,  howeArer, be  acknowledged, that  he  never
gave a satisfactory  explanation of what causes solu-
tion.  Still, his views were more just and comprehen-
sive than those  of  the present day.   That he  also
referred  vital attraction to the same cause which pro-
duces  ordinary capillary  attraction, is  evident from
the  following observation: " The same principle which
causes a sponge to suck in water, causes the glands in
animal bodies to suck in  the various juices from  the
blood, according to  their several  natures and disposi-
tions." (Opticks,  page  367.)
   In the  time of NeAvton, it was ascertained experi-
mentally by Hawkesbee,—
   1. That Avater rises to the same height in capillary
glass tubes of equal diameter, Avhether the tubes be
thin or thick.
   2. That it rises  to the same height  in vacuo as in
 atmospheric air.
   3. That the  velocity with which water ascends in
 capillary glass tubes, and its elevation, cceteris paribus,
 is inversely as their diameters.
   4. That the upper surface of water, spirit of wine
 and various  other  liquids in  capillary glass tubes, is
 concave;  which he rightly attributed to  a stronger
 attraction of the particles of Avater in immediate  con-
 tact Avith the glass  for it, than to each other.
   In 1805, Dr. Young read a paper before the Royal 
238            CAPILLARY ATTRACTION.
Society on the cohesion of fluids, in which he reduced
all the phenomena to the joint agency of a cohesive
and  repulsive force, which  in fluids, he  thought ba-
lanced each other.  But as he does not explain what
causes the particles of liquids to approach or recede
from  each other, his whole  theory is vague and very
difficult to comprehend.
  The following passage, taken from a paper on capil-
lary  attraction, by Professor Sang of Edinburgh, may
be regarded as a specimen of the obscure manner in
Avhich this interesting  subject  has been  generally
treated;  and  of the prevalent  opinion in  regard to
the recondite  nature  of the cause which determines
the attraction between  liquids and solids.   He ob-
serves, that "the whole of the phenomena are due to
a change in the corpuscular  arrangement  produced by
the simple contact of heterogeneous substances, the
laAvs and nature of which change are, and  perhaps for-
ever will remain, unknown  to us."  (Edinburgh Philo-
sophical Journal, vol. viii. 253.)
  Sir H. Davy maintained,  "that water  is combined
Avith  rocks, earths, salts, wood, muscular  fibre, &c. by
chemical attraction; but that it combines with  glass,
porcelain, &c.  by cohesive attraction."  This is con-
trary to his own  and the general vieAV  of chemical
attraction, which is defined  as "the force that unites
different elements and as the antagonist of cohesion,"
which is supposed to unite homogeneous elements.
But  there  is  as much difference between water and
glass or porcelain as between water and  salts, rocks,
wood or muscular fibres.
  There is no end  to the ambiguities and contradic- 
CAPILLARY ATTRACTION.
239
tions that have resulted from regarding cohesion and
capillary attraction, as  referable to a different cause
from that which produces chemical affinity.   I have
already proved that the particles of water and other
compound bodies, are held together by the same agent
which  causes the cohesion of gold or any other homo-
geneous body.  The same power that unites the atoms
of quartz, feldspar and mica and holds them together
in the form of granite  or gneiss, maintains the cohe-
sion of liquids.  This  principle has been recognized
by Laplace, in a supplement to the 10th Book of the
Mechanique  Celeste,  in  which  he treats  of capillary
attraction as a modification of chemical affinity.
   That  this is really  the  case, would  appear from
various considerations:—
   1. Capillarity  is  the force  by which liquids  and
solids  are made to cohere, whether homogeneous or
heterogeneous.
   2. Every solution of a solid in  a liquid, is  the re-
sult of a chemical force, by which their particles are
united.
   3. The force of capillary attraction, by which liquids
permeate solids, is always in proportion to their che-
mical  affinity for  each  other;  for example, water has
a strong affinity for sugar.  It also rises rapidly through
it by capillary attraction.
   Considering the vast importance of the subject, it is
really surprising hoAv imperfect and limited the num-
ber of experiments that have been instituted for the
purpose of elucidating its nature.  Sir David BreAvster
has given the relative heights to which fifty-two dif-
ferent liquids  rose through a capillary glass tube, the 
240      EXPERIMENTS OF BREAVSTER AND LINK.
bore of which Avas 0*0561 of an inch—the general re-
sult of which Avas, that water rose to a greater height
than any other liquid.   The next  in order Avere mu-
riatic,  nitric and nitrous  acids;  then the volatile oils;
after Avhich Avere alcohol and the ethers;  and lastly,
sulphuric acid.*  But if capillary attraction represent
the force by Avhich all liquids and  solids cohere, it is
obvious, that before we can arrive at any just conclu-
sion, the attraction of innumerable other solids for as
many  liquids must be ascertained.
   As  if to show the uncertainty of all experiments,
M. Link states, that distilled water, nitric acid, spirit
of Avine, sulphuric ether, sulphuric  acid  and the aque-
ous solution  of potassa, (one oz. to  six  of  water,) all
rose to the same height between glass plates.   What
is still more  remarkable,  he states that  the  above
liquids rose to the same height between plates of cop-
per, of zinc and of copper and zinc soldered together;
first, Avith the zinc surface opposed to the copper; next,
the zinc surfaces opposed; and then the copper surfaces
opposed.f
   Mr. Challis observes, after recounting the above ex-
periments, that "the heights of ascent  under similar
circumstances, would seem to be alike independent of
the liquids and solids."!   But if this conclusion were
  * Edinburgh Encyclopedia, Article Capillary Attraction.
  f Transactions of the British Association, vol. iv. p. 293, Re-
port on Capillary Attraction, by the Rev. James Challis.
  % This error has been amply refuted by the late experiments of
Matteucci, who  found that  when  six capillary glass tubes were
plunged into as many  different  liquids, at the temperature of
53 6° F., they rose to the  following heights in ten hours, the 
SIR JOHN HERSCHEL.
241
well  founded, water  ought to rise between plates of
sulphur, bees-wax, gum lac, resin, spermaceti, tallow,
&c. as freely as between plates of glass, which is not
the fact.   The truth is, that liquids rise most rapidly
through such porous solids as are most soluble in them
—that is, bodies for which they have  a  strong che-
mical affinity.  Water rises freely through sugar, salts,
ashes and porous rocks, because it has a strong che-
mical affinity for  them.  For the same reason, alcohol
rises  through all  such solids by capillary attraction, as
are soluble in it;  and so of the strong acids.   Tallow
and water have no tendency to unite chemically when
cold.   For the same  reason,  when  glass plates  are
smeared with tallow and brought close together, Avater
Avill not rise betAveen them, unless they be first Avetted.
But in this last case, the Avater rises, owing to its at-
traction for its own particles, for the same  reason that
they  aggregate into spherical drops.
   It  Avas observed by  Sir  John  Herschel, that "the
discovery of a new law or general fact is scarcely an-
nounced Avhen  its traces  are  found  everywhere, by
Avhich unexpected lights are shed over parts of science
liquids being of the same specific gravity, viz., 1*075.  Solution
of carbonate of potassa rose 85 millimetres;  sulphate of copper,
75;  serum of blood,  70;  carbonate of ammonia, 62;  distilled
water, 60; solution of common salt,  58; milk, 55; white of egg
diluted with its own volume of water, 35.  He also found, that
when glass tubes were filled with pounded glass, alcohol rose 175
millimetres, and water 182; but that when filled with sawdust, the
alcohol rose  125 millimetres, and the water only 60.  (Physical
Phenomena of Living Beings, p. 23.)
                          16 
242        ARISTOTLE, NEWTON AND LAPLACE.

that had  been abandoned in despair, and given over
to hopeless obscurity."  (Discourse on the Study of Xut.
Phil. p. 131.)   Nothing could  more aptly illustrate
this  observation than  the phenomena of capillary at-
traction, the cause of which, when once pointed out,
may be traced everywhere around and within us. But
such is the blinding influence of custom, that men dis-
regard what is common and familiar, though it be from
analyzing  the most ordinary phenomena, that the
greatest discoveries  have been  made, such as that of
steam power, the art of printing, railroads, &c.
   It was said by Aristotle, that everything is best
seen in its  smallest proportions.  Such is the admir-
able  simplicity with which  Infinite Wisdom directs
and governs the stupendous frame of nature, that the
physical cause of chemical force, and of universal at-
traction may be recognized in the  smallest dew-drop
that glitters on the grass.
   It has been shown for example, that the atoms of
oxygen and hydrogen, are  chemically  united by the
agency of caloric, making compound particles of water,
which  are aggregated into the spherical form by the
attraction of cohesion; and  that it adheres to  solid
bodies  by capillary attraction—all of which, according
to Newton and Laplace, are modified effects of the
same cause  that  actuates the vast machinery of the
universe.
   When a certain proportion of caloric is  combined
with this little dew-drop, it  assumes  the  solid and
crystalline form—in another  proportion it  renders it
liquid,  and enables it to combine with other bodies—
while an additional quantity of  the same ether which 
ILLUSTRATIONS.
243
held its particles together, separates and expands them
into thin air.
  Again, the phenomena of a burning candle demon-
strate the agency of caloric hr chemical and capillary
attraction, as  effectually as  a thousand experiments,
though contrived with the greatest skill.   By the ap-
plication of heat to the wick, it is  ignited, Avhen it
attracts oxygen rapidly  from the atmosphere, causing
combustion.   During this process, the tallow is ren-
dered fluid, and attracted by the burning wick, afford-
ing  a  continual supply  of melted matter, which is
decomposed, and expanded into flame or dense light.*
  Other things being  equal, the  force and  rapidity
with which the fluid tallow is drawn up, are in pro-
portion to the  amount of caloric given  out by  the
wick.   Thus,  it Avould  appear that the rationale of
oxidation, capillary attraction and the generation of
light, are clearly exemplified by a familiar process that
has been overlooked by the  unreflecting million, and
neArer  fully investigated by philosophers.   With a
view of ascertaining  the force of capillary attraction
caused by the heat of a burning candle, I performed
the following simple experiments:—
  About five  grains of the heaviest coal  ashes  were
placed  around the wick of a  burning candle; eA^ery
particle of which was drawn up in a few minutes, ad-
hering closely to the wick.
  I next put about the  same  quantity of iron filings

  * But if light  and flame be identical, and if flame be gaseous
matter raised to a white heat, as maintained by Newton, Davy and
others, it follows, that the light of combustion is an expanded con-
dition of ponderable matter by caloric. 
244
ILLUSTRATIONS.
into the bole of a large candle, all of which Avere soon
drawn up and collected around the wick, as in the for-
mer experiment.
   There can scarcely be a doubt that filings of silver,
lead, gold and even platinum, would present the same
results under like circumstances; nor is it a Avhit more
remarkable,  than that  red-hot  iron  should attract
oxygen,  sulphur,  mercury  and  other  bodies  more
strongly than cold iron.
   In reply  to  the above  facts, I have been told by
grave and learned men, that " fluidity is indispensable
to capillary attraction, and that  the only agency of
caloric in the process  is to cause  fluidity."  But this
does not explain why hot water rises far more rapidly
through  lumps of white  sugar, salts,  &c. than  cold
water, nor why those bodies which have the strongest
affinity for caloric, attract and absorb water most ra-
pidly, such as the deliquescent salts that are employed
in freezing mixtures.
   If it be urged that the absorption of Avater by sugar
and salts, is not owing to capillary  attraction, but to
chemical affinity,  I answer,  that hot Avater  passes
through numerous porous solids and capillary tubes,
with a force and velocity proportionate to its temper-
ature.   This fact  may be  verified  in  the following
simple manner.   Take  two bunches of  spun  glass
about four inches long; insert the end  of one  into
water at 50° F. and the other at 180°, when the lat-
ter will be found to rise with greater force and rapidity
than the former, in the ratio of at least three to one.
   The same is true  of amianthus,  flaxen thread,
bunches of hair, hemp and other textile fibres, when 
AN APPARENT EXCEPTION.
245
arranged in a similar manner.   But it would be un-
philosophical to maintain, that  an agent which aug-
ments capillary attraction, is different from its primary
and efficient cause.
  It has been maintained by Laplace, that an increase
of temperature diminishes the ele\Tation of liquids in
capillary glass tubes; first, by augmenting their  ca-
pacity;  and secondly, by lessening the density of the
liquid.  He further regards it as a general law, that
the elevation of any  liquid that completely wets the
sides of a capillary tube at different temperatures, is
in the direct ratio of its density.  This  view of the
subject  has been  partially corroborated  by the  expe-
riments of  Sir David Brewster, who found that cold
water rose  somewhat  higher in a capillary glass tube,
than when hot—a fact which I also have verified by
repeated experiments.   Whatever the reason may be
of this apparent objection to the views which I have
offered, innumerable other facts decisively prove that
the rapidity with whicla  liquids pervade porous  solids
and  capillary tubes, is  in proportion to  the  temper-
ature of the liquids, caeteris paribus.
  When I come to treat of the  agency of caloric in
the phenomena of life, it will  be shown  that it is the
proximate  physical  cause of  capillary  circulation
throughout the  animal and vegetable world,  without
which there  could be no absorption, secretion, nutri-
tion and groAvth; that trees and plants are mere aggre-
gations of  capillary tubes and pores, through Avhich
many hundred million tons of sap are forced up by
the power of vital attraction, under the immediate
agency of solar heat, and that all the phenomena of 
246
ENDOSMOSE AND EXOSMOSE.
life (which result from an attraction between liquids
and solids)  are arrested by cold.   The principal dif-
ference between ordinary capillary attraction, and the
capillary circulation  of plants  and animals, is, that
the  vessels  or  tubes of the latter  are almost incon-
ceivably  small, while the  force  of all  attraction is in-
versely as the  distance;  hence the force with which a
moistened rope contracts, and raises immense weights;
or the force and  velocity with  which  blood  and sap
are draAvn through  their minute vessels.
   The mutual interchange of  tAVO different liquids,
separated by a membrane or other porous body, which
has been referred by Dutrochet to  the operation of a
peculiar force,  termed by him endosmose and exosmose,
according to their direction, is doubtless a modification
of capillary attraction, and of the force which causes
all chemical combinations.*

  * Dutrochet's endosmometer consists  of a glass tube, with a piece
of bladder attached to its lower extremity, expanded into the form
of a funnel. On pouring into it an aqueous solution of either gum
or sugar, and  then immersing the closed extremity in pure water,
the latter passes through the membrane into the tube, with a force
which raises the liquid within it to a considerable height; while a
small portion of the liquid within passes out through the bladder,
and  mixes with  the water, which he  calls exosmose.   From an
immense number  of experiments with  this instrument, Dutrochet
found, that, other things being equal, the force which produces the
endosmotic current, is in  proportion to the excess  of  density of
the interior liquid over that of  the water;  that with a solution of
sugar, whose density was 1145, the force of the current was equal
to 34 divisions of the scale, but rose to 53  divisions when its den-
sity was 1*228; and that syrup, whose  density was 1*300, produced
a current  capable of raising a  column of mercury 127 inches in
height, which  is  equal to the pressure of  four and a half atmo- 
ENDOSMOSE AND EXOSMOSE.            247
   There is another general fact which connects the
theory of capillary attraction with that of heat.
   Those bodies  which  have  the least  attraction  for
caloric, have the least power of absorbing water, such
as furs, silks, woollens,  cottons,  resins, sulphur, phos-
phorus  and other non-conductors of caloric and elec-
tricity.   Hence  it is that  when water is poured on a
perfectly dry  clean silk  dress, it runs off, or collects in
large  globules, while it is rapidly absorbed by linen,
which is a much better  conductor of caloric.   For the
same  reason,  a lock of wool, cotton, down or  fur, will
float on Avater a long time without becoming wet.   Or
if one end of a perfectly dry skein of silk be suspended
in a vessel of cold water, it remains  for  hours  without
attracting the Avater through its fibres;  Avhereas a skein
of linen or hemp becomes very  soon Avetted through-

spheres,  or about 160 feet  of water.   He also found, that the
endosmotic current was  generally determined by the liquid which
has the greatest affinity for the interposed substance, and by which
it is imbibed with the greatest rapidity.  In regard to the cause
of the  current,  Matteucci, has, after carefully  investigating the
subject, arrived at the conclusion, that it is not electricity, (as sup-
posed by Dutrochet and others,) since  the latter is not  developed
by the  contact of water  with solution of sugar and other liquids.
(Op. cit. p. 38.)  The  fact is, that in  all such phenomena, there
is a transition of caloric from the outer liquid to the  interposed
membrane, and  thence to the interior liquid, just as there is from
all liquids to solids during the  process of chemical solution, and
just  as there is in all cases of  capillary attraction.  I have also
shown, that there is a transition of caloric from hydrogen to chlo-
rine during  the act of their chemical union to form hydrochloric
acid,—as there  is  from hydrogen to  phosphorus, sulphur, &c,
during the  formation  of  phosphuretted hydrogen, sulphuretted
hydrogen, &c. 
248    CONNECTION BETWEEN GRAVITY AND THE

out.  But if the water be made hot, it rises through
the silk also.
   Li accordance with the  above facts, it has been
found that mercury and other melted  metals, instead
of rising through capillary glass tubes, are somewhat
depressed, because they have a stronger attraction for
their own particles than for those of the glass.   That
they have also a stronger attraction for caloric, is evi-
dent  from their greater conducting power.  Hence,
there can be no transition of caloric from liquid metals
to the glass, for the  same reason  that  there is none
from cold water to silks, resins, &c, therefore no attrac-
tion.   But if plates of gold, silver  and tin, be inserted
into mercury,  the latter is attracted  by  them, rises
above its level, and is incorporated with them by vir-
tue of the same power that causes all other attractions
between liquids and solids.   When mercury is poured
on a marble or Avooden  table, it collects in large glo-
bules, for the same reason that water aggregates into
large drops when poured  upon  dry  silk, a duck's
feathers and other non-conducting bodies; or for the
same reason that when plates of glass are smeared
with tallow they do not attract water unless previously
wetted.

ON  THE CONNECTION BETWEEN GRAVITY AND THE  MOLE-
             CULAR FORCES  OF NATURE.

  It has been said that the attraction of atoms is not
like that of gravitation, inversely as the squares of the
distance.   This assertion is not  only refuted  by all
analogy,  but by the well-established  fact that the ele- 
            A10LECULAR FORCES OF NATURE.        249

vation and force with which liquids rise in capillary
tubes, cateris paribus, is inversely as their diameters.
The principal  difference between  the  attraction  of
atoms and that of masses is, that the former acts at
exceedingly small  distances, corresponding  with the
minuteness of atoms; while the poAver of masses ex-
tends to comparatively  great distances.  The aggre-
gate force of cohesion Avith Avhich a  mass of granite is
held together, other things being equal, is proportional
to the number of its  ultimate particles.   The force of
gravity with Avhich it presses upon the earth is in the
same ratio.
   The specific gravity and cohesion  of bodies augment
in proportion as they are deprived of caloric.   The
force and rapidity with  which they gravitate toward
the centre of the earth,  when elevated above its sur-
face,  augment in a  corresponding  ratio.  We  have
learned from  Sir Isaac Newton that the attractive
poAver of bodies is in proportion to their mass, and
inversely as the squares of the  distance.   The  force
with which caloric tends to unite with the particles of
other matter, and  hold  them together, is also in pro-
portion to the  amount of matter, cceteris paribus, and
inversely as the squares of the distance.  For example,
if one pound  of water condense two ounces of  steam
by attracting and absorbing  its caloric, two pounds
will condense four ounces, and  so on.  For the  same
reason, the force Avith which the caloric of space  tends
to unite with the matter of the sun, maintains that
immense body in the globular form, while it preserves
the planets in their orbits  around him,  being in pro-
portion to his mass,  and operating  Avith a poAver that 
250         AGGREGATE FORCES  OF NATURE.

varies inversely as the squares  of the distance.  In like
manner, the force with Avhich the caloric of space tends
to unite Avith planets being in proportion to their mass,
cceterls paribus, must be  sufficient to  hold them to-
gether in the  spherical form, and to maintain  the
satellites in tlieir orbits.
   If caloric be the physical cause of cohesion, capil-
lary attraction, and chemical affinity, as I have demon-
strated; and if gravitation result from the aggregate
action  of atoms, as  maintained by Newton, Laplace
and many other philosophers, the centripetal force of
the heavenly bodies  must be  owing to a modified ac-
tion of the same cause.*
   We  are so  accustomed to  the  great poAvers and
movements which mark the  course of nature, that we
are scarcely aware of their existence until aroused by
some extraordinary phenomenon.   What can be more
obvious and familiar than the  power of heat in modi-
fying  the surface of our  planet?  a poAver absolutely

  * According to all the  best-established canons of philosophiz-
ing, that is the most important principle in physics, to which the
greatest number of phenomena may  be traced.  But if we admit
that the accelerated motion of falling  bodies, the aggregation of
planets, with their annual and  diurnal  revolutions, are resolvable
into the Newtonian law  of gravity, it is certain that many other
equally important  phenomena of nature cannot be referred to the
principle of gravitation, such as those of heat, light and electricity,
together with the innumerable operations of  chemistry, geology
and meteorology, all of which are immediately connected with, and
may be traced to  that law of caloric  by which it produces the
opposite effects of  contraction and expansion, and without which,
we cannot explain the most simple modifications  of molecular
motion. 
AGGREGATE FORCES OF NATURE.        251
incommensurable, though  for  the most part  unob-
served.   Were it possible  to compute the aggregate
forces of capillary attraction in the circulation of the
blood and sap of all the animals and plants that in-
habit the earth, we should be  amazed at the result.
Yet they are all produced by the subtile agency of
caloric, a definite amount of which is indispensable to
all  vital action, from that of the insignificant moss or
animalcule, to the most perfect developments of or-
ganized existence.
  On beholding for the first time so grand a spectacle
as the Falls of Niagara, the mind is bewildered by an
impression of irresistible power.   But if Ave compare
this thundering exhibition of might, with the vast but
silent poAver of solar caloric in evaporation, or of sub-
terraneous caloric in upheaving  mountains, the ocean
cataract dAvindles into a  fractional  item;  for  it has
been already shoAvn, that a mass of water equal to
415 square miles in  area, and one mile in depth, is
daily conArerted into steam, and carried into the atmo-
sphere by the expansive energy of solar heat, and that
all the lakes, rivers and springs of the earth are sup-
plied by its precipitation.
   We are sometimes aroused to a perception  of the
wonderful poAvers that are in  nature, by the sudden
and awful coruscations of the electric fluid, when dart-
ing through the  heavens like arrows of Omnipotence,
rending rocks, trees and dAvellings. But few are aware
that it  is only a concentrated  exhibition of the same
agent which causes evaporation, solution, crystalliza-
tion and vegetation.
   It is generally conceded by  philosophers, that all 
252       AGGREGATE FORCES OF SOLAR  LIGHT.

the operations of nature are referable to attraction and
repulsion, Avhich I have proved in the preceding chap-
ters  are  resolvable  into the agency of caloric alone.
But if the stupendous forces of chemistry, geology and
meteorology, are determined  by the agency of solar
radiation, why should  it not  be adequate to produce
the annual and diurnal revolutions of planets?   That
rays of subtile matter, capable of producing heat and
light, are continually  proceeding from the centre of
our system, is self-evident from experience and obser-
vation.  It would, therefore, be contrary to all analogy,
and  the  indications of  common sense,  to refer the
planetary motions to some unknown hypothetical in-
fluence exerted through a vacuum, Avhile there is a
known cause sufficient to explain the  phenomena.  Is
it not self-evident that if the radiating power of the
sun  were  suspended,  they would   no longer  move
around that luminary, and upon their own axis, but
desert their orbits, and join the parent orb from which
they originally came?  It is impossible  to -conceive
how the  sun could  exert any agency whatever upon
the earth, independent of his potent beams.  Besides,
Avhat can be more simple and natural than the infer-
ence, that the same  power Avhich aggregates and holds
together  the particles  of  planets, guides  their move-
ments round the  heavens?
  It was laid down by Newton himself, as a funda-
mental axiom, that  no more causes  of natural thirty*
ought to be admitted,  than such as are both true and suf-
ficient to explain the phenomena. (Principia, book hi.)
  Lord  Brougham also observes in  his Natural  The-
ology: "Great as our  achievements in physical as- 
AGGREGATE FORCES OF SOLAR LIGHT.      253
tronomy have been, Ave  are Avholly unable  to  under-
stand why a power pervades the system,  acting in-
\rersely  as the squares of the distance, rather than
according to any other law."  He adds: " It is incon-
ceivable to our minds how power or  any other thing
or influence, can act at a distance." (Vol. ii. p. 74.)
   When commenting on the NeAvtonian law of gravity,
by Avhich every particle  of matter in the universe is
supposed  to attract every other  particle inversely as
the squares of the distance, Mr. Whewell asks, " Why
do the  attractions of masses, or those of their consti-
tuent particles, follow this law of the inverse square
of the  distance?"  (Bridgewater  Treatise, chapter x.)
But if it be a fact, that  all the separate forces of na-
ture, including those of caloric, are  governed by the
same law, it is difficult to avoid the conclusion that
they are connected together as cause and effect, though
we may not yet fully comprehend in what way.
   The  truth is, that the force of all  ethereal  emana-
tions is inversely as the squares of  the distance, for
the  obvious reason that they are necessarily diffused
in the same ratio.   Other things  being  equal, the re-
pulsiA^e force of caloric in gases and vapours  diminishes
in the ratio of the distance of their particles from each
other.  Its heating power decreases  in the same  pro-
portion, while  the attractive  and repulsive forces of
electricity are known to follow the same law.
   Such is the love of mankind  for the marvellous,
that the most obvious causes of natural phenomena
are  disregarded, and their explanation sought after by
resorting to such as are hypothetical and  remote, or
obscure.   Hence it is, that our books on natural  phi- 
254         SPACE FULL OF SUBTILE MATTER.

losophy are filled \vith speculations about the vacuum
of space, Avhile Adsible and palpable floods of luminous
ether are continually pouring upon the earth from the
great fountain of physical motion and life.   When Sir
H. Davy observed, that it "was absolutely necessary
for the explanation of the planetary motions, to sup-
pose space in the universe AToid of all matter," he over-
looked the  existence of solar light, and even of that
subtile medium, the vibrations of Avhich are supposed
by some to constitute light.   That  he did so from
authority, and  Avithout reflection, would appear from
what he  says in another part of the same work.  "It
cannot be  doubted  that  there is matter in motion
through  space  betAveen the  sun, and stars, and our
globe." (Chem. Phil. p. 67.)
  There is  no  decisive  evidence that any of the an-
cient philosophers  adopted the  theory of a perfect
vacuum in  nature.  It was the opinion of Bacon, that
the ancient Pan  " was represented as hairy to denote
the rays of things,  because everything which acts at
a distance may be said to  emit rays." (Wisdom of the
Ancients.)
  It was also maintained by Lucretius, who is regarded
as the advocate of a vacuum, that subtile streams are
perpetually flowing from everything, without which
bodies could not be  discovered at a distance.   (De Na-
turd Rerum, book vi.)
  It has  been repeated a thousand times, that by re-
ducing the  phenomena of gravitation to a general law,
Sir I. Newton had revealed the whole  mechanism of
the universe.   But he entertained a far more accurate
estimate of what he had done, when he compared him- 
HYPOTHESES OF NEWTON.
255
self to "a little boy collecting a feAv choice pebbles
and shells on the sea shore; Avhile the great ocean of
truth lay all undiscovered before him."
  When he resolved the aggregation of planets into
the action of their  minutest particles, he left his fol-
lowers in doubt whether gravitation Avas a primary
agent, or only  an expression of the  mode in which
some  universal cause is observed to operate  inversely
as the squares of the distance; and whether it resulted
from  the pressure of an all-pervading ether, or  from
the inherent properties of elementary atoms.  (See
 Opticks, p. 351.)
  The power of generalization  by which  he traced
remote analogies and reduced a vast multitude of ap-
parently opposite phenomena to the dominion of one
law, displayed an admirable faith in the uniformity of
nature.   Yet the projectile force, the vacuum of space
and the vis insita which he represents as the cause of
attraction and repulsion, were mere hypotheses, wholly
unsupported  by evidence.  And that the  illustrious
author himself was fully convinced of this during the
latter period of his life, is manifest  from  the whole
tenor of his speculations concerning the ether, which,
as I have already  shoAvn, he finally regarded as the
primary physical cause of cohesion, capillary attrac-
tion and of gravitation; but without  explaining how
it produces the repulsion of atoms  and the centrifugal
force of the heavenly bodies;  or in Avhat Avay the phe-
nomena of chemistry, geology, meteorology  and plane-
tary motion  are connected with the  influence of the
imponderables  and  the  relations of the latter to each
other. 
250
CALORIC  THE  CAUSE OF  FORMS.
   But in the total  absence of caloric, if such a thing
Avere possible, the whole  material  universe would dis-
appear  no less  completely than if annihilated:  for it
is obvious that  in  their  separate  state, the chemical
atoms of passive  matter could not be  recognized  by
the  senses.   And I haA'e  proved  that  caloric is the
organizing principle  by  Avhich  they are  aggregated
into visible and tangible forms; consequently, that it
is the  self-active  and universal essence on Avhich  all
the manifestations of being or existence depend.*
   Yet Ave  are told that  caloric is  not a material sub-
  * And if the particles of all bodies be surrounded by a self-active
principle, there can be no such thing as absolute inertia in nature.
  In opposition to this view of the subject, we are informed by Dr.
Arnott that "the greater part of the phenomena of nature may be
referred to four elementary truths, viz., atom, attraction, repulsion
and inertia.''''   He observes, that "inertia  expresses the fact, that
atoms, as regards motion,  have a stubbornness about them, which
tends always to keep them in their existing state, whatever it may
be." (Elements of Physics, vol. i. pp. 1  and 2.)  In what way
atoms have been  endowed with  this  imaginary property has not
been explained; nor does Dr.  Arnott  assign the cause of attrac-
tion.   Until this is done, let no man  flatter the world, that even
the foundation of physical  science has been  established on the solid
rock of fixed principles.
  If it be true  that caloric is the physical cause of attraction as
well as repulsion, and that cohesion and gravity are modifications
of the  same power, it becomes the business of philosophy to investi-
gate the mode of its operation in maintaining all the molecular and
aggregate movements of nature.
  The  connection of caloric with the phenomena of motion has
been virtually  recognized by all those  philosophers who have re-
garded heat and motion as identical.  But  it is obvious that there
can be no motion without  an agent; consequently, that they have
confounded the effect with its cause. 
            CALORIC THE CAUSE OF FORMS.         257

stance, because it is imponderable.  It is evident, how-
ever, that Avhatever the cause of gravity  may be, it
must be Avithout  gravity; otherwise Ave must explain
gravity by itself,  which would be absurd.  The truth
is, that when reduced to a state of ultimate diffusion,
all matter is imponderable, as in  the form of the  elec-
tric spark, flame, &c.   And  if caloric were "motion
and nothing else," as maintained by Bacon and other
philosophers, it would follow that the prime mover in
a steam engine and throughout all nature, is motion,
—a proposition which  involves the glaring absurdity
of explaining motion by itself.
  But without plunging further into the profound
abyss of chaos or practical  non-existence  that would
follow the entire extinction  of  the organizing prin-
ciple, it is the  legitimate province of science to ascer-
tain how it produces all the phenomena of nature in
accordance with the invariable laAvs of supreme intel-
ligence.  Nor is it possible to predict the results Avhich
Avould flow from a searching method of analyzing facts.
We often mistake our own inattention  and indolence
or the mystical inventions of fanciful theorists for im-
penetrable obscurities, that Avould vanish before a bold
and  determined  spirit of inquiry.  Could  the veil be
drawn aside which  conceals  from our inspection the
whole mechanism of the universe, nothing, perhaps,
would so much  excite  our astonishment  as  its  sim-
plicity.
  From a careful review of the foregoing chapters the
folloAving conclusions may be deduced:—
  1. That cohesion, chemical affinity  and  capillary
                         17 
258
GENERAL CONCLUSIONS.
attraction are modifications of that universal force by
Avhich planets and  all other bodies are held together:
  2. That the particles of all bodies are surrounded
by, and  intimately combined A\rith,  an exceedingly
subtile, active and  mobile principle, which in certain
proportions holds them together, but in larger propor-
tions separates or decomposes them:
  3.  That  the prevalent theory of  physics Avhich
ascribes the  phenomena of attraction to the inherent
or immaterial properties of ponderable matter is falla-
cious  and wholly unsupported by evidence:
  4. That there is no such thing as  a perfect vacuum
in nature; neither  in the pores of bodies nor in those
widely extended pores  of the universe, termed the
planetary spaces:
  5.  That the  inertia of matter  is a philosophical
fiction, because there is nothing quiescent in nature
or which possesses  the power of not eictlng—neither in
the starry heavens  nor in the frame of the earth.  The
sun revolves  on his axis, and planets around the sun.
The air, the ocean and the solid ground are forever in
motion.   The molecules of plants and animals are in
a state of rapid circulation  and change.   Yea, the
invisible atoms of  inorganic matter  are  in a state of
perpetual oscillation and transformation:
  6. That the "unknoAvn hypothetical ether of Sir I.
Newton  is identical with a true physical agent, the
properties of which may be ascertained by the various
mechanical, chemical and physiological effects it pro-
duces; that it determines the aggregation and chemi-
cal union of  bodies, Avhether simple  or compound, by
A'irtue of its  attraction for ponderable matter; Avhile it 
GENERAL CONCLUSIONS.
259
causes liquefaction, evaporation, explosion, with all the
separations and expansions of matter, by virtue of its
idiorepulsive power:
  7. That the same ethereal principle Avhich lights
up the universe with radiant glory, directs the planets
through their orbits and preserves them in a state of
perpetual motion, circulation and renovation:
  8. That in the total absence of caloric,  if such a
thing Avere possible, the  universe Avould be involved
in the darkness, silence and death of primeval chaos:
  9. Finally, that caloric is the first of physical causes,
or the essence which causes things to be what they are. 
BOOK  III.
                  CHAPTEK  I.

                    ELECTRICITY.

  "Nature will not deliver her oracles to the crowd, nor by sound
of trumpet.  We must open our minds to her in solitude, with the
simplicity of children, and look earnestly in her face for a reply."—
Walter Savage Landor.

  The grand requisite to a right understanding  of
nature, is to watch attentively  all the  changes that
mark her progress and the various circumstances by
which they  are attended.  Perhaps  there  is  not a
more striking characteristic of the present age than
the vast amount of industry and talent that are de-
Aroted to the cultivation of separate branches of science,
which cannot be understood but as connected parts of
one  harmonious system.  The division  of labour,  so
beneficial to  the arts, has not been equally favourable
to the progress  of enlarged vieAvs.   Men avIio devote
their attention  chiefly to one branch of science, be-
come narrow, technical and incapable  of embracing
universal truths.  The leading object  of all science is
to reduce a multitude of phenomena to  some compre-
hensive principle or general law, Avhich  pervades the
      (260) 
ELECTRICITY.
261
entire constitution of matter.   But how is it possible
to arrive at universal facts or fundamental laws, with-
out regarding nature as a whole ?
   The more profoundly Ave scrutinize her operations
the more we discover of simplicity and unity of power
amidst all  her diversified movements and transforma-
tions.  Who could have suspected, without a general
survey of  the widely extended provinces of nature,
that the aggregation of liquids into spherical  drops
and their  adhesion to  solids are  resolvable into the
same poAver that determines the solidity and rotundity
of the earth?—Avhich causes rain to descend from on
high, rivers to Aoav toAvard the sea and planets to re-
A^olve around the sun?  Yet these various movements
Avere traced by Newton to one and the same law.
   What can be  more unlike to the mass of mankind
than the opposite forces of attraction and  repulsion,
contraction and expansion?   Yet I have proved that
they are both produced by one and the  same agent;
which  in certain proportions binds the atoms of pas-
sive matter  together, as  in cohesion  and chemical
union; Avhile in other proportions  it diminishes or de-
stroys their cohesion, as in liquefaction, vapourization,
combustion, &c, by Avhich the forms, properties and
poAvers of all bodies are perpetually changed.  I have
shoAvn  that combustion is the disengagement  of that
principle by which the earth is maintained in  its pre-
sent form;  that it is forever  flowing from the sun
throughout  the  solar system;  and that  as it is the
spring of all motion and poAver throughout the earth,
it must also  be the cause of the  annual and  diurnal
motions of  planets. 
262
ELECTRICITY.
   If, then, caloric be the physical cause of all motion,
an universal principle of action in nature, Avhat is elec-
tricity?   Is  it a distinct fluid, sul generis? or is it a
modification of the igneous  principle?  These ques-
tions, so intimately connected Avith the Avhole theory
of physics,  have never yet  been  satisfactorily  an-
swered.   If  electricity Avere the generic moving prin-
ciple throughout  nature, it ought to  be  everjAvhere
present.   But so far is this from being the fact, that
it is only under peculiar circumstances that it  is de-
veloped so as to be appreciable by the senses; Avhereas,
it is impossible to realize the  absence of caloric, which
is indispensable to all the phenomena of climate, sea-
son, the growth of plants and the  life of nature.   If
we admit the existence of an  electric fluid, sul generis,
which darts  through conductors and communicates a
shock  to  the liAdng  frame,  we  cannot refer to its
agency the melting of winter snows  and  polar ice-
bergs, the conversion of water into vapour or steam,
the  elastic force of the  atmosphere and other gases,
the  phenomena of winds, &c, Avithout recognizing its
identity with the cause of temperature.
   As the subject is acknowledged by all philosophers
of the present day to be involved  in the  utmost ob-
scurity, I shall offer no apology for endeavouring  to
place it  in a neAV light.   While  many regard elec-
tricity as  the cause of all  molecular attractions and
others as the vital  principle, almost everything con-
nected with its origin and laAvs is either debatable or
unintelligible; some maintaining with Franklin, that
it is  a subtile and inconceivably  refined species  of
matter, diffused throughout nature; others, that it is 
ELECTRICITY.
263
a compound  of  two fluids,  each of which repels its
OAvn particles and is  attracted by the other; while a
third party maintains that  it is neither, but a mere
effect or property of ponderable matter.
  Such differences of opinion  are  alone sufficient to
show how vaguely and imperfectly it is understood.
Since the time  of Franklin, many thousand experi-
ments have been repeated, Avithout affording any pre-
cise or satisfactory information in regard to its origin
or the mode  of its operation in the work of the uni-
verse.  The  discoveries  of  Galvani, Volta,  Davy,
CErsted and  Faraday have opened  to  us an immense
store of new facts; but where is the general principle
Avhich connects them with the theory of cohesion,
capillary  attraction, chemical  solution, vapourization
and the elastic force of gases? What the present state
of the science requires, is not the repetition of experi-
ments that have been performed a thousand times, but
a more comprehensive and profound  investigation of
those  properties which connect electricity with the
laws of heat and light  and with  the  general phe-
nomena of nature.
   If ever we shall be  enabled to  lift the Aeil Avhich
nature has spread over the first  principles of things
and behold the secret spring of her simple and sublime
mechanism, we must first learn the relations of caloric
and electricity.   If it can  be  shown, that under all
circumstances they are modifications  of one and the
same agent,  the  science  of nature will be at once
divested of that complexity which has hitherto  baffled
every attempt to reduce the phenomena to fixed prin-
ciples. 
264                 ELECTRICITY.
   It is not nvy object to enter into a detailed exami-
 nation  of the various conflicting hypotheses  Avhich
 have been invented  to explain  the  phenomena  of
 electricity; and which, for the most part, have been
 founded on the partial and often ill-conceived experi-
 ments of a little  laboratory.   The truth is, that all
 our  experiments are but feeble  and imperfect  imita-
 tions of what is perpetually going on in the laboratory
 of nature.   But Avho has ever studied the natural his-
 tory of lightning, by tracing its genealogy or nascent
 production, as connected with  evaporation and  all
 the phenomena of precipitation?  Who has carefully
 observed the  connection  betAveen flashes of lightning
 and  torrents  of rain, hail, tornados, hurricanes, &c?
 The fundamental  laws of electricity which connect it
 with  caloric, light, magnetism or  the sublime move-
 ments of geology and  meteorology, will never be de-
 duced Avith unerring fidelity from mere  artificial ex-
 periments.  The greater part  of those on electricity
 are calculated rather to amuse and astonish children
 than to edify those who  are in quest of useful know-
 ledge.
  It may be proper to observe, before  I  proceed  fur-
 ther, that some of the most enlightened  men of the
 last  century supposed  that  the phlogiston  of Stahl,
 (Avhich Avas the undiscovered latent heat of Dr. Black,)
 Avas the basis of heat, light and  electricity.  Dr. Kir-
 Avan,  Avho  strangely  confounded  hydrogen  Avith  the
phlogiston  of Stahl, supposed  that electricity might
be composed of this  substance greatly rarefied,  in  a
state  of  combination Avith elementary fire;  Avhile M.
Benedict De Saussure regarded  it as a fluid composed 
ATMOSPHERIC ELECTRICITY.
265
 of heat and some other unknown principle.  (Voyages
 dans les Alpes, tome ii. p. 243.)  The Abbe Nollet, Dr.
 Hill, the Rev. W. Jones and some others have main-
 tained that heat and electricity Avere modifications of
 the same agent:  but as their opinions were not sup-
 ported by an extended examination of their recondite
 analogies or fundamental laws, philosophers have con-
 tinued to regard them as distinct imponderables.

              ATMOSPHERIC ELECTRICITY.

   The most direct and compendious method of ascer-
 taining the relations of caloric and electricity', would
 be a  careful history of all the phenomena connected
 Avith  the origin of lightning.   If it can be shown that
 the caloric of aqueous vapour is the basis of lightning,
 their radical identity must follow as a  necessary con-
 sequence, notwithstanding the widely different proper-
 ties Avhich  they exhibit.   The  truth is, that diversity
 of form and external  appearance is no evidence of a
 difference in the nature and fundamental constitution
 of things; for it has been demonstrated experimentally
 by numerous philosophers, that  all  the varieties of elec-
 tricity are  essentially the same.  What can  be more
 different than ice, water and steam?   Yet they  are
 composed of the  same  elements,  combined Avith  dif-
 ferent proportions of caloric.   What more opposite in
 all their properties than nitric acid and the  gases of
A\Thich it is formed? And so of a thousand other bodies.
  It Avas long imagined that Avhen Franklin drew  the
lightning from heaven and demonstrated its identity
with common electricity, that he had laid the founda- 
266
ATMOSPHERIC ELECTRICITY.
tion of its true theory.  But it is now evident that his
views in regard to its origin and nature were partial
and erroneous.   At one time he supposed that it was
generated in the ocean by  the friction  of salt and
water; that oceanic vapour was held in a state of ex-
pansion by electricity and heat united, Avhile evapora-
tion from the land was caused by heat alone. He also
maintained  that the  fusion of metals by the electric
fluid was a cold fusion; whereas it is now well knoAvn
that lightning  heats, melts, ignites and volatilizes all
bodies.
  That the general  reader may have a distinct idea
of the existing  state of knowledge  in  regard to  the
origin of lightning, it may not be amiss to present the
statements of some of the most distinguished  recent
writers on the subject.
  It is observed by Mr. Daniell, that "since the time
of Franklin, atmospheric electricity has been almost
entirely neglected;"  and that on this most  important
branch of physical  science, he had "nothing decisive
to offer." (Meteorological Essays, p. 135 and 374.)  The
consequence of which is, that he has left unexplained
many of the most striking and important phenomena
of meteorology, such  as hurricanes, tornados and hail-
storms, with all those violent movements of the atmo-
sphere which accompany rapid discharges of lightning.
Dr. Arnott also  states, that tornados, whirlwinds, &c.
are owing to some chemical changes in the atmosphere
not fully understood.  (Elements of Physics,  vol. i.
p. 397.)
  Dr. Thomson  observes, in his late work on Heat and
Electricity, that " the formation of vapour seems to be 
           EVAPORATION AND CONDENSATION.       267

connected with  electricity, though in what way we
have no conception, and that the change of vapour
into clouds is probably connected with electrical phe-
nomena not understood."  (Page 275 and elsewhere.)
He adds, that "the formation of rain is still invohTed
in impenetrable obscurity."
   It is also observed by Professor Forbes, that on the
noble science of  atmospheric electricity, almost every-
thing has yet to be done.  (Transactions of the British
Association, vol. i. p. 252.)
   As the phenomena of lightning have  been univer-
sally known  to  be immediately connected with  the
production of rain, it becomes necessary to ascertain
with certainty the cause of evaporation and condensa-
tion, before attempting to solve the problem of atmo-
spheric electricity.
   That caloric is the true and only cause of evapora-
tion, or the formation of steam, is one of those self-
evident propositions which would  seem to require no
proof.  But to remove all doubts upon the subject, the
fact has been experimentally demonstrated by  Dr.
Dalton, to whom the science of chemistry and meteor-
ology is so largely indebted.
   He  put a little water in a dry glass  flask, with a
thermometer in  it, when he found that a small quan-
tity of vapour was formed at  32° F.   At 40°  the
amount Avas increased;  at 50° it contained still more
vapour;  while at  60° the  quantity wras  yet  further
augmented.   He also found that when the tempera-
ture of the  flask was suddenly  reduced from 60° to
40°, a  portion of vapour was converted into water,
and that  the quantity retaining the elastic form was 
268        EVAPORATION AND CONDENSATION.

precisely the same as when the temperature Avas origi-
nally at 40°.
  The above is a simple and beautiful representation
of what is perpetually going on throughout the atmo-
sphere and in the steam engine.
  By  another series  of  admirable  experiments, he
ascertained that the quantity of water evaporated in
a given time, Avas exactly in proportion to the elastic
force  of  vapour at  the same temperature,  whether
formed in vacuo, or  under  the pressure of the atmo-
sphere, with this  difference, that in the  latter  case
the process goes on much  more slowly, because the
atmosphere presents a mechanical impediment to its
diffusion   somewhat  analogous to  the obstruction of
water by  porous sand.  From which he inferred  that
A^apour is not chemically united with the air, as had
been  formerly supposed,  but mechanically  diffused
through it, forming  a distinct atmosphere of  its own,
the elastic force of which is always in proportion to
temperature.
  At 0° he found the elastic force of vapour  equal to
the pressure '064 inch of mercury; that is, about one-
fifteenth of an inch.  At 32° it amounted to  one-fifth
of an inch;  at 47°, about one-third of an inch, or *339;
at 59°, *507, or one-half of  an inch;  at 80°, one inch;
and at 90°, 1*360.  He also ascertained that the elastic
force of vapour at 212°, is equal to the pressure of the
whole atmosphere,  or 30 inches of mercury.*  (Man-
chester Memoirs, vol. v.)

  * Dr. Prout observes, that " atmospheric air, under ordinary cir-
cumstances, exerts an elastic force equal to the weight of a column
of mercury  30 inches high; and that at 21*2°, aqueous vapour 
            EVAPORATION AND CONDENSATION.        269

  From the above experiments it follows, that if the
temperature of the  earth were 80°, from the equator
to the poles, the quantity of vapour would be  every-
where the same and equal to about  one-thirtieth  of
the average weight of the whole atmosphere; but that
if its temperature Avere reduced from 80° to 59°, one-
half of  the vapour would be precipitated in the form
of rain;  if to 32°, four-fifths of it would be converted
into snow; and if reduced to 0°, 14 out of 15 parts  of
the Avhole would descend to the earth in the form  of
ice, in obedience to  that universal law of  nature by
which  bodies  cohere  and  tend toward a common
centre.
  But  as the temperature  of the earth diminishes
from the equator to the poles, it is obvious that the
amount of Avater which is capable of existing in the
atmosphere  in the state of transparent elastic \7apour,
must vary proportionally in different latitudes.   There
is also more vapour  in the  atmosphere of  the  ocean,
other things being equal, than over extensive  bodies
of dry land.
  According to the observations of Captain Sabine and
Mr. Caldcleugh, as detailed by Professor Daniell,  it
Avould appear, that within the tropical ocean, between
the Avestern coast of Africa  and the eastern  coast  of
obeys precisely the same  laws and exerts the same elastic force as
atmospheric air under similar circumstances." (Bridgewater Trea-
tise, chap. v. section 2.)  But it has been shown that the  elastic
force of atmospheric air is equal to the pressure of more than 1200
atmospheres, (3000 feet of mercury.)  It is therefore obvious that
Dr. Prout has mistaken the weight of the atmosphere for its elastic
force. 
270        EVAPORATION AND CONDENSATION.
South America, the point of deposition, or dew-point,
is  generally about 4° or 5° beloAv  the existing  tem-
perature;  sometimes  only 2°; and rarely  more  than
8°; while in the interior of large continents it is often
20° or 30°, and sometimes 50° or more, below the pre-
valent temperature.  As the atmosphere is in a  state
of nearly  constant circulation, it is removed from one
place to another before arriving at the point of  satu-
ration, and therefore  contains less vapour  than  it is
capable of sustaining at the  existing  temperature.
Within the torrid  zone, it is perpetually expanded by
solar heat, where it rises into the  upper regions, whence
it  flows to higher latitudes; while  it is removed by
horizontal currents termed sea breezes, from the ocean
to the heated land.
   If at the temperature of 80°, the atmosphere con-
tain an amount of Arapour equal to the pressure of only
half an inch of mercury, while it is capable of sus-
taining twice that quantity, it will require a reduction
of temperature below 59° to cause precipitation.  Hence
it is, that  the atmosphere often undergoes great reduc-
tions of temperature  without producing rain.   But
when the  air is full of vapour the process of evapora-
tion is arrested; which explains why a cold dry air is
more favourable to evaporation than warm air that is
already saturated, especially if the former be in a  state
of rapid motion.
   Dr. Dalton found that when boiling Avater was ex-
posed to a current of  air that carried off its vapour as
fast as formed, vapourization went on a third faster
than in a  room where the air was still.   Hence  it is,
that northeast  and east winds,  which, in  the west of 
           EVAPORATION AND CONDENSATION.        271

Europe are generally dry, and  far below the point of
saturation, seldom condense the vapour of France and
England;  but, on the contrary,  often redissolve the
clouds already formed, producing  clear Aveather.  Dur-
ing summer, when the atmosphere has been for some
time comparatively still, it is soon saturated with va-
pour, which is  indicated by heavy dews, and the for-
mation of clouds  termed cumuli, in which case the
weather becomes hot and sultry; because  the caloric
Avhich is usually carried off by evaporation and winds,
accumulates on the surface of the earth and heats the
superincumbent air.   Such a state of things generally
forebodes  an approaching thunder-storm.
   That the condensation  of atmospheric vapour is
owing to  the abstraction of its caloric by colder cur-
rents of air, is evident from  the  fact, that in the tro-
pical ocean far from land, where the  trade-wind blows
steadily in one direction, and Avhere the temperature
seldom varies  more  than two or three degrees, there
is less rain than in the vicinity of continents and large
islands, where currents of air of different temperatures
frequently meet.
   In the great desert of Sahara,  there is scarcely any
rain, because the wind blowing over it is generally in
the same  direction;  Avhile the vapour transported by
it from the ocean is still further rarefied by the intense
heat  reflected from  the  scorching sands, where there
are no mountains to arrest  its progress.   There are
also long  droughts in Egypt, Palestine, New Holland
and many other  parts of the world Avhere the Avinds
Woav long in one direction, without encountering colder
currents."   During summer, in  the United  States, the 
272        EVAPORATION AND CONDENSATION.
atmosphere is often so much heated, that the Aapour
brought from the ocean by southern winds is not con-
densed for several Aveeks, and sometimes tAvo months,
but  is further  expanded, until it becomes saturated,
or meets with a current from the northern  points of
the compass, Avhen thunder-gusts follow.
   When  I come to treat of winds it Avill be shown,
that the  most extensive  falls of rain in  the middle
latitudes  are produced by the meeting of  immense
masses of air from opposite quarters of different tem-
peratures, as during the equinoctial floods and storms.
When both contain as much vapour as they can sup-
port at their respective temperatures, the amount of
precipitation is of course the greatest.
   Corresponding Avith  the  experiments of Dalton, is
the well-established fact, that the greatest quantity of
rain falls within  the tropics, where the average tem-
perature is from 80° to 85° F., and diminishes on to
the regions of lowest  mean temperature, where it is
about 0°.   Hence it is that the  largest rivers in  the
Avorld are found in the tropical regions, as the  Amazon,
La Plata and  Orinoko of  South America;  and  the
Indus, the Ganges, the Nile, the Tigris, &c.  of the east-
ern continent.
  The following  table exhibits a  general view of  the
relative depths of rain in different latitudes:—

                             Lat. N.           Inches.
     Coast of Malabar........................ 12°   .................. 136
     Grenada.................................... 12°   .................. 126
     Cape Francois............................. 19° 46/.................. 120
     Senegal..................................... 00°.................. 115
     Calcutta.................................... 22°   .................. 81
     Havana .................................... 23° 19-".................. 109 
EVAPORATION AND  CONDENSATION.        273
                             Lai. N.         Inches.
    New Orleans.............................. 29° 58/..................  63
    Cincinnati................................. 39° 06'..................  36
    Philadelphia............................... 39° 57'..................  3653
    Boston...................................... 42° 21'..................  39-22
    Rome....................................... 41°  ..................  39
    England (Dalton's mean).............. 50°  ..................  31
    Petersburg ................................ 59°  ..................  16
    Uleaborg................................... 65°  .................  13£

  The above results are greatly modified by a variety
of circumstances, such as prevalent Avinds, the relative
positions of land and sea, mountain ranges, &c.   For
example, the trade-wind which blows  constantly from
oast to west over the Atlantic Ocean Avithin the tropics,
deposits a far greater amount of rain on the  eastern
slope  of South  America, than  on its Avestern coast.
At Vera Cruz, 278 inches have  been observed to fall
in the course of one  year, and  at  San Luis, in south
latitude, 2° 30',  it has been 280 inches.   But in the
middle latitudes of the northern  hemisphere, where
the prevalent wind is from the opposite direction, the
case is reversed.  Hence the greater amount of rain
Avhich falls on the western coasts of Europe and North
America, than  in the  interior  of those continents,
being wafted from the  Atlantic and  Pacific oceans.
There is also more rain in mountainous regions than
on  extensive plains.  It has been ascertained,  that
about double the quantity of rain falls on Mount St.
Bernard, that falls  at Geneva; and  that the mean
annual amount of twenty places in the lower valleys
at  the base  of the Alps, is 58*5 inches, according to
M. SchoAv.   The reason is, that the onward progress
of vapour is arrested by mountains, which cause it to
                         18 
274
EVAPORATION AND CONDENSATION.
accumulate.   Even so far north as Bergen, in Norway,
where the soutliAvest winds are impeded by mountains,
the annual depth of rain is 88 inches.
   There is nothing more admirable in the great drama
of nature than  the process  of evaporation  and con-
densation, by which all the waters of lakes, rivers and
fountains are elevated from the ocean;  transported
over continents and islands;  precipitated by polar cur-
rents; and  distributed in the  form of great natural
shower-baths over the dry land.
   Notwithstanding the greater amount of evapora-
tion and rain in the tropical  than higher latitudes, the
atmosphere is more  transparent, and  there  are more
clear days in the equatorial regions; and more during
summer than Avinter in temperate climates.
   According to the estimate of La  Cotte, which may
be regarded as an approximation  to the truth, the
average  number of rainy days between lat. 12° and
60° N. are in the folloAving ratios:—
                     N.                   Days.
        From lat,  12° to 43°....................................  78
               43° to 46°.................................... 103
               46° to 50°.................................... 134
                50° to 60°.................................... 160
   It is therefore evident that the transparency of the
atmosphere, other things being equal, is in proportion
to temperature, which diminishes from the equator to
the poles.   It  is also known to decrease from below
upward.*   Hence  it is, that the loAver atmosphere is

   * It was supposed by Leslie and Dalton, that the diminution of
temperature in the atmosphere, on  ascending above  the earth's
surface, was owing to its increased  capacity for heat, caused by 
EVAPORATION  AND  CONDENSATION.         275
transparent,  even  when  the  sky is  overcast  with
clouds,*  the  elevation of which is in  proportion to
temperature;  that is,  the plains  of condensation  are
higher within the tropical than middle latitudes; while
in  the latter their  elevations  vary Avith the  season.
From  the observations  of Mr. Crosthwaite  it Avould
appear that  the under surface  of dense clouds in  the
north of England does not exceed  1300 yards during
winter, nor 2000 yards in summer.   (Daltons Meteor-
ological Essays, p. 136.)

augmented rarefaction from diminished pressure.   But this is not
the only cause;  for it is well known, that large portions of Asia,
Africa and South America are from  eight to ten thousand feet
above the level of the ocean; whereas their average  temperature
is much higher than that of isolated mountains of equal elevation
in the same latitudes.   Mount Lebanon  is not much higher  than
the plateau of Mexico ;  yet the former is covered with snow  nine
months in the year, while there is  perpetual summer on the table-
lands of Mexico, about the  same latitude and elevation.   The
plains of Michigan are about 600 feet above the sea; yet there is
no State in the Union in which the temperature rises higher during
summer.  The truth is, that the greater warmth of the lower at-
mosphere over extensive plains, than that of mountains, is owing in
part to the absorption of the sun's rays by the earth's surface.   The
stratum of  air in contact with the earth becomes heated and rises,
when the next stratum is heated and rises, until  the whole atmo-
sphere becomes warmed to a considerable height.  Hence it is, that
the  plain of perpetual congelation varies in height in different parts
of the world in nearly the same latitudes.
  * The dryness of the atmosphere is  in proportion to the eleva-
tion of its temperature above the dew-point, which decreases from
the  surface of the earth to  the region of clouds.   This  explains
why rain often ceases about mid-day, when the clouds are redis-
solved by the increasing power of the sun; and why the lower
atmosphere is so often obscured in England by a misty rain after
sunset during winter. 
270
LIGHTNING AND RAIN.
   To pursue this subject through all the complicated
 phenomena of  meteorology, would far exceed the scope
 of the present inquiry, the principal object of which
 is to trace the  origin and history of  atmospheric elec-
 tricity.
   The cardinal facts Avhich connect the phenomena of
 lightning with the  theory of rain may be reduced to
 the  following propositions:—
   1. In  the torrid  zone, where evaporation and rain
 are  most copious, the amount of lightning is greatest.
 There is also far more during summer than winter in
 the  middle latitudes, and scarcely any  in  the  polar
 regions.
   2. In  those  parts of the Avorld where  there is  no
 rain, there is no lightning, as at Lima in Peru; nor
 is there any in Egypt, Palestine and other parts of the
 world during the prevalence of dry weather. It there-
 fore  follows,—
   3. That Avhere there is no condensation of aqueous
 vapour, there is no lightning.
   The most superficial observers of nature have been
 impressed Avith the  immediate  connection between
 lightning, intense heat  and  rapid  precipitations  of
 rain.  By a careful  analysis of the phenomena it be-
 comes  self-evident, that if caloric be the true and only
 cause of evaporation, condensation and precipitation can
 be effected only by the evolution of the same agent.  Dur-
ing Avinter, the  quantity and elastic force of vapour in
the  atmosphere are comparatively low in the  middle
latitudes, where it is condensed gradually on meeting
with colder air.  During spring, evaporation augments
Avith increase of temperature, when  masses of warm 
LIGHTNING AND RAIN.
277
and cold  air often  meet, causing frequent showers of
rain and  sometimes hail, still without much thunder
and lightning.   But during  summer, when the tem-
perature  becomes tropical, and the atmosphere satu-
rated Avith highly elastic vapour, we have tremendous
explosions of thunder and lightning, with rapid pre-
cipitations of rain and hail.  Corresponding with the
temperature of the torrid zone, and the amount of
evaporation, thunder-storms occur almost daily during
the rainy season, on  the coasts of India and  South
America.
  One of the most  prominent errors in regard  to the
natural history of lightning, is the prevalent notion
that it collects around the surface of clouds, as if they
Avere solid insulated conductors; and that when it be-
comes  accumulated to a certain extent, it darts from
one to another.  Nothing could be more in opposition
to all analogy and experience.  Clouds are only banks
or strata of moisture, Avhile  it is universally known
that electricity cannot be accumulated in a moist at-
mosphere; that it is diffused and dissipated by moist-
ure, and thus  prevented from  being collected in a
Ley den  battery.  It  is accumulated  in transparent
aqueous vapour,  (as I shall proceed to shoAV by the
most decisive facts,) from which it darts through the
neighbouring clouds in such a manner as  to present
the appearance of proceeding from them; Avhile it is
an optical illusion that may be corrected by a philo-
sophical  examination; in short, that a large body of
transparent  elastic  vapour from the  tropics, may be
compared to an  immense  Leyden  battery, filled with
an igneous fluid, Avhich is discharged  in the concen- 
278
LIGHTNING AND  RAIN.
trated form of lightning on approaching mountains, or
meeting Avith currents of cold air.
   When the inquiry is divested of all extraneous and
hypothetical  considerations, it may be reduced to the
following conditions.
   If it can be shown, that transparent elastic vapour
is the  vehicle  of atmospjheric electricity, and  that It is
rapidly condensed during discharges of lightning, it will
necessarily follow,,  that  the caloric of such vapour is
given out in the concentrated form of electricity during
a thunder-storm.
   In  reply to this reasoning it may  be objected, that
heavy rains are often unattended Avith lightning.   To
Avhich I ansAver, without fear of contradiction, that  the
formation  of  clouds and precipitation of rain  are far
more rapid during  thunder-storms than when there Is no
lightning.  It is stated by Humboldt and others, that
Avithin  the tropics during  the rainy  season, the first
indication of an approaching storm is  generally a light
wind, with a  feAV scudding clouds; but that Avhen it
begins to lighten, the whole sky is suddenly obscured
by dense clouds that immediately descend in torrents
of rain.
   That  atmospheric  electricity is a  constituent  of
aqueous vapour, will appear from  the description of a
thunder-storm among the  Alps, as  recorded  by the
celebrated De Luc, in his. " Ideas sur la Meteorologie."
He states that it commenced with abundant discharges
of electricity from dry transparent  air, which contained
neither vapours nor the electric fluid, but the constituents
of both,—and that clouds were suddenly formed around
the summit of the Buet, during each explosion.  In other 
DE LUC  AND MURPHY.
279
words, that simultaneous with the discharges of light-
ning from dry transparent air, was the sudden forma-
tion of clouds, and precipitation of rain.
   From another  portion of  De Luc's work, it is obvi-
ous  that he mistook  transparent aqueous vapour for
"dry air."   He supposed that clouds were formed by
the union of oxygen and hydrogen gases by the agency
of electricity, as water is generated by passing an elec-
 tric spark through them*
   It was long ago supposed by Plato,  that fire, when
 concreted,  becomes air, which, on being further con-
 densed, constitutes clouds and water;  which are  also
 convertible into earthy bodies;  and all of  them again
 into flame  or fire.  (See Timcvus, ch. xxxi.)
   According to  Seneca, the  ancient  Stoics taught a
 similar doctrine—"that air  was  converted  into fire
 and water," during a thunder-storm:—(Natural  Ques-
 tions,  book ii.)  from Avhich it Avould appear, that they
 were  ignorant of the process of evaporation, by which
 water is expanded into elastic vapour like air; or that
 they  confounded the one Avith the^other.____________
   * This hypothesis has been  revived by Mr. Murphy of  Cam-
 bridge, in a recent work on Electricity, the  professed object of
 which is to reduce the science to mathematical laws.  Had  this
 author traced the history of rain from the first process of evapo-
 ration, he would probably not have maintained that heavy showers
 of rain which accompany lightning,  may be produced from  the
 combination of oxygen  and hydrogen by electricity, after it  had
 been demonstrated by Dalton that vapour or steam is composed ot
 water and caloric, and that its condensation is owing to the evolu-
 tion of caloric, whether attended with lightning or  not.  The  sup-
 position of Dr. Darwin was more consistent, who maintained  that
 electricity was the cause of evaporation, because discharges of
 lightning are attended with rapid precipitations of rain. 
280
SENECA AND THE STOICS.
   In the  22d  chapter of  the same  book, in Avhich
Seneca gives his oavh opinion, he maintains that five
and lightning are the same, because the latter produces
the same effects as fire, such as the heating and melt-
ing of metals, the combustion of  forests, &c.; but that
in lightning, fire was greatly condensed.* That caloric
and electricity Avere regarded as  identical  during the
earliest  ages of  the world,  would appear from  the
fact, that  the oriental Avord ~)1N, aur, was emplojed
to denote both fire and lightning.   It is generally sup-
posed  that the Avord  electricity Avas derived  from the
noun TjXexrpov, amber,  a  shining substance;  which,  on
being  rubbed, Avas observed  by the Greeks to attract
light bodies.   But this last word was doubtless derived
from TjXexrwp, a name of the  sun, the great  fountain of
electric fire.
   But to return from this digression; if it be true that
caloric is the cause of evaporation, (as proved by De
Luc himself,) and if transparent vapour be suddenly
condensed  into clouds  and  rain, Avith a  rapidity pro-
portional to the  amount of lightning, the conclusion
is  inevitable, that  solar  caloric  is  the real basis of
lightning;  for it would be a violation of all  the rules of
  * Aristotle and Pliny also  speak of the fusion of metals by
lightning,—the first, of  the copper on a shield, while  the wood
which it covered was uninjured;  the  latter, of gold, silver and
copper coins, sealed up in a bag, which was not burned.  In sup-
port  of  their  statements,  M. Arago  relates  that in  1781, M.
D'Aussac, and the horse on which he was mounted, were killed by
lightning in the neighbourhood of Castres, when the  blade of his
sword was fused upon its surface at several places, while the scab-
bard containing it was not burned. 
             OBSERVATIONS OF THE AUTHOR.         281

philosophrdng, to maintain that water is converted  into
vapour by one agent, and again reduced to water without
the evolution of the same agent.   No sophistry can evade
this simple but rigorous logic.  That the rapid precipi-
tation of rain during a thunder-storm is in proportion
to the amount  of lightning, is attested by all experi-
ence  and observation.   Hence it is, that during the
fiery  tempests  of the tropical regions, termed  hurri-
canes, more  rain is precipitated in a few hours, than
during as many months in colder latitudes.
   It may be said that lightning is  sometimes unat-
tended Avith rain:  to Avhich I  answer, that vivid
flashes never occur immediately over head, Avithout a
precipitation of rain or hail.   This is  the most con-
vincing proof, that  the caloric of vapour is giAen out
in the condensed form of lightning, and  is that kind
of evidence from which  there is no appeal, being the
spontaneous declaration of nature herself, made in the
most sublime and ostensible manner.
   On the 2d of June,  1833, the author had an oppor-
tunity of observing for himself, that lightning proceeds
from treuisparent vapour, and  not from clouds already
formed, as many persons suppose.  This beautiful dis-
play, which Avas Avitnessed by  hundreds of individuals
with admiration, occurred  at  NeAv York,  about 7 p. m.,
after a shoAvery day.  The wind was from the south,
while  the Avestern  sky Avas of a brassy hue, through
which the descending sun was perfectly visible.   In
this state of the atmosphere,  a vivid streak of light-
ning Avas seen to dart from  it, Avhen clouds Avere imme-
diately formed that intercepted the solar rays, as if an
immense black  curtain  had  been draAvn across  the 
282            MARCORELLE AND DUPERREY.
Avestern  sky, and  attended Avith  copious precipitation
of rain.*
   Such facts  afford more decisive information in re-
gard to the nature of  lightning, than volumes of mere
speculation, or  than   thousands  of  artificial  cxperi-
  *  Since the London edition of this work was published, I have
met with many similar statements in the newspapers of the United
States, and in the writings of the older meteorologists of Europe.
It was maintained by Franklin, Saussure and others, that thunder
never proceeds  from a solitary cloud.   But, in opposition to this
opinion, it  is related  by M. Marcorelle of Toulouse, that on the
12th of September, 1147, the  sky being generally clear, a single
small cloud was observed, from which lightning and thunder pro-
ceeded, by which a female named Bordenare was killed.  Duhamel
also relates, that on the 30th of July, 17G4, at half-past five p.m.,
in bright sunshine and a clear sky, there  appeared a small dark
solitary cloud, from which lightning and  thunder proceeded, by
which an elm-tree near the chateau of Denainvilliers was stricken.
Capt. Duperrey, of the French corvette  Urania, further relates,
that being in the Straits of Bombay, in  Nov. 1818, he saw a small
white cloud in a clear sky, about the magnitude of the  sun, from
which lightning issued of a zigzag form, followed by thunder which
resembled the  irregular discharge of musketry.  It is also stated
in the New York Sun, of July 31, 1845, that on Monday, the 28th
of the  same month, at Worcester, in  Massachusetts, a building was
struck  by lightning which  proceeded from  a small cloud and was
not attended by any rain.  But it is  here worthy of notice, that in
such cases, where the lightning is at a considerable distance, there
may be rain at that place, though not  perceived by an observer.
Several of  the above  examples are related by Dr. Lardner, who
has not, however, perceived their bearing in regard to the identity
of caloric and atmospheric electricity.   The immediate connection
of rain with discharges of lightning from  aqueous vapour, seems
to have been noticed  in the  Book of Job: "Who hath divided a
way for the lightning of thunder, to cause it to rain on the earth?"
(Chapter xxxviii. v. 25.) 
BECCARIA AND FRANKLIN.
283
ments;  for they completely establish  the important
fact that elastic vapour is the proximate source of atmo-
spheric  electricity, and not clouds.   Nevertheless, I
shall  prove by the experiments of De Saussure, Read
and Pouillet, that electricity may be disengaged from
all v^apours generated by the agency of caloric, whether
by natural or artificial means, or by combustion; that
it rises from the earth in a latent state of combination
Avith aqueous vapour, Avhich it maintains in the elastic
form,—whence it may be withdrawn  by conductors,
and tested by the electrometer.
  Scarcely one of  the  older Avriters on meteorology,
clearly understood  the  simple process of evaporation.
Beccaria supposed  that the earth Avas full of electric
matter, Avhich rises to the  upper regions of the atmo-
sphere, carrying with it Avater in  the form of vapour.
(Priestley s Hist, of Electr. p. 340.)
  Franklin also  supposed,  that vapour Avas  elevated
from the sea, by the  united agency of heat and elec-
tricity.   But it is now Avell established, that caloric is
the vapourizing agent all OArer the world; that wherever
there is heat, Avith Avater in sufficient quantity, vapour
is produced, whether from the ocean, fresh water lakes
and rivers, or from the surface  of the  dry land;  and
that, other things being equal, its amount, like that of
lightning, is determined by temperature.  Had Frank-
lin clearly understood the process of evaporation, and
traced the connection betAveen discharges of lightning
and  precipitation, he Avould probably have  added  to
his discover}- of the identity of lightning and  common
electricity, the still more important fact,  that caloric 
284
VOLTA, LAVOISIER AND  LAPLACE.
 and electricity are different manifestations of the same
 potent element.
    The celebrated Volta adopted the opinion of Frank-
 lin, Avith some slight variation.  He supposed that all
 bodies contained  electricity,  a portion  of  Avhich Avas
 evol\red Avhenever they undenvent a change of state;
 that  Avhen Avater Avas converted into vapour  by the
 agency of solar heat, it acquired a greater capacity for
- electricity, Avhich it absorbed and  carried into the at-
 mosphere during the  process of evaporation;  that it
 Avas liberated Avhenever the vapour Avas condensed by
 cold, and thus accumulated in the upper regions of the
 air;*  that  Avhen  clouds are  formed, Avhich  are good
 conductors of electricity, they become  a medium by
 Avhich it is conveyed back to the  earth in a tranquil
 manner, or in the form of lightning, according as it
 is more or  less abundant.  (Journal de Physique, Aout.
 1783.)
    Some experiments of Lavoisier and  Laplace, pub-

    * Seneca informs us that Anaxagoras taught that lightning de-
 scended from the ethereal regions, and was collected in clouds, from
 which  it  was discharged after being greatly accumulated.  The
 same hypothesis has been recently brought forward as new by Dr.
 Hare, with this difference, that he supposes the earth to constitute
 another great reservoir of the electric fluid, and that the atmo-
 sphere is situated  between  two  oceans of electricity; while the
 clouds formed in the non-conducting air operate as movable in-
 sulated conductors.   He further supposes,  that thunder-storms are
 more  frequent  during warm than cold weather,  in consequence of
 the greater elevation to which the clouds then attain, and their
 consequent  approximation to the  celestial ocean of electricity.
 (Theoretical Suggestions Bespecting the Causes of the Tornado,
 or Water-spout, &c,  by Robert Hare, M.D., of  Philadelphia.) 
DE SAUSSURE AND READ.
285
lished  in the Memoirs  of the French Academy in
1781, were intended to prove that electricity is disen-
gaged  during the process of evaporation: but their
results were vitiated by the agency of chemical action,
Avhich accompanied the process of evaporation in most
of their  experiments.  Besides, they did  not  extend
their researches to the connection of atmospheric elec-
tricity with  the phenomena  of  meteorology;  they
have therefore  been very little  attended to by  phi-
losophers.
   Lavoisier  and Laplace found, that Avhen water Avas
poured by drops into an iron vessel heated, Avhile the
vessel communicated with  an electroscope,  it gave
signs of positive  electricity;  that  when  dilute  sul-
phuric or nitric acid was poured upon iron filings,
electricity was  evolved;  also,  during the action  of
dilute sulphuric acid  on chalk and  during the com-
bustion of charcoal.  Their experiments tend to shoAV
the  relation betAveen  chemical action and the evolu-
tion of electricity, but throw very little  light on the
connection of electricity with evaporation.
   The most decisive results are those of De Saussure
and Mr.  Read, Avho performed many hundred experi-
ments with the  greatest  care, for the purpose of ascer-
taining the source of atmospheric  electricity; the re-
sult of  Avhich  led  them to the conclusion, that  a
perpetual circulation  of the electric fluid  is  kept up
by means of evaporation and condensation.
   De Saussure found  that when Avater, spirit of wine
and ether were  made  to boil in silver, or white porce-
lain vessels heated, and suspended by silk cords, nega-
tive electricity Avas obtained; but when a piece of red- 
 286         EXPERIMENTS OF DE SAUSSURE.

 hot iron Avas throAvn into a vessel containing a small
 quantity of Avater,  positive electricity Avas strongly
 developed.  He supposed that the vast quantities of
 electricity discharged from volcanos Avas generated by
 the action of so great a heat on waters that find tlieir
 way to those immense furnaces.   In all such'cases, it
 is  disengaged partly by  chemical action,  as Avill be
 noticed when I come to treat of voltaic electricity and
 volcanic forces.
   The following experiments of De Saussure  show
 that aqueous vapour, hoAvever produced, contains elec-
 tricity.   He caused  Avater  to boil in a coffee-pot by
 placing it on an insulated chauffer, (heater,) when the
 coffee-pot Avas electrified  negatively, during the con-
 densation of the vapour.   He varied the experiment,
 by causing the vapour of boiling Avater to pass into
 the cap  of an  insulated  alembic, to which he applied
 snoAv, causing  a condensation of  the vapour con-
 tained within it, when the  apparatus became electri-
 fied negatively.  The same effect was  produced in  a
 more remarkable manner, by applying a mixture of
 common salt and snow as a refrigerant.  He observes,
 that in all such cases, electricity is disengaged from the
 vapour and conducted to the metallic vessel during the
process of condensation.  (Voyages dans les Alpes, tome
 ii. p. 251.)
   De Saussure adds,  that the electric fluid is generated
 during the conversion of water into vapour by heat; that
 it combines with vapour and contributes to Its formation;
 " that it  rises invisible and inactive, hid in the bosom
 of vapours; but aftenvards displaying its energy Avhen
 those vapours are changed  in form, it  redescends ac- 
THOMSON AND DE  SAUSSURE.           287
tive, animated by its penetrating and expansive force.'1
(Voyages  dans les Alpes,  tome ii. p. 244.)  But it is
quite evident that his ideas were vague and unsettled
in regard to the origin of atmospheric electricity;  for
he observes in another volume of the same  work, that
it seemed to be produced by  the friction of clouds
against the air;  by the  action of the solar rays; or by
these tAvo causes united.  (Vol. i. p. 241.)
   Dr. Thomson has expressed nearly the same opinion
in his late work on Heat and Electricity: "that atmo-
spheric electricity may result from the friction of two
currents of dry air moving different ways." (Page 441.)
   De Saussure supposed that there were tAvo kinds of
vapour; the  one  vesicular* and visible, Avhich con-
tained  electricity;  while transparent elastic ATapour
Avas combined with, and  sustained  by, the  expansive
agency of heat alone. (Vol. ii. p. 259.)
   But I have shoAvn, from the observations of De Luc
on the Alps  and from my own at  NeAv York, that
lightning is disengaged rapidly from transparent  va-
pour, by which the latter  is condensed into  rain. The
observations and experiments of De Saussure are highly

  * The vesicular theory originated with Derham, who supposed
that vapour was composed of hollow sphericles of water filled with
highly attenuated air, which Mr. Leslie terms a " fanciful notion,
countenanced by certain dubious optical appearances."  Saussure
says, that while travelling in the Alps he was enveloped in a mist
which was almost stagnant, when he was astonished  to see drops,
as he thought them, floating slowly past him, without  falling to the
ground, some of them larger than the  largest peas ;  but catching
them in his hand, he found them to be bladders, inconceivably thin.
Truly, the philosopher must have been in a mist.   But how was
Berzelius trapped into the same illusion ? 
288         TRANSFORMATIONS OF CALORIC.

valuable; Avhile his theoretical views are often incon-
sistent.  He supposed that electricity AAras destroyed by
explosions of thunder; that is to say, it is generated by
evaporation  and destroyed by condensation.   But I
have already shown, that such phenomena result from
changes  of  state;  and it will  be  seen hereafter, that
there are no assignable  limits to the metamorphoses
of this subtile agent.  They are as diversified as the
multitudinous forms of external nature.  Though in-
visible per se, it is  everywhere busy in all the trans-
mutations of matter.  The fabled Proteus of old is but
a feeble representation of the  rapid  changes  through
Avhich  it passes—noAV silently bearing  the Avaters of
the ocean aloft in the atmosphere in a state of trans-
parent ethereal vapour—now  darting in vivid corus-
cations from its aerial palaces on high—leaping upon
the mountains and cleaving rocks asunder—resound-
ing through the heavens  with its  great  music, and
sprinkling the earth  with genial showers  of  fruitful
rain.   Though constantly changing,  it is never de-
stroyed, but is ahvays the same powerful agent by
Avhich  Infinite Wisdom directs and governs the uni-
verse.  Who can refrain from  sentiments of profound
admiration  of its godlike energy and  the  Avonderful
manner in which it produces  an endless succession of
the most diversified effects?
  There  is not a more striking evidence of beneficent
design  in the whole mechanism of creation, than the
rapid evolution of  heat  from  atmospheric vapour, in
the concentrated form  of lightning, during hot and
sultry weather.  Were it evolved gradually, as during
Avinter, the  number of rainy days would be so far in- 
         EXPERIMENTS OF POUILLET AND READ.      289

creased, as greatly to interfere with the operations of
agriculture.   On  the other hand, being given out in
the diffused form of sensible  heat  during the forma-
tion of clouds, rain and snow in the higher latitudes,
it moderates the excessive cold which would otherwise
prevail during Avinter.
  It was finely observed by a distinguished writer of
the present day,  " that the delight with which specu-
lative minds contemplate universal truths, does not so
much spring from perceiving that  some general prin-
ciple holds good  and reappears in  a great number of
instances very nearly, or perfectly  resembling one an-
other, as from discovering the occult presence or  effi-
cacy of some such principle in a multiplicity  of cases
which  have few points, or perhaps no other  point of
resemblance  besides  this  one of their obedience to
some abstract law." (Isaac Taylor. Saturday Evening.
p. 181.)
  When men shall thoroughly comprehend the agency
of caloric in all the diversified forms of electricity, and
how they are resolvable into one  general principle,
innumerable  new truths, the existence of which  has
not been suspected, will gradually  open to view, until
the vast and complicated mechanism of nature shall be
fully unfolded and reduced to an intelligible theory.
  I cannot dismiss this subject without  noticing the
recent experiments of M. Pouillet,  in connection with
those of  Mr.  Read, which  Avere performed fifty years
ago; because their conclusions are  in direct opposition
to each other.  Mr. Read  maintained that electricity
is given out by  aqueous Arapour, (the constituents of
Avhich  are oxygen, hydrogen and caloric,) and by the
                         19 
290      EXPERIMENTS OF POUILLET  AND READ.

vapours  that are  exhaled from burning substances;*
while  M. Pouillet contends that  electricity is  never
developed by evaporation, unless attended with chemi-
cal action.
   It was before stated, that De Saussure obtained elec-
tricity during the  evaporation of Avater from silver and
porcelain vessels, Avhere no chemical action can be sup-
posed  to have existed.   Mr. Read insulated a large
hollow tin cone, Avith many yards  of small wire  coiled
up within it, one end of which extended from the apex
of the cone,  which was open, and  Avas connected Avith
a sensitive electrometer.   Under this cone was placed
a vessel  of water, the vapour from which, on rising,
was  condensed and  collected  by the  cone  and Avire,
when positive electricity was produced, (which De Saus-
sure could not obtain without chemical action.)   The
same result  Avas  obtained by burning different sub-
stances under the  cone.  He maintained that the elec-
tricity which he derived from the atmosphere in dif-
ferent degrees, at  all seasons  and times  of the day,
was elicited from  its vapour. He observed that during
the formation of thick fogs  electricity was  abundant,
but scarce during  their solution and dispersion. (Spon-
taneous Electricity,  p. 15.)  He also  found that  his
lightning-rod was less charged with  electricity while
immediately under a cloud, than  when at some dis-
tance from it; and that it acquired more  electricity
before the rain commenced than  afterwards; a fact
which was also observed by Beccaria.
  * Mr. Read considered combustion as a species of  evaporation,
by which solid and fluid bodies were converted more or less rapidly
into the gaseous state. 
EXPERIMENTS OF POUILLET.
291
  These  beautiful  and important experiments  will
enable us to comprehend those of M. Pouillet, which
he seems not to have rightly understood himself.  He
placed a cylindrical piece of charcoal in a vertical posi-
tion, the top of which was  two and  a half or three
inches below a plate of brass that was connected Avith
the condenser.  When the upper part of the charcoal
was ignited, a current of carbonic acid arose and came
in contact with the brass plate, by which the condenser
was positively electrified in a few minutes.  By placing
the inferior end of the charcoal on the condenser and
igniting  the upper end, the  condenser was charged
Avith  negative electricity.   From these experiments
Pouillet  concluded, that during the combination  of
oxygen Avith carbon, it gave out  positive  electricity,
while the carbon gave out negative electricity.
  During some of his experiments, both positive and
negative electricity were evolved  by the combustion
of charcoal and hydrogen; from which it would seem
to follow, that positive and negative electricity are
only plus and minus conditions of the  same agent;
although  this  seems not to have been suspected by
Pouillet.  The following experiments are  among the
most  instructive  Avhich have  been recorded  by the
French philosopher.  He caused hydrogen  gas to flowr
out of a glass tube.  When it was ignited, a vertical
flame was produced, nearly half an inch  in breadth
and three inches  in height.   A coil of platinum  wire
Avas employed to conduct the electricity from the flame
to the condenser.  When the coil was large enough to
inclose the flame, and to be  about four inches from its
external surface, positive electricity was indicated, as 
292
EXPERIMENTS OF POUILLET.
in the experiments of Mr. Read, which became  more
and more intense as the distance diminished, until the
coil touched  the flame, when nearly all signs of elec-
tricity  disappeared.   Hence it  was concluded, that
around  the flame of hydrogen gas there is a sort of
atmosphere at least four inches in  thickness, Avhich is
ahvays charged with positive electricity.
  Noav, it is obvious that aqueous  vapour is produced
during the combustion  of hydrogen gas, constituting
an atmosphere above and around  the flame; which
vapour gives  out positive electricity as proved by Mr.
Read.   It  is also evident,  that  in the  immediate
vicinity of the flame, the vapour cannot be condensed
by the  platinum coil; and therefore cannot give out
much, if any, electricity.  It is for the same reason,
that the vapour of the atmosphere gives out less elec-
tricity during the heat of a clear day, than in the even-
ing.  When  Pouillet  placed a small coil of platinum
wire in  the  centre of the flame, so that it was enve-
loped on all  sides, and  made to communicate vvith a
condenser, the instrument was  electrified negatively.
This is a thermo-electric phenomenon which has very
little connection with atmospheric electricity, as will
be seen hereafter.  He found that  during the combus-
tion of  alcohol, ether, wax, oils, fat and  many vege-
table bodies,  the same phenomena were • exhibited as
in the experiments with burning  hydrogen. (An. de
Chim. et de Phys. xxxv. 401, et xxxvi. 5.)
  The principal error of M. Pouillet was in  supposing
that electricity is never produced by evaporation, un-
less attended Avith more or less chemical action; that
Avhen Avater was evaporated from platinum cups, no 
          POUILLET, DE SAUSSURE AND  HARRIS.      293

 electricity was evolved.  In  addition to the evidence
 of De  Saussure, are the  recent  experiments of Mr.
 Harris, who has found  that  the evaporation of pure
 water from  platinum vessels is attended Avith a dis-
 tinct evolution of electricity; so  that  the doctrine of
 Pouillet cannot  be  admitted, that atmospheric elec-
 tricity is wholly  supplied by  chemical  action and the
 growth of plants.   It is impossible  to conceive that
 the vast amount of lightning disengaged from aque-
 ous vapour,  could  be generated  by  chemical action,
 which is far  more energetic upon the dry land than  in
 the ocean, from which the vapour is obtained: nor can
 it be maintained that the process by  which Avater is
 separated from the  ocean brine is  chemical; for I
 haAre shown  that it is  a  mechanical  force, which  is
 proportional  to temperature.   (See chap. iii. book i.
 and the subsequent  examination of  the tAvo  electric
 fluids.)
   From the brief history thus presented  of atmo-
 spheric electricity, it must be obvious to the intelli-
 gent reader, that  the knowledge hitherto derived from
 experimental researches, has been extremely vrague
 and imperfect, and  that its relations to the caloric of
 evaporation have scarcely been inquired into.  On the
 other hand, it is  equally evident, that  if we analyze
 the phenomena of evaporation and  condensation, as
 they are constantly going on before all eyes, we obtain
 a simple and satisfactory solution of the  problem.  The
 fact Avhich  Avas announced by Dalton,  that  caloric is
 the only cause of evaporation, taken in connection with
another fact,  that  aqueous vapour is condensed into rain
or hall, with a reipldlty proportional  to  tlve amount of 
294
OPINIONS OF LUCRETIUS.
lightning, are  decisive in regard to the convertibility
of caloric into electricity.
   The ideas of the ancient Greek philosophers, which
Avere derived  from  observation without experiments,
were more  in  accordance with nature and reason than
the hypotheses of modern times.   It was maintained
by Lucretius,  who  gives  the  doctrines of Epicurus,
that lightning consisted of fire alone, and that it was
derived  from the sun.   He represents the igneous par-
ticles  as rushing to a focus, by which concentration
they acquire the power  of instantaneously fusing me-
tals *  (De  Naturd Rerum, lib. vi. 108.)   That this
subtile  agent  is greatly concentrated  on quitting a
mass of vapour in the form of lightning, is proved by
the fact, that  a single spark or flash, causes a precipi-
tation of rain  over  several thousand acres; and that
it is a material agent, is demonstrated by its mechan-
ical force in rending rocks, buildings, ships, trees, &c.

  * He further states, that it is by the meeting  of warm and cold
air that they are elicited.   It is not very obvious how this subtile
matter becomes concentrated  into a ball of fire on quitting a mass
of vapour; but such is  the fact.  It is equally difficult to explain
how the electricity of a Leyden  battery is condensed on presenting
a metallic knob.  Perhaps it is owing to all its particles being
attracted  to the centre of the knob; or that the igneous matter of
vapour is  attracted to the centre of whatever object excites it.  It
is worthy of notice,  that when a metallic  point is presented to the
knob of a Leyden bottle charged with electricity, the igneous fluid
is drawn off gradually, and no visible spark is produced: but when
a larger mass of matter  is presented, as a  knob of brass, or the
knuckle, it is all withdrawn at once.   Thus mountains,  clouds,
buildings, &c. attract a large portion of  the electric  fluid at the
same moment, producing a concentrated spark many hundred thou-
sand times larger than one from a Leyden jar. 
         ELECTRIC SPARK OBTAINED FROM STEAM.     295

 as  effectually as if it were a ball of iron discharged
 from a cannon.
   Lord  Bacon supposed that the greatest heat in na-
 ture  was that  of  lightning, from  its instantaneous
 power of fusing metals, and of igniting other combus-
 tibles. As an additional proof that it is a concentrated
 exhibition of the igneous principle, it may be observed,
 that when solar caloric  is  greatly concentrated by a
 large burning-glass, it fuses, ignites and volatilizes the
 hardest  gems in a few moments, thus approximating
 the character of lightning.  But since  the time of
 Bacon, philosophers have discovered  that  electricity
 can produce  all the above effects without being a ma-
 terial fluid; others, that it proceeds from the earth to
 the clouds, and not from  atmospheric vapour to the
 earth; Avhile others again resolve all its mechanical
 and heating  properties into undulations of  the  "un-
 known ether."
   If  any additional evidence were  required to esta-
 blish the proposition that the caloric of aqueous vapour
 is convertible into electricity, it is afforded  by the re-
 cent discovery that the electric spark may be obtained
 from steam as it issues from  the boiler of what is called
 the hydro-electric machine.   This discovery was made
 in 1840,  by a man who was intrusted with the care of
 a steam engine at Seghill, near Newcastle, in  England.
 Having accidentally immersed one of his hands in the
 steam that issued from a crack in the cement by which
 the safety-valve was secured to the boiler, while the
 other was applied to  the lever of the valve for the
purpose of adjusting the weight, he  was surprised by
the appearance of a brilliant spark betAveen  the lever 
296
EXPERIMENTS OF FARADAY.
and his hand, accompanied by a violent Avrench in hi*
arms.  The man further observed that the same effect
Avas produced whenever he attempted to touch any
part of the boiler or iron-work connected Avith it, pro-
vided  one hand \vas exposed to the steam; and  that
he  also communicated a shock to every person whom
he  touched with the other.
  These facts led  Mr. H. G. Armstrong to the  con-
struction of what he calls the hydro-electric machine.
It consists of a cylindrical boiler,  (insulated by glass
legs,) to which a number of metallic tubes are  con-
nected, for the purpose of conveying off a large quan-
tity of steam, which is made to issue from a single
opening.   When the steam was let into the tubes,
sparks about fifteen inches long were observed to pass
between the opening from which  it issued and the
prime conductor, affording a miniature display of light-
ning and  thunder.   In a paper on  the subject, which
has been  greatly overrated, the  celebrated Faraday
maintains  that  the electricity is   not developed by
evaporation, nor by the condensation of steam, but is
wholly the result of friction; that steam is merely the
mechanical agent by which the particles of water are
made to rub against the sides of the tubes; and  that
the phenomena  are in  no way connected Avith atmo-
spheric electricity.   (Exper. Researches, ser. xviii. pp.
20,  21.)
  Yet Mr. Faraday relates in this  very paper experi-
ments which demonstrate in the most decisive manner,
that electricity is developed during the  condensation
of steam,  in  the same way that lightning is evolved
from atmospheric vapour, during its condensation into 
EXPERIMENTS OF PELTIER.
297
 rain, on meeting with a wave  of cold  air.  For he
 found that whenever the  tubes through which  the
 steam issued from the boiler were made hot before the
 steam Avas let  on, no electrical phenomena aa ere pro-
 duced; but that if while the steam ivas issuing, the pipes
 were cooled by a jet of water, electricity teas evolved.
 Like Armstrong, he also found that the  electricity
 thus obtained  was ahvays  positive, while the sparks
 obtained from the boiler were negative.   Will it be
 credited, that after all these results, Faraday attributes
 the electricity  of steam to friction, and not to the con-
 densation of steam?  and that his opinion is adopted
 by all professed electricians in England ?
   M. Peltier also found  by experiment, that the elec-
 tricity is evolved neither before nor after the steam is
 projected, but only at the instant of its condensation into
 aqueous vapour; in  other words, that  so  long  as the
 steam remained in the elastic  state,  there were no
 signs of electricity;  but that whenever  it was con-
 densed into watery vapour, there was a disengagement
 of the electric  fluid.  He further ascertained that the
 quantity and intensity of the electricity evohed Avere
 in proportion to the temperature and elasticity of the
 steam.  He adds, that with a small  Papin's digester,
 the amount of electricity obtained was in proportion
 to the quantity of  steam  that  escaped, its  tension
 remaining  the  same.  M. Peltier also  found, that by
 elevating an electrometer, terminated  by  a polished
 copper ball, under the column of vapour given off by
 the boiler of a locomotive engine,  electrical phenomena
Avere produced; being more considerable in proportion
to the velocity of the engine, and the rapidity with 
298           EXPERIMENTS OF PELTIER.

which the steam was condensed. (Electrical Magazine,
Oct. 1844, pp. 450-7.)   The  most notable  fact con-
nected Avith this part of the subject is, that M. Peltier
was not led by his own beautiful experiments to the
simple  and natural  conclusion, that  the caloric ivhlch
converts icater into vapour or steam, is given out In the
form of electricity during the process of condensation. 
CHAPTER II.
               THEORY OF WINDS.

  Of all the subdivisions of general philosophy, there is none so
little entitled to the name of science as meteorology. — Mason
Good.

   That the  reader may comprehend  more  fully the
connection between  caloric, evaporation and atmo-
spheric electricity, it becomes necessary to present a
cursory view of atmospheric currents generally.
   The  unequal distribution of solar caloric over the
earth's  surface, together with its  annual and diurnal
reATolutions, determine the periodical movements of the
atmosphere which surrounds it.
   It has been long known, that there  are three great
currents of the aerial ocean, by which it is kept in a
state of perpetual circulation: one from the  polar re-
gions toAvard the equator, which is an  under current;
another  from the equator to the  poles,  which is an
upper current; and a third,  called the great tropical
current, or trade-wind, which blows  from east to west
around  the globe for about 30° on  each side of the
equator; thus sweeping over a breadth of 3000 miles.
  There is another general wind, Avhich blows from
Avest to east in the middle and higher latitudes, about
tAAro-thirds  of the  year  in the northern  hemisphere;
                                         (299) 
300
THEORY of winds.
Avhile in the middle latitudes of the southern hemi-
sphere, where there is little or no land, it is said to be
nearly as uniform as the trade-wind.  Dr. Hadley, and
after him Dr. Franklin, attributed these general cur-
rents to the folloAving causes.  " The air between the
tropics,  being constantly  heated  and rarefied by the
vertical  sun, rises,  Avhen  its place is supplied by air
from the higher and polar latitudes,  which, coming
from parts that had less diurnal motion, and not sud-
denly acquiring the swifter motion  of the equatorial
regions, becomes  an east wind; the earth moving from
west to  east, and  slipping under the air." (See Frank-
lins Works, vol. iii.  p. 236.)
  These general  vieAvs have been greatly extended by
Dr. Dalton and Mr. Daniell.   The first of these philo-
sophers  observes, that the diurnal motion of the earth
at the equator is  1040 miles per hour, and diminishes
gradually on to the poles,  where it is nothing.  (Meteor-
ological  Essays, page 88.)    And  Mr. Daniell has de-
monstrated in the most conclusive manner, that from
the greater density of the polar  atmosphere than the
equatorial, its height  is proportionably less;  so that
the expanded  air between the tropics must  rise and
flow toward the  poles as  an upper  current.   Before
rising, it has acquired the tropical motion of the earth
from Avest  to east,  Avhich  it retains, until descending
in higher latitudes, where the earth's diurnal motion
is less, it mixes with the lower air, and  gives it a Avest-
erly direction.
  The force and  direction of the trade-winds are in-
fluenced by the proximity of islands and continents.
Along the Avestern side of Africa,  their direction is 
THEORY OF WINDS.
301
reversed.  To the distance seaAvard of about 300 miles,
they blow toward the heated land: they are reversed
in a similar manner in the Pacific,  west  of South
America.  When the sun  is in the northern tropic,
they extend several degrees farther north than during
our Avinter;  and Avhen the sun is south of the equator,
they prevail farther south.
   There is,  near the equator, in the Atlantic and Pa-
cific oceans, a belt  that separates the  trade-winds,
where the great  polar  currents from  the north and
south meet  and neutralize each other,  and the regular
course of which is arrested by a tendency of the  atmo-
sphere to floAv toward the heated coasts of Africa and
South America.  The  regions within this tract are
characterized  by a  constant succession  of  irregular
winds and  calms, Avith storms  of thunder, lightning
and rain: they are termed by seamen the swamps or
horse  latitudes, and  are extremely sultry,  OAving to
the motionless  state of the atmosphere, caused  by
opposite forces that neutralize each other.
   During Avinter, in the  northern hemisphere, the
polar latitudes being  deprived of the sun's rays, while
the tropical parallels are heated, we have a predomi-
nance of northerly Avinds, the dense polar air pressing
toward the  tropics, to restore the  equilibrium; Avhile
the greater velocity  of the  middle and  tropical than
 of the northern latitudes,  causes  a deflection  of the
 polar  currents  to the  soutlnvest  and west, making
 northeast  and  east  Avinds, which almost uniformly
 succeed to  north winds, and continue blowing until
 an equilibrium is established between the higher and
 middle latitudes.  In the mean time,  under the influ- 
302
THEORY OF WINDS.
ence of the solar beams, the land soon becomes more
heated than the ocean, even south of it, Avhich causes
a south Avind until the equilibrium is restored betAveen
the sea and land atmosphere.
  During summer, in the United States, southwestern
Avinds  predominate, and  northern winds during Avin-
ter.   The  same thing is true of India, China and
Arabia.  They are heated during summer, and the
atmosphere  over  them is rarefied, which causes the
air to flow in upon them from the tropical seas, Avhen
it is deflected to the  east, by passing  from latitudes
that move rapidly, to those which move more sloAvly.
This is what seamen term the southwest monsoon.
  When the sun is south of the equator, the air moves
from the northern land, which is cooled down, toward
the equator, that has a swifter motion, thus causing
the northeast monsoon, which corresponds with the
northeast wind of the North American cold season.
It was supposed by Volney that the prevailing south-
west Avind of the Mississippi valley was a recoil of the
tropical trade-Avind, deflected by the Andes of Mexico;
but the  fact which  he states, of its crossing the Al-
leghany  Mountains, and advancing northeastward, as
far as Montreal and Quebec, is sufficient to prove that
it must  be owing to  a cause far more extensive and
general in its operation than mountain ranges.
  During summer in North  America, the land is
greatly heated, and the air presses from the Atlantic
ocean, especially during the day, causing a sea breeze;
when  from  the south, it is  changed into a southwest
wind,  by passing  from latitudes  that  revolve at the
rate of eight or nine hundred miles per hour, to those 
THEORY OF WINDS.
303
which move only six or seven hundred miles per hour.*
The southwest and northeast are the prevalent winds
in the  United  States and  the  west of Europe.   In
Great Britain they blow about 300 days in  the year.
  It has been observed in the United  States of Ame-
rica, that regular winds generally follow the sun, ex-
hibiting a tolerably uniform succession of circuits from
left to right, and  blowing from all points of the com-
pass within a few days.  For example, the ordinary
succession of Avinds  is, first,  from  the north; next,
from the northeast,  then from the east;  southeast;
south;  southwest;  west;  northwest, and so on,  in
pretty regular succession, and rarely, if ever, perform-
ing  an entire circuit in  the opposite  direction.   As
the greater portion of the United States is more heated
by the sun than  the ocean, even south of them, (be-
cause the surface  is stationary,)  and for a longer time,
the wind blows from the southAvest a greater  number
of  days than from any other quarter.  At the same
time, it is  worthy of notice,  that during extremely
cold  winters, the  wind has  continued from a month to
six weeks from the northern points of the  compass.f

   * It is the meeting of this wind, charged with aqueous vapour
from  the ocean, with the colder northerly currents, which causes
vast precipitations of rain in the United States, during the latter
part of summer and  beginning of autumn, attended  with the most
fearful displays of thunder and lightning, when extensive hurricanes
prevail in the West  Indies, the Gulf of Mexico and the southern
 portions of the Union.
   f According to observations made at sixteen different military
 posts in the United States, from lat. 35° to the northern extremity
 of the Republic,  including those  of  Sir  Edward Parry, in  the
 polar regions, winds prevail from the southwest, west and north- 
304
THEORY OF  WINDS.
   In  addition  to the above  winds, opposite currents
frequently meet in the  higher atmosphere, which are
not observed at the eartlis surface, and thus cause preci-
pitations of rain.   A striking proof of this Avas wit-
nessed on the 4th of July, 1834, at New York.  When
Robertson, the  aeronaut, ascended in  a balloon from
Castle Garden, the wind Avas from the east, Avhich car-
ried him westward across  the Hudson river.   At an
elevation of about 4000  feet above the earth  he dis-

west, nearly two-thirds of the year; or in  the  ratio of 15,830 to
8785, while the northerly winds are to  the southerly as 1190 to
1231.  In the  southern portion of  the Union  below 35°, eastern
winds predominate over western in the ratio  of 3102 to  1717;
from which it would seem that they are  subject to the general in-
fluence that governs the  regular trade-winds of the tropics.  In
the same section of country, northern winds are to southern in the
ratio of 508 to 721.
  As Cincinnati, lat. 39° 06', affords a tolerable  specimen of the
Ohio valley generally, it may be stated that western winds prevail
over  eastern in the ratio of 631 to 325;  while  at New York, lat.
41°, they are as 580 to 279.   They are also nearly in the same
proportions throughout the Atlantic Ocean, between North Ame-
rica  and  western Europe.  (See Darby''s  View of  the United
States.)
  Mr. Daniell states, that upon an average of ten years,  westerly
winds exceed easterly in the ratio of 225 to 140 in Great  Britain;
while northerly winds  are to southerly,  as 192 to 173.)  Meteor-
ological Essays, p. 114.)  During  spring, the prevalent wind is
from the  dry, cold, northeastern regions of Russia, Sweden and
Denmark.   Throughout the Mediterranean, Egypt, Palestine and
the south of Europe generally, the wind blows  nine months in the
year  from the northern points of the compass; because situated
between the cold  regions of Arctic Europe  and Asia  and the
burning plains of Africa,  where  the temperature is from 100° to
113° F. in the shade, and upwards of 120° in the great deserts. 
THEORY OF WINDS.
305
 appeared  in  a mist or  cloud, when he  met with a
 counter-current from the west, that brought him back
 over  the  city, and landed him  ten  miles to the east-
 Avard of Long Island.  It is  quite  evident  that the
 canopy of clouds, which overspread the city and coun-
 try in  the afternoon, was  condensed by  the colder
 upper current from the west.
   From the  7th until the  10th of  July, (1834,) the
 heat Avas excessive, ranging from 86° to 96° F. in the
 shade, while  the wind was from the southeast.  On
 the 10th, about noon, the  wind prevailed from the
 Avest, condensing the vapour  of the heated air into
 floods  of  rain, attended  with  violent thunder  and
 lightning.  It is thus that a land-wind, which usually
 brings fair weather, causes precipitation, by meeting
 Avith a southerly wind charged with  aqueous vapour.
 It is highly probable, that at  all times when rain at-
 tends a southerly wind,  and when  the land temper-
 ature exceeds that of the sea, precipitation  is owing
 to the prevalence of a colder  upper  current  from  an
 opposite direction.
   What can  be  more impressive and sublime than
 those great movements of the atmosphere, by which
 the waters of the ocean  are  Avafted over continents
 and islands;  pestilential  vapours dispersed;  the face
 of nature  refreshed and adorned with living robes of
 surpassing beauty?  In his usual metaphorical style,
 Lord  Bacon  speaks of winds  as the wings  of com-
 merce.  They are also the  great natural ventilators
 of the earth by which  the dry land is furnished with
pure air from the ocean, whose waters absorb the car-
                        20 
306
THEORY OF WINDS.
bonic acid contained in it.   Were it not for this con-
stant interchange of air  between  the  tropical and
higher  latitudes, the earth Avould be scorched by in-
supportable heat during summer, and blasted by the
rigours of deadly cold in  winter.  But in the present
order of  things,  such hurtful extremes are  prevented
by a never-ceasing circulation of the atmosphere from
one zone to another.*
   If the  whole earth  were of uniform surface and
elevation, its temperature would be the same in given
latitudes  and seasons, and  the currents of  the atmo-
sphere  would  present  a succession  of regular  move-
ments.    There  would be  no sudden  mixing of winds

  * By the agency  of warm southerly winds immense  masses of
aqueous vapour are  transported  from the ocean over  North Ame-
rica  to the higher  latitudes, where,  meeting with a body of air
from the frozen regions, it is condensed into cold rains or extensive
falls  of snow, according  to  the  season of  the year;  while the
northern atmosphere is  thus warmed  by the disengagement  of
caloric from southern vapour.
  If southerly winds prevail for a long time from the ocean during
autumn, until the atmosphere  is saturated with vapour over a large
portion of  the northern hemisphere, without  meeting with a mass
of northerly air to  condense it, the  commencement  of winter is
marked by an extensive  fall of snow,  from a foot  to  eighteen
inches, or even three feet in  depth,—over which the polar winds
pass without being  warmed, to the lower  latitudes, causing exces-
sive winters.  This  is one reason why during some winters in the
United States, the  temperature occasionally falls from 30° to 40°
lower than during others.  After such a fall of snow the wind has
prevailed for six weeks together, from the northern points of the
compass, as in the winter,of  1779 and 1780, and about the same
length of time during the winter of 1834 and 1835, when the mer-
cury fell from —20° to —40°, in latitude 35° to 43°.  I shall have
more to say on this  subject in another place. 
             THEORY OF HURRICANES, ETC.         307

from opposite quarters, and no  lightning nor  rapid
precipitations of rain, because there would be a regular
gradation  of temperature and density of the  atmo-
sphere from the equator to the poles.   But, as the sur-
face  of the  earth  is diversified  by  land and water,
mountains and valleys, hills and plains, unequal tem-
peratures  in the  same latitudes  and seasons result,
causing all  those irregular  movements in  the  atmo-
sphere termed variable winds;  and which  can  never
be predicted with  unerring certainty until all these
modifying circumstances are classified and reduced to
general laws.

THEORY OF HURRICANES, HAIL-STORMS, WATER-SPOUTS AND
                     TORNADOS.

   Having shown in the preceding chapter,  that light-
ning is always attended with the precipitation of atmo-
spheric vapour, I  proceed  to prove  that  no violent
squall, hurricane, tornado or  water-spout, ever occurs,
loltJiout the sudden  condensation  of aqueous  vapour, by
which a vacuum is formed, causing a rush of air from
different quarters.
   The typhon of the  Greek philosophers was a hur-
ricane, accompanied with vivid  flashes of  lightning,
which they called fire; while  the tornado  was de-
scribed by the Romans as vortex igne factus, meaning
a whirlwind made by fire.   It is evident on  the slight-
est reflection, that violent winds which spring up sud-
denly, and  often  immediately  after  a calm, cannot
possibly be owing  directly  to the rarefying influence
of solar heat, like regular winds, the velocity of which 
308           THEORY OF HURRICANES, ETC.

rarely exceeds twenty or  thirty  miles  per hour;*
whereas the  tornado moves at the rate of from one
hundred to one hundred and twenty  miles per  hour.
It is during the rainy season, that the tropical regions
are visited by those  dreadful hurricanes or fiery tem-
pests which tear up trees by tlieir roots, destroying
everything  in their  resistless course,  and  Avhen rain
is precipitated in floods with a rapidity proportional
to the amount of lightning.   Those of the East Indian
seas occur during the shifting of the monsoons, and
are obviously owing to the condensation of vapour,
caused by the meeting of extensive masses of air from
opposite quarters, of  different  temperatures.   The
equinoctial  storms that sweep over the West Indies,
the Gulf of Mexico and the southern portions of the
United  States, are also produced in  the same  way,
and are attended by extraordinary floods of rain, with
fearful  displays of thunder  and lightning.   An eye-
witness of the tremendous hurricane which desolated
the island of  Barbadoes on the 10th of August, 1831,
informed  the author, that it began about ten o'clock
at night, with torrents of rain  and  broad sheets of
fire in  rapid succession,  which threatened  to  over-

        *----We often see against some storm
        A silence in the heavens, the rack stand still,
        The bold winds speechless, and the orb below
        As hush as death: anon the dreadful thunder
        Doth rend the region.—Hamlet.
  The calm is owing to the meeting of large  masses of air from
opposite quarters, and thus tending to neutralize their movement,
until condensation is produced,  when the stillness is succeeded by
the roaring tempest. 
THEORY OF HURRICANES, ETC.         309
Avhelm the inhabitants in a flood, or sweep them away
in a tempest of flame.   This storm  swept over St.
Lucia,  St. Domingo, Cuba, the whole of the Mexican
Gulf, Louisiana and most of the southern States.  A
similar storm occurred on the 12th of August, 1830,
at St.  Thomas, and  extended  along the  southern
shores  of the United States  over a tract 500 miles
in width.
   On the other hand, in the tropical portions of the
Avide Pacific, where the temperature  is uniform, and
the winds blow steadily in the same direction, there
is but  little  thunder,  lightning  and rain,  and  no hur-
ricanes.   The same is true of the equatorial parts of
the Atlantic, which are far from land.  It is stated by
Capper, in his account of  winds and monsoons, that a
hurricane Avas  never  known to occur at St. Helena,
situated  as it is, nearly midway between Africa and
South  America.  It  is near  the continents of  Asia,
Africa and America, or in the vicinity of large  islands,
Avhere  immense masses of vapour from the sea  meet
with mountains and cold masses of air from the land,
that hurricanes of wind, lightning and rain, are most
poAverful  and  frequent, as in the Bay of Bengal, on
the  coast of Madagascar, Mauritius, &c.  In short,
there never was a hurricane, tornado or gale in any
part of the  world during the  existence  of perfectly
dry Aveather.  It is therefore evident that  lightning,
and all violent  winds, are immediately connected Avith
the rapid condensation of aqueous vapour  or steam,
which  owes its existence to  the expansive agency of
solar caloric.  Even the  winter gales, so  fatal  to ship-
ping on  the coasts of Great  Britain and France, are 
310          THEORY OF HURRICANES, ETC.

always attended with copious precipitations of rain or
snow, and sometimes with lightning.
  This may be readily understood when it is remem-
bered, that all the water which falls on the earth ex-
isted previously in  the atmosphere  in  the form of
steam,  which, at the temperature of 60°, is lighter
than air  in the ratio of 622 to 1000.   This steam is
confined  chiefly to the  lower regions of the air, and
must necessarily augment its volume  in proportion to
the quantity  diffused through it;  the consequences of
which  are, that immense vacuums are produced by its
condensation and a violent rush of the surrounding air
from elifferent quarters, until an equilibrium is restored.
  Perhaps there is no part of the world where thunder-
storms are so frequent as in the Bay of Mexico and on
the borders of the Gulf Stream.  It has been said, that
of all the vessels in the world, which are annually de-
stroyed by lightning, tAvo-thirds have been lost on the
track of  the Gulf Stream.
  We  may readily comprehend all this when Ave re-
flect that the Gulf Stream is a  portion of the  great
equatorial current, (caused by the trade-wind,) which
is obstructed by South America and deflected into the
Bay of Mexico, where its temperature is from 70° to
80°, according  to the season.  With its tropical tem-
perature it issues from the Bay of Mexico through the
Florida Channel,  advancing along the southern  coast
of the United States northeastward to the Banks of
Newfoundland, and thence  to the western coast of Ire-
land, until it is lost.  For the distance of 1500 or 2000
miles its temperature is from 10° to 20° higher than
that of the ocean on its northern extremity; the con- 
THEORY  OF  HURRICANES, ETC.          311
sequence of which is extensive evaporation.   The va-
pour thus formed is  perpetually meeting with bodies
of cold air, by which it is condensed, causing a succes-
sion of vacuums, local storms, water-spouts, &c*  We
are informed  by seamen, who navigate the Atlantic
between the United States and England, that while
one vessel encounters  a thunder-storm, others enjoy
mild  breezes within  thirty or forty miles of the same
place.
   The  same general agency, modified by the relative
position of land  and water,  oceanic currents, moun-
tains and valleys, operates to a greater  or less extent
over  all the earth. Off Cape Hatteras, which is washed
by the  Gulf Stream, there is a constant succession of
gales, Avhich are obviously caused by the mingling of
Avarm and cold air,  as seamen always observe a sensi-
ble change of  temperature on passing the Cape.  The
 same cause renders  the Cape of Good Hope a theatre
 of perpetual Avar of conflicting tempests, occasioned by
 the difference of  temperature between the great equa-
 torial current, as it doubles the Cape, and  the colder
 Avater of the Southern Ocean.
    The  streaked  and  forked appearance of ordinary

   * As  many as sixteen water-spouts were seen  at the same time
 by Captain Lawrence on the borders of the Gulf Stream, in lat.
 32° 48', when off Charleston, on a voyage from New Orleans to
 New York in 1834.  They are all formed by the sudden condensa-
 tion of aqueous vapour, caused by the meeting of opposite currents
 of air that deflect  each other, producing a funnel-shaped cloud,
 that descends in torrents of fresh, and not salt  water, as has been
 generally supposed.  In short, they are what Franklin termed them,
 whirlwinds at sea. 
312          MISCELLANEOUS  PHENOMENA.

lightning are optical illusions, which result from the
rapid passage  of the electric spark  through  the air,
which makes  an impression on  the optic  nciwe that
remains during  its passage,  in  the same Avay that  a
burning stick, when involved, presents the  appearance
of a continuous circle of fire.  The fork is OAving to a
division of the original spark or ball into two  or more
sparks, which  diverge from  each other.   The zigzag
appearance is  owing  to frequent  slight deflections of
the  spark, as  it moves through strata of air of dif-
ferent densities.  Whenever an electric explosion takes
place near to the spectator, it always presents the ap-
pearance of a ball of fire, attended by a simultaneous
report, like that of artillery.   The reason that the re-
port is usually heard  many seconds after the  flash is
seen, is owing  to its  distance from the point of obser-
vation and to  the  sloAvness with which vibrations are
propagated through  the  atmosphere; Avhile its rum-
bling or prolonged existence is owing to  the space
over which it passes.*  The  report itself is probably
caused  by a  sudden  collapse of the air as it  fills the
vacuum produced  by the passage of the electric bolt
through it; and by its violent collision against the air,
causing a tremour of the atmosphere to the distance
of many miles, which is  communicated to buildings
  * For example, sound travels through the air at the rate of 1130
feet per second; so that 60 seconds, or one minute, must elapse be-
fore it can be heard at the distance of 12*84 miles, becoming fainter
as the more distant vibrations  reach the ear.  And we may easily
ascertain the distance of the flash by looking at the second-hand of
a watch, until the report is heard. 
SUMMER GUSTS.
313
and  other solid bodies.*  It is likewise probable that
the luminosity of the spark is owing to a sudden com-
bustion of air or vapour by so intense a heat.
  It was first observed by Dr. Franklin, that the cold
summer gusts of the middle latitudes generally come
from the  west;  from which he concluded that  they
were caused  by a descent of cold air from the upper
current of the atmosphere, on  its passage from the
equatorial to the polar latitudes.
  That this is the  true mode of accounting for many
of our thunder-storms, would appear reasonable  from
the folloAving considerations.   They occur during the
most sultry weather and hottest time of the day, gene-
rally the  afternoon, when the  lower atmosphere is
greatly rarefied, so  as to favour a descent of cold air
from above, which  rapidly condenses the  transparent
vapour of the krwer  atmosphere into floods of  rain,
that are often attended with hail, and always with a
great reduction  of temperature.  In this way clouds
are often  formed suddenly, the whole sky becoming
obscured  by dense black clouds, accompanied  with
thunder and lightning, violent winds and  copious pre-
cipitations of rain.   During such storms, more vapour
is condensed into rain in twenty or thirt}r minutes,
than usually falls during a whole day, or even a week

  * This was proved by Beccaria, who constructed a glass siphon,
in one leg of which air was inclosed above a column of mercury,
and compressed by the column in the other leg of the siphon. On
discharging  a Leyden jar through the air thus inclosed, the column
of mercury in the other leg was suddenly elevated, and recovered
its position  after several oscillations.  (Electric. Artific, Turin,
1753, p. 227.) 
314
HAIL-STORMS.
when there is no lightning.  All the phenomena par-
take of the violence which characterizes discharges of
the electric fluid when greatly accumulated.
  Lord Bacon observes, in  his Natural  History of
Winds, that  "tornados are  caused by the sudden
breaking of clouds," by which he meant those rapid
precipitations of rain that accompany lightning  and
thunder.  And we often hear from seamen that a vio-
lent hurricane issued out of a dense  cloud.   Bacon ob-
serves again, that "when it lightens  in a clear  sky,
Avinds and rain are at hand from the quarter where it
lightens:  but if it lightens in different quarters, there
will follow  cruel and  horrid tempests."   He might
have added,  that  they have already begun in  the
places Avhere  the lightning is seen.


                    HAIL-STORMS.

   On the subject of hail-storms, Avhich are intimately
related to whirlwinds, water-spouts, &c. much learning
and ingenuity have been  expended since the days of
Franklin, without any satisfactory explanation of their
cause.
   The celebrated Volta supposed that they were pro-
duced by " an highly electrical condition of the atmo-
sphere ; that the frozen masses were kept in a state of
reciprocating motion  between  two clouds,  oppositely
charged with  electricity, until  the  mass rendered the
force of gravity predominant; or until the electric ten-
 sion of the cloud was exhausted by mutual reaction.
 In his report on the present state of meteorology, Pro- 
HAIL-STORMS.
315
fessor Forbes observes, that no better solution has yet
been offered to the world.  (Transactions of the British
Association, vol. i. 1832.)
  The leading facts connected  with hail-storms are
the folloAving:—
  1. They are generally confined  to  the  middle lati-
tudes, Avhere masses of cold air from the polar regions
meet with warmer  air  from the  tropical latitudes,
loaded with  aqueous vapour.   When such currents
encounter each other at the usual height of spring and
summer  clouds, the  vapour  of  the warm air is con-
densed into cold rains, or showers of small hail, but
Avithout  much lightning or violent Avind; whereas all
the most destructive hail-storms are accompanied with
tremendous flashes of lightning,  and often with fearful
A\birlwinds, or tornados.
  2. They occur chiefly during  warm Aveather in the
United States, when the lower  atmosphere  is full of
vapour, and  heated  to the  temperature  of 80°, and
sometimes 90° F.
  3. They usually run in veins of limited extent, and
are most frequent in level districts, especially such as
are  hemmed  in  by mountains, as  in the  south  of
France, Avhere they are very destructive to the  crops.
  4. They are often attended  with  the  sudden pre-
cipitation of immense quantities of ice, which descend
in large  globular masses, and always Avith a great re-
duction of temperature.
  Several of the above facts are exceedingly difficult
to explain, without admitting the hypothesis of Frank-
lin  in regard to the cause of thunder-gusts;  that is, a
sudden descent of cold air from the upper regions, by 
316
HAIL-STORMS.
which the vapour of the loAver atmosphere is rapidly
condensed and congealed into globules of ice.
  In opposition to this view of the subject, it is main-
tained by Dr. Thomson, that the upper air cannot de-
scend Avithout undergoing condensation and giving out
a portion of its latent caloric, which he thinks would
prevent it from  cooling the  atmosphere.  (Treatise on
Heat and Electricity, p. 129.)  Whatever may be the
just weight of this objection, the fact  is certain, that
aqueous vapour is suddenly and rapidly congealed by
very cold air; by which the temperature of the lower
atmosphere  is often  reduced from 80° or 90° down to
32°, or even less, within a few minutes, during exten-
sive and violent hail-storms.
  It is also certain, that a vacuum must be formed in
the lower atmosphere proportional to the volume of
vapour thus suddenly condensed;  the extent of Avhich
may be estimated from the vast quantities of hail that
are occasionally precipitated in a few minutes, amount-
ing to a depth  of nine  inches in as many minutes,
according to M. Pouillet.  The formation  of such a
Aracuum is always attended by a rush of air from oppo-
site quarters, creating a gyratory or whirling  motion,
the force of which is in proportion to the extent of the
vacuum  and the rapidity of its formation.
  That  the  reader  may perceive the more  readily
how intimate is the connection  between  lightning,
the  condensation of vapour, hail-storms  and whirl-
winds, it may be proper  to present a brief  account of
a few thunder-storms which have occurred in  Great
Britain:
  On  the 10th of August, 1835, Durham Avas visited 
LIGHTNING, RAIN AND HAIL.          317
by a violent whirlwind, accompanied with  incessant
lightning and thunder.   At seven o'clock p.m., a most
vivid flash  of lightning struck  the cathedral,  and
hurled down an  immense mass of stone  that killed
tAvo of a party of students, who at the moment fled
from the interior of the cathedral.
  "On the same day Chesterfield was visited by a vio-
lent  storm of thunder, lightning,  rain and hail.  A
large ball of fire fell in the Commercial  Inn yard,
where there  Avas an accumulation of water, splashing
it in  all directions into spray,  which  for a moment
seemed to be enveloped in flames.
  "Many such storms occurred about the same time
in different parts of England, Scotland and Ireland.
On the 10th  of June, about three o'clock, there was a
storm of lightning, thunder and hail, at Dumfries,—
and at Ardach on the following day, there was a vio-
lent thunder-storm, Avhere the drifted hail was two feet
in depth in some places, and remained on the ground
for tAventy-four hours.
  "At Sheffield, during a thunder-storm, the  electric
fluid entered the works of Mr. Ellin, and struck a pile
of ivory-handled  knives, the blades of  which were
fused into one mass, and the hafts split off in a singu-
lar manner.  Twelve individuals were thrown down;
they supposed that the boiler of a steam engine in the
room had bursted.*

  *  It is related in  some of the  older books on natural philoso-
phy, that Erfurt, a small  city of Germany, was struck  by light-
ning during a storm, in forty-two different  places.  Seven persons
were  killed, and three houses  set on fire, which were quenched by
the rain, that fell in torrents. 
318
TORNADOS OF THE  UNITED  STATES.
  "On the 6th of June, forty-two head of cattle Avere
killed by lightning in one field, at JohnstoAvn, near
Tuller.   Some had their heads and horns burnt, and
some their shoulders.   On the lands of Mr. Lynham,
at the Hill of Talloght, eighteen cattle, twenty-three
sheep and a goat, were also killed by lightning." (Bells
Weekly Messenger, June 14,1835.)

          TORNADOS OF THE UNITED STATES.

  It was observed by Lord Bacon, that "all tornados
or great whirlwinds  have a manifest precipitous mo-
tion, or darting downward more than other Avinds, so
that they seem to fall like torrents, and run as it Avere
in channels."
  Such  tornados are  remarkably  frequent  in the
United  States during hot  sultry  weather, and are
attended with the most striking displays of electrical
phenomena:  always with rapid  condensations of va-
pour, and often with enormous quantities of hail.  They
generally run in narrow veins from 100 yards to half
a mile wide;  while the equinoctial hurricanes of the
Southern States, like those of the tropics, sweep over
a vast extent  of surface, and are rarely if ever accom-
panied with hail.   The tornado is sometimes attended
by a rapid succession of  lightning;  at other times it
presents the appearance of an inverted fiery pyramid,

  On the 15th of August, 1836, twenty-eight houses were set on
fire by lightning  in the town of Grundelbruch; while at Villexon,
nineteen dwellings were consumed about the same time, during a
thunder-storm, attended with hail and a tornado.  (Galignani's
Messenger.) ■ 
TORNADOS OF THE UNITED  STATES.
319
from which is heard a continuous roll or deep roar of
thunder, like that of a heavy unremitted cannonade,
the sound of Avhich is greatly modified and obscured
by the noise of the raging Avind, crashing of buildings,
falling timber, &c.
  The whirlwind which destroyed a large portion of
NeAv Brunswick, in the State of New Jersey, on the
19th of June, 1835, presented many of the above phe-
nomena.   Those who Avitnessed its commencement,
observed the formation of several inverted  cones of
dense black  Arapour, Avhich descended from the upper
regions.   Dr. Lewis Beck describes one of these "as
resembling in  appearance the  eruption  of a volcano,
Avhich produced the impression, at  a  distance, that
some large building had been set on fire by lightning,
a vivid flash or two of which had preceded the forma-
tion of  the  cones.  But in a few minutes the dense
column Avas dissipated, Avhen another black and well-
defined  cone was formed, which remained stationary
for a short time, and then gave place to the eruptory
appearance and gyratory movement that characterized
the other.  The first occurred about three miles west
of New  BrunsAvick.  But when the second movement
commenced,  a dense black  cloud  overshadowed  the
city.  Slight, but distinct explosions were heard from
the column  in  rapid succession, like the bluffing of
sails. Volumes  of  smoke and flame were thought to
be issuing forth, and rolling over in various directions,
Avhen the idea  of an extensive and rapid conflagration
Avas suggested.   The alarm bells were rung, and  the
firemen repaired to their engines.   But while all eyes
Avere directed to the black and  dreadful column that 
320
TORNADOS OF THE UNITED STATES.
Avas approaching, no one could fix upon the exact spot
to which efforts should be directed.  This uncertainty
Avas soon removed by the  desolating  progress of the
whirlwind through the city, prostrating houses, and
Avafting heavy beams of timber to a  great distance."
Like most tornados, it was  attended with hail, as well
as rain.   The width of its  tract varied from  100 feet
to 200  yards, in the neighbourhood  of  New Bruns-
Avick; while  three miles eastward it  was half a mile
wide.   A writer in the New York Times states, that
on the banks of the Baritan, for 1000 yards, vegeta-
tion was  scathed,  as  if a  flame  had passed quickly
over it.
   Similar storms  desolated different  portions of the
Union about the same time.   "Late  in June, Lynch-
burg,  in Virginia, was visited  by a tremendous whirl-
Avind  and tempest of hail, which was preceded for
several minutes by a monotonous rumbling sound, re-
sembling  the bass  tones of distant thunder or the deep
roll of the muffled drum; and reminding us of the
ominous notes which precede an earthquake." (Lynch-
burg  Virginian.)  Dense black clouds are described
as pouring forth immense  masses of ice, and so dark-
ening the air, that houses within a  few paces were
totally invisible.
   During the summer of 1834, which was unusually
sultry,  tornados and  hail-storms of  limited extent,
visited  almost every State  in the Union, from Maine
to Louisiana;  several of  them  attended with great
loss of lives  and property.  In most cases, they pur-
sued a course from west to east.
   About the 20th of March, 1832, a tornado occurred 
A TORNADO WITH  SNOW.
321
in the southern  portion  of Tennessee, lat. 35° N.
which differed in some respects from any of the pre-
ceding.
  After several remarkably warm days for the season,
accompanied with a southerly wind, a tornado came
on suddenly, without  the  slightest warning,  about
seven o'clock p.m.   It excited great  astonishment, as
the whole day had been Avarm, serene and clear, with
the exception of a slight haziness, up to the moment
when the crashing noise  of  falling timber announced
the approaching storm from  the northwest.   The tem-
perature Avas  immediately  reduced several degrees
below 32° F. and attended with a rapid fall of snow,
which continued  for several hours;  but the tornado
blew with violence for only  about ten minutes.  The
next morning, the wind was cold and north westerly,
and continued northerly for  tAvo days.
  This storm seems to have been owing to the preva-
lence of  a cold upper current from the north, which
met  and mingled with the  warm southerly air,  and
suddenly congealed its vapour into snow.   It had not
the local character of the summer tornado;  for it was
followed by great cold over a large extent of country.
  I shall close this imperfect history of thunder-storms
with the account of an extraordinary and sudden cold-
ness Avhich occurred in the island of Cuba, on the 24th
of May,  1809.
  Cornelius Roberts, a sugar and coffee  planter, who
resided forty years on the island, informed the author,
"that after a hurricane  had been bloAving from the
southeast  and south, from  the  22d until eleven
o'clock a.m. of the 24th,  a calm followed for an hour,
                         21 
322
GREAT COLDNESS IN CUBA.
when the wind prevailed from the northwest.  At the
same  time, the atmosphere became extremely dark,
like night, accompanied with a roaring in the air, tre-
mour of the  earth  and intense cold.  Everything
green Avas killed and  became black, as if a fire had
passed over  the country for several miles in breadth,
and about sixty miles  in length:" Avhich proves that
a mass of air may descend from above  and  refrigerate
the loAver atmosphere of  the tropical regions, as in the
middle latitudes, though such a phenomenon is ex-
tremely rare. 
CHAPTER  III.
   INFLUENCE OF TERRESTRIAL  TEMPERATURE ON THE
                    BAROMETER.

  It has been long known that the fluctuations of the
barometer are intimately connected with all the phe-
nomena of meteorology; that during winter, in the
middle and higher latitudes, its depressions are fol-
lowed by rain, snow and tempestuous Aveather; Avhile
its rising  is accompanied  Avith cold, frosty and dry
Aveather; and that during summer its falling forebodes
storms of thunder, lightning and rain, Avhich are often
attended with violent hurricanes; Avhile its rising in-
dicates clear and serene weather.  Yet the theory of
its variations has  never been  clearly reduced to the
simplicity of established principles.  Without stopping
to examine the relative merits of those who have de-
voted their attention to this  difficult and important
problem, it may be observed without injustice to any,
that Ave are chiefly indebted to the labours of  Dr. Dal-
ton for the true mode of investigating it.
  The most important facts  connected with the ba-
rometer may be reduced  to the following  proposi-
tions :—
  1.  The mean height of the mercurial  column at the
level  of the sea, is  nearly the same  over all the earth,
the average amounting to about thirty inches.
                                        (323) 
324    INFLUENCE OF TERRESTRIAL TEMPERATURE

   2.  The density or specific  gravity of the atmosphere
Increases  gradually from the eepiator to the regions of
lowest mean temperature, corresponding with the decrease
of  temperature;  the  consequence  of winch is, that the
height of  the atmosphere must  diminish from the equator
to the poles.
   3.  Within the tropics, the temperature is always nearly
the same:  the range of the barometer is also small, vary-
ing from  two lines to a quarter of an inch.
   4.  The range of temperature augments from the equa-
tor to the  regions of maximum cold:  the variation of the
barometer augments in a corresponding  ratio,—amount-
ing to about three inches in the coldest latitudes.
   The range of temperature  is  much greater in North
America  than in  the same latitudes of Europe, as will
appear  from  the following facts.   During the winter
of 1831 and 1832, the  thermometer  fell to —20° at
Florence,  in  the  State  of  Alabama,  lat. 35° N., and
—40° at  Plattsburg, lat. 44°, where it sometimes rises
to 95°,  and even  100° during summer, making its ex-
treme annual range  from 130°  to 140° F*  The diur-
  * It is, however, but seldom that the temperature falls below Q°
in the States south of Philadelphia and New York; so that the
usual annual range does not much exceed  that of England, which
is about 80°, according to Mr. Daniell; that is, from 11° to 90°.
Hence it is, that the mean range of the barometer is  about the
same in Great Britain that it is in the middle States of America, as
observed by Dr. Dalton forty years ago.  Perhaps there is no part
of the world where the fluctuations of temperature are  more  fre-
quent than in England;  the reason of which is obvious from its
insular and  geographical position, being  situated about  midway
between  the burning plains of Africa to the south, and  the frozen
regions of the north;  while on  the  east  and northeast it is in- 
ON THE BAROMETER.
325
 nal variation is  also very great, as the thermometer
 often rises to 90° in September and October, during
 the hottest part of the day, and falls below 32°  at
 night, making the daily range of temperature 60° F.
   Still  more extraordinary are  the changes from heat
 to cold in those extensive regions of North America
 beyond the limits  of the United States, which have
 been explored by Scoresby, Parry, Franklin, Ross and
 other British navigators.  We are informed by Captain
 Back, that on the 17th  of January, 1834, the ther-
 mometer was —70° F.  at six a.ai. on the Great  Slave
 Lake, lat. 62° 46';  but rose to 45° in the afternoon of
 the same day,—making a diurnal range of 115°.  He
 also states, that on  the  preceding day the temperature
 rose to  52°; while  the long summer days were often
 oppressively warm.   Hence it is, that as we approach
 the polar regions,  Ave  find the winds irregular and
 variable, coinciding with  the frequent changes in the
 density of the atmosphere and consequent fluctuations
 of the barometer.
   5. Corresponding with  the foregoing facts, the baro-
 meter rises to the greatest height during  cold northerly
 winds in the middle  latitudes, and falls during warm
 southerly winds.  That is, a mass* of air from the torrid
 zone is specifically lighter than  one from the polar re-
 gions, and must cause a proportional fall of the mer-
 curial column, until the equilibrium is restored.   For
 example, the maximum height of the  barometer at
 Philadelphia  was on the morning of  May 5,  1847,

fluenced by Sweden, Poland,  Russia and the cold elevated  plains
of Tartary;  and by the Atlantic Ocean on the west;  all of which
contribute their share successively in forming the climate of Britain. 
326    INFLUENCE OF TERRESTRIAL TEMPERATURE

when the  wind was from the  northeast;  but  the
minimum Avas on the  29th, at noon, Avhen the Avind
was from the southAvest, and the temperature 94° F.
On the  next morning the wind was  from the  north,
and the temperature 52° at nine o'clock in the even-
ing, having fallen 42° in 31 hours.
   But in addition to the  immediate agency of tem-
perature in modifying the specific graAity of the atmo-
sphere, the amount of aqueous vapour diffused through
it  exerts a material influence.  It has been already
shoAvn that the quantity of vapour in the atmosphere,
cceteris paribus,  is proportional to temperature;  the
greater  part of  this is confined to its  lower strata,
(within tAvo or three miles of the earth's surface;)  and
at the temperature of 80° F. the atmosphere is capable
of containing an amount of vapour equal to the pres-
sure of an inch of mercury, or one-thirtieth of its whole
weight.   If, then, we take the estimate of Gay-Lussac,
that the specific  gravity of aqueous vapour is less than
that of air at the same temperature, in the ratio of six
to ten, it is evident that the specific gravity of the atmo-
sphere must be diminished in proportion to the quantity
of vapour diffused through it.  Hence it  is, that Avarm
southerly winds, which have been expanded by heat
and charged with vapour, cause the barometer to fall.
It also  follows, that as rains are supplied  chiefly by
warm southerly winds, in the middle and higher lati-
tudes of the northern  hemisphere, the sinking of the
barometer must be  an indication of falling weather.
And as it has been shown that all violent winds, such
as hurricanes, tornados, &c. are owing to the rapid con-
densation of aqueous vapour, the falling of the bare- 
ON  THE BAROMETER.
327
meter must also forebode tempestuous Aveather.   It is
equally evident,  that  currents  of cold air  raise the
barometer, not only because of their greater  specific
gravity, but because they condense the steam of Avarm
air.   Hence  it is, that for two or  three  clays before
storms of thunder and lightning, wind and rain, during
the prevalence of warm southerly winds, the barometer
falls;  but rises during cool and serene dry weather.*
  * From several passages in Mr. Daniell's work on  the atmo-
sphere, it would seem that he referred the sinking of the  barometer
to the evolution of caloric from aqueous vapour during its conden-
sation, by which the atmosphere is expanded where it takes place.
But it has been shown that within the tropics, where the amount
of condensation is greatest, the fluctuation of the barometer is very
small; while it is obvious from the foregoing facts  and observa-
tions, that the barometer is depressed by the  accumulation of aque-
ous vapour in the atmosphere, and elevated by its condensation.
  Dr. Dalton ascertained by a series of observations continued for
five years at Kendal, in the north of England, that the  barometer
fell below twenty-nine inches during forty days, only two of which
were fair; but that when it stood above its  mean monthly height,
there was but little rain, and generally fair weather.
  He also found that  the heaviest rains fell when the  barometer
was about 29*47, and not when at a minimum, as might  have been
expected, a  priori.  His explanation of this  fact is simple and
ingenius.  He observes, that  "when the barometer is  above the
mean high extreme for the season of the year, the air must, rela-
tively speaking, be extremely dry or cold, or both.  If extremely
dry, it is in a state for absorbing vapour; and if extremely cold,
no further degree of cold can be expected, and therefore in neither
case can there be any considerable precipitation.  On the contrary,
when the barometer is very low for the season, the air must rela-
tively be extremely warm, or extremely moist, or both; if extremely
warm, it is in a similar state to dry air for imbibing vapour; and
if extremely moist, there must be a degree of cold introduced to 
 328    INFLUENCE OF TERRESTRIAL TEMPERATURE

   6.  The range of the barometer is greater during winter
 than summer in the middle latitudes.
   The  reason of which  is,  that the advancement of
 the sun toAvard the pole brings the temperature of the
 higher  latitudes to nearly an equality  over forty or
 fifty parallels, and almost to the. same state  as within
 the tropics, as observed by Dr. Dalton: whereas during
 winter, the warm and rarefied  air of the tropical re-
 gions is often encountered  by  widely  extended  cur-
 rents of cold  dense air from the polar latitudes; the
 consequence of which is, that the barometer will rise
 or fall at the  same  time, over a great extent of coun-
 try, according as the warm and vapoury or cold and
 dry currents of air  predominate, and will be greatest
 when the extremes of temperature in  the  opposing
 currents are at a maximum.
   7. The regular elevations and depressions of the  baro-
 meter, termed Its horary oscillations, follow the daily fluc-
 tuations of temperature.
   According to the observations of Mr. Daniell, the
 daily average   height of the  barometer  at London is
 *010 inch higher at night than  the afternoon,—and
 •005 inch higher in the morning than at night;  it is
therefore  *015  inch  higher in the morning  than the
afternoon. (Essay on the Climate of London.) The daily
variation  is still greater in the interior of North Ame-
rica, lat. 41° 25' at the Rocky Mountains, where Colo-
nel Long found the mean height of the barometer, in

precipitate the vapour, which  cold,  at the same time, raises the
barometer.  From which it follows,  that no very heavy and con-
tinued rains can be expected  to happen whilst the barometer re-
mains about the lowest extreme." (Meteorological Essays, p. 143.) 
ON THE BAROMETER.
329
March, 28*713 inches in the morning, 28*609 at noon
and 28*630 at night.
  From the observations of Captain Sabine and others,
it would seem that the diurnal variation of the baro-
meter is greatest at the equator, where the power of
the sun's heat  is a maximum, and diminishes on  ap-
proaching the polar circles, as shown in the following
table, given by Mr. Daniell:—

     At St. Thomas, lat. 0-24/ the diurnal variation was -074 inch.
       Trinidad,   " 10-39'     "      "     " *063  "
       Jamaica,   " 17-56'     '•      "     " *058  «
       Paris,     " 48-50'     "      "     " *028  "

   Finally, all  the  variations of the barometer  are
greater at the level of the sea than in high situations,
corresponding with the  greater fluctuations  of tem-
perature of the  lower atmosphere.


                  DEW AND FROST.

   After the  setting of the sun, the surface of the earth
is cooled down by radiation from 12° to 15° F. below
the  temperature of the superincumbent atmosphere;
it then  abstracts  caloric from the  stratum of trans-
parent aqueous  vapour immediately over it, by which
it coalesces into dew, or crystallizes into frost, accord-
ing to the temperature of the surface.
   If the atmosphere be full of vapour, there is a large
deposition of dew  during summer, on perfectly clear
nights; but during spring and autumn, instead of heavy
dews,  we  have large white  frosts,  which  are gene-
rally followed in two or three days  by rain;  of which 
330
THEORY OF DEW.
they are regarded by the people as a sure indication.
But when the cold is more intense, and the  atmo-
sphere contains less vapour, we have what is called a
black frost, which is attended with a congealed state
of the ground.  As a general rule, the quantity of dew
is in proportion to the amount of invisible vapour in
the air, and to the difference between the temperature
of day and night.  It is profuse in hot climates, and
more abundant on continents than islands, cceteris pari-
bus;  while on the ocean, far from land, there is little
or no dew, because  the difference between  the tem-
perature of day and night at sea is only two or three
degrees.   In the United States of America, the differ-
ence  is  sometimes 60°  F., the consequence  of which
is a copious deposition of clew, resembling the effects of
a shower of rain.  It is also copious in England during
the prevalence of Avarm winds from the ocean.
  All other  things being equal, a greater amount of
dew is condensed between midnight and sunrise than
between  sunset and  midnight, according to the obser-
vations  and  experiments of Dr. Wells—obviously be-
cause the surface of the earth is  then colder,  from the
loss  of caloric  by radiation.  Dew, then, is  not con-
densed and precipitated like  rain  by the coldness of
the atmosphere, but by the coldness of the earth's sur-
face, which is proved by the well-known fact  that deAV
and  frost are formed on the under surface of planks,
&c. as well as the upper.
  It  has been  long  known that little or no deAV is
formed under a cloudy canopy, but that it is abund-
ant during clear nights.  Dr. Wells referred this cir-
cumstance  to the obstruction of  caloric radiated from 
THEORY OF DEW.
331
the earth's surface by clouds.  It is extremely pro-
bable, however, from his own statement of facts, that
he mistook a mere concomitant for the real  cause of
the phenomenon.  He informs us, that when clouds
begin to form during the night,  the  surface of the
earth rises  several  degrees, and that deAV  formed
during clear intervals often evaporated again Avhen
the sky becomes thickly overcast;  from which  it would
appear, that the caloric evolved from aqueous vapour
during its condensation into clouds,  warms the atmo-
sphere and  prevents the  surface  of the  earth  from
being cooled to the deAAr-point.  Admitting that a por-
tion of the  caloric  radiated from the surface of the
earth, is reflected back, instead of being absorbed by
clouds, it is insufficient to produce so  decided a change
of temperature.  During clear and serene nights, when
no caloric is given out to the atmosphere  by the con-
densation of vapour, the earth is cooled down by radia-
tion, because it receives nothing to compensate for the
loss of what is given off; so that the transparent  aque-
ous vapour of the lower strata of the atmosphere is
condensed into deAV.  There is no dew on windy nights,
for the same reason that evaporation is accelerated by
wind;  or that a renewal of water and agitation pro-
mote the solution of salts.
   It was before stated, that caloric  is radiated  more
copiously from rough surfaces  than from such as are
smooth.   In accordance with that general fact, Ave find
that dew is  formed  more copiously on  swansdown,
wool, cotton, raw silk, flax, fine shavings of wood, &c.
than upon compact  pieces of the same materials.   It,
forms more copiously on rough metals than on polished 
332
MISTS AND FOGS.
ones; doubtless because the former present a more ex-
tended radiating  surface. (See Theory  of Radiation.
book ii. chap, i.)

                  MISTS  AND FOGS.

  The formation  of all fogs is owing to a partial con-
densation of aqueous  vapour, caused by the abstrac-
tion of  caloric  from  colder  bodies — often by  the
mixture  of air  of different  temperatures  near  the
earth's  surface.   For  example, during autumn,  the
temperature of the Mississippi, Ohio and other great
rivers, is nearly the  same during  night and day;
while that of the land is greatly reduced at night by
radiation, especially toward  morning,  when it is at
the extreme of reduction.   Under such circumstances,
the intermixture  of the land atmosphere at the tem-
perature of 35° or 40° F., with  that  of the water,
which is from 50° to 60°, produces a  fog or mist.  The
same  effect is produced  on the eastern coast of the
United  States during autumn.   The  land is cooled
down by radiation at night, while the temperature of
the ocean and the air over it remains nearly the same.
During this state of things, whether the wind blows
from the sea or land,  a mixture of warm and cold air
produces fogs.
  Over the Banks of Newfoundland, where the warm
air  from the Gulf Stream is intermixed with that of
the cold  water and icebergs of the north, they prevail
throughout the year.  Nova  Scotia is,  proverbially,
the region of fogs.  The dark and thick fogs of Eng-
land occur during the latter part of  autumn and Avin- 
INDIAN SUMMER.
333
 ter,—owing to the more rapid  cooling of the land by
 radiation, than of the surrounding ocean.
   The frost rime of the polar seas is produced in the
 same manner as fogs, but by the agency of a loAver
 temperature.
   During summer,  mountains  are generally covered
 with fog in the morning, when the weather is serene
 and clear.   Being cooled down at night by radiation
 below the  dew-point, they abstract  caloric  from the
 transparent aqueous vapour that is always mixed with
 the atmosphere in  greater or less quantity, by which
 it is condensed into  huge volumes of mist or fog, which
 envelope the mountains with giant  folds of majestic
 drapery, and which are not  redissolved by the solar
 rays before nine or  ten o'clock in the morning.

                  INDIAN SUMMER.

   In  all parts of the United States, there  is an au-
 tumnal  period  of  most delightful  Aveather,  which
 usually commences late in  October, and  continues
 with occasional intermissions  through  the greater  part
 of November, during some seasons, in the Mississippi
 valley, until Christmas.   It is generally  attended with
 a southerly wind, which, being warm,  is filled with
 transparent aqueous vapour.  But as  the  earth be-
 comes gradually cooler on the approach of winter, by
 radiating more  caloric than it  receives from the  sun,
 the air over  it is also  cooled down;  the transparent
 vapour is slightly  condensed into a  fine hazy mist,
 which  reflects and  refracts the solar rays in such a
manner as to produce the most rich and softened lus- 
334
INDIAN SUMMER.
tre  of the  bluish-purple and  golden  air, which con-
tinues  until  there is a change  of Avind—sometimes,
for three weeks in succession.  As the Indian summer
is generally a dry season, and as  the mountains and
prairies are frequently on  fire during such weather,
the hazy appearance of the atmosphere has been  at-
tributed by many persons to the vapour of burning
substances  diffused through the  air.   But this cause
is altogether too limited in its operation to account
for the prevalence of Indian summer throughout the
greater  part of the  American continent;  and often
many hundred miles from burning prairies.  The con-
flagrations  that occur during this season are local and
transitory;  Avhile the gradual cooling down of the
earth,  during  the  prevalence  of warm   southerly
breezes,  is  all-sufficient to account  for the  pheno-
menon.   The same cause produces in England dense
and gloomy  fogs, during  the same beautiful season
in  America.  This is readily understood,  Avhen Ave
reflect   that  England is  surrounded  by the ocean;
that its  atmosphere is  much  nearer  to  the point of
saturation  by aqueous vapour, than  that of a large
continent;  and, therefore, that the same  or even a
less reduction of  temperature must  occasion denser
fogs and darker days in Great Britain and other in-
sular  countries of the higher  latitudes, than in con-
tinental regions.
  The Indian summer of the  United States is closed
by the commencement an4 predominance of northerly
winds, which condense the aqueous  vapour that has
been borne from the ocean by  southerly breezes, caus-
ing dark, cloudy Aveather, and general rains or snows, 
AURORA BOREALIS.
335
 according  to the  latitude and elevation;  after which
 the reign of winter is established, and the air becomes
 dry, clear  and  cold, except in  the neighbourhood of
 the lakes or of  the ocean, where it partakes of an in-
 sular character.

                  AURORA BOREALIS.

   Before concluding this general  and imperfect sur-
 vey of the agency  of caloric in  meteorological phe-
 nomena, it may not be improper to notice the leading
 facts connected  with the  aurora borealis and australis,
 or the  northern lights, as  they  are commonly called
 on this side of the equator.
   It has been  already shoAvn, that the  atmosphere
 and all gaseous bodies owe their volume and elastic
 force to the agency of an  igneous  ether  Avhich sur-
 rounds their atoms—and  that after being greatly  ac-
 cumulated in aqueous vapour, it is given out in the
 form of lightning  on the meeting of warm  and cold
 currents of air.   We have also  seen, that the great
 aerial  ocean is  in  a  state of  perpetual  circulation
 from the poles to the equator by under  currents, and
 from the equator to the poles by  upper currents; and
 that the density of the  atmosphere increases as we
 advance from the tropics,  to the points of lowest mean
 temperature: from which it follows, that caloric must
 be evolved by  the tropical  atmosphere as it passes
 from a rarer to a denser state.   It is equally certain,
 that the tropical air must carry with it a considerable
proportion of aqueous vapor, that must  be condensed
into fogs or clouds, rain or snow;  which accounts for 
336              AURORA BOREALIS.
a very common attendant of the aurora, viz., a low,
black cloud, apparently beyond it, and near to the
horizon.
  M. Hansteen, who has travelled much in the north
of Europe and Asia, observes, " that Avhile the aurora?
are streaming, the sky becomes opaque or misty." He
further  states,  that "it is a matter of common obser-
vation in the arctic  regions, confirmed  by long expe-
rience, that the aurora is usually followed by intense
cold, especially after a mild  day;" doubtless, for the
same reason, that warm  and sultry weather in the
middle  latitudes is rendered cool by a thunder-storm;
viz., by the mixture of cold with warm air.
  M. Hansteen has  given a  singular explanation of
the aurora, which shows  how  vague  and  indefinite
the views of philosophers still  are  in  regard to the
origin and nature of  this beautiful meteor.  He ob-
serves, that "it is probably the result of a struggle of
powers  put in activity by the variously constituted
substances composing the mass of the earth, which we
may one day, perhaps, learn  to know."  He thinks,
that " it produces  the  arctic fogs, by decomposing the
aqueous vapour of the polar atmosphere."  (Edln. Phil.
Journal, vol. xii.)
  It has been asked, why the  aurorae are not con-
tinually formed, as the atmosphere is constantly Aoav-
ing from the tropical  to  the higher latitudes.  We
might as well be asked, why there  is not perpetual
thunder and lightning while the atmosphere is moving
from the sea over the land, charged with aqueous va-
pour.   The condensations which occur in both cases
are local and temporary, and depend on the relative 
AURORA BOREALIS.              337
temperatures of different  aerial masses.   When  the
upper current of rarefied air from the tropics, charged
with vapour, comes in contact Avith the cold air of the
polar regions, it gives out a large portion of caloric or
electric matter, Avhich,  not  being compressed, as in
the lower atmosphere, expands  like the electric spark
in an exhausted glass tube, into broad bands  or zones
and columns;  filling the sky with halos and crowns
of lambent  light or undulating coruscations.  It is
highly probable, that the aurora is  given  off, during
the condensation of  the  upper  equatorial  currents
with the vapours which they contain, in a mode simi-
lar to the evolution of silent  lightning on a summer's
evening, Avhich is generally very far off, and is seen
through numerous strata  of atmospheric air, produc-
ing a diffused  or lambent phosphorescence, Avhich re-
sembles the  aurora much  more than it does lightning
Avhich is near at hand.
   Sometimes the Avhole northern hemisphere  presents
that kind of luminosity Avhich announces  the daAvn
of morning  in the east.   At other  times the aurorae
seem  stationary during changes of temperature from
heat to cold.  They  often present the appearance of
a  bank of light, (resembling the effect  of a distant
conflagration,) resting on  or  flanked by a low, dark
cloud,  which  is occasionally illuminated  by  broad
flashes.  Captain Bonnycastle,  of Toronto, in Upper
Canada, observes, that during the formation of all re-
markable  aurorae,  dark volumes of vapour suddenly
appeared, Avithin the space comprehended by the arch.
(Sllllmans Journal,  vol. xxx.  p. 132.)  Sometimes,
though rarely, the aurora presents the appearance of
                        22 
oon
OOO
AURORA BOREALIS.
a Avide arch  extending across the firmament, which
breaks up into columns or streamers that extend to-
ward the zenith.
  Various conjectures have been offered  in regard to
the height at which the aurorae  are  formed,—nearly
all of which  have been founded on  imaginary data.
Some philosophers have supposed  that they must be
formed at a great elevation, because  they have been
seen at the same time in very distant  countries, as
England and America.   But it would be quite as rea-
sonable to conclude, that ordinary  lightning is given
off at a great elevation, because it lightened  at the
same time in England and America.   There is no ra-
tional ground for supposing that the aurorae are formed
above our  atmosphere, and probably never beyond a
few miles;  while there is every reason to  believe that
they may be formed in hundreds of places over different
parts of the earth at the same time.
  It was the opinion of Franklin,  Parry, Ross, Hood
and  Dr. Richardson, that the aurorae of the arctic re-
gions were frequently not higher than ordinary clouds;
and  Dr. Richardson thinks that they are always at-
tended with the formation of clouds, or of that kind
of haziness which causes a halo around the moon—a
very important fact, which would seem  to establish
their connection  with  the  condensation  of aqueous
vapour, as suggested by Dr. Franklin.
  They are most probably in the upper regions of the
atmosphere,* what thunder-storms are  near to the
  * Most of the appearances presented by the aurorae have been
imitated by artificial means.   Dr. Priestley inserted with cement, 
AURORA  BOREALIS.
339
surface of the earth.  The aurorae are seldom, if ever,
seen  betAveen  the tropics, because  the  upper atmo-
sphere is not condensed there, being of uniform  tem-
perature.   Even  near  the  earth's  surface,  there  is
comparatively little lightning where  the temperature
is uniform, as over the tropical ocean, and where the
wind bloAvs uniformly in the same direction.
   It is highly probable, that the electric fluid is nearly
all given out, before the upper  current  reaches the
centre of  maximum  cold;  Avhich  explains why the
aurora is less brilliant at Melville  Island, than at Bear

into the top of a tall receiver, a wire not very acutely pointed.  He
then exhausted the receiver, and presented the knob of the wire to
the conductor, when every spark  passed  through the vacuum in a
broad stream of light, which often divided into a variety of  beau-
tiful rivulets, continually changing  in their  course, uniting and
dividing again in the  most pleasing manner:  thus representing in
miniature what has been called the streamers of the aurora. When
the wire is electrified negatively, instead of streams  of fire, there
is an uniform luminous  appearance like a white cloud, or like the
milky way in a star-light night, which remains for a considerable
time, representing the apparently stationary and diffused light of
the aurora. (Priestley's History of Electricity, p.  524.)
  We can  assign no  limits to the various phenomena which the
electric fluid may exhibit under different circumstances.   The me-
dium in which it is formed, in the upper regions of the atmosphere,
is doubtless greatly rarefied;  perhaps equal to that of a receiver
which has been rarefied  100 times.   It would seem, however, that
the aurora sometimes reaches the surface of the earth.   It is re-
lated by Bergman, that persons travelling over the high  mountains
of Norway, have been enveloped in it; and Captain Ross states,
that he has witnessed it very near to the surface of the earth ; and
that it has caused the deflection of his compass needle as much as
thirty and forty degrees.   M. Hansteen also found that when the
aurorae  were vivid, the horizontal needle was restless, quivered, and
varied from three to five degrees from its ordinary place. 
340               AURORA BOREALIS.
Lake, the  Shetlands, Orkneys and many other places
in loAArer latitudes.  It also explains why in the coldest
regions, as at Port BoAven, Winter Island, &c. the mag-
netic needle is less often disturbed by it than in loAver
latitudes;  and why in the former places, it Avas almost
ahvays  seen  by the  British navigators  southward of
them.*
   Another important fact, that shows  the intimate
connection betAveen   the  aurorae and the  change of
temperature  which the equatorial air undergoes, is,
that the northern lights are more numerous and bril-
liant during  the  coldness of winter, when  the  upper
currents from the tropics, in their passage to the polar
regions are greatly condensed; and that they are then
formed  in  much lower latitudes than during summer.
   It is  also an important corroboration of this theory,
that they are seen in lower latitudes in the middle  and
eastern portions of America and Europe, than on tlieir
Avestern coasts; while  the  former are known  to be
much colder than the latter  in the same  latitudes;
Avhich is owing to the prevalence  of  west winds that
blow from the  Pacific and  Atlantic  oceans, and thus
temper the middle latitudes of western coasts, by  giv-
ing them an oceanic  or insular climate.-}"

  * It is stated by Captain Scoresby, that the aurora was disco-
vered more  frequently south than north of Spitzbergen;  and by
Sir Edward Parry, that  it was generally seen south of Melville
Island; from which we may conclude, that the upper current of
the atmosphere  has acquired nearly its maximum density, and de-
posited nearly all its vapour, before arriving at the limits of great-
est cold.
  f The effect is increased by the condensation of aqueous vapour
which is brought from the ocean by westerly winds, and which gives 
AURORA BOREALIS.
341
   The northern lights are seen much oftener in Ver-
mont, which is a cold mountainous State, between lati-
tude 42° and 44° N. than  in France  or England;
though they are much farther north.  This is evidently
owing to the excessive coldness of winter in Vermont.
General Martin Field has recorded, in the American
Journal of  Science, that, during the year 1830-31, the
winter of Avhich Avas  excessively  rigorous, the aurora
Avas perceived on fifty-six nights;  and that during ten
years  previously, it was  observed  eighteen nights on
an average, annually, at Fayetteville in  the above
State.  Besides which, it must have  existed during
many cloudy nights, Avhen it was invisible.   But in
lat. 70° N. betAveen September, 1838, and April, 1839,
M. Lottin observed at Bopekop, in the Bay of Alten,
on the coast of West  Finmark, 143 auroras, being an
interval of  206  clays.  (Becquerel, de l Electric lie, &c.
tome vi. p.  205.)
   The arched appearance of the  aurora  is an optical
illusion, produced by the  limits of vision, according to
the laAvs of perspective;  for the same reason that the

out caloric during its condensation and precipitation on the western
coasts.  Hence, the greater amount  of  rain which  falls on the
western coasts of North America and  Europe, than on the interior
and eastern portions.   Hence  also, the dryness of west winds in
the United States, east of the Rocky Mountains, which deposit their
vapour on the western slope, before reaching  the interior.  In the
great Mississippi valley, the east wind is dry, while in the Atlantic
States it is often moist during winter and spring. On moving west-
ward, it deposits most of its vapour on the  eastern slope of the
Alleghany Mountains.   These  facts enable us to  understand why
in the vast regions drained by the Mississippi, west winds are dry;
while in Britain and France they are wet,  and east winds dry. 
342
AURORA BOREALIS.
sky presents  a  vaulted appearance—or, that clouds
present the appearance of a canopy, while in reality
they are suspended in horizontal strata.  The different
apparent heights of the aurorae are OAving to their va-
rious distances from the points of observation.  When
the lower atmosphere  between the observer and the
lights is hazy, they appear irised or rose-coloured; pro-
bably for the same reason that the sun rises and sets
red, when the lower air is filled with vapours.
   The oscillations of the magnetic needle are as varia-
ble as the aurora; when  the arch is quiet, the needle
is often motionless; its disturbance  in these cases com-
mences when the streamers begin to fly.  The position
of the dipping needle has been observed to be as vari-
able as  that of the compass needle, the  former rising
and falling  with the corona.   The intensity  of the
magnetism of the needle is also diminished.  (Kreil.
Bibl. Univ.,  tome viii. p. 114.)
   Siberia, Lapland and the Norwegian Alps, are dis-
tinguished  by the frequent display of  this beautiful
and mysterious  phenomenon, which I have  thus en-
deavoured  to explain  in accordance Avith the best-
established principles of meteorology.   After all, it is
quite probable, that some very important facts have
been overlooked, which, if known and rightly consi-
dered, might place the Avhole  subject in a neAV light.
It  is to  be hoped, that fifty years hence, we shall have
fifty accurate observers  of natural phenomena for one
at  the present time.
   Very little is  known of the  aurorae in the southern
hemisphere, except what has  been observed  by Cap-
tains Cook and  Weddel,  who  relate that they have 
AURORA BOREALIS.
343
been frequently  seen  south of Van  Dieman's  Land,
and off  Cape Horn, where the cold is excessive.*
  * From a general view  of  the  foregoing chapters, it must be
obvious:
  1.  That all the phenomena of evaporation  and rain, lightning
and winds, hurricanes and  tornados, fluctuations of the barometer
and formation of the aurorae,  are immediately connected with the
theory of caloric, and those fundamental laws which govern its dis-
tribution over our planet.
  2.  That the aurora is a  thermo-electric phenomenon, produced
during  the  condensation of vapour contained in the equatorial
upper current of the atmosphere, on its passage to the polar lati-
tudes, in a mode analogous to the evolution of lightning from the
more elastic vapour of the lower and denser atmosphere, on mixing
with colder currents, as  during thunder-storms.
  In opposition to this theory, it is maintained by  Dr. Faraday
and others, that "the electric equilibrium of the atmosphere  is
preserved by the aurora conveying electricity from the poles to the
equator."  Can it be possible that  the vast amount of lightning
perpetually disengaged  within the tropics, and during summer in
the middle latitudes, is thus obtained ?  With  sentiments of unaf-
fected and profound humility, the preceding facts are  offered as an
answer to this query. 
CHAPTER IV.
            GALVANIC  ELECTRICITY.

  "Thou mayest babble about electricity, but what is it?  whence
comes it ? whither goes it ?"—Carlyle.

  If Ave would know Avhat electricity is, we must care-
fully investigate all the  phenomena  that make up its
natural history.   Nor does it become the philosopher
to despair of discovering its nature and origin,  before
he has ascertained Avhat office it performs in the econ-
omy of the universe.  Thomas Carlyle has done  in-
jury to the cause  of science, by his  want of faith in
the Avell-directed powers of the human mind to com-
prehend the mysteries of nature, for which he seems to
have a  more profound reverence  than for the  know-
ledge of nature.
  The  first discovery connected with  this branch of
physical science is found in a German work, published
in 1767, by Sultzer, entitled  The General Theory of
Pleasures.   He  observed, that if  two metals  be  ap-
plied, one above, and the other below the tongue, and
brought in contact, a  peculiar taste wras perceived,
attended with a gentle  flash of light;  but that if  ap-
plied separately, no such effects were produced.
  It was next discovered  accidentally by Galvani, a
distinguished professor  of anatomy  at Bologna, that
      (344) 
GALATANIC ELECTRICITY.
345
on touching the crural nerve of a recently killed frog,
(Avhich lay on a table, near the conductor of an elec-
trical machine in action,) with the point of a scalpel,
all  its  muscles were thrown into convulsions,  as if
seized Avith tetanus.   By repeating the experiment on
different  animals, he found that the effect was  most
remarkable in those Avhich are  cold-blooded, and  have
Avhite muscles.   He ascertained afterwards, that when
the nerves and muscles of such animals were armed
Avith small pieces of different  metals, similar pheno-
mena Avere produced on bringing the metals in con-
tact.
  From these obscure results,  Galvani arrived at the
conclusions, that there is a peculiar species of electricity
in all animals, Avhich resides in the brain, and is con-
ducted to different  parts of the body by the nerves,
causing animal motion and secretion; and  that  posi-
tive electricity resides in  the nerves, and negative in
the muscles.   He supposed it to  be conducted  from
nerves  to muscles by the metallic arc, as the electricity
of a Leyden battery is conducted  from it by means of
a common discharger.
  In opposition to the vieAvs of Galvani, it was main-
tained  by the celebrated Volta, professor of natural
philosophy at  Pavia, that the phenomena were due to
the agency of common electricity, which he supposed
Avas developed by the contact of different metals.
  Finding  that Avhen sticks of zinc  and copper, zinc
and silver, &c. were made to touch at one of their ex-
tremities, and the other brought in contact Avith the
spine and muscles of a newly killed  frog, convulsions
Avere excited, it occurred to Volta, that by a repetition 
346      ,       GALVANIC ELECTRICITY.

of circles, or series, composed of tAvo different metals
and  moistened  cloth, he might greatly increase  the
electrical effects.  This led to the construction of  the
Avell known pile, and the couronne de  tasses, which
has been modified into different forms of the  battery.
In.reply to  the  hypothesis of Volta, that the  convul-
sions of the frog were owing to the agency of common
electricity, and  generated by the contact of different
metals, Galvani objected that  he  had  succeeded in
producing  convulsions by means of a single metal.
And it was further shown by Aldini, a nephew of
Galvani, that by bringing a portion of a warm-blooded
animal in contact with a cold-blooded one, as the nerve
and  muscles of a frog with the bloody flesh of  a newly
decapitated ox,  energetic contractions were  produced.
When he held a prepared frog in his hand, moistened
Avith a solution  of salt, and applied  the crural nerves
of the animal  to the tip of his tongue, convulsions
AArere also excited*—from Avhich he  inferred, with Gal-
vani, that there is a peculiar electricity in animal bo-
dies which  does not require the contact of metals for
its development.  It  is somewhat  surprising  that he
was never  led  to suspect, from these  curious experi-
ments, the  identity of animal  heat with the  cause of
muscular contraction; and still more remarkable, that
neither Galvani nor Volta ever suspected the connec-
tion of the phenomena Avith chemical action.
   The agency of caloric in exciting convulsions in re-
cently killed fish, was strikingly demonstrated  by sqme

   * The experiments were successfully repeated before a  committee
of the  National Institute of France,  and afterwards at the Ana-
tomical Theatre in London, Great Windmill Street. 
GALVANIC ELECTRICITY.            347
experiments of Mr. Clift, Avho found  that four hours
after the head of a carp had been cut  off and its heart
taken out, (the fish being considered as perfectly dead,)
when put in hot water, it leaped out of the vessel with
a degree of vigour equal to the struggles of a living
fish.  M.  Dessaignes  also observed that convulsions
were  produced in the  frog, when the muscles  and
nerves were  connected by  a silver spoon  in which
lighted  charcoal was  placed.  (Phil.  Transactions for
1815.)
  A similar fact was observed  by Lord Bacon, who
relates that he saw, with his own eyes, the heart of a
criminal taken out of his body some time after execu-
tion, and thrown into the fire, when it leaped up seve-
ral times to a considerable height. Without comment-
ing on these facts, which belong to another portion of
the present work, it may be observed that they demon-
strate the agency of heat in animal motion, at least as
clearly as that of electricity,—even admitting  (what
has never been  proved) that electricity could exist
independent of caloric.
  The first philosopher who referred  the phenomena
observed by Sultzer, Galvani and Volta to chemical
action, was Fabroni, in a paper communicated to the
Academy  of  Florence, in 1792.   He had  often ob-
served that fluid mercury retained its lustre for a long
time when alone; but that  when amalgamated with
other metals, it speedily tarnished by oxidation;  and
that similar effects were produced on some alloys of
tin.  He had remarked  in  the  Museum of Cortona,
inscriptions engraved on plates of pure lead in a per-
fect state of preservation; while in the Gallery of Flo- 
348
GALVANIC ELECTRICITY.'
rence, he found that medals composed of lead and tin,
or lead and some other metal, were entirely reduced
to a wdiite powder, though carefully wrapped up in
paper, and preserved from the atmosphere in drawers.
He had further noticed, when in England, that the
iron nails then employed  in fastening together the
copper sheathing of ships, caused so much corrosion of
the copper, that the holes  made by them were some-
times larger than the heads of the nails; all of which
he referred  to chemical action produced by the mutual
contact of different metals exposed to moisture, atmo-
spheric air, &c.  That this  was the case in the experi-
ment of Sultzer, he thought was proved  by the fact,
that when the tongue was wiped dry, scarcely any per-
ceptible sensation was excited.
   In another set of experiments, Fabroni put different
metals in vessels filled with water, two and  two, in
contact, when  he found that the most oxidizable metal
was visibly oxidized  at the moment of contact.  A
month afterwards, the connected metals had acquired
so strong a degree of cohesion as to require a consider-
able force  to separate them.  Not only were the metals
oxidized, but covered over with small crystals of va-
rious forms, which had been deposited from a state of
solution.  (Traite de VElectricite et du Magnetlsme, par
M. Becquerel, vol. i. p.  88.)
   The above passages are  sufficient to show that Fa-
broni clearly recognized the necessity of chemical ac-
tion in all  galvanic phenomena, and that his views
were much more accurate than those of his contempo-
raries.   Still it must be acknoAvledged that he never
explained why tAvo metals  in  contact oxidize more 
"GALVANIC ELECTRICITY.
349
rapidly than when  isolated;  and that no satisfactory
account has yet been given of the primary source of
galvanic  action by  his successors; the consequence of
which is, that the theory of the pile, like that of uni-
versal chemistry, is still involved in obscurity.
  This much, hoAvever, is  certain, that all  the  dif-
ferent  elements of ponderable  matter have  various
degrees of attraction for caloric; and  that  during all
chemical combinations, there is  a transition of caloric
from one to the other.
  When treating of freezing mixtures, it Avas shown that
when chloride of sodium, chloride of calcium, potassa
and many other salts are brought in contact Avith ice,
there is a rapid  abstraction of caloric from the ice to
the salts, by Avhich both are dissolved and chemically
united; that when  lead, tin and bismuth are brought
in contact, they dissolve  at a much loAver temperature
than when isolated, and thus unite chemically into an
alloy.  For  the same reason, many other metals, rocks
and gems are rendered more fusible, and combine more
readily Avith each other  by the  addition of what has
been termed a flux. Clay is more fusible wrhen  mixed
with fluor spar, and quartz with lime, than when sepa-
rately exposed to the action of heat.
  Whatever may  be  the true  explanation  of these
phenomena, it is evident that  caloric is essential to
oxidation, solution, and to all chemical combinations,
whether of gases and liquids with each other, and with
solids; or of solids  with each other.   It therefore fol-
lows, that if chemical action  be indispensable  to the
disengagement of galvanic electricity, caloric must be
the primary source of all the  resulting phenomena. 
350
GALVANIC ELECTRICITY.
Passing over the long  and idle  controversy between
the partisans of Volta, (who maintained that galvanic
electricity results from the contact of different bodies,
and those of Fabroni, who contend  that  it is wholly
the result of chemical action,) it  may be sufficient to
state, that  the combined researches of nearly all the
most  distinguished philosophers of modern times de-
monstrate,  that there can be no galvanic  action with-
out chemical decomposition.
   For a long time it was supposed by Sir H.  Davy
that contact was necessary to its commencement, and
that it was kept up by chemical action.  But from the
experiments  of Wollaston, Gautheraut, De la  Rive,
Avogadro, Parrot, Becquerel and Faraday, the question
may now be  regarded as decided.  Davy" himself ob-
serves, in the Bakerlan  Lecture, read before the Royal
Society on  the  8th of June, 1826, that  there is no in-
stance of electro-motion, (by Avhich he meant galvanic
action,)  without  chemical  decomposition.   He also
states, that when  oxidizing  liquids  are employed in
maintaining the action of the battery, the  more oxidiz-
able metal  always  afforded positive electricity in rela-
tion to a less oxidizable one; that potassium, Avhich is
the most oxidizable of all the metals, is positive in
relation  to all others;  and so of its amalgams; that
barium and its amalgams are positive in relation to an
amalgam of zinc, which is positive in relation to pure
zinc,  zinc to cadmium, the latter to tin, tin  to iron,
and iron to bismuth.
   Corresponding Avith the above  results  are  those of
De la Rive, avIio found that the direction of a galvanic 
GALVANIC ELECTRICITY.
351
current is "not determined by metallic contact, nor by
the nature of the metals relatively to each other, but
by their chemical relation to the exciting liquid; that
of two metals composing a voltaic circle, the one which
is most energetically attacked is positive with respect
to the other.  Thus, when tin and copper are placed
in acid solutions, the former, Avhich  is most actively
corroded, gives a positive current through the liquid
to the copper: but if put into a solution of ammonia,
Avhich acts  most on the copper, the direction of the
current is reversed.  Copper is positive in relation to
lead in nitric acid, which oxidizes the former  most
rapidly; Avhereas, in  dilute nitric acid, by which the
lead is most speedily dissolved, the  lead is positive.
He found that even two plates of copper, when im-
mersed in solutions of the same acid, but of different
strength, form a voltaic circle, the plate on which che-
mical action is most energetic giving  a current of posi-
tive electricity to the other;  and that  a compound
circle might be formed solely of zinc plates and one
acid,  provided the  same side of each  plate be  more
rapidly oxidized than the other.
  The following experiments are decisive against the
theory of Volta.  M. De la Rive ascertained that when
zinc and copper plates were brought in contact in an
atmosphere  of hydrogen or nitrogen, wholly deprived
of oxygen,  moisture  and other  bodies, no electricity
Avas evolved;  and when he  purposely increased che-
mical action by exposing the zinc to acid fumes, or by
substituting for zinc a more oxidizable metal, such as
potassium, the electrical effects  observed, on  contact 
352             GALVANIC ELECTRICITY.

with  copper,  were  greatly  augmented,  the amount
being in proportion to the chemical action.  (Ann. de
Chim. et de Phys. xxxviii. et ix.)
   The above facts have an important bearing on the
general theory of electricity, for they seem to prove
that what are termed positive and negative electricity
are only plus and minus conditions of one  and the
same  ethereal element;  consequently, that the oxy-
gen, chlorine, fluorine, iodine  and bromine of acids,
salts,  &c. are attracted by the  minus or negative pole
of the battery;  and hydrogen, metals and alkalies to
the positive pole, because in their natural state these
two classes of bodies are combined with different pro-
portions of thermo-electric ether.  But as  I have be-
fore shown,  (pp. 193 and 194,)  that bodies are neither
essentially positive nor negative, but vary according
to circumstances, and  that those which belong to the
electro-positive class unite with each other, as Avell as
with  those that belong to the  opposite class, it is evi-
dent that chemical attraction is not wholly the result
of electric polarity, as maintained by Davy.
   It has been often said that the energy of the voltaic
battery is in proportion to the conducting power of the
liquid that acts on the plates.   The absurdity of this
hypothesis will  appear in a striking point  of view,
when it is remembered, that of all liquids mercury is
the best conductor;  yet when  employed  between the
plates of a  battery, no electricity whatever is disen-
gaged.  The simple matter  of fact is, that the quan-
tity of electricity evolved is proportional to the rapidity
with which the intervening liquid is decomposed by
the metallic  plates;  and that Avhen  the chemical 
GALVANIC  ELECTRICITY.
353
action  ceases,  the  disengagement  of  electricity  also
ceases*

  * From the experiments of Ritter, Davy and  others it would
appear that two different metals are not requisite to the disengage-
ment of the galvanic fluid, but to its concentration.  Sir Humphrey
Davy formed  galvanic series of a single plate of  zinc, one side of
which was exposed to  an acid, and the other side to water;  also
bv a single metal acted upon one side by an acid, and on the other
side by hydro-sulphurets.  (Philosophical Transactions for 1821.)
  It has been further  shown by M. Becquerel that electricity is
evolved whenever metals  are immersed  in  acid solutions that act
chemically on them.   The  same  effect was produced during  the
combination of acids  and alkalies,—when  nitrate  of iron acts on
leaves of platinum foil;  or nitro-muriatic acid upon gold;  and
even on mixing a concentrated acid  solution with a diluted solu-
tion of the same acid. (Ann. de Chem. et de Phys. xxxv. 120.)
  From such experiments  it has been inferred that electricity is
disengaged during all  chemical  actions.  But it  is certain  that
all chemical combinations and decompositions are attended with
changes of temperature;  that is, by the absorption or evolution of
caloric.   The disengagement of electricity  during the action of the
strong acids on  metals, alkalies, &c. has been deduced from  the
fact, that when the two ends of a multiplying wire are made to
communicate  with the  combining bodies,  the magnetic needle is
deflected, as it is during the passage of a current of voltaic elec-
tricity through it.  But the same effect is  produced when one  end
of the multiplying wire is made to communicate with melted silver,
and the other end with a portion of  the same  metal in the solid
state; or when the two extremities of the  multiplier are made to
communicate  with different parts of other metals when of different
temperatures; from which it would appear that the magnetic phe-
nomena are independent of chemical action, and  result from  the
transition of caloric through the multiplying wire, as will be proved
further on.
                             23 
354
THEORY OF GALVANIC,
    THEORY OF GALVANIC, OR VOLTAIC  ELECTRICITY.

  On the first introduction of the voltaic pile into
Paris, Napoleon was so strongly impressed Avith  its
importance, that  he offered  60,000  fr.  to the indi-
vidual, of whatever nation, who should make a de-
cided advancement in the knowledge of its theory, as
Franklin did in common electricity.   Had  this extra-
ordinary man devoted  himself to the task, it is pro-
bable that he would have gained the prize.  He pro-
posed several interesting points of inquiry in regard
to the theory of its action.   He wished that  experi-
ments should be made on the pile at very different
temperatures, for the purpose of ascertaining whether
caloric created any remarkable difference in its power
of producing electricity.  On witnessing the transport
of the elements of salts to its respective poles, he is
represented  to have said to his physician, Corvisart,
"Docteur, voila l'image de la vie."  (TraltS  de Tfllectr.
et du Magnetlsme, vol. i. p. 108, par M. Becquerel.)
  It sometimes happens  that new  discoveries  retard
the general progress of science for a time, by with-
drawing the attention  of philosophers from a general
and comprehensive survey of  nature, to that of some
obscure and isolated province.
  The brilliant discoveries of Galvani, Volta and Davy
directed the inquiries of men to the chemical and phy-
siological properties of electricity, to the neglect of the
still more obvious agency of caloric.  Had philosophers
studied the cause of solution, combustion, fermentation
and ordinary decomposition with half the attention 
OR VOLTAIC ELECTRICITY.
355
bestowed on electro-chemistry, they would have dis-
covered that caloric is indispensable  to  the chemical
union  of oxygen  with  combustibles;  of salts with
water; metals  with acids, and with each other;  in
short,  that without caloric, there is  no chemical at-
traction.
  This would have led  them to investigate the rela-
tions of caloric  and electricity, one of the most im-
portant problems in physics, from its intimate relation
to the  whole constitution of nature.  If they be only
modifications of one and the same universal principle,
we cannot  expect  fully to comprehend the most sim-
ple  phenomena of attraction  and repulsion, without
understanding its general laws.
  When treating of chemical  solution, it was demon-
strated that metals are dissolved by the caloric of the
strong  acids, and combined chemically with them  as
certainly as that salts are dissolved by the caloric of
water,  and  thus chemically combined with it.
  If then there be  not two causes of  chemical  attrac-
tion, it is evident that the same agent which  causes
sulphuric acid to combine with copper, making a trans-
parent solution of copper, causes  the same acid  to
combine with the  plates of the voltaic battery, by
which  they are oxidized and dissolved, when a por-
tion of the  latent  caloric of the acid is given out  in
the  concentrated form of electricity,  conducted from
the plates by the connecting wires, and thence to the
extremities of the battery.
  I have already shown that sulphuric acid is com-
posed of oxygen, sulphur and caloric; that nitric acid
is composed of  oxygen, nitrogen and caloric; and  so 
356
THEORY OP GALVANIC,
 of other  compounds.   When  solutions of nitric, sul-
 phuric or hydrochloric acids are  poured upon metals,
 there is a rapid transition of caloric from the acids to
 the metals, by which  they are made to combine che-
 mically, with great diminution of volume and evolu-
 tion of heat.  When poured on copper and zinc filings,
 they are  decomposed, and  the metals oxidized still
 more rapidly.  But when the same metals are arranged
 in the  form of a galvanic battery, and immersed in
 the same  solutions, electricity is evolved:  from which
 it would  seem  to follow, that the latent caloric of
 acids is given out in  the  form of calorific or electric
 ether, according to the mode of its disengagement.
   Another fact of fundamental importance to a right
 understanding of the nature of voltaic electricity and
 its relation to caloric is, that its character is modified
 by the size and number of plates composing the bat-
 tery.   For example, when  it  is  composed of  a few
 large plates of zinc and copper, an imponderable fluid
 is evolved, possessing all the properties of  highly con-
 centrated caloric,—which fuses and ignites the hardest
 gems and  densest metals submitted to its action;  while
 it is destitute of nearly all  the  properties by which
 common electricity is characterized.   The largest bat-
 tery of this description ever constructed, was that of
 Mr. Children, Avhich was composed of twenty plates
 of zinc  and copper, six feet long, and thirty-two inches
 broad.  When immersed in  a strong acid solution, it
melted, ignited and fused  a large platinum wire, six
feet in  length; but communicated little or no shock to
 the system; would not  charge a Leyden jar; produced 
OR VOLTAIC ELECTRICITY.             357
no sensible  effect on the electrometer; and, unlike com-
mon electricity, was conducted slowly by metals, minerals,
fluids, &c*
  When  the  battery  is  composed of two extensive
coils of zinc and copper;  or of many  plates, so  ar-
ranged as to constitute only a single  pair of  zinc and
copper plates of enormous dimensions, as in Dr. Hare's
calorimotors, the calorific effects  are still more remark-
able.
  On the other hand, when  the battery is composed
of a large number of metallic plates of small  size, and
immersed in the same solutions, electricity is  evolved,
which affects the electrometer, communicates  a shock,
and passes through conductors with the speed of lights
ning.-j-
  * The large battery of the Royal Institution, employed  by Sir
 H. Davy, which consisted of 2000 pairs of four-inch plates, melted
 platinum, quartz, the sapphire, magnesia and lime, like wax, both
 in vacuo and in the atmosphere; while charcoal, plumbago and
 the diamond were rapidly dissipated in the form of vapour.
  f When the battery is composed of a few large plates and im-
 mersed in an acid solution, caloric is evolved until the acid is de-
 composed, or until the metallic plates are consumed.  But if the
 battery be composed of a large number of small plates of the same
 metals, and immersed in the same acid, electricity is produced,
 until the plates or acid are consumed by oxidation; which demon-
 strates the identity of caloric and electricity beyond the possibility
 of a doubt; for it would be a perversion of common sense to sup-
pose, that by merely changing the size and number of the plates,
a radically different  fluid could be evolved, while the metals and
solutions in which they are  immersed, are the same.  Shall I be
asked for clearer proofs that the latent  caloric of acids is the basis
of electricity ?  We might as well  be asked to prove that the sun 
358
THEORY  OF  GALVANIC,
  These striking facts led Dr. Hare to suppose that
both caloric and  electricity are developed during all
galvanic operations;  and that they are combined Avith
each other by what he calls " the reciprocal attraction
of imponderables."   He supposed  that when two or
more large plates were employed,caloric predominated;
but that wrhen  a large number of small  plates were
used, electricity predominated.   One thing is certain,
that the character of the  electricity is modified by
every variation in the size  and number of the plates
composing the battery.  But if we suppose that caloric
is combined with  galvanic electricity, because it fuses
and ignites  metals or other bodies, we shall be forced
to admit that  it is also a constituent portion of com-
mon electricity, for this fuses and ignites bodies like vol-
taic electricity.  He further supposes, that "electricity
fuses and ignites metals, &c, by combining with their
latent  caloric; thus  augmenting its  repulsive agency
and  causing it to overcome their cohesion."  But he
omits the important  fact, that electricity also increases
their  temperature,  and  that its former properties are
changed and merged  into  those of caloric, as it fuses
and ignites  bodies.
  The  unavoidable conclusion from the above facts is,
that caloric and electricity are only  different forms of
is the fountain of light and heat; or that rain accompanies light-
ning.
  It is generally known that the most powerful batteries are com-
posed of bodies which  act with  the greatest energy upon each
other, such as zinc, copper and nitric acid;  and that such as un-
dergo no  chemical  changes exhibit no electrical effects, such as
gold, silver and water. 
OR VOLTAIC ELECTRICITY.
359
the same elementary agent, varied by the numerous
modes of its  separation from ponderable  matter:  or,
that there are two distinct and universal  agents com-
bined with  ponderable matter and with  each other,
"by the reciprocal  attraction of  imponderables,"  as
maintained by Dr. Hare.  It need scarcely be observed,
that there has never been the slightest evidence ad-
duced that  such an attraction exists between caloric
and electricity, admitting them to be distinct fluids;
while it is contrary  to the simplicity which character-
izes all the operations of nature to suppose the exist-
ence of two universal agents, endowed with the same
fundamental  properties.   There  cannot be two uni-
versal principles of action in nature;  because if they
were different they would  interfere with each other
 and produce discord;  and  if they were alike  they
 would produce like results, which amounts to the same
 thing as if they were radically identical*  If every
 apparent difference  between caloric and electricity be
 taken as an argument  against their identity, it would
 be easy to prove that there are  more than one hun-
 dred electricities.   There is  a far greater difference
 between  the voltaic  fluid  disengaged by Children's
 battery and that from a common electrical machine,
 than between the former and the caloric evolved by
 ordinary combustion;  while the  deflagration of steel

   * Sir Isaac Newton thought it " inconceivable  that  two ethers
 could be diffused through all nature, one of which acts upon the
 other, and by consequence is reacted upon, without retarding, shat-
 tering, dispersing and confounding one another's motion. (Opticks,
 p. 339.) 
360
THEORY OF GALVANIC,
wires in oxygen gas and the detonation of gunpowder,
are more like an electric explosion than anything else.
   The ordinary process of  combustion by which heat
is evolved, consists in the combination of oxygen with
other elements.   The galvanic fluid is decomposed by
the same process:  wdiile it would be contrary to all
the rules of a sound induction, to suppose that two or
more distinct ethereal agents could be disengaged from
the same elements.  If we  reject this simple mode of
reasoning, we shall be compelled to admit the existence
of as  many electricities as there are modes of sepa-
rating it from ponderable  matter;  which would be
absurd.  It is far more consistent with facts and the
harmonious simplicity of nature to suppose that one
agent produces all the diversified powers and activities
of matter; that  it exhibits different properties and
appearances under different circumstances, according
to its diffusion, concentration, compression, &c.;  and to
the mode of its combination with different substances,
in a solid, liquid, gaseous or imponderable state, as in
the matter of light.
   We hav^e already seen, that a certain temperature
is indispensable to combustion, fermentation, putrefac-
tion and to every process of oxidation, however slow,
as the rusting of metals; that when atmospheric oxy-
gen is thus made to combine with metals, its volume
is diminished, and a portion of its latent caloric libe-
rated, in the form of radiant ether, by which the pro-
cess of oxidation is kept up.  I have also proved, that
when metals  are exposed to the action of strong acids,
there  is a transition of caloric from  the acids to the
metals, by which the latter are dissolved and  chemi- 
OR VOLTAIC ELECTRICITY.
361
cally combined with  the menstruum; that caloric is
the cause of all  attraction between fluids and solids;
that the solvent power of water, acids, &c. is greatly
augmented by heat;  and that  when metals are dis-
solved in the strong acids, caloric is given out in great
abundance,  as  in ordinary  combustion.   So nearly
does the operation of a voltaic battery resemble com-
bustion, that more or less heat is  always disengaged
by its action.  When the acid solution is strong, and
chemical action  energetic,  the whole apparatus  be-
comes warm; viz., a  portion of the latent caloric of
the acid is conducted from  the plates to the connect-
ing wire in the form of electricity; while another por-
tion is liberated in the diffused  form of sensible heat,
as when water and acids are poured upon quick-lime.
  That the  caloric of liquids  is  the cause  of their
chemical action  on the plates of the battery, is proved
by the fact,  that when the apparatus is supplied with
hot solutions of the strong acids, its energy is greatly
augmented,  and the metallic plates rapidly dissolved;
in other words, the battery is very soon burned out.
  It is  stated by Singer, Donne and  others,  that  the
energy of De Luc and Zamboni's columns* is greatly
augmented  by  an elevated temperature, and  dimi-
nished by a reduction of temperature;  that  they are
more active during  summer than winter: and in  a
warm than a cold room.  Dr. Jaegar found, that after
  * The first is formed of disks of writing-paper, interposed be-
tween thin leaves of zinc and silver; while that of Zamboni was
composed of paper disks gilt or silvered on one side, and the other
side covered with a layer of black oxide of manganese mixed with
honey. 
362
THEORY OF GALVANIC,
the dry pile had  lost its energy, it was restored by a
temperature of from 104° to 140° F. That the energy
of this  pile is owing  to chemical action, like every
other form of  the battery, is proved by the oxidation
Avhich it undergoes, and by the total loss of its power
Avhen perfectly dry.
  When isolated plates of zinc and copper are  im-
mersed  in dilute nitric acid, they are oxidized and
dissolved, when caloric is liberated as during combus-
tion;  but when  they  are  connected by  means of a
metallic wire,  galvanic electricity  is evolved.   There
can scarcely be a doubt that if the caloric evolved by
ordinary combustion could  be concentrated and con-
ducted  off like the galvanic fluid, it would  exhibit
electrical phenomena.   Pouillet has actually shown
that electricity is disengaged during nearly all com-
bustions, though in a slight degree, as had been proved
long ago by Lavoisier and Laplace, De Saussure, and
by Mr.  Read.   Were it not for  the caloric contained
in nitric acid, it  would not dissolve zinc and copper
filings.   For the same reason, it  would not combine
Avith the plates of the battery; nor would it enter into
chemical combination  with any other substances.  The
battery owes all  its energy to chemical action, as cer-
tainly as that combustion is a chemical  action.   Can
common sense admit that caloric  causes  atmospheric
oxygen to combine with combustibles, and  that some
other agent causes the  oxygen of acids to combine Avith
the plates of a voltaic battery?  The supposition is
wholly unphilosophical, and is contradicted by all the
analogies of nature.  Combustion is a chemical process
to all intents and purposes, and is produced by the same 
OR VOLTAIC  ELECTRICITY.
363
agent which causes  all other chemical actions.   An-
other important general fact, showing the intimate
relation between combustion and galvanic action, is,
that the action of the pile, like that of combustion, is
far more energetic in oxygen gas than in atmospheric
air;  and ceases in vacuo, in nitrogen, and other gases
that do not act chemically on it.
   If we compare  the effects of galvanic electricity
with those of caloric evolved by ordinary combustion,
we find that they are the same.   When voltaic  elec-
tricity fuses, ignites and volatilizes metals, gems and
all other  combustibles, does it not produce the same
effect as that of an  oxy-hydrogen bloAV-pipe, or the
concentrated heat of a forge?  and if it produce the
same effects, must  it not  be the same agent?   Can
electricity render bodies hot, and yet not be an  igne-
ous fluid?   When charcoal is submitted to the action
of a galvanic  current under water, it is ignited, and
decomposes the water  as  when heated by  ordinary
 combustion: and if an iron wire, connecting the ex-
 tremities  of a battery in  action, be made  to  pass
 through water, the  latter becomes hot  and  boils.
 When the wire is thus heated, it attracts oxygen from
 water,  as when  rendered  red  hot by other means.
 Like caloric, electricity causes oxygen and hydrogen
 to combine  to form water, and again causes its decom-
 position.
   If then it be an established axiom in philosophy,
 that the  same effects should  be ascribed to the  same
 cause, caloric and  electricity must be essentially the
 same agent.
   The recent experiments of Dr. Faraday have fur- 
364
THEORY OF GALVANIC,
nished many important facts, Avhich show the intimate
relation between combustion and the eA^olution of elec-
tricity by galvanic action.
  It is very well  known, that oxygen is  not  indis-
pensable to combustion;  that during the rapid combi-
nation of  chlorine, fluorine, iodine, &c. with hydro-
gen, sulphur, phosphorus  and  the metals, caloric is
evolved  in the form of radiant  heat, as in ordinary
combustion;  in short, that caloric is  evolved during
nearly all rapid chemical combinations.  By folloAving
up the experiments of Sir H. Davy, Dr. Faraday has
shown, that when chlorides, iodides, fluorides, oxides,
cyanides, nitrate of potassa, chlorate  of potassa, sul-
phate of soda and various other compounds were fused
by heat, and interposed  between the plates of copper
and platinum of a  voltaic  battery,  electricity  was
evolved  as when acids were employed; and  in some
cases much more freely.   He adds, "there are  hun-
dreds of bodies which evolve  electricity in the same
manner, when in a  state of fusion;  but that  when
they become solid, the decomposition and the electric
currents cease."   He thinks  that solidification  pre-
vents  decomposition, &c.  "merely by chaining the
particles to their places, under the influence of  aggre-
gation."  (Experimental Researches in  Electricity, 4th
series.)  Had this distinguished experimenter  recog-
nized the agent by which particles are aggregated and
chained together, he would have found that it is the
alpha and omega of  chemical action, without  which
there could be no voltaic electricity; and that it is the
source of all electro-chemical combinations and decom-
positions. 
OR VOLTAIC ELECTRICITY.
365
  But  there are certain minute philosophers,  who
maintain that the slightest difference between  any two
agents destroys their identity.  If such objections to
the unity of caloric and electricity were well founded,
Ave should be compelled to admit the existence of more
than a hundred species of electricity; for it differs with
every modification of the process by which it is pro-
duced,  from thermo-electricity of the lowest tension
to the fluid of a Leyden battery, which darts through
metals  and  the  living body  Avith the speed of light-
ning.
  It is known, that the different forms of voltaic elec-
tricity pass with different degrees of velocity through
the same conductors; and that in this respect there is
an  almost infinite variety in the properties which it
presents.  Yet  these differences  have not  prevented
Wollaston, Faraday and many  of  the most distin-
guished philosophers of the continent, from maintain-
ing the identity of electricity under every variety of
form and  appearance Avhich  it exhibits, from that of
Children's battery to De Luc and Zamboni's pile;  and
from a flash of  lightning to the magnetic spark, or the
shock of a torpedo.  Surely there is a far greater dif-
ference betAveen the electricity developed by a common
machine and Children's  battery, than  between the
latter and solar heat concentrated by means of a large
burning-glass.   It was shown by Mr. Parker of Fleet
Street, that  the  most intense heat of a burning-glass
three feet in diameter, though  sufficient to fuse and
volatilize  gems and metals in a few seconds, passed
through water without heating it like electricity;  and
that when it was made  to strike upon the finger, it 
366       ANALOGIES  BETAVEEN VOLTAIC  ACTION

produced  little or no sensation of heat, but that of a
sharp cutting instrument.

 ANALOGIES BETWEEN VOLTAIC  ACTION  AND  SUBTERRA-
               NEAN  CHEMICAL FORCES.

  From a general view of the foregoing facts and ob-
servations, it would appear that the galvanic or voltaic
pile  affords a miniature  representation of nearly all
the chemical changes perpetually going on throughout
nature; while it exhibits the relations of caloric and
electricity, in all  their multiform states, in the  most
instructive manner.   There is a striking resemblance
betAveen the phenomena of galvanic heat and  that
developed  by volcanic agency; not only in the che-
mical mode, of their  production, but in the effects they
afterwards exhibit.   In both cases the radiating power
of the igneous ether evolved is exceedingly small,
compared  with its  power of fusing  rocks, metals,
gems, &c, while they are both attended with thermotic
and  electrical  phenomena.  A large voltaic  battery,
capable of producing a current sufficiently powerful to
fuse  and ignite the  most obdurate bodies, excites no
sensation of warmth beyond the apparatus.   It is
stated by Mr. Scrope, on the  authority of Dolomieu,
corroborated by his  own observations, that very  little
heat is radiated from a mass  of red-hot lava;  that at
the distance of a few feet, the thermometer is scarcely
affected by it, which induced Dolomieu to suppose that
its fluidity was due to some other cause than caloric.
(Scrope on Volcanos, p. 20.)
   The reason why incandescent  lava does not radiate 
AND SUBTERRANEAN CHEMICAL FORCES.     367
heat like  coal, wood, &c. when in a state of ignition,
is doubtless owing chiefly to the  greater attraction of
caloric for metallic and rocky masses, than for combi-
nations of animal and vegetable  matter, as  explained
under the head of radiation.
  It has been long known, that the most intense elec-
trical phenomena are displayed during volcanic erup-
tions.   If it  be  inquired why persons near to a mass
of incandescent lava experience no electric shock, it
may be answered, that no  shock is received from a
voltaic battery of large plates; nor should we be able
to discover that any electricity  was evolved, Avere it
not conducted off by the connecting wires  to the ex-
tremities of the  pile: even then,  it exhibits  chiefly the
phenomena of concentrated caloric, and but slight in-
 dications of  electricity.
   Mr. Scrope has given a highly graphic description of
 the electrical action that accompanied an eruption of
 Vesuvius that  he  witnessed in October, 1822;  and
 which  resembled the awful displays of lightning that
 attended its eruption in 79, when Pompeii and Hercu-
 laneum were overwhelmed with  lava; and by which
 the elder Pliny lost his life.  " From every part of the
 immense cloud  of ashes that hung suspended over the
 mountain, flashes of forked lightning darted continu-
 ally.   They proceeded in  greatest number from  the
 edges of the cloud.  They did  not consist, as  in  the
 case of a thunder-storm, of a single  zigzag streak of
 light, but a great many coruscations of this kind ap-
 peared suddenly darting in every direction, from a
 central point, forming  a group of brilliant rays, resem-
 bling the thunder-bolts placed by the ancient artists in 
368      ANALOGIES BETWEEN VOLTAIC ACTION

the hands of the cloud-compelling Jove." (Scnpc on
Volcanos, p.  81.)
  It is also related by Sir William Hamilton, that the
eruptions of Vesuvius in 1767,1779 and 1793, were at-
tended with the most tremendous exhibitions of light-
ning ; and the  two latter with extremely loud explo-
sions of thunder.  Zigzag lightning darted incessantly
from the enormous black clouds  that  hung over the
crater, resembling  in  all respects that  of ordinary
thunder-storms; and accompanied by heavy showers of
rain, with whirlwinds,  like those which attend water-
spouts.  Sometimes balls of fire issued from the black
cloud, which burst into serpentine  streams of fire.  He
thought that the violence of the subterranean action
might be known from the height to which the vapour
and  smoke ascended, and by the amount of ferilli, or
volcanic lightning. (Philosophical Transactions of the
Royal Society for 1795.)
  Dr. Daubeny further relates, on the authority of M.
Monticelli and  other persons who  witnessed the erup-
tion of Vesuvius in August, 1834,  that from a current
of lava which  overwhelmed one  hundred and fifty
houses, and covered about five hundred acres of ground,
there arose a black cloud, from which  emanated very
vivid flashes of lightning, sometimes followed by thun-
der, but not always. (Philosophical Transactions, 1835.)
  It is also related in the Amerlcein Journal of Science,
that on the  20th of January, 1835, Nicaragua, in Cen-
tral America, was visited by a tremendous earthquake,
and followed by an eruption  of the volcano of Cosi-
guina, by which  the atmosphere was filled to a great
height and distance with phosphoric sand, smoke and 
        AND SUBTERRANEAN CHEMICAL FORCES.     369

vapour,—from which issued perpetual flashes of light-
ning throughout the night of the 20th and the whole
of the next day.  On the  23d, toward morning, tre-
mendous loud thunder-claps were heard in succession,
like the firing of the largest cannon,—from which it
was supposed by the inhabitants at the Port of Balize,
on the Bay of Honduras, that a naval action was going
on, or that a ship was in distress.  It is stated that
during this earthquake the  country was convulsed for
more than a thousand miles.
   It is  here worthy of special  notice, that nearly all
the volcanos of our planet that are situated  on dry
land, amounting to about two  hundred, have  been
found in the vicinity of the ocean;  while it is pro-
bable, from the \7ast number of the volcanic islands,
that there  are  at least three times as many beneath
the sea.
   It is  well known  to modern geologists that sub-
marine  eruptions are  exceedingly frequent.   On the
12th of  June, 1811, immense volumes of smoke were
observed to arise from  the sea, near the island of St.
Michael, one of the Azores, by Captain Tillard of the
Sabrina; from Avhich  issued at intervals, for  several
days, the most vivid  flashes  of lightning,  and some-
times a  continual blaze.   During these eruptions an
island was formed, about a mile in circumference and
two hundred and eighty feet high, which Captain Til-
lard  visited, in company with several of his  officers,
on the 4th of July, when he named it Sabrina, after
his ship.  By the middle  of October it had disap-
peared, leaving a dangerous shoal.
                        24 
370      ANALOGIES BETAVEEN VOLTAIC ACTION
  During an earthquake on the 9 th  of July, 1757,
eighteen small islands emerged from the sea, near the
northwest corner of St. George, another of the Azores;
which also disappeared in a few months.
  The destruction of the town of Conception, in Chili,
by an immense wave of the sea, twenty-eight feet in
height, which rolled over it, must have been  caused
by a submarine volcano, as we are  informed  by Mr.
Caldcleugh that two eruptions of dense smoke  were
observed to issue from the sea, with violent ebullition,
and the evolution of large quantities of gas.
  About the  same time, flame and smoke burst  from
the sea, near the island of Juan Fernandez, over which
the waves rolled to a great height,  as at Conception.
(Phil. Trans. 1835.)   And Ave learn from the captain
of an English ship from the  Mediterranean, that  on
the 18th of May, 1845, in lat. 36° 40', and long. 13°
44', immense balls of fire were seen  to issue from the
sea. .(New York Sun, July 22,  1845.)
  But to return; it has been  shown that the voltaic
fluid, whether thermal or electrical, is disengaged  from
nearly all bodies when in a liquid state—from water,
acids, saline solutions,—from oxides, chlorides, iodides,
&c. when in  a  state of fusion, during  their chemical
decomposition by the plates of a battery.  The resem-
blance of this process to that of subterranean chemical
action is  somewhat remarkable.  For example, the
products of volcanic eruptions render it almost certain
that  subterranean caloric is disengaged from sea water,
which finds its  way to the interior through  fissures
and  submarine  craters,—where its  oxygen combines
with sulphur, metals, &c. as the oxygen of acids unites 
AND  SUBTERRANEAN CHEMICAL FORCES.      371
with the plates of a common battery.*  That volcanos
are in  some way abundantly supplied with sea Avater,
is evident from the vast quantities of steam discharged
during  their  eruptions,  which contains  chloride ol
sodium, hydrochloric acid, chlorides of copper,  iron,
&c. as well as from their geographical positions  near
the sea.  In  short, the earth  may be regarded  as a
huge galvanic pile, kept in a state of perpetual subter-
ranean chemical action by the waters of the ocean, as
our little batteries are maintained in action by various
solutions.
   When the  plates of a  common battery  are  com-
pletely oxidized, chemical  action  ceases:  so when all
the materials within a given range  of subterranean
territory become saturated with oxygen, sulphur, chlo-
rine, &c. chemical action ceases, and the volcanic forces
become quiescent, to be renewed  elsewhere for indefi-
nite periods of time, until exhausted or burned out like
the plates of a voltaic battery.
   In  North America  they have  been  nearly extinct
since the elevation of the Rocky and Alleghany Moun-
tains  above the  ancient sea  that once  covered  the
northern  hemisphere;  Avhile in  South America, and

  * The hydrogen of water may unite with sulphur, making sul-
phuretted hydrogen; while the union of oxygen with sulphur makes
sulphurous acid, which combines with lime, and drives off carbonic
acid, a common product of hot springs and volcanos.  The nitro-
gen of atmospheric  air, which is admitted through craters, and is
mixed in greater or less quantity with all water,  combines with
hydrogen, forming ammonia.  In fine, there is no limit to the play
of affinities that take place in this  grand laboratory, under the
agency of so intense a heat. 
372      ANALOGIES BETWEEN VOLTAIC ACTION

on  the eastern continent, volcanos  are numerous, but
confined chiefly to  the  borders  of the  ocean.   The
only feeble remains of subterranean chemical action
in North America are its warm springs, which convey
off whatever heat is generated beloAv the surface, in a
tranquil manner.
   The same observations apply to  the greater part of
Europe and Asia.  The Alps, the Apennines, the Hima-
layas and many other  mountain  ranges  of the  old
world,  afford  no  evidence  of existing  subterranean
combustion, except the numerous warm springs  that
issue from their sides.   Were it not for this continual
discharge of heat, it is probable that they might still
be convulsed at long intervals by volcanic  explosions,
or  by earthquakes, which are owing to the confine-
ment of volcanic steam  by superincumbent  pressure.
Warm springs may therefore be regarded  as "safety-
valves of the  globe" still more emphatically than vol-
canos.   It is  very well known that when the great
geyser of  Iceland  is obstructed  by  throwing stones
into its funnel, its temperature rises rapidly, Avhich is
soon followed by eruptions of steam and  water to a
great  height.   It  is equally certain, that if the  ob-
struction were equal to the pressure of  two or three
thousand  feet of  rocks  or  lava, earthquakes would
follow.
  It was  before stated that the  rapidity with which
acid, alkaline  and  other solutions are decomposed by
the plates of the battery, is augmented by increasing
their temperature,—that  the  amount of chemical ac-
tion, like that of evaporation  and rain, is  greatest on
the surface of the earth within  the tropics, cceteris 
AND SUBTERRANEAN CHEMICAL FORCES.     373
paribus, and  diminishes  as we  approach the regions
of perpetual frost.
   The same  thing would  seem to be true of subter-
ranean chemical action, which points out the agency
of solar heat in the production of volcanos, and con-
nects the Avhole theory  of geological dynamics with
that of solution, combustion and of universal chemis-
try.   It is a remarkable fact, which has never been
explained by geologists, that the highest mountains of
the earth  are within the torrid zone, where they rise
to an elevation of  from four to five  miles  above the
ocean level; while in the middle latitudes they do not
exceed the height of fifteen or sixteen thousand feet;
and seldom more than five or six thousand feet beyond
the polar circles, although they are nearer to the centre
of the globe than any other part of its surface.   The
islands of the Pacific and Atlantic oceans are also far
more numerous within the tropical than  the higher
latitudes; while it is certain that nearly all of them
have been elevated by submarine volcanos.
   All the chemical and geological operations of our
planet Avould seem to  be in proportion to the energy
of solar radiation.   Within the tropical regions, the
aggregate  quantity of earthy and metallic matter con-
veyed from the interior of the earth in a state of che-
mical solution  by springs,  is immense.  The amount
of evaporation  and  rain being great, the  rivers are
large, and rapidly destroy rocks, hills and mountains
by mechanical  agency; these are transported to lakes
and seas, which are rapidly filled up by fluviatile de-
posits of sand, gravel, clay,  pebbles, boulders, &c. form-
ing new lands.  The waters of the  ocean that find 
374       ANALOGIES BETWEEN VOLTAIC ACTION

their Avay to the interior are warm, and rapidly oxi-
dize its metals  and other minerals, by which a cor-
responding amount of heat is disengaged.
   Thus it is evident that all the phenomena of meteor-
ology, chemistry and geology are  resolvable into the
agency of caloric, or thermo-electric power.  If rocks
and  hills are dissolved  by running water, and trans-
ported to lakes and  seas, caloric  is the universal sol-
vent.  And here must end forever the long and idle
controversy between  the Plutonian and Neptunian
geologists.   If caloric be indispensable  to fluidity and
solution, it  is as necessary  to the formation  of sedi-
mentary rocks as to the generation of  granite, basalt
and other volcanic products, which are composed chiefly
of metallic oxides, such  as those of silicium, calcium,
aluminum, iron, potassium and sodium, the oxygen of
which is derived mostly  from sea water.
   There is something  great and sublime in the  sim-
plicity of the idea, that the same familiar power which
"warms  in  the  sun,"  and clothes the world Avith en-
chanting beauty, raises mountains  from  the ocean, and
keeps the whole stupendous fabric of the universe  in
a state of perpetual motion and circulation.
  It was supposed by some of the older geologists that in
the earlier periods of the world there were no volcanos—
by others, that they were far more active than at present
—while Descartes, Leibnitz, Buffon, Fourier and a mul-
titude of more modern philosophers, have maintained
that the earth originally existed in a state of fusion  or
incandescence throughout; and that it has been gra-
dually cooling down ever since.  To those who believe
in the uniformity of nature's  laws, it  is needless  to 
         AND SUBTERRANEAN CHEMICAL FORCES.     375

insist that  none of these opinions have  any founda-
tion in fact; and that they are discountenanced by all
analogy.  We are rather  authorized to  believe  that
the amount of chemical action going on throughout
the earth is the same in all given periods of time, and
in proportion to the amount of matter.   But if vol-
canic agency were due to a central fire, it is  difficult
to comprehend why the tropical mountains should be
from four to five times  higher than those of the polar
regions,—why volcanos are confined chiefly to the
vicinity of  the ocean,—why  they should discharge
enormous quantities of steam saturated Avith muriatic
salts,—why they should continue in action at inter-
vals  for unknown periods of time, and then become
extinct,—why volcanic islands are more numerous in
the  tropical  than  higher  latitudes,—and Avhy hot
springs should not be equally distributed all over the
earth.
   The facts collected by M. Cordier and others, prov-
ing that the temperature of the earth increases as we
descend below  the surface, have been regarded by
many geologists as conclusive evidence  that earth-
quakes and volcanos are caused by a central  fire.  It
is true, that in many parts of the world, the temper-
ature of  rocky  strata  and of the water that issues
from them  is higher  at the  bottom of deep mines
than at the surface, varying greatly however in differ-
ent places.   Humboldt says, that the bore  at  Mew
Salaweak, Minden, in Prussia, is 2094i Prussian feet.
and  the  temperature  of the  water 90° F.; which
gives a rise of 1*6° for 97*6 feet English.   From which
he infers, that at the depth of 40,000 feet, the  tern- 
376      ANALOGIES BETWEEN VOLTAIC ACTION

perature would  be  435° F.   Mr. Fox  found that in
the Dalcoath copper mine, in  Cornwall, at the depth
of two hundred and thirty fathoms, or 1380 feet, a
thermometer placed in  a hole in the rock, stood at
76° F., and at 82° in water, ten fathoms deeper; the
mean annual  temperature of  the  surface being 50°.
But the same gentleman states that about two mil-
lion gallons of water are daily pumped from the Pol-
dice mine, at  the  temperature of from 90° to 100°;
while the mine is  only  one hundred and  seventy-six
fathoms'(or 1056 feet) deep.   It is therefore evident
that the temperature is  not proportional to depth.
  On the other hand, when we reflect that water is
continually  acting  upon  the   metals, causing  their
oxidation, and that chemical  action is the grand pro-
cess by Avhich latent heat is  disengaged,  we need be
at no loss  to account for its   accumulation at great
depths beneath the surface, where metals are abundant.
  It is impossible to know with certainty how  far the
waters of the ocean penetrate  beneath  the  surface—
probably not beyond the depth of a few miles; nor is
there any good reason to suppose that there is much
chemical action at greater depths, owing to the super-
incumbent pressure; while it  is known that  on the
surface of the earth there is  very little chemical  ac-
tion without moisture.   This  much however is cer-
tain, that so far  as we can trace back the history of
our  planet,  it has been  composed  as  at present, of
mountains and valleys, seas and plains, and stocked
with plants and  animals that have successively arisen
and passed away, leaving their fossil remains as a re-
cord of  their former existence.  We have  the  most 
AND SUBTERRANEAN  CHEMICAL  FORCES.     377
indubitable  proofs,  that our mountains of  granite,
gneiss, basalt, &c. were formed during long geological
epochs, by  successive volcanic  movements, and con-
temporaneous with  the deposition of our  stratified
rocks; while there is not the slightest evidence that
the earth Avas ever in a state of  liquid fusion through-
out.  According to  the estimate of Mr. Lyell, there
are about two thousand volcanic eruptions every cen-
tury, which in  six  thousand years would make one
hundred and twenty thousand.
  If then it be admitted, that an equal amount of
caloric  is removed by thousands of hot  springs, it is
evident that such an enormous loss, if not compensated
by the waters of the ocean, (which receive their tem-
perature from the sun,) would  cause a sensible dimi-
nution  of the internal heat of the globe, and conse-
quently, of its volume.   But it is acknowledged by
Fourier, Laplace and Arago, that the temperature of
the earth has not varied  the one three-hundredth of
a degree in two thousand years.   This conclusion was
deduced from the fact, that the length of the day has
not diminished  perceptibly since  the  time of Anaxa-
goras, which, it is maintained, must have  been the
case, had any diminution of the earth's volume taken
place.
  With the exception of Mr. Lyell and Dr. Daubeny,
nearly all geologists of the present day have embraced
the hypothesis  of a  central fire,—maintaining that
the superficial  crust of the earth is  supported  by a
mass of incandescent lava.   Baron Fourier supposed,
(for he certainly never proved it,) that the earth was
originally projected in a  state  of fusion  or of incan- 
378      ANALOGIES BETWEEN VOLTAIC ACTION
descence into  the planetary space,—the temperature
of which he estimates at about —58° F., due to radia-
tion from the sun and fixed stars.
  By a  long  and  laborious series  of  mathematical
investigation, he  arrived at the conclusion "that the
earth, once heated to any temperature whatever, and
thus plunged into a colder medium than itself, Avould
cool no more in 1,280,000 years, than a  globe of a foot
in diameter composed of the like materials, and placed
in the same circumstances would in a second of time,
—that is to say, in this immense time, no appreciable
variation would  take  place."  (Ann. de Chim. et de
Phys. October, 1834.
  The absurdity  of supposing that " all the caloric of
the earth below  the invariable stratum (which does
not extend much beyond one hundred feet below the
surface) comes  from a  central fire,"  is  too obvious to
require a serious refutation.
  If there have been two thousand volcanic eruptions
every century, according to the estimate of Mr. Lyell,
it would give 25,600,000 eruptions in 1,280,000 years:
yet the  temperature of the  globe has  not sensibly
diminished in that time according to the estimate of
Fourier.  But  if 25,600,000  volcanic  eruptions, to-
gether with several hundred thousand times as many
hot springs, had proceeded from a central fire, the re-
duction of the earth's temperature  must have been
enormous.  It  is therefore evident, that the  Avhole
theory is not only hypothetical, but incompetent to
explain the phenomena.
   There is nothing so  remarkable in the natural his-
tory of our planet,  as the great revolutions of climate 
AND SUBTERRANEAN  CHEMICAL  FORCES.     379
and organic life which it has undergone  during the
countless ages of the past.  The most fertile imagina-
tion  never conceived anything  so  wonderful as the
varied scenes which the  surface of the earth has ex-
hibited during different epochs, before it was inhabited
by man or any of the higher orders of animals.  The
rationale of these mutations is by far the most com-
prehensive and important problem in geology;  for it
involves the whole  theory of organic  life, and its im-
mediate relation to  the vast science of physical astro-
nomy.  The leading facts hitherto discovered may be
reduced to the following general propositions:—
  1. That throughout the northern hemisphere, from
the shores of the Mediterranean to the north of Eu-
rope and Asia, and from  the southern United States
to Melville Island, in lat.  75 N., the secondary forma-
tions are  filled with the fossil  remains of plants and
animals, which could have existed only in an uniformly
warm climate, analogous to that of our present tropics.
   2. That at different epochs, the land and sea were
inhabited by totally different orders, genera and species
of organized beings, which successively arose, flourished
for a time and then gradually passed away, leaving
only their  petrified  remains as a lasting record  of
their existence.  A  similar doctrine seems to have
prevailed among the ancient Persians, Avho maintained
that "the earth had been seven times replenished with
beings different from man, and seven times depopu-
lated,"  as Ave  are  informed by the  Rev. Mr. Faber.
 (Pagan Idolatry, vol.  i.)
   3.  That the  more ancient the formations, the more
simple are the organisms they contain, and the more 
380          REVOLUTIONS OF ORGANIC LIFE.
unlike any which  now  inhabit  the earth,*—until we
arrive  at  the newer secondary, in which  have been
found a few birds and marsupial remains.
   4.  That during the uniformly elevated temperature
which  prevailed in  the middle and higher latitudes,
there was a corresponding uniformity in the zoological
and botanical character of the earth, from the equator
to the  polar regions.f

  * For example, from the commencement of the transition to the
termination  of the coal  formation,  (supposed  to represent  three
subdivisions or geological epochs,) the sea everywhere abounded
with encrinites, polypi,  terebratulae,  trilobites, orthoceratites and
other testacea, with a few species of strange fishes, which seem to
have been the only vertebrated  animals then existing.   But all of
these  passed away, (unless we suppose, what has  not yet been
proved,  that they underwent a gradual  change under the influence
of a different climatic condition of the earth,) and gave place to
animals wholly different from any that have existed since the newer
secondary eras, such as the huge icthyosauri, plesiosauri, pterodac-
tyli, turtles and other reptiles.   As we advance toward the present
epoch, we find in the older tertiary formation, the palseotherium,
the anoplotherium and  remains of cetacea resembling the manati.
These also  passed away, and  were succeeded by a still greater
variety  of warm-blooded animals, some of which are represented
by living species ;  such as the elephant, rhinoceros, hippopotamus,
fragments of the ape and several species of the feline  genus; to
which may  be added  the dinotherium, the megatherium, the gi-
gantic  mastodon and the elasmotherium, (a  strange quadruped
resembling both the horse and rhinoceros,) all of which belonged
to the newer tertiary epoch, and  which have also long since been
numbered with the myriads of extinct animals.
   f For example, nearly all  the fossil plants  hitherto  discovered
in the  older formations  consisted of ferns, coniferae, equisetaceae
and cycadese; which in all, comprised only about five hundred spe-
cies, that presented very little diversity of form.  It is even as-
serted by the most intelligent botanists who have carefully examined 
THEORY OF MR. LYELL.
381
  In his recent excellent work on geology, Mr. Lyell
refers all the past revolutions of organic life to changes
of climate, and the latter to geological causes alone;
such as the gradual shifting of sea and land, brought
about  by  the agency  of volcanos,  earthquakes,  hot
springs,  currents and waves of the ocean, the corrod-
ing action of rains, rivers, springs and chemical decom-
position.  But if we admit Avith  Mr. Lyell, that  the
greater  part of the dry land noAV scattered over the
northern  hemisphere,  may have  been formerly con-
fined within the  tropics, and the mean temperature of
the whole earth  thus elevated 20° or 30°, as he main-
tains,  it is still evident,  that  the polar regions would
be excluded from the sun several  months in the year,
during Avhich time  all vegetation would be arrested.
Dr. Lindley observes, that "in the present condition of
the earth's axis,  the polar regions must have been al-
Avays  several months in the year exposed to darkness;
 a condition in which no plants can exist."  Yet the

 the subject, that for  a long period, during which the climate of the
 middle latitudes seems to have exceeded the present temperature
 of the tropics, cycadeae alone formed about one-third of the entire
 Flora; whereas they now constitute only one two-thousandth of
 the whole.  But in the present diversified condition of the earth,
 as regards temperature, it contains about one hundred thousand
 species of plants, and above five  hundred thousand species of ani-
 mals.  It would therefore appear that diversity in the generic and
 specific character of organized bodies, depends chiefly on varieties
 of climate and season, which differ in all the higher latitudes, and
 owing to the influence of local causes, are scarcely ever exactly
 alike, even in the same latitudes, as will be shown in the first chapter
 of book v.  This subject opens a vast field of inquiry to those phy-
 siologists who may be disposed to investigate the origin of organic
 species. 
   382      INFLUENCE OF ASTRONOMICAL CAUSES.

   older formations around Baffins Bay abound with tro-
   pical plants in the fossil state. (Fossil Flora, preface,
   p. xxi.)   It is therefore evident, that such a climatic
   condition of the earth  would be wholly incompatible
   with the existence of a tropical vegetation,  which is
   known to require a  mean temperature of about 80°
   throughout the year.
     Among all the causes  which modify the temper-
   ature of our planet, the most influential by far is the
   obliquity of the  earth's axis.   In reality, this condi-
   tion determines  chiefly the vast difference  between
   the climate of the tropical, temperate and frigid zones,
   together with all the varieties of season.   The ques-
   tion therefore naturally arises, whether all the great
   changes  of climate which the  earth has undergone,
♦   may not have been owing to modifications of the same
   cause, such as variations in the inclination of its axis,
   or even  a  gradual transposition of the equator and
   poles ?  In support of this natural view of the subject,
   it may be observed, that the successive generation and
   extinction of tropical plants and animals in the higher
   latitudes, would  seem to require  the repeated  occur-
   rence  of such  astronomical  changes, which,  in their
   turn, afford a complete explanation of all  the phe-
   nomena.  And that such changes are not inconsistent
   with the laAvs of nature is evident from the various
   degrees of inclination in the axis of different planets.
   Some astronomers have maintained, that the axis of
   Yenus is inclined to her  orbit 75°.  Should this  be
   actually  verified  by future observations  it will follow,
   that her  polar circle extends into the tropics, Avithin
   15° of the equator, and that her tropics extend to the 
         INFLUENCE OF ASTRONOMICAL CAUSES.      383

frigid zone, within 15° of the poles, so as to cause the
annual extremes of winter and summer from the tro-
pical to the polar regions.
  It has been often asserted by writers on astronomy,
that great changes in the planetary inclinations would
be inconsistent with the stability of the system,—as if
all the operations of the universe were not maintained
by unceasing changes and revolutions.  But, as Mr.
Whewell observes, " the  cause of perturbation has the
whole extent of time to work  in," there is reason to
believe, that in  the progress of long astronomical
cycles, every part of the earth has  successively been
exposed to a vertical sun, and  that such changes are
absolutely essential to the conservation of the system
in its existing  state.  For if the  equatorial  protube-
rance of  the planets be owing to the greater amount
of light which  falls upon the  tropics than upon the
higher latitudes, it is obvious that they would in time
lose their present spherical forms, by which  their ro-
tary motions would be  deranged,—unless prevented
by a gradual transposition of  the  equator to higher
latitudes, or even to the  polar circles.   And that such
a transposition has actually taken  place, is  strongly
corroborated by  the high and uniform temperature
which prevailed  throughout the  middle and higher
latitudes of the northern hemisphere when it was the
abode of tropical plants and animals.
  Nor is it less obvious, that if the inclination of the
earth's axis should go on augmenting from 0° to 40°,
there would  be such a general  refrigeration, as Avould
destroy nearly  all  the  pre-existing  organisms of the
middle latitudes,—when the mountain valleys wTould 
384              THEORY OF M. AGASSIZ.
be filled  with ice, perhaps  to  the level  of the sea, as
in Greenland, Spitzbergen and the southern polar con-
tinent.  In short, there would be what has been called
the  Glacial  Period  by  Dr. Louis Agassiz, Avho  has
traced  the evident marks  of moving glaciers on the
polished and scoriated rocks of Switzerland, the Tyrol,
Germany,  Scotland,  Ireland,  England  and  France.
And  they have  since been observed in  the  United
States.*
   If  we extend  our view to the solar system, we per-
ceiA'e  that floods of ethereal  matter, in  the  form of
light, are  perpetually flowing from the sun,  and keep-
ing the air,  the  ocean  and the  earth,  in a  state of
unceasing circulation—converting solids  into liquids,
gases  and vapours,  which  are  successively changed
into plants and animals.  The atmosphere is continu-
ally Avasted by oxidation, combustion and the respira-
tion  of animals.    But is it not as  constantly repro-

  * I cannot, however, agree with M. Agassiz, that  during what
he calls  the glacial  period, the whole surface of  the earth pre-
sented a vast field  of ice, from which projected only the highest
mountain ridges; nor that a cold by which every living being was
benumbed, suddenly appeared, and destroyed the  myriads  of or-
ganisms which but a moment before had been enjoying existence;
because  it is impossible to account for such " a catastrophe" in
accordance with any of the known laws of nature.   For example,
whence came all the waters required to produce a field of ice many
thousand feet in thickness ?  And what had become of the heating
power of the sun, when the earth was seized with that sudden Jit
of the ague ?  Yet there is ample proof, that immediately ante-
cedent to the existing  order of things, a climate  of polar severity
prevailed throughout  the middle latitudes  of the northern hemi-
sphere, and quite sufficient to destroy nearly all the pre-existing
orders of tropical plants and animals. 
SUBTERRANEAN CHEMICAL FORCES.        385
duced by vegetable and  animal  decomposition? and
are we not  authorized to conclude, that if the whole
atmosphere were annihilated, it would be again repro-
duced? or that if  all the waters of the ocean were
extinguished, they would be gradually regenerated by
igneous chemical agency? Wherever there is chemical
action there must  be liquids and gases generated.*
During respiration  and  putrefaction  carbonic acid is
generated, the appropriate food of living vegetation,
which returns a portion of oxygen to the atmosphere
under the influence of solar light.   During the decom-
position  of  organic matter, a portion of atmospheric
oxygen combines with its hydrogen, forming water,—
and so on through  all the endless ramifications of  na-
 ture, Ave perceive that death is only a transformation
of matter, by which the earth is perpetually renovated,
and crowned with immortal beauty.

   *  Hence the improbability of the astronomical hypothesis,  that
 the moon, Vesta and some other  planets, have no atmospheres;
 or that the atmosphere of Ceres is more than 668 miles high, and
 that of Pallas 465 miles, according to the observations of Schroeter
 and others.
25 
CHAPTER Y.
        HYPOTHESIS OF  TWO ELECTRIC FLUIDS.

  Is the electric fluid one and the same in all bodies?
or is it a compound fluid?   Each of these hypotheses
has been zealously maintained since the time of Dufay
and  Franklin.  But  the  controversy  has consisted
rather in  pointing out frivolous  distinctions in the
phenomena produced, than in tracing the fundamental
laws by which they are governed.  After a patient
examination of the facts adduced  by the British and
continental philosophers, I have not been able to dis-
cover any decisive  evidence that  there are Iavo elec-
tricities.  On the contrary, it might as well be main-
tained that there are fifty, or an  indefinite number;
for this protean agent exhibits an  endless diversity of
appearances and effects  under different circumstances,
according  to the various bodies  from which it is  ob-
tained, the mode of its  development, &c.
  It was discovered by Dufay, about a century ago,
that when glass, rock crystal, diamond, precious stones
and many other substances, were warmed and rubbed
with silk or woollen cloth, they repelled  light bodies
in their vicinity;  but that when resinous bodies were
made electric by friction  in the same manner, they
attracted light bodies which had  been electrified by
      (386) 
             HYPOTHESIS OF TWO FLUIDS.          387

excited glass.  Having caused a piece of gold leaf to
be repelled, and suspended in the air by an electrified
glass tube, and meaning to chase it about the room by
a stick of excited gum copal, he found that, instead of
being repelled  by it as it was by the  glass tube, it was
eagerly attracted.  From which  he concluded that
there were  two  kinds of electricity, residing in two dif-
 ferent classes of bodies; one of which he termed vitreous,
and the other resinous,—and that bodies charged with
either kind repel  bodies charged with the same kind,  but
attract bodies charged with the other kind.   But when it
was afterwards discovered by Dufay, that all bodies
acquired  the power of attracting and repelling  the
same substances, according to the  manner in which
they  were electrified,  he frankly acknowledged that
vitreous and resinous electricity were  only different
degrees of one and the same fluid. (Priestley s Hist, of
Electricity, pp. 43 and 412.)   Yet the doctrine of two
electricities has been constantly imputed to Dufay by
 nearly all writers on the  subject for the last seventy
 years.*
   It is said  by those who still  maintain  the doctrine
 of tAvo fluids, that if the gold leaves of an  electrometer
 are made  to diverge by means of an electrified stick
 of resin, they  will collapse on the approach of an ex-

   * It is related by Yan Marum, that the doctrine of two electric
 fluids became general in France from the fact, that M. Hauy was
 ordered by Napoleon to prepare a treatise on natural philosophy
 for the use  of the Polytechnic School, and not having time for re-
 flection, he hastily adopted Coulomb's version  of  the two fluids.
 Well might Count Oxenstiern say to his son, "Come and see  with
 how little wisdom the world is governed!" 
388
HYPOTHESIS OF TWO FLUIDS.
cited  glass tube; when  all signs of electricity disap-
pear as if annihilated.   Nothing could be more falla-
cious  than such experiments;  for I have often found,
that after the gold  leaves were  made to diverge by
excited glass, they expanded still further on the ap-
proach of excited wax, and vice versa.   The result is
evidently modified by the degree of friction employed,
and by the quantity of electricity thus disengaged.
  It was long since observed by  Dr. Watson, that the
rubber of a common electrical  machine, exhibited the
same  electricity in all respects as that which had been
produced by the friction  of sealing-wax, sulphur, rosin,
&c, and afterwards by Canton, Franklin, Beccaria and
Wilson,  that whenever two  vitreous  bodies were
equally electrified they repelled each other, but when
unequally, they attracted each  other;  and that  the
same  Avas true of resinous bodies.   Dr. Franklin also
found, that when glass globes were excited by friction,
the spark was larger and longer than when a sulphur-
ous globe was used, and made a louder noise; from
which he inferred that the glass contained on its surface
more electricity than sulphur ;  he therefore denominated
that of the glass plus or positive, and that of the sul-
phur  negative—terms which  are now in general use.
He might have added, that  positive electricity gives
larger and more divergent brushes of light than nega-
tive, on presenting a metallic point to the prime con-
ductor of a machine in action.
  It was subsequently ascertained, that whenever two
different bodies are rubbed against each other, they are
in different states of electricity—that when a glass
tube is rubbed with a dry silk handkerchief, the former 
HYPOTHESIS OF TWO FLUIDS.
389
is rendered positive and the latter negative;  but if an
insulated metal be brought near to the glass, the latter
becomes negative  and the  metal positive.   Hence it
was concluded by  Franklin, that during the action of
a common machine,  electricity is evolved  from the
rubber, and attracted by the cylinder of glass, from
which it  is  attracted by the prime conductor, and
thence to  other conducting bodies.   When amber and
the tourmaline are rubbed together, the latter becomes
plus or positive  in relation to the  amber;  but Avhen
the tourmaline  is  rubbed against the diamond, it is
minus or  negative, and the diamond positive—and so
of many hundred other bodies.
   The above facts are exceedingly important, and are
 alone sufficient to prove that positive and negative are
 only  different degrees of one and the same fluid, which
 accumulates in various proportions on different bodies,
 according to the relative degrees of their attraction for
 it.   There are no two bodies in nature which have the
 same degrees of attraction for electricity; nor are there
 any two bodies which exhibit the same electrical state
 when rubbed against each other.   It has  even  been
 found that the same bodies exhibit positive or negative
 electricity according to their  colour, or the condition
 of their  surface—that smooth glass is rendered posi-
 tive  by friction with woollen cloth,  and negative when
 made rough by grinding it with emery, all other things
 being equal.*

   * Is not the attraction of rough  glass  for electricity less than
 that of smooth glass, for the same reason that caloric escapes more
 rapidly from rough than from smooth metals? and does it not ac- 
390
HYPOTHESIS OF TAVO FLUIDS.
   It cannot be denied that the electricity of a common
machine is derived chiefly from  the rubber;  for it is
Avell known that its  quantity is  greatly increased  by
spreading  over the rubber an amalgam of zinc or tin,
the oxidation of which supplies  electricity freely,  as
in the action of a \roltaic battery; while amalgams of
silver and platinum, which do not oxidize at ordinary
temperatures,  are  of  no use.  But is it  not evident,
that if  the prime conductor receive its electricity from
the rubber, that positive  and negative are only dif-
ferent proportions of  the same fluid ?—that it accumu-
lates and becomes plus on the prime conductor, because
of its  greater attraction for  it?f—and  that whether
positive or negative, its essential  properties  are the
same under all circumstances ?  Is it not owing to the
attraction  of metals  for electricity,  that during the
concretion  of melted sulphur, chocolate, calomel and
glacial  phosphoric acid  from a state  of vapour, in in-
sulated metallic vessels, the  latter  become electrified
plus, and the former  minus?
   It was before stated, that the more oxidizable metal
in the galvanic circle furnishes positive electricity  in
relation to the less oxidizable one, which is in direct
opposition to the theory of two fluids.   M. Becquerel

cumulate upon insulated metals in greater quantities than on elec-
trics for the  same reason  that the  former  are good conductors?
(See page 183.)
  ■f* Something  analogous takes place during the action  of the
galvanic  pile.  When the battery is composed of zinc and silver,
and immersed in an acid  solution, the zinc is oxidized, by which
electricity is  disengaged, and passes to the silver, which is rendered
positive; while the zinc, like the rubber from which the electricity
proceeds, is negative. 
              HYPOTHESIS OF TAVO FLUIDS.           391

 regards it as a proof of tvvo galvanic fluids, that posi-
 tive electricity permeates imperfect conductors more
 readily than negative.  But this  is just what might
 be expected from the plus and minus conditions of the
 same agent.  In accordance Avith this view, it has been
 found that, other things being equal, the heating effect
 of voltaic electricity is in  proportion to its quantity,
 and that the heating  effect of positive electricity ex-
 ceeds that of negative.
   It  was maintained by Winterl, CErsted,  Berzelius,
 and at one time  by Davy, that heat and light Avere
 produced by the union of positive and negative  elec-
 tricity.  After what has been already offered in regard
 to the relations of caloric and electricity, it would be
 useless  to multiply arguments  against so bald an hy-
 pothesis.  It Avas afterwards shown by Sir Humphrey
 Davy himself, that  both heat  and light  are produced
 by either positiA^e or negative electricity alone, though
 he adopted the doctrine of two fluids.
   The following experiments  of De Saussure clearly
 illustrate  the  identity of positive  and negative, with
plus and  minus conditions of the electric fluid.   On
 pouring  water  into heated iron or copper vessels
 when insulated, and connected with an electrometer,
 rapid oxidation was produced, and positive electricity
evolved;  but  after the metal  became  covered over
with  a  coating of oxide,  less  electricity was disen-
gaged, Avhich Avas negative.  (Voyages dans les Alpes,
tome ii. p. 244.)
   It is also worthy of special notice, that he procured
electricity from the vapour of water without any che-
mical  decomposition—a fact which has been  recently 
392
HYPOTHESIS OF TWO FLUIDS.
controverted by Pouillet, as before stated, (page 292;)
that the evaporation of water from heated silver and
white  porcelain vessels was  attended Avith  a disen-
gagement of electricity, that was generally  positive,
but  sometimes  negative.  The same thing  Avas ob-
served on placing incandescent pure white quartz in
water.
   The advocates of the theory of two fluids explain
the phenomena of electrical attractions in a singularly
gratuitous manner.  They say that when an electrified
glass tube  or stick of Avax is brought near to light
bodies, it communicates to them the opposite electricity
from its own; and that they are brought together by
the mutual attraction of the two electricities for each
other—that when they touch the  excited  electric,
they acquire the  same  kind of electricity which it
has, and consequently are repelled. (Thomson on Heat
auel Electricity, p. 362.) It might as well be said, that
liquid metals attract the same metals when solid, be-
cause they are in opposite states of electricity; or that
the attraction of the living body by frozen mercury is
owing to the combination of the former with  positive,
and the latter with negative electricity;  and  that the
effect is  produced by the mutual affinity of  the tAAro
fluids: whereas  I have proved that the attraction of
frozen mercury,  and other  cold metals, for the living
body, is in proportion to their affinity for caloric, which
is plus in the one, and minus in the  other; and that
all such phenomena are owing to the attraction of ca-
loric and electricity for ponderable matter.
  The whole train of Dr. Thomson's  reasoning  in
favour of two fluids is founded on groundless  assump- 
HYPOTHESIS OF TAVO FLUIDS.          393
 tions.   1.  That there is no attraction between electricity
 and ponderable matter;  2.  That there is ein attraction
 between positive and negative electricity; 3. That matter
 does not repel matter; and 4. That nothing but the pres-
 sure of the ambient atmosphere prevents the escape of elec-
 tricity from bodies.  (Idem, p. 424.) Feeling some doubt
 in regard to the last position, he elsewhere speaks of
 "the unknown cause which prevents it from  leaving
 them."  (Page  431.)   Dr. Thomson  maintains, that
 "matter does not repel matter, because, in the motions
 of the  heavenly bodies,  no such repulsion has ever
 been observed,"—from which it would  seem that he
 denies the existence of a repulsive agency in nature.
 Having assumed the above premises, he adds:—"If
 matter  does not repel matter,  and if there does not
 exist any attraction or affinity between electricity and
 matter, then the Franklinian  theory of positive and
 negative electricity cannot be correct."  (Page  425, on
 Heat and Electricity.)
  In accordance with  the hypothesis, that there are
 two  electric fluids which have a mutual attraction for
 each other, it has been maintained by several writers
 on natural philosophy, that when a cloud passes over
 a mountain, or any other portion of the  earth,  it com-
 municates to the mountain, &c. the opposite electricity
 from its own, when the two fluids attract each other,
 producing a discharge of lightning.  Such is the mystic
jargon of which this  great and  beautiful science  is
 composed at the present  day.  The truth is, that, not-
 withstanding the many  new  facts which have been
 discovered within the last thirty-five years, the theory
of electricity is  far more unintelligible than it was left 
394
HYPOTHESIS OF TAVO FLUIDS.
 by Franklin, Canton, Wilson, Beccaria and Priestley;
 for they did recognize the important fact, that all the
 attractions  and repulsions produced by electricity are
 OAving to its affinity for common matter, and repulsion
 of its own particles.  Many of  its phenomena are yet
 involved in profound obscurity.  We know not Avhy
 it is,  that  Avhen an insulated oblong  conductor is
 brought near to an  electrified  body, the end nearest
 to it becomes negative,  and the opposite  end positive,
 Avhile in the centre there is no sign of electricity.  We
 do not comprehend  clearly why  the electricity of a
 large battery, or of  an  immense mass of aqueous va-
 pour, becomes concentrated into a spark or ball of fire.
   If, however, it be true, that all the forms and modi-
 fications of  this mysterious agent are  convertible into
 caloric, the  theory of both will be greatly simplified,
 and must shortly be reduced to  a very few fundamen-
 tal axioms.
   I have proved from the  most  elaborate series of ex-
 periments on record, performed by De Saussure and
 Read, that all atmospheric electricity, even that of the
 most serene Aveather, is disengaged from aqueous va-
 pour; and by the experiments of  Dalton, that caloric
 is the  true  and only cause of evaporation.  There is
 also a perpetual flux and reflux of the electric fluid,
 corresponding with the diurnal variations of temper-
 ature, and fluctuations of the barometer.  According
 to De Saussure,  it diminishes from nine or ten o'clock
 in the morning until five  or six p.m., and  increases
 until  eight, when it again decreases until  sunrise,
when it is  almost null; that is, it is most abundant
when the vapour of the air is  undergoing condensa- 
THEORETICAL VIEWS OF CALORIC AND ELECTRICITY.  395
tion, (for the same  reason that it is plus or positive
during the formation of clouds,  and during rain or
snow;) but diminishes during the heat  of  the  day,
Avhile the vapour of the air is undergoing expansion;
by which it is connected with  the  Avhole theory of
evaporation, condensation and lightning.  It is fur-
ther stated  by De  Saussure and  many  others, that
atmospheric electricity  is constantly changing  from
positive to negative, which  is also quite inconsistent
Avith the hypothesis of two fluids.
  It is only by extending our knoAvledge of nature,
that Ave  are enabled to trace an endless diversity of
apparently isolated effects  to some principle which
connects and governs them; or  to distinguish an un-
known cause  from the individual and  ever-varying
phenomena it produces. The most signal and delight-
ful triumphs of philosophy spring from the perception
of  analogies that  seem  remote  and obscure,  until
closely analyzed.   From the imperfect outline which
has been already presented of this  vast and compli-
cated  subject, it is obvious that all the  operations of
nature are so  intimately connected, that we cannot
make  any substantial  progress  in  the  discovery of
general principles without ascending to  the primary
source of all physical power.
   I have shown that nearly all the most  distinguished
philosophers, ancient and saodern, have recognized the
existence of such an agent.  It was the mP xaSapom
of  Hippocrates—the  ^ of Aristotle,—or the form
of forms,—by which  he meant  the  cause of causes—
the anlma mundi of the Romans—the archceus of Para-
celsus and Van Helmont—the materia subtilis of Des-
cartes—the pneumatical power of Bacon—the phlogis- 
 396     ANALOGIES  OF CALORIC AND ELECTRICITY.

 ton of Beccher and  Stahl—the electric fluid of Franklin,
 Priestley and Beccaria—the latent heat of Dr. Black—
 and the caloric of modern times.

       ANALOGIES OF CALORIC AND ELECTRICITY.

   It has been shown throughout the preceding portion
 of this work, that all the motive poAvers of caloric are
 resolvable into the primary and universal law by Avhich
 it repels its own  particles, and attracts those of ponder-
 able matter, with forces that vary inversely as the squares
 of the distance.
   The phenomena  of electrical attractions  and repul-
 sions are clearly  resolvable into the same law.
   It would be a  needless waste of time to bring for-
 ward the numerous proofs, that  all the forces of at-
 traction and repulsion are inversely as the squares of
 the  distance.   It has been demonstrated  by Buffon,
 Laplace, Coulomb  and other  philosophers, that the
 power of all emanations, such as light, caloric, and
 electricity in the  diffused state, are subject to the same
 law, like that of gravity.  The ringing of electric bells,
 the dancing of pith balls under an electrified tumbler,
 of paper images,  and many other similar experiments,
 performed  for the  amusement of popular assemblies,
 are referable to the above law.  When light leaves of
 gold, copper, silver, zinc, &c. are brought near to the
wire that connects the extremities of a battery in ac-
tion, or to insulated metals when  electrified by a com-
mon machine, they are attracted by them.
  When  treating  of chemical attraction,  (book ii.
chap, ii.) it Avas shown  that caloric causes  oxygen to 
        ANALOGIES OF CALORIC AND  ELECTRICITY.     397

combine with all other elements, from the slowest pro-
cess of oxidation, as in the rusting of metals, fermenta-
tion, &c. to the most rapid combustion.  Electricity
produces the same effects.   It was first observed by
Dr. Franklin, that when iron or steel wires were  sub-
mitted to a few electrical shocks, they became covered
over with a coating of rust.  Dr. Priestley observed the
same effect on  other metals; after which Cuthbertson
proved, by  a great variety of experiments, that all the
knoAvn  metals  might be rapidly oxidized by common
electricity—even gold and platinum, which are difficult
to oxidize by the ordinary modes of applying heat.
   By the attraction  of caloric for  ponderable matter,
it combines with various solids, produces their fusion,
and causes them to cohere with each  other.  By its
repulsion of its own particles, it  decomposes  oxides,
chlorides, iodides, bromides, alloys and  all other com-
pounds.
   The same is  true of electricity, which dissolves and
decomposes the most refractory bodies, such as the
earths,  alkalies, and all  other metallic oxides,  and
again causes  their elements to recombine.   In short,
there is no combination  or decomposition which may
not be effected by either caloric or electricity, when
sufficiently  concentrated, and in due proportions.
   When treating of cohesion, it was shown  that ca-
loric has various degrees of  attraction for different
bodies;  and that their conducting poAver is  in propor-
tion to that attraction,—that the lightest knoAvn solids
give out large quantities of caloric during combustion,
and are bad conductors; while metals and other dense
bodies  that evolve  much less  caloric,  are  good con- 
398    ANALOGIES OF CALORIC AND ELECTRICITY.

ductors,—and that, other things being equal, the con-
ducting power of metals is augmented in proportion as
they are deprived of caloric.
   It is also known that the lightest solids, cceteris pari-
bus, afford the largest amount of electricity by friction,
—and that they are bad conductors of electricity.  It
was further ascertained by Sir H. Davy, that the con-
ducting power of metals for voltaic electricity is dimi-
nished  in proportion to the elevation  of their  tem-
perature, (Phil.  Trans.  1821;) and I have shown that
their cohesion is diminished in the same ratio.   It is
therefore evident, that the conducting power of bodies
for both  caloric and electricity is  modified by every
alteration in the relative proportions of ethereal and
ponderable  matter of which they  are composed; and
that as a general rule,  with few exceptions, the same
bodies  are  conductors  and non-conductors  of  both.*
(See Theory of Conduction.)
   It may be  observed,  that no two series of experi-
ments, hitherto instituted for the purpose of ascertain-
ing  the relative degrees of cohesion and conducting
power  of the different metals, have  presented the
same results.   It  is however certain, that copper,
gold, silver, platinum, iron and zinc, are the best con-

  * It may be objected, that some bodies which are non-conductors
of electricity when solid, become conductors in the liquid state.
But it is doubted by Dr. Faraday whether such bodies ever do
conduct electricity without undergoing decomposition,  as he found
that, whenever they act chemically on the plates of a battery, elec-
tricity is disengaged.  Query. Is it not more probable that the
non-conducting power of such bodies in the solid state is owing to
the crystalline arrangement of their particles, as in the form of ice
or snow ? (See page 179.) 
ANALOGIES OF CALORIC AND ELECTRICITY.
 ductors  of electricity,—and it has  been shown by
 M. Becquerel, that potassium is of all others the worst
 conductor.  (Ann. de Chim. et de Phys. xxxii. 420.)
   In opposition to the simple and rational theory of
 Franklin,  Canton, Wilson and Beccaria, that elec-
 tricity repels  its own  particles, and is attracted with
 various  degrees  of force by different species of pon-
 derable matter, it  has been maintained  by Coulomb,
 Poisson and other philosophers, that there is no affinity
 between electricity and ponderable matter,—and  that it
 Is confined to the surface of bodies by the pressure of the
 atmosphere.
   Nothing could  more clearly illustrate the tendency
 of mankind  to  take things upon  trust,  and Avithout
 examination, than the general adoption of this partial
 and erroneous doctrine by numerous modern writers
 on physical science.   It seems  to  have  been founded
 chiefly on  the fact, that electricity escapes from the
 surface of bodies more readily in vacuo than under the
 pressure  of the atmosphere.   But it has been demon-
 strated by Morgan, Cavallo,  Ampere and Sir  Hum-
 phrey Davy,  that electrical attractions and repulsions
 take  place in vacuo as well as  under the pressure of
 the atmosphere.  (See  Philosophical Transactions  for
 1822, where the experiments of Davy are recorded.)
   It is very true that electricity, in the diffused state,
 moves more  freely over the  surface  of  bodies  than
 through  their substance;  and that  atmospheric air,
 Avhen perfectly dry, assists in preventing its escape
from  other bodies,  because it  is a bad conductor.  It
was before stated, that an electric spark expands in an
exhausted receiver into a diffused lambent light; and 
400     ANALOGIES  OF  CALORIC AND ELECTRICITY.

Mr. Harris of Plymouth, has proved that the striking
distance of the  spark varies inversely as the density
of the air through which it passes, the charge being
the same.  But these experiments afford no proof that
electricity is not attracted by ponderable matter.  The
important practical application of metallic conductors,
as lightning rod's by Franklin, was founded wholly on
their attraction for the electric fluid.  It never entered
into the imagination of that eminent philosopher, that
flashes of lightning  are determined to the earth and
its conductors by the pressure of the atmosphere.
  That electricity, when concentrated, is  capable of
passing through the substance of bodies, was proved
seventy years  ago by  M. Jallabert of Geneva, who
found  that it might be readily transmitted through
metals, covered over with pitch.   (Priestley s Hist, of
Electricity, p. 127.)   But the same thing is  fully de-
monstrated by the fusion of metals, rocks, gems and
all other bodies by lightning and other forms of elec-
tricity, and by the transmission of shocks through liv-
ing bodies.
  Notwithstanding the mathematical  demonstrations
of the Coulombian theory, it is founded on hypothetical
and false assumptions; and, when applied to the ex-
planation  of  natural  phenomena, is  evidently of  no
practical value.   It  is therefore  not  surprising, that
Sir John Leslie should have  observed, in his History
of  Physical Science, that it deserved  the Dunciad.
   To  trace the analogies  of  caloric  and electricity
through all their diversified manifestations would be
an endless task.  They are both disengaged from all
bodies by friction, pressure,  percussion and by chemical 
ANALOGIES OF CALORIC AND ELECTRICITY.     401
action; but vary according to the manner in which the
operation is performed.  It was proved by Becquerel,
that the  intensity of electricity evolved by pressure
was in proportion to the force employed; from which
it would  seem, that, Avhen the particles of bodies are
forced  nearer together suddenly, a portion of their
latent caloric is disengaged in the concentrated form.
  The greatest of all  mysteries  connected with elec-
tricity is the protean  poAver by which it assumes an
endless variety of forms, under different circumstances.
We have seen that voltaic electricity, evolved from a
single  pair, or from a  few series of large plates, with
an Interposing  liquid,  differs greatly from that which
is obtained  from a battery composed of the same ma-
terials, but  consisting  of a great number of  smaller
plates; and  the latter is equally different from the
 electricity of the atmosphere, or that procured from a
 common machine.  In fine,  these differences  are  as
 numerous  as the  circumstances are various under
 Avhich the phenomena take place.  What then?^ Shall
 Ave  assume the existence of an indefinite variety of
 electric  fluids?   Nothing could be more in opposition
 to  the fundamental laws by which they are governed.
   It has been  supposed that electricity is far more
 subtile and refined than caloric, because of the ease
 and rapidity of its passage through metals and other
 conductors.   This is a partial view of the subject;  for
 caloric  passes freely  through  mica, glass and  some
 other transparent  bodies, which arrest the  electric
 fluid when  in the  concentrated form.   Nor i^ it true
 that glass is altogether impervious to the electric fluid.
 Compared with lac, it may be regarded  as a conductor;
                          26 
402
MECHANICAL AGENCIES OF
for electricity produces  attractions  and  repulsions
through  glass.  If  a small  pith  ball  be suspended
within a glass jar by a fine silk thread, it Avill  be at-
tracted by an electrified glass tube on the outside.  It
is  further stated by Dr. Priestley, that  electricity es-
capes through some species of glass, like water through
a sieve.  (History of Electricity, p. 592.)   Besides, if a
metallic wire be inserted into a glass receiver exhausted
of air, and  connected Avith an electrical machine in
action, a stream of electric light  is  seen  to proceed
from the Avire in a straight line to the plate of the air-
pump ; but  if a conductor be presented  to the side of
the glass, the electric light is drawn toward  it, which
sIioavs that  electricity is attracted through glass.  The
same thing  is true, to a certain extent, of sealing-wax,
as shown by Dufay a hundred years ago; it is there-
fore evident, that all bodies are permeable to this sub-
tile ether.
   The rapid passage of electricity through conductors,
and its power of communicating a shock, are the most
remarkable properties which  distinguish it from ca-
loric.  But  this difference A7anishes when we perceive
that it is only electricity of a peculiar tension or con-
centration that exhibits these powers, and that many
of its forms produce no such  effects.   That the pas-
sage of electricity through  living bodies, without pro-
ducing the  sensation of  heat, is chiefly owing  to its
velocity,  would appear  from the fact,  that a  spark
from  a Leyden  battery may be passed  through gun-
poAvder Avithout igniting it, unless retarded in its pro-
gress by an imperfect conductor, such as water, Avhen
it  inflames gunpoAvder.   When electricity of high ten- 
CALORIC  AND ELECTRICITY.
403
sion passes without interruption  through conductors,
it does not heat them; whereas,  if they be too small
to allow its free passage, or if the conductors be im-
perfect, they are heated, fused and volatilized.  The
same is true of solar caloric, when concentrated by a
large  burning-glass;  for it  passes through water and
other  transparent  substances without  heating them;
but if made to act on bodies that obstruct its passage
through them, they are fused, ignited and dispersed in
the form of flame.
  It has been a leading object of this inquiry to show
how partial and erroneous is the  prevailing notion,
that the agency of caloric is limited to the production
of temperature, liquefaction, combustion, &c.  It is in
its power of producing motion, and of maintaining the
harmonious action of all the elements, that we are to
seek for the laws which connect it with the science of
universal nature.
  We have  seen  its mechanical  agency in  steam;
which has given to man a poAver over  matter superior
to all the achievements of ancient or modern times,
—in gunpowder and other fulminating compounds,—
in volcanic eruptions,—and in that process of evapo-
ration by which the rains of heaven are distilled from
the ocean, transported through the atmosphere, and
deposited in fertilizing shoAvers,—that it holds together
the atoms of  solids with inconceivable force, and  dis-
aggregates them with equal force,—in  short, that it is
the executive principle in creation.
  The  mechanical  agency of  electricity is equally
striking, though less constantly exerted.   It over-
comes the cohesion of all bodies, Avhether simple or 
404            MECHANICAL AGENCIES OF

compound, and  acts equally on  particles or masses.
It transports the  different  elements of bodies to op-
posite poles of  the battery.  Acids may  be conveyed
through alkalies, and alkalies through acids, to their
respective poles without neutralizing  each other.  It
has been  shown by M. Fusinieri, that electric sparks
issuing from the brass conductors of ordinary machines
contain incandescent  particles  of zinc  and copper.
When draAvn from silver,  they contain impalpable
particles of silver,  that  may be seen with a good
microscope, and discovered by chemical tests.  When
a spark issuing from a knob of gold passes through a
plate of silver,  a circular spot or stratum of gold is
seen on the surface of the  plate where the spark en-
tered  and emerged, which  soon volatilizes and disap-
pears; and  when  it issues from  a  ball of copper,
similar  phenomena  occur.  The spark also acquires
new particles from the metal through which it passes.
In all such cases,  the colour of the spark depends on
the nature of  the metal thus  ignited—from Avhich
Fusinieri concludes, that  electric light is  always com-
bined with  ponderable matter;  and  that lightning
OAves  its luminosity and  odour to the combustion of
such matter.  (Giornale del Pavia, 1825.)
  Dr. Priestley  relates, that when the steeple of St.
Bride's Church in London was torn by a flash of light-
ning, it acted as an elastic fluid; and that its effects
were  exactly similar to what would  have been  pro-
duced by gunpowder pent up in  the same places and
exploded.
  It is also  related  by Mr.  Lyell, on the  authority of 
CALORIC AND ELECTRICITY.           405
Dr. Hibbert, that at Funzie, in Fetlar, one of the Shet-
lands, about the middle of the last century, a rock of
mica schist, one hundred  and five feet long, ten feet
broad, and in some places four feet thick, was torn in
an  instant, by a flash of lightning, from its bed, and
broken into three large and several smaller fragments.
One of these, twenty-six feet long, ten feet broad and
four feet thick, was simply turned over.  The second,
Avhich was twenty-eight feet long, seventeen broad and
five in thickness, was  hurled  across a high point, to
the distance  of fifty yards.   Another broken mass,
about forty feet long, was thrown still farther in the
same direction, quite into the sea, while many smaller
fragments were scattered up and down. (Principles of
Geology, vol. i. p. 260.)
  A similar effect of lightning wras related, not long
since, in the German papers.  It was stated that an
enormous rock had been  removed from the bed of a
stream in Prussia, by  boring  a  deep hole in it, into
which  was inserted a bar of iron tAventy-eight feet
long.   The consequence was,  that soon  after, during
a thunder-storm, the  lightning  was  directed to the
bar, and  the rock shattered to fragments.  It would
be useless to dwell on  the  mechanical effects of elec-
tricity  in  rending rocks, trees, buildings, &c, were it
not that  there are still many  writers on natural phi-
losophy, who affect to doubt its materiality; and some
Avho resolve it into undulations of the unknown ether,
—as if it could not be bottled  up in a Leyden battery
like water or any other material fluid,—or as if it did
not act upon the sense  of sight, hearing, feeling, smell- 
406          EXPERIMENTS OF DR. FARADAY.

ing and even of taste, like other material agents;  and
as if undulations were capable of causing horizontal,
vertical and rotary motion.
   It was  shown in  book ii. chap. ii. that, other things
being equal, the chemical effects of caloric are uniformly
In proportion to its absolute quantity.
   It has also been shown by Davy, Children and many
other modern  experimenters,  that both the  heating
and  chemical powers of voltaic electricity are in direct
proportion  to its quantity; and that  the quantity
evolved is  in proportion to the amount of chemical
action;  corresponding with  the  universally acknow-
ledged fact  that the  heat of combustion  is  in  the
same ratio.
   Without  deciding wmether electricity be a material
agent, sui generis, or mere motion of ordinary matter,
Dr. Faraday maintains, that " the atoms of matter are
in some way endowed or associated with  electrical
powers, to which they owe their most  striking quali-
ties,  and among others, their mutual chemical affinity,"
—and he has endeavoured to ascertain experimentally,
the  absolute amount of  this agent, motion or power,
which is associated with the particles or atoms of mat-
ter.  He found  that uone grain of water required an
electric  current to be continued for three minutes and
forty-five  seconds to  effect its  decomposition; Avhich
current was powerful enough  to retain a  platinum
wire ik of  an inch  in thickness, red hot in the  air,
during  the  whole  time."   He  therefore concluded,
that an equal  quantity of electricity is employed in
holding the  particles of one grain of water  together;
and that it is probably equal to a very  poAverful flash 
            EXPERIMENTS OF DR. FARADAY.         407

of lightning. (Experimental Researches  in Electricity,
sixth series, Phil.  Transactions, 1834.)
  He adds, in  another section, (873,) that "the che-
mical action of a grain of  Avater upon  four grains of
zinc, can evolve electricity equal in quantity to that
of a powerful thunder-storm."
  If this  inference were Avell founded, the chemical
action of a pound of water upon four pounds of zinc,
would afford as  much electricity as many thousand
thunder-storms,—each of Avhich is often attended with
from  twenty to fifty or more  flashes of lightning;  so
that if the doctor should devise a mode of disengag-
ing it in the concentrated  form and in rapid  succes-
sion,  his experiments  would eclipse the  thunders of
Jove.
   But this  is not the climax of modern discoveries:
for if we are to credit the account of Professor Ritchie,
"Dr. Faraday  has  found from a recent experiment
that,  by the  action of electricity on a copper Avire, as
much light was given out in the course of a few days,
as could be emitted from the sun in a year." (Records
of Science, vol.  i.  p. 315.)  And  that this miraculous
story was not intended as a satire, would appear from
the gravity Avith which Dr. Ritchie adduces it " as a
strong argument in favour of the  undulatory theory
of light,"—of which he was known to  be a strenuous
advocate.  Nor is it easy to comprehend  the philo-
sophy of Dr. Faraday when he says, that "gravitation
is a certain  property of matter, dependent on a cer-
tain force, and it is this force which  constitutes the
matter." (Phil. Mag.  1844.)  At the time this neAv
definition of gravitation and matter appeared, a mecli- 
408
ELECTRIC LIGHT.
cal gentleman of London was asked his opinion of its
meaning, to Avhich he frankly  replied  that  he "did
not profess to understand it," adding, hoAvever, that
" Dr. Faraday  doubtless  understood himself."  But I
must return to my subject.
   Like caloric, we  have found that electricity  fuses the
most hard and refractory bodies.  As an  example of
this, we  are informed by Becquerel, on  the authority
of Dr. Fiedler, that in  eastern  Prussia and Silesia,
large glass tubes  are frequently found in banks of
sand, from  twenty to forty feet in length, formed by
the sudden fusion of silicious  matter  by flashes of
lightning; and, as  might naturally be supposed, that
the inner surface of these fulminary tubes is smooth,
while the outside is rough.  In regard to the  mechan-
ical  effects of lightning  in rending  trees, displacing
large rocks  and perforating the walls of buildings,
the community is generally more or less informed.
   Again, like caloric, electricity expands cdl bodies Into
flame or light.   But Sir I. Newton, and after him Sir
H. Davy, defined flame  as gaseous matter raised to a
red or white heat:  from which it would  seem that
they both  regarded flame as a solution of ponderable
matter.  And I have already shown that all  bodies
may be converted into light, whether by heat or elec-
tricity; and that its colour  varies  according to  the
nature of the  ponderable matter employed;* that

  * Much additional information might be obtained on  this im-
portant subject, by submitting  all the elements of ponderable mat-
ter to the  agency of voltaic electricity, separately in succession;
and by analyzing their light with a prism, or by causing it to pass
through differently coloured transparent media. 
CAUSE OF MAGNETIC POWER.
409
potassium, strontium, lithium, boron  and some other
bodies, burn with a red light; chloride of sodium, with
an orange light; oil, tallow and resins,  with a yellow
light;  hydrogen and  some others, blue light; and
iodine, violet light,—but that when different elements
are burned  together, the result is a  compound light,
A\rhich may be decomposed by a prism into different
primitive colours like the solar rays—in short, that
there is no  essential difference betAveen electric light
and that of ordinary combustion,—and that electricity
is never luminous or visible, except  when  in  a state
of combination with ponderable matter, as maintained
by Fusinieri.
   Since the discovery of CErsted, that a metallic wire
which connects the extremities of a voltaic battery in
action, is capable of deflecting a magnetic needle placed
near it from its ordinary position; and of  Davy and
Arago, that it is capable of attracting iron filings dur-
ing the passage of an electric current through it, phi-
losophers have seemed to suppose  that the production
of  magnetic effects was a peculiar  and  distinctive
attribute of electricity.   But if it were established,
that  electricity is  a distinct  fluid,  sui generis, it  is
nevertheless demonstrable, that caloric is  capable  of
producing magnetic phenomena in a still more remark-
able and  universal  manner—and that electricity  of
high  tension, which  produces a shock,  and darts
through metals with  the greatest velocity, produces
very feeble and partial effects on the  magnetic needle,
during  its passage  through a multiplying Avire.   It
was first remarked by Davy, that the magnetic influ-
ence  of a  voltaic current  was in proportion  to the 
410
MAGNETIC EFFECTS OF
heat deAreloped in the wire connecting the extremities
of  the  battery.  (Philosophical  Transactions, 1821.)
And it is' now universally known, that batteries com-
posed of a feAv large plates of zinc and copper, or even
of a single pair of plates, are the best adapted for ex-
hibiting  magnetic phenomena—in fine, that the mag-
netic power of voltaic electricity is proportional to the
quantity evolved, and inversely as its tension or power
of communicating  a  shock—that  thermo-electricity
which  affords none  of  the usual  signs of  common
electricity, such as diverging the  gold  leaves of an
electrometer and passing rapidly through conductors,
deflects a delicate magnetic needle.   It was long  since
observed by M. CErsted, that common electricity passed
too rapidly through metallic Avires to affect the needle
—an hypothesis which has been confirmed by M. Col-
ladon of Geneva, who found that when the wire was
covered with  three  folds  of silk,  (which must  have
retarded the velocity of the electric current through
it,)  the needle was deflected as by a current of Aroltaic
electricity.  .
  The most important  application  of Oersted's  dis-
covery was the invention of what has been termed an
electric multiplier or galvanometer, by M. Scrnveigger of
Halle, which has  been  variously  modified by other
philosophers.  Before the invention of this beautiful
instrument, a prepared frog was considered the  most
delicate test of galvanic electricity.  But it has  been
found, that  the  multiplier is not only a far nicer test
of electricity,  but that  it is also the most delicate
thermoscope ever invented—that one fiVe-hundredth
part of a degree of Fahrenheit's thermometer produces 
CALORIC AND ELECTRICITY.
411
a sensible movement of a small needle  suspended by
a fibre of silk.  From Avhich it folloAvs, that magnetic
phenomena are not confined to the action of electricity,
but also result from the agency of caloric in quantities
too small for measurement by any other test.
   It is, therefore, not  a little surprising, that when
Dr. Faraday offered as a proof, that all the varieties
of electricity are essentially the same, because they all
produce magnetic effects, that he did not recognize the
identity of caloric and electricity.
   Guided by the  general fact discovered  by GErsted,
that a magnetic needle  placed over the Avire connect-
ing the poles of a battery in action  has a tendency  to
arrange itself at right  angles to the conducting wire,
Schweigger covered a  common brass Avire Avith silk
thread, for  the  purpose  of insulating it.   This wire
was then Avrapped  round a piece of wood, 50, 100  or
200 times.  When its two extremities were connected
Avith the poles of a battery in action, the galvanic cur^
rent passed through all the windings of the Avire, by
which  the magnetic effects Avere multiplied with every
turn of the wire; so that Avhen a magnetic needle Avas
suspended in  the  middle of the hank of Avire, it was
placed at right  angles to it.   In  this way the power
of the multiplier was made to detect, not only  minute
portions of electricity that  could not be otherwise ap-
preciated, but the smallest  changes of temperature,  as
before observed*

  * It was also by wrapping a piece of soft iron, bent in the form
of a horseshoe, with insulated copper wire, and connecting its ex-
tremities with the poles of a galvanic battery, that Professor Moll,
of Utrecht, was enabled to convert it into a temporary magnet of
great power. 
412
MAGNETIC EFFECTS  OF
  By an improvement of this important instrument,
MM. Nobili and Melloni were enabled to  detect the
heat of phosphorescent wood, dead fish, living insects,
and that of the different coloured rays of the  solar
spectrum.  But it Avas  previously discovered by Dr.
Seebeck, of Berlin, that when a circuit is formed  by
soldering together two metals, and applying the heat
of a lamp  to one  of the junctions, a  needle placed
Avithin it was deflected  from the magnetic meridian,
and placed at right angles to the metals forming the
circuit.   It was afterwards found by Dobereiner, that
the heat of the hand was sufficient to cause a deflec-
tion of the  needle, when applied to the junction of the
tAvo metals—and by others, that the  same effect was
produced by  applying ice, ether, or anything which
alters the temperature in one part of the circuit from
that of  the rest.  M. Becquerel found, that when one
end of the  multiplying wire was heated and brought
in contact  with the  other end, the  needle  was de-
flected.   Hundreds of similar experiments might  be
adduced, all of  Avhich demonstrate the agency of ca-
loric in producing magnetism, Avhere there is no sign
Avhatever of electric  tension; and  that the magnetic
needle is a true  test of the smallest quantities of caloric
that have ever  been measured.
  Some of the  most delicate experiments on record
Avere performed by Dr. Locke, of Cincinnati.  By in-
terposing one-quarter of a grain of antimony between
the two copper  wires of a multiplier, and applying the
warmth of his finger, the needle was deflected 22°.  In
another experiment,  one of the copper wires was laid 
CALORIC  AND ELECTRICITY.
413
upon the other, without the interposition of any other
metal, and the warmth of the hand applied as before,
when the needle was deflected 6°.  The same results
were obtained by substituting the Avarmth of the breath
instead of that of the hand.  The temperature of the
room in which the experiments were made was 65° F.
(American Journal of Science, April, 1834.)
  But  the most decisive proof that caloric and elec-
tricity  are only modifications of one  and  the  same
agent is, that they are mutually convertible into each
other;  and that the electric fluid obtained from  a per-
manent natural magnet, fuses, volatilizes and ignites
charcoal, metals and other solids, like ordinary caloric.
  From a general review of the foregoing chapters, the
folloAving conclusions have been deduced:—
  1. That the latent caloric of aqueous vapour  is the
true and only basis of lightning.
  2. That the latent caloric of liquids  is the basis of
voltaic electricity in all its various forms.
  3. That they are both governed by the same uni-
versal law of attraction for ponderable matter, and re-
pulsion of their own particles.
  4. That the essential properties of positive  and
negative electricity are  the same under all circum-
stances.
  5. That when metals are made red hot by elec-
tricity, Avhether it be disengaged from a galvanic bat-
tery, a common machine, or from a magnet, it imme-
diately  loses its peculiar  power  of darting  through
conductors and producing a shock, being transformed
into caloric, Avhen it excites the  sensation of heat, and 
414
GENERAL CONCLUSIONS.
converts solids into  liquids, vapours and gases, Avhich
present the same properties as if generated by the ac-
tion of ordinary caloric.
  6. That if caloric and electricity be not modifica-
tions  of one  agent,  and the cause of  all mechanical
and chemical action, the whole of modern science is a
mere  chaos of contradictions. 
BOOK   IV.
                  CHAPTER  I.

                        LIFE.

  "First, then, if any one think that the secrets of nature remain
shut up, as it were, with the seal of God, and by some divine man-
date interdicted to human wisdom, we shall address ourselves to
remove this weak and jealous notion; and, relying on simple truth,
shall bring the inquiry to this issue, not only to silence the howl of
superstition, but to draw religion herself to  our side."—Bacon.
  "In physiology, what a vast advance would that philosopher
make, who should establish a precise, tenable  and consistent con-
ception of life !"—Whewell.

  The animating principle, whether considered in a
theoretical or practical point of view, is the most im-
portant problem  that ever engaged the  attention  of
mankind;  for it connects all that is profound and fas-
cinating  in  physics,  with  the science of preserving
health and prolonging life. •  Never can  the healing
art take its appropriate rank among  the exact sciences,
until the cause of vital force and animal motion is dis-
tinguished from the operations which it produces; but
must remain, as in all the  ages that are past, a mere
collection of empirical rules.   If it be true that every
deviation from health is immediately connected with
                                            (415) 
416          OBJECT OF  MEDICAL SCIENCE.

some derangement of the vital principle, there cannot
be a doubt, that a clear comprehension of what  it is,
and of the laws by which it operates, would do more
to meliorate  the condition of mankind, than all the
systems that have been  invented from the age of Hip-
pocrates to the  present time; because  it would lead
not only to a certain  method of curing diseases, but,
what  would  be of vastly greater consequence, the
theory of life AATould  become intelligible  to  all; and
its chief glory would be the prevention rather  than
the cure of maladies.
  The whole object of medical science  is to regulate
the forces of  life—to  increase them when and Avhere
they are deficient—to restrain them when excessive—
and to  restore their natural  balance  Avhen deranged.
But how can  we know the best means of maintaining
the functions of life in a healthy state, while ignorant
of the physical cause on which they all depend ?  How
is it possible to counteract with  certainty those in-
voluntary movements that constitute tetanus, hydro-
phobia, and other forms of convulsive disease, Avithout
knowing the cause of muscular contraction in a state
of health ?  How can we adopt the best treatment of
fever, inflammation, and the various  species of mala-
rious affections, without comprehending the true theory
of animal heat, and  the specific office which it performs
in the economy of  life?  Why are so many diseases
pronounced incurable, though attended with no organic
lesion, and ranked  among the opprobria medlcorum,
but that men are ignorant of what causes the heart
to beat, the stomach to  digest, the brain to think, the
nerves to feel, and our active limbs to move? 
            OBJECT OF MEDICAL SCIENCE.          417

  The  true  panacea,  or elixir of life, must not be
sought  in  specifics and  nostrums, but in a clear and
definite knowledge of the mode in which the organiz-
ing principle operates in the different functions of life.
Were it not that  all  the phenomena of nature  are
linked  together as parts of one great whole, it would
be of far higher importance to knoAV the cause of vital
motion  than that of the heavenly bodies.   Nor was it
ever  intended by Infinite Wisdom and Goodness, that
knoAvledge, so essential to the happiness of our race,
should remain a sealed book.   Life is the problem of
problems, the solution of Avhich would clear up a thou-
sand other mysteries, and banish innumerable errors
from the pages of science.   And it may be asserted
with confidence, that whoever is without faith in  the
power of well-directed efforts to resolve it, will never
accomplish much toward enlarging the empire of man
over  the numerous evils by which  he is  surrounded.
A complete knoAvledge of this subject would do more
to elevate the condition of mankind than the power of
transmuting the baser metals into gold, or even char-
coal  into the precious  diamond; for all the riches of
the earth are not to be compared with health.
   But, unfortunately for the best interests of the world,
an impression has long prevailed, that the animating
principle is something beyond the powers of the human
mind to comprehend.  That such dogmas  should have
been inculcated by the founders of narrow creeds, and
individuals interested  in keeping the people in igno-
rance, is not to be wondered at;  for in all ages of  the
Avorld, the empire  of imposture  has  been founded on
                        27 
418
VIEAVS OF THE ANCIENTS.
pretended msyteries, and upheld by ignorance.   It is,
hoAvever, melancholy to reflect, that philosophers haAe
given  countenance  to  this prejudice.   Enslaved  by
ancient errors, even the wise Socrates is said to have
thought it dangerous, unprofitable, and not acceptable
to the  gods, for men to pry into the hidden mechanism
of nature.  (Xenophon, Cyropedia, iv. 7.)   And in  an
article on Life, contained in his Philosophical Diction-
ary, Voltaire, a professed champion of free  inquiry,
asserts, that "the cause of animal motion, like that
which  determines all things to a common centre, and
the needle  to the  pole, is the  secret of  the Deity."
The general adoption of this opinion by  the instruc-
tors of mankind has done immense injury to the cause
of science, by discouraging the efforts of genius to press
forward into the undiscovered regions of truth;  while
it has fostered ignorance, indolence, and every descrip-
tion of quackery.   If  there be  any primary and effi-
cient cause of vital  force, it must be either a portion
of the air we breathe, or of the materials by which we
are nourished;  and if so, there is no good  reason Avhy
it should be more  mysterious than any of the other
phenomena  of nature.
   It was remarked by Cicero, that "to  be  ignorant of
what has been done before our time, is ever to remain
in a state of childhood;" and Lord Bacon observes, that
" whoever undertakes to investigate the first principles
of science, should  know the opinions of the ancients
concerning  the  foundations of  nature."   Coinciding
with these  views, and having often  felt the want of
such information, I shall give a brief  outline of the
leading doctrines which have come down to us from a 
VIEWS OF THE  ANCIENTS.
419
remote antiquity, in regard to the  primary cause  of
motion and life throughout nature.
  From the earliest dawn of civilization, men sought
to resolve this great problem; and there is  nothing
more remarkable in the history of mankind, than the
universal consent with which  they regarded element-
ary fire as the organizing principle;  a doctrine which,
although but vaguely understood by the ancients, was
the basis of all their physiological theories; and which,
when clearly unfolded, is destined to survive  all the
more  elaborate systems of later  ages, because it was
the result of observation, experience  and the dictates
of common sense.
  It was from beholding everywhere  the transforming
and life-giving power of the sun, as displayed in the
generation  and growth of organized bodies,  that all
the early nations of the earth were led to regard that
glorious luminary  as the  Supreme Lord of creation,
and as the  special  object of religious adoration.  In
accordance with  the views of Macrobius, it has been
fully established by the learned researches of Bryant,
Dupuis, Sir William Jones and many other distin-
guished oriental  scholars, that all the deities of the
ancient world are resolvable into the powers of nature,
and that they Avere mythological personations of the
sun or solar fire, by which everything is produced.*

  * The primitive solar worship is strikingly illustrated in the fol-
lowing passage, (translated from one  of the Vedas, or ancient Hin-
doo scriptures, by Sir W. Jones,) which  also contains the germ of
what is called the oriental  theory of emanations, referred to in a
note to page 112, book i.:■—"Let us adore the supremacy of that
divine sun, the godhead who illuminates all,  from whom all pro- 
420            VIEAVS OF THE  ANCIENTS.

   It was because the old  Sabeans  regarded fire as the
universal spirit or soul of  nature, that they Avorshipped
the sun, moon and planets, Avith all the host of heaven,
which they represented as the body of God.   It Avas
the sun that was adored as the fountain of light, life,
wisdom  and  goodness, in  ancient  India,  under the
titles of Boodh-ha  and Chreeshna; Avhich, in  the old
Celtic language of Ireland, also signify the sun, accord-
ing to Higgins.  (Anacalypsis, vol. i. p. 159.)  The Baal
and Belus of  the early Chaldeans were names of the
solar orb, which they represented  as the seven-rayed
god that fills  the  planets with life, power and har-
monic  motion.  Nor is it less certain,  that under the
various titles  of Saturn, Jove, Osiris, Vulcan, Hercules,
Molech, Elion, Adonis, Jupiter, Apollo,  Pan, Dionusus,
Esculapius and a multitude of other appellations, the
worship of fire was practised for thousands of years in
Egypt,  Phoenicia,  Arabia, Persia, Greece, Italy and
among all  the ancient tribes of Europe.*   Nor is it

ceed, to whom all must return, whom we invoke to direct our under-
standings aright, in our progress toward  his holy seat." (Asiatic
Researches, vol. i.; Works, vol. vi. p. 417.)
   It may also be worthy of notice, that in the ancient Sanskrit the
seven days of the week are called after the heavenly bodies; Sun-
day after the sun, to  which that day  was  consecrated; Monday
after the moon, Tuesday after Mars, Wednesday after Mercury,
Thursday  after Jupiter,  Friday after Yenus, and Saturday after
Saturn,  as in several of the more modern languages, including
French and Italian.
   * Under the mythological titles of Boodh and Fo, the sun has
been worshipped from the earliest ages to the present time, in the
vast empire of China, where elementary fire is still regarded as the
formative  principle, which was called Tien by the great Confucius
and his disciples.  Nor  is it unworthy of notice, that the ancient 
VIEAVS OF  THE ANCIENTS.
421
surprising, that in the  absence  of revelation, all  the
religious and philosophical systems of mankind should
have been founded on  the sensible operations of the
material universe.
  The truth  is, that all the names of the Supreme
Being in the ancient Hebrew, as in every other written
language, seem to have been  originally derived from
the operations  of the sun, light or fire, as we learn
from the researches of Bryant,  Parkhurst and  other
learned etymologists.
  Innumerable passages  might  be quoted from both
the Old and New Testaments,  in which the Creator of
all things is represented by the brightness of the sun,
and  under  the similitude of light  or  fire,  as in  the
burning bush, the lightnings of Sinai, the pillar of fire,
the visioh of Ezekiel, who beheld brightness and flashes
of lightning;  that of Daniel, to whom the  throne of
God appeared like a fiery flame;  the representation
of angels as  fiery spirits or seraphs; and the cloven
tongues of fire that appeared on  the day of Pentecost.
Persians represented light as the source of all good, and darkness
as the evil principle, which, according to Bishop Theodorus, they
termed Satana, or Arimanius.  (Enfield's Hist, of Philosophy,
vol. i. p. 64.)  We also  learn from Macrobius, that in Egypt, as
in several other oriental countries, the sun was worshipped under
the symbol of a bull, which, like the ram, the serpent and many
other animals dedicated to the sun, were regarded as sacred by the
vulgar.  And so  deeply rooted was  this superstition among the
Israelites, that they made them a golden calf in the wilderness.
We further read in the  books of the Kings, Chronicles and Pro-
phets, that under the titles of Baal, Moloch and Chemosh, the
Chaldean and Phoenician worship of the sun  was almost constantly
practised by the Jews in  groves and high places. 
422
SPIRITUALITY OF LIGHT.
There are also many other passages in the sacred writ-
ings in Avhich  the Deity is more especially described
as residing  in, and operating through  the  agency of
light or fire: "AArho dwelleth in light inaccessible and
full of glory—who is clothed with light as Avith a gar-
ment—who maketh his  ministers a flaming fire," &c.
   Whatever may be the  true interpretation  of such
language, it clearly shows how exalted were  the views
of the inspired writers in regard to the agency of light
in the work of the universe. The plain matter of fact
is, that there is  nothing in nature  so  divinely pure,
spiritual and beautiful  as  light.   By means  of this
ethereal medium, Ave hold communion with the starry
worlds, and journey  as  on the wings of imagination,
through the celestial plains.  The health and spirits
of all animated beings are awakened to reneAved energy
by the  solar rays, but  languish in  their absence, or
when intercepted by mists and clouds.  When sur-
rounded Avith  cold  and darkness,  the brightness of
fancy, like the external colours of creation, is quenched,
and all the energies of life are brought low.
   The unsophisticated language of mankind, in every
age and country, has been obviously founded on the
intuitive belief, that  fire is in some way immediately
connected with all the operations of life, sensation and
thought.  The following expressions are not  merely
metaphorical, but vivid and faithful representations of
nature, derived from experience  and observation:—
The  lamp of life, the glow of health, the warm vigour of
youth, the lustre of a beaming eye, the brightness of fancy,
the light of reason, the fire of genius, the heat of passion,
the chillness of age, and  the coldness of death,—with a 
GRECIAN MYTHOLOGY.
423
thousand others that might be adduced; which are not
less philosophically correct than poetically beautiful.
  In the mythology of Greece,  the germs of which
were derived chiefly from the traditions of a remote
antiquity, the solar  orb  was represented, under the
name of Apollo, as the god of health,  poetry and
song; or as the grand dispenser of life, and the univer-
sal  poet of nature.   The harp of Memnon,  that  re-
sponded in sweet and melodious tones to the rising
sun, was probably intended  to  represent his benign
agency in filling the world with music and gladness.
When he sheds his  beams upon  the earth the still air
begins to move and resound through the  groves with
gentle murmurs; Avhile the waves of the  sea re-echo
Avith a bolder song.   When the  sun returns  from be-
yond the equinoctial line, to recall the sleeping world
to a neAV existence, the icy bands of winter give way,
Avhen the floods leap forth and join the universal cho-
rus  of the living world.  The buds of leaves and
floAvers expand;  the fields are clothed with a verdant
carpet;  the trees with luxuriant foliage;  and we can
almost hear the  fluids  gushing through their  veins.
  The earliest teacher of art among the Greeks Avas
Prometheus, an  Egyptian, who  has  been represented
in fable as stealing fire from heaven.  But it is pro-
bable that he merely taught them the use of fire, in
the manufacture of metals, and  the other arts of life.
Cecrops, who introduced the science of agriculture into
Greece, was also a native of Egypt;  and Cadmus, who
taught the use of letters, was from Sidon.  But  the
most renowned of all the ancient pioneers of civiliza-
tion among the Greeks, was Orpheus, of Thrace, who, 
424
DOCTRINE OF ORPHEUS.
after visiting the East, is said to have instructed them
in music, poetry, religion and philosophy.   The sum
of his doctrine concerning the origin of things, as col-
lected from the fragments of hymns preserved in the
writings of Eusebius, Clemens Alexandrinus, Proclus,
Cedranus and Apuleius, and collected by M. Eschen-
bach, is, that  the  primitive seeds from which every-
thing wras produced, existed from all eternity in a fluid
and chaotic state; but that at a certain  finite period,
the formless mass  was reduced to order by the agency
of an  intelligent,  eternal and self-active  ether.* (En-
field, vol. i. pp. 126 and 130.)
   In the Theogony of Hesiod, Chaos and Night were
represented under the emblem of an egg, over which
the  Ether  brooded,  and  disclosed the  innumerable
forms  of things.   And it is probable that the fable of
Cupid and Psyche was an  allegorical impersonation of
passive matter, and of the  principle by which it is ac-
tuated; or  that Cupid was intended to represent the
  * The views of Orpheus concerning the nature of this ether,
and its omnipresent agency in the phenomena of life, may be
further seen in the fragment of a hymn, Be Mundo, translated by
M. Good:—
          "Jove is the ether, Jove the boundless fire,
           That fills the world with feeling and desire."

As also in the following beautiful invocation to light:—

          "0 thou who fillest the palaces of Jove,
           AVho flowest round sun, and moon, and stars above;
           Pervading, bright, life-giving element;
           Supernal ether, fair and excellent,
           Fountain of hope and joy, of light and day,
           AVe own at length thy tranquil sway." 
AVHAT  WAS MEANT BY THE ANCIENT CHAOS?   425
universal attraction that causes the loves of the ele-
ments, and binds the universe together.
  The generation of the world from a fluid and chaotic
state, was a leading doctrine in all the ancient oriental
cosmogonies,  from the time  of Moses, Orpheus  and
Hesiod, down to the  period  of Ovid; and may be
traced in  the writings of  Aristotle, Epicurus, Zeno,
and  the Stoics generally.  For example, we are in-
formed in the first chapter of Genesis, that "in the
beginning, the earth Avas without form, and void, and
darkness was on the face of the deep."  And it is re-
lated by Berosus, that the ancient  Chaldeans main-
tained, that in the beginning, all things consisted of a
dark fluid mixture, that Avas separated and reduced to
order by the divine power of Belus,  (light;) and  that
the  human soul is an emanation from the  divine
nature. (Enfield, vol. i. p. 54.)
  The Egyptian magi also  maintained, that  before
the  regular forms of nature arose,  an eternal chaos
existed; but  that  the passive and formless mass was
reduced to order by the agency of a self-active, intel-
lectual and eternal ether, which gradually developed
all  that we behold of the external universe.  (Idem,
pp. 89 and 132.)   The  sum of the Phoenician cos-
mogony, as related by Cumberland, on the authority
of Sanchoniathon, is, that  the elements  of all  things
originally existed in a fluid and  chaotic  state, until
called forth by the energy  of a self-active principle, in
obedience to the laws of an immutable necessity.   It
is therefore evident that the generation of all things
from chaos was  a fundamental tenet  in  most  of the
ancient theogonies, as described by Ovid:— 
426    WHAT  WAS MEANT  BY THE ANCIENT CHAOS?

      " Ante mare, et terras, et quod tegit omnia coelum,
       Unus erat toto naturae vultus in orbe
       Quern  dixere chaos, rudis indigestaque moles,
       Nee quicquam nisi pondus iners congestaque eodem
       Non bene junctaram, discordia semina rerum."
                                    (Met. Lib. 1. v. 5.)

  Whatever may have been the origin of this widely
diffused  tradition, it  contains  at least a  nucleus of
truth; for it is certain, that  all  the forms of nature
with which we are acquainted, have actually emerged
from a fluid  state.  The primitive mountains of  the
globe have been formed  from a state of fusion by  fire
—and the sedimentary rocks  from a state of solution
in the water  of lakes  and seas; or from the ruins of
mountains and elevated plains, that have been carried
down by rains, rivers and springs, in a state of chaotic
mixture.   Plants  are formed  from  sap, and animals
from blood, in which all their  organs are confounded,
until  developed by the  powers of life.  And if it be
true that the planets have been formed from the ag-
gregation of phosphorescent nebulous matter, in which
all  the elements, active and  passive, are mixed up
and confounded, it presents the most important phy-
sical conditions of the ancient chaos.   The successive
destruction of the world by alternate submersions and
conflagrations,  and its renovation  from a state of  dis-
solution, was another  doctrine of antiquity, that may
have originated from  a confused notion of the perpe-
tually destroying and  regenerating influences that
make up the history of universal chemistry, geology,
life and death. 
PHILOSOPHY OF THALES.
427
  The first philosopher who  introduced an exact me-
thod of studying nature among the Greeks, was Thales
of Miletus, who Avas descended from Phoenician parents,
and flourished about six hundred years before the com-
mencement of our era.   This illustrious founder of
what  has been called the Ionian school, after travel-
ling through the East, for the  purpose of  acquiring
knowledge among the renowned magi of Egypt, re-
turned to his native country, where he laid the foun-
dation of mathematical and  physical  science on the
basis of established principles.   With the  sages of the
oriental  nations,  he maintained the  existence of an
omnipresent fiery ether, as the primary efficient cause
of motion throughout the universe;  and  which he
termed  aurou^rov, for the  purpose of  representing its
self-moving  power.  According  to  Cicero, he  also re-
garded  it as the soul or mind of universal nature,
because  he  conceived that  a self-moving  principle,
wherever it exists, must have intelligence.  (De Naturd
Deorum, lib. i.)   Aristotle termed  it  x^ruov, as indi-
cating its power of giving motion to other bodies.
(De Anima, lib. i. c. 2.)   By the energy of this prin-
ciple, Thales maintained  that the passive elements of
matter were reduced to order from a fluid  state, and
that it  is the  proximate cause of  life in plants and
animals.
   In conformity with the above doctrine, Parmenides
and Archelaus maintained that heat was  the cause of
motion, and cold of  rest;  or  that heat and cold were
the first principles  of action in nature.   Heraclitus
also regarded fire as the cause of  energy throughout 
428
DEMOCRITUS AND PYTHAGORAS.
the universe;  and as it  seemed to produce all effects
in a regular series, in obedience to perfectly wise laws,
he conceived that it must be omniscient and divine.
  It has been often  asserted by both ancient and mo-
dern Avriters, that Democritus denied the existence of
any independent principle as the primary and efficient
cause of motion and life  in the universe, distinct from
the primitive, indivisible and immutable atoms of mat-
ter; which he supposed Avere all of the same essential
nature,  but different in form and magnitude.   It has
been said that he referred all the generations and dis-
solutions of bodies to certain innate forces of attrac-
tion and repulsion, residing in these ultimate atoms;
and that the various properties of bodies are owing to
the different mode of tlieir arrangement, as determined
by the inherent powers of atoms.  But Lucretius says
that Democritus regarded heat as composed of exceed-
ingly  small atoms of a round form, more active and
penetrating than  those of other matter; and the soul,
or animating principle in man, as a portion of the same
fiery nature that actuates  the universe.   With very
slight variations, the Epicurean theory of  physics was
a copy of the above  doctrines.
  Another distinguished teacher  of natural philoso-
phy among the Greeks was Pythagoras, the son of a
Tyrian merchant, born in the island of Samos, 586 A.c.
After visiting the different countries of the East, and
residing twenty years in Egypt in quest of wisdom,
he established a school of science in his native place,
and afterAvards at  Crotona in western Greece, from
AAdiich he Avas driven by persecution to Metapontum,
Avhere he is said to have perished of hunger in the Tem- 
PYTHAGORAS.
429
pie of the  Muses, a martyr to the ignorant jealousy
of his enemies.
   The sum of his  doctrine  concerning the primum
mobile of nature was, that it  is an all-pervading fiery
ether of boundless energy, possessing within itself the
united power of motion and intelligence,  abxoixwnaijM
twv izavrmv, the self-moving principle of all things; and
that the human soul is a portion of the same essence.
This first principle of action  in nature he represented
as unity; the passive  elements of matter  as duad;
and the universe perfectly  formed as a physical triad,
all the operations of Avhich are  governed by exact
numerical laws.   He  also  maintained that the earth
and  heavenly bodies  revolve  around  a fixed fiery
globe; and that the spheres of the different planets,
by striking against the ether through which they pass,
must produce sounds that vary according to  their mag-
nitude, velocity and distance from  the centre of the
motion—those which are  farthest off  producing the
deepest, and the nearest the  highest tones :*

        " Forever singing as they shine ;
         The hand that made them is divine."—Addison.

Whether anything  more was intended than to repre-
sent the harmonious relations between the times, dis-
tances, magnitude and velocity of the heavenly bodies,
the music of the spheresf is the  finest conception of

   * Aristotle, Meteor, lib. i.  c. 6;  Plutarch, de  Placila Philoso-
phorum, lib. iii. c. 2.
   f The earliest mention of  this celestial harmony is found in the
Book of Job, where it is said that  when the work of creation was 
430
MUSIC  OF THE SPHERES.
all antiquity, and is  said to  have  led Kepler to the
most  important  discovery ever made in astronomy;
viz., that the times in which the planets perform their
revolutions are as  the cubes of their distance from the
sun.   Nor  is it  unvvorthy of notice, that as the velo-
city  of the planets is in  proportion to  the  heating
power of the  sun, so the velocity  with  which sounds
are  propagated  through  gases  and  other vibrating
media, is in proportion to the  amount of caloric around
their particles, ceteris paribus.
   About  fifty years  after Pythagoras, arose Hippo-

finished, "the morning stars sang together;" and it has been con-
secrated by the noblest poets of modern times.
     " Look how the floor of heaven
       Is thick inlaid with patines of bright gold:
       There's not the smallest orb 'mong all which thou behold'st,
       But in its motion like an angel sings,
       Still quiring to the young-eyed cherubim," &c.—Shakspeare.

  It is also grandly expressed in the following lines from an ode
of Milton on the Nativity :—

           " Ring out, ye crystal spheres,
            And let your silver chime
            Move in melodious time,
       And let the base of heaven's deep organ blow;
            And with your ninefold harmony,
            Make up full concert to the angelic symphony."

  A still more philosophical account of this great music is con-
tained in the  opening chorus of Faustus, by  Goethe, who refers
it to the fountain of all harmony:—

           " The sun his ancient hymn of wonder
              Is pouring out to kindred spheres,
            And still pursues with march of thunder
              His preappointed course of years," &c. 
HIPPOCRATES.
431
crates, avIio flourished  in  the  age of Anaxagoras, So-
crates, Heraclitus and  Democritus, when Greece was
the centre of light and  civilization to the whole world.
To this illustrious man is due the glory of having re-
duced the healing  art to a  regular and  systematic
form.  He maintained that,  although  it is not the
province of the physician to  speak of divine things,
unless so far as they may serve to improve our know-
ledge of the causes and nature of the diseases incident
to the human body, it  is yet necessary for him to lay
down some general principle  from which he may rea-
son.  He then declares  his opinion, that elementary
fire is the cause of perpetual  motion throughout the
universe, and when united with organized bodies, con-
stitutes  the animating  principle; that it resides  in all
matter, producing an endless variety of effects, accord-
ing to fixed and definite laws; and that, as it operates
Avith consummate  skill in  the  generation of animal
motion, sensation and intelligence, it must be  some-
thing immortal, that sees, hears  and knows all things.
This mighty  agent, which  he  terms fusts or nature,
was supposed to produce all the phenomena of living
bodies, by attracting what  is necessary for their de-
velopment and expelling whatever is superfluous  or
injurious; and he maintained  that the science of medi-
cine should be founded on a comprehensive knowledge
of the mode  in which  it governs all the operations of
nature;  xara ipociv fetopew.  (De  Princlplls, et de Ali-
mento.)
   He maintained that the solid parts of animals, and
their various  secretions, were formed from the blood,
which was  composed  of four primary  humours, cor- 
432
HIPPOCRATES.
responding  with the  four  proximate constituents of
modern physiologists, viz., red particles, fibrine, albu-
men and serum.*  But he supposed that the liver Avas
the great organ of sanguification, and termed the car-
dinal humours, red blood, black  bile, yelloAv bile and
phlegm.   On the qualities and relative proportions of
these four humours, all the diversities of the consti-
tution were supposed to depend.   An  abundance of
red blood Avas marked by a Avarm  and sanguine tem-
perament;  whereas, an excess of yellow bile produced
the choleric temperament, both of which were warm
and  characterized by  a high degree of vital energy.
On the other hand, the melancholy temperament was
supposed to arise from an excess of black bile, and the
phlegmatic  from a predominance of phlegm, both of
which were cold and  marked by a general debility of
the system.  But it is evident that what Hippocrates
called phlegm was only another  name for the serous
portion  of the blood;  and  that he confounded the
dark  venous blood which abounds in feeble, melan-
choly constitutions, Avith black  bile.  It is equally
certain, that what  he called  red  blood was what we
term arterial blood, the abundance of which is marked
by a vigorous, sanguine  temperament.   And there is
good reason to  believe, that the yellow bile of Hippo-
crates was  only another name  for the coagulating

  * In his treatise on the Nature of Man, he observes, that " when
a man has been mortally wounded by cutting his throat, blood flows
first, which is very hot and very red ; after which it comes mixed
with phlegm, and  finally with much bile."  From which it would
appear, that he regarded phlegm and bile  as constituents of the
blood. 
HIPPOCRATES.
433
lymph or  fibrine,  as he supposed  that it imparted a
yelloAV colour to the  watery portion of the blood;  for
the  bile secreted  by the liver never produces this
effect, unless  when the system is in a  diseased  state.*
   * Several passages were published in the Lancet of September,
 1835, by Mr. Girtin, from the writings of Hippocrates, which,
 taken separately, would seem to show that he was acquainted with
 the circulation.  For example, in  his treatise, De Insomniis, as
 quoted by Mr. Girtin from the Yander Linden edition of his works,
 he observes, that "rivers  return to their  sources in an unaccount-
 able and extraordinary manner, like the circulation of the blood."
 (Tome i. p. 460.)   In another treatise, he says, " I protest I know
 not where it begins nor where it ends, for in a circle there is neither
 beginning nor ending."  (Idem, Be  Alimento,  tome i.  p. 596.)
 "The heart and veins are always in motion." (Idem, Be Prin-
 cipiis, tome  i. p. 116.)  In the  Timeeus, Plato also  represents
 "the  heart  as the fountain  of both the veins and of the blood,
 which is vehemently impelled through all the members of the body
 in a circular  progression."   And here it is necessary to observe,
 that by <pte(3<;, veins, the ancients meant all vessels that convey blood.
 There is a similar passage in Seneca, who speaks of the blood, the
 circulation of which maintains the vital caloric:  " Unde sanguinem
 cujus cursu  vitalis continetur calor."  (Be Beneficiis, lib. iv. c. 6.)
 But there are many passages in the writings of  Hippocrates, Plato
 and Aristotle, which  prove that they regarded the arteries  as
 destined to convey spirits and heat to all parts of the  body, and
 the veins as  blood-vessels.  When  describing the use of different
 parts of the  body, Galen  says, that air was  supposed to be taken
 into the lungs, where the most pure and subtile portion was sepa-
 rated from it, conveyed from the trachea to the heart, and thence
 to all parts of the body by the arteries, which were called pneu-
 matic  vessels; and that  the  fuliginous  portion  of the  air  was
thrown off from the lungs by expiration.   He further states, that
all the Greeks, from  Hippocrates down to his own time, believed
that after food was dissolved in the  stomach, it was  conveyed to
the intestines and thence to the liver, where it was converted into
                             28 
434
HIPPOCRATES.
   The pathological views of Hippocrates were founded
on the above doctrines.  He  taught, that whatever
alters the natural condition of the fluids, whether im-
pure  air, bad diet, want of rest, fatigue,  retention  of
the excretions, or the depressing passions of the mind,
deranges the  healthy condition of the whole system;
that  inflammation or fever is an  effort of nature,  or
the fuatq to expel morbific matter  from  the humours;
and that the highest wisdom of the physician is  to
follow the  proceedings  of nature  in practice: above
all, to preserve  and restore  the healthy  condition  of
the blood by nutritious food, pure  air, exercise, &c.;
to moderate its motions  when  excessive, and increase
them Avhen languid;  to open the  bowels, skin  and
other emunctories when obstructed, and  dissipate  or
resolve tumours by fomentations or cataplasms.
   If  we pass  in review the leading doctrines of the
different philosophical sects that arose from the Ionian
and Italian schools, we  shall find  that, while on some
points they differed from Thales and Pythagoras, they
blood, prepared for nutrition, and then conveyed to the vena cava,
to be distributed to all parts of the system; he further taught,
that the office of respiration was to cool the blood.  (Be Usu Par-
Hum, lib. iv.)  It was not until the time of Herophilus and Erasis-
tratus, that the brain and nervous system were fully recognized as
the organs of sensation, perception  and  voluntary motion.  Nor
was  it until the  middle of the sixteenth century, that  Servetus
distinguished the pulmonary circulation from that of the general
system, or that the lungs were discovered to be the  organs of
sanguification.  It is therefore clear, that  the knowledge of the
Greeks in regard to  the specific office of the lungs, heart, liver,
blood-vessels and nerves, was not only vague and imperfect, but
fundamentally erroneous. 
PLATO.
435
nearly all maintained that heat is a self-active princi-
ple, and the noblest of the elements.   Plato, who was
born thirty years after Hippocrates, regarded the soul
of the world  as  an all-pervading fire; and he argues
in the Timceus, that it  is endowed with  intelligence,
or it could not produce animal motion, sensation and
cogitation in organized bodies.
   But he maintains elseAvhere, that the first Mover is
an incorporeal, immutable and eternal intelligence, not
appreciable by the senses,  the Being of beings, and
the Fountain of  all laAv; that the visible  forms of na-
ture have  been organized by an active principle, pos-
sessing the power of moving itself, and of generating
organized  bodies, after the  model of certain  ideal
archetypes that  reside  in, or emanate from, the un-
created, SUPERESSENTIAL AND ALL-BEAUTEOUS MIND;—
by which  it  is probable, he  meant to represent the
eternal conceptions of  the  Infinite  Mind in framing
the laws of the  universe.   At one time he refers the
origin of evil to the creation of  the world by inferior
divinities;  at another, to an inherent stubbornness, or
imperfection of matter,  that could not be entirely over-
come by the Supreme Architect.*

   * There is reason to believe, that a more profound knowledge of
nature than the  human mind has  ever yet attained, will show that
all the works of  God are absolutely perfect in their kind; and that
              "All partial evil is universal good,
              All discord harmony not understood."
   In the great circle of unceasing change that makes up the order
of things, the earthquake and volcano produce apparent disorder,
and sometimes destroy life;  but without them the earth would not
be fit for the habitation of man.   The hurricane and tempest are 
436
ARISTOTLE.
   In the treatise of Aristotle concerning the soul, or
animating  principle, he  maintains  that  a self-active
spirit, which he terms  Uveoiia or  ¥uXtj, is  the cause of
all effects in  the living  body.    To  this  spirit  he as-
cribed three different faculties;  the first of  which was
manifested in the  thorax,  and  termed vital;  the se-
cond, or nutritive,  in  the abdomen; while the third,
or  reasoning  faculty, was supposed  to  reside  in the
head.   He adds, that whether  the vital  principle be
identical with elementary fire, or something analogous,
constituting a fifth  element, it is a portion of the same

as necessary to the salubrity of the air, as sunshine  and rain to the
growth of vegetation.   And it is probable, that to a superior in-
telligence, death would  not be regarded as an evil, any more than
the ripening and decaying of  fruits, or the successions of winter
and summer, light and darkness.   In short, everything in the fun-
damental constitution of nature,  and  mechanism of the living
frame "is very good;"1  and tends to produce the greatest amount
of happiness to the greatest number of animated  beings.  Even
the  passions of the human mind are as necessary to happiness as
reason  itself; nor is it possible that pleasure could exist without
sensibility, or the susceptibility of  pain.   Let us then confess, that
by far the most fruitful  source  of  physical  and  moral evil is our
ignorance of  the innumerable  springs of happiness  that a more
perfect knowledge of nature would unfold.   The truth is, that the
choicest blessings of life become evils when misapplied.  The che-
rishing power of heat, without  which nothing could exist, becomes
a consuming fire in excess; and so of our food and  drink, exercise,
repose  and everything  else.   The beautiful light  of the sun, the
physical  source  of all  good, excites inflammation  of the eyes, if
ignorantly gazed at too long.   Nor is it unworthy of notice that
misfortune and sorrow have been, far more frequently than pros-
perity, instruments of good, by leading thoughtful minds to investi-
gate the causes of human suffering, and the best modes of prevent-
ing it. 
ARISTOTLE  AND PLATO.
437
principle that maintains the universe in a state of per-
petual motion.  (De Anima, lib. i. c. 2.)
  But in his metaphysics, he maintains that the First
Mover is incorporeal, immutable, immovable and  in-
dependent  of the material universe.  In what way
this immaterial First  Mover, itself incapable of mo-
tion, communicates motion to other bodies, he never
clearly explained; but  supposed that it acted on the
first celestial sphere in a mode similar to that in which
the mind acts on the body. (Lib. xi.  c. 6, 7, 8, as cited
by Enfield.)
   As for the rest, he maintained with  Plato, that the
earth is the centre of motion to the planetary spheres,
the velocities of which are inversely as their distance
from the first sphere.  (De Coelo, lib. ii. c. 13,14.)
   It Avas observed by Bacon, that Plato corrupted  na-
 tural philosophy by mixing it up with theology, as did
 Aristotle by metaphysical refinements and a sophisti-
 cal  logic.   That  they were both exceedingly ill in-
 formed concerning  the nature of  heat, will appear
 from the following examples.   Plato says,  "it is com-
 posed of very fine particles that separate and dissolve
•bodies, but cold of grosser particles  that press upon,
 and  shut  up their pores."   (Opticks, vol.  ii. p. 100.)
 From which it is clear, that he confounded a mere
 privation,  or diminution of heat,  as darkness is of
 light, with a material  agent; and that  he knew not
 how the same agent produces the opposite  effects of
 attraction and repulsion.  Aristotle regarded heat  and
 cold as the cause of density and  lightness;  but main-
 tains that  fire is composed of heat and dryness; air of
 heat and moisture; water of cold and moisture; earth 
438
OPINIONS OF CICERO.
of cold and dryness;  thus confounding mere qualities
and modes of being with material agents.   Epicurus
also maintained that cold is composed of irregular par-
ticles that hold bodies together;  and that the vital
principle  is composed of heat,  united with different
gases,—color vitalis ventusque. (Lucretius, De Naturd
Rerum, book iii.)
  Cicero relates that  Zeno, Cleanthes and the  Stoics
generally, maintained the  existence of an all-pervad-
ing fire as the animating principle, or soul of nature;
but that it was governed  by the eternal laws of an
immutable necessity,  which they termed  Fate, or Ju-
piter;  and that the  mind of man is a spark  of the
same  ethereal  principle; that as  the loss  of heat  is
always attended with the extinction of life, sensation
and thought, it must  be a spirit or mind.  Cicero adds,
" Quoniam ex mundi ardore motus omnis oritur, autem
ardor  non  alieno impulsu  sed  sua  sponte movetur
animus sit necesse est."  (De Naturd Deorum, lib. ii.
c. 12.)
  And when  summing up the  opinions  of the most
distinguished philosophers of Greece, he observes, that
" whatever the nature of the Divinity may be, whether
air, fire or the fifth element  of  Aristotle, the human
soul  is a  portion  of  the same  divine nature; that
every one is conscious of having within him a  some-
thing  capable  of  self-motion;   and that a  principle
possessing  such a power  must be  the fountain of mo-
tion to everything else, therefore immortal, according
to the reasoning of Socrates and  Plato.   Hence the
swiftness of thought,  the poAvers of memory, the plea-
sures of heroic virtue; the joy with which we con tern- 
SENECA AND  VIRGIL.
439
plate the boundless extent of the starry heavens, the
earth and sea; and  the delight with which the soul
traces  its connection Avith the  Eternal  Reason  from
Avhich all causes proceed." (Tus. Disp. lib. i. c. 23.)
   Similar views were entertained by Seneca, and the
most celebrated of the Roman poets, Avho speak of the
anima  mundi as an  all-pervading  fiery ether, Avhich
they regarded as the cause of motion throughout na-
ture, and  of life in men, beasts and  birds, as in the
following lines from the 6th iEneid of Virgil:

     " Principio coelum, ac terras, camposque liquentes
      Lucentemque globum lunse, Titaniaque astra,
      Spiritus intus alit, totamque infusa per artus.
      Mens agitat molem, et magno se corpore miscet," &c*

    The fire that was kept perpetually burning in the
 Temple of Vesta, termed color vitalis, and ardor cce-
 lestis, was also a type of  that eternal globe of fire, the
 sun, from which it was kindled.
    From the  foregoing brief summary, the following
 conclusions may be deduced:
    1.  That amidst the innumerable conflicting opinions
 that  have prevailed among the most enlightened na-
 tions of antiquity, they nearly all  united in the belief

    * " Know first, a spirit with an active flame
       Pervades and animates this mighty frame;
       Runs through the watery worlds, the fields of air,
       The ponderous earth, the depths of heaven, and there
        Glows in the sun, and  moon, and every star:
        Thus mingling with the mass,  the general soul
        Lives in the parts, and animates the whole."-Warton. 
440
GENERAL CONCLUSIONS.
that fire is the active principle in nature, and the phy-
sical cause of life.
   2.  That the  whole universe  is composed of two
descriptions of matter, the one active, the other pas-
sive; and that  everything has  been formed from a
fluid or chaotic state.
   3. That, with very few individual  exceptions, they
have all maintained  the existence of an Intelligent
First Cause; whether united with, and  constituting
the informing mind of the stupendous whole, as taught
by the  Chaldeans,  Egyptians,  Phoenicians,  Hindoos,
Orpheus,  Thales,  Pythagoras,  Hippocrates  and the
Stoics;  or existing  apart from nature, as an incorpo-
real Intelligence, who governs the uniA'-erse by dele-
gated laAvs.
   4. That Bishop Berkeley Avas right in vindicating
the ancients from  the  charge  of Atheism, (however
erroneous their views concerning the Divine Nature
may have been,) which is wholly incompatible with
their  almost universal belief in a presiding Intelli-
gence.
   It was observed by Cicero, that " the higher we as-
cend  toward the origin of antiquity, or the  divine
descent of knoAvledge, the more clear are the traces of
truth."  And notwithstanding many striking  excep-
tions might be adduced  in opposition to this remark,
it  is extremely probable that in the primitive ages of
the Avorld, before it was filled Avith books, and the at-
tention  of men withdrawn from the  study of things
to that of words, they were more open to the genial
impulses of  nature, and communed with her  more
familiarly face to face. 
MOSES, HOMER AND  VIRGIL.
441
  In support of Cicero's opinion, it may be Avorthy of
notice, that in the Books of Moses, though not intended
to teach the  principles of natural  science, two funda-
mental doctrines of physiology are incidentally pointed
out.   I allude  to the life-sustaining office of the lungs,
and the vitality of the blood.  For when it is said, as in
the first chapter of Genesis, that " God  breathed into
the nostrils of man the breath of life, and  he became
a living soul," we can  understand only, that he was
created with breathing organs, for the purpose of ob-
taining life  from the atmosphere, which, in the Book
of Job, is termed  " the breath of the Almighty."  And
it is said  in  the Levitical  code, that  " the life of all
flesh is the  blood  thereof." (Gen. ix. 11;  Lev it.  xvii.
14; Deuter.  xii.)   " He hath poured out his soul unto
death."  (Isa. liii. 12.)  The truth of these doctrines
is corroborated by the  universal language of all en-
lightened nations, with whom, to live,  and  breathe, are
synonymous phrases;  and who have  ahvays repre-
sented  the  destruction of life  by the shedding  of
blood.*                                        _______
  * It  may here be worthy of  notice, that throughout the Old
Testament, as  in  all the writings of  the Greeks  and Romans, the
word soul is used for life.  "I shall require back your souls from
the hands of both man and beast." (Leviticus.)  In the following
lines from Homer's Iliad, translated  by Pope, the living principle
is represented as escaping with the blood :
         "The vital spirit issued at the wound,
          And left the members quivering on the ground."
  And  in the  description of a dying hero by Virgil, the soul is
identified with the blood:
" Purpureas vomit ille animam."—Ms. ix. 
442
DOCTRINE OF THE ANCIENTS.
  Again, the true doctrine of the solar system, Avhich '
seems to have been partially anticipated by Pythago-
ras, was rejected by all his successors, down to the
time of Copernicus; while the atomic theory of Mos-
chus, Thales, Pythagoras, Anaxagoras and Democri-
tus was  rej'ected  by Plato, Aristotle and  the Stoics,
Avho maintained that the different elements are mutu-
ally convertible into each other. Besides, the universal
doctrine of the ancients, that  all  space is filled with
subtile matter, is supposed  to  have  been rejected by
Epicurus, who is generally understood to have main-
tained the vacuum of space.*
  But with  all due reverence for the wisdom of the
ancients, it  must be acknowledged,  that  they never
fully established  any one  great  principle  in physics,
capable of widely-extended application to the benefit
of mankind.   Many of their views were simple, inge-
nious and grand; but their knoAvledge of natural his-
tory, including geography, geology, mineralogy, che-
mistry, botany and comparative anatomy, was far too
limited to form the  basis of a comprehensive  theory.
And notwithstanding the high importance attached by

  * Mason Good says,  "it required 3000 years to render the doc-
trine of a vacuum  probable, and 5600 years to establish it on a
solid foundation.  For its probability, we are indebted to Epi-
curus; for its certainty to Sir Isaac Newton."  (Book of Nature,
vol. i. p. 343.)  But the following lines from Lucretius, translated
by Good, leave it doubtful whether any of the ancients ever be-
lieved in a perfect vacuum :—
         " The myriad seeds of fire dispersed at large
          Through all things, back to the same fountain flow;
          And hence well fortli o'er all the exulting world
          In boundless flood." 
DEFECTS  OF THE GREEK PHILOSOPHY.      443
the Greeks to the agency of fire in the phenomena of
nature, they never made anything like a regular and
systematic attempt to point out  the laws by which it
operates, in separating  and recombining  what  they
called the elements of air, Avater and earth.  Nor did
Hippocrates explain the manner in which animal heat
is derived from the atmosphere by respiration;  how it
is connected with fever, inflammation and  the various
forms of disease.  The same observation applies to all
his successors, down to the time of Galen, against
whom  Bacon brought  the heavy accusation, (which
applies equally to the modern teachers of medicine,)
that "he took away the infamy of ignorance in phy-
sicians, by declaring so  many diseases incurable;  thus
paralyzing  their exertions, cutting off the hopes of
improvement, and proscribing the sick." It was there-
fore justly observed by this great reformer of science,
that " inventions for enlarging the power of man over
the university of things must be sought in  the light of
nature, and not in the dim shades of antiquity."
  From  the decline of Grecian  and Roman civiliza-
tion, until the revival of learning in the fifteenth cen-
tury, was a long dreary night of ignorance and super-
stition.   The great book  of nature, "writ by God's
OAvn hand," Avhich speaks a language more  instructive
than that of men, was  exchanged for the  mystic jar-
gon of the schools; and the voice of truth was drowned
by the clamour of bigotry.   But about this time a new
era began to dawn upon the darkened world.  By the
reformation of Luther,  the fountains of thought  Avere
renovated throughout Europe.   The invention of gun-
poAvder, the art of printing, and the directive power 
444
CIRCULATION  OF  THE BLOOD.
of the compass, did more to improve the condition of
mankind, than all the united discoveries of antiquity.
For the first time in the history of our race, the true
theory of the solar system Avas established by Coper-
nicus and Kepler.  By means of the telescope an high-
Ava}* of communication was  opened up with  the hea-
venly bodies by "the starry Galileo," Avho demonstrated
the annual and diurnal motions of the earth; for Avhich
he Avas denounced as the enemy of religion, and  the
propagator of false philosophy.*
  For the first time in the  history of science, the cir-
culation of the blood was  systematically established
by the immortal Harvey, for which he Avas reAvarded
with  persecution, accused of "confounding all medical
theory, and  of rendering physiology  unintelligible."
Truly may it be said, that prejudice is a frightful ogre,
and bigotry a very fiend.   Then arose Bacon with a
holy zeal, and  proclaimed,  " Only let men aAvake and
fix  their eyes one while on the nature of things;  an-
other Avhile on their application to the benefit of man-
kind."  The ghostly ministers of superstition  had long
denounced the knowledge of nature as  dangerous;  but
Bacon showed  it to be "more beautiful  than any ap-
parel of words that can be  put upon it," and the true
foundation of human happiness,—Avithout which even
religion is perverted into an engine of oppression and
misery.
  It is not my object to examine all the metaphysical,

  * When summoned before the Inquisition for maintaining the
motion of the earth, and required to give his reasons for such a
heresy, he was answered by the commissary of  the holy office,
x" Terra autem in eternum stabit, quia terra in eternum stat." 
A'ARIOUS THEORIES OF LIFE.
445
mechanical  and chemical theories  of life that have
arisen and passed away since the time of Harvey.  So
vast are the troops of error, that to notice them all in
detail would be an endless task.  It would doubtless
be far better to establish one important truth, than to
refute a thousand  errors;  or, as Bacon observes,  "to
set up one  great  light, or  branching  candlestick of
lights, than to go about with a watch-candle in every
corner."  Yet as it is necessary to know what has been
done, that future inquirers may know Avhat remains to
be accomplished, I shall devote the remainder of this
chapter to a brief review of the leading doctrines on
Avhich  the  modern systems of medicine  have  been
founded.
   Amidst the revolutions of empire, religion and phi-
losophy, that followed  the decline  of Grecian  and
Roman  civilization, the establishment of Christianity,
and the rapid diffusion of  Mahometanism after the
sixth century, the doctrines of the  ancients in regard
to the agency of fire as the ruling principle of  nature,
seem to have  shared the same  fate as that of the
heathen mythology.*  It is true that Harvey repre-
sents what  he termed ccdldum innatum as the imme-
diate cause  of vitality in the blood, and of the heart's
action.   But so vague were his vieAvs of its nature and
laws, that he describes it  as something different from
  * Had knowledge continued to advance from the time of Cicero,
Seneca and Galen, until that of Bacon, Galileo and Harvey, as it
did from the epoch of Pythagoras, to the time of Galen, the phy-
sical and moral condition of mankind would probably have been
elevated as far above what it now is, as the civilization of modern
Europe has surpassed that of the Xew Zealanders. 
446         PARACELSUS AND VAN HELMONT.
solar heat, or that of combustion;  and sometimes called
it the naturd naturans, or the facultas vegctativa.  (De
Generatlone, p. 170.)
  The truth is, that nearly all the great writers of this
epoch recognized the existence of an active principle
in nature, as the cause of motion and organization, to
which they gave different names; but without identi-
fying it with any known  agent.   The  Archeus of Pa-
racelsus and Van Helmont was only another name for
the  Ttop ~Noepov of Pythagoras, Heraclitus and Hippo-
crates;  for  they maintained  that  it was  diffused
throughout all matter, and operated with consummate
intelligence in the formation of mineral, vegetable and
animal bodies; that vdtal heat is generated in the blood
by fermentation, through the  agency of the animal
spirits, derived from the air  by breathing; that food
is dissolved in the stomach by means of an acid liquor,
and  not  by the  agency of heat,  because digestion is
carried on in cold-blooded animals,  and arrested in
man during fever—in short, that  all the functions of
life are governed by the immediate  agency of an in-
telligent  principle.*
  The pneumatical body of Bacon was clearly derived
from the  meu,ua  of  the  early Greek philosophers; for
in his Treatise on Life and Death he represents it  "as
the master-Avorkman of all effects in the living body;"

  *  This doctrine,  which seems to have been almost universal
among the ancients, has been recently revived by Isaac Taylor, who
maintains that, in all cases, mind alone is capable of putting mat-
ter in motion; that it is the cause not only of muscular contrac-
tion, but of secretion, nutrition,  &c. (Physical Theory of another
Life.) 
BACON AND DESCARTES.
447
Avhile, in various other parts of his Natural  History,
he describes it as an imponderable spirit, and the cause
of evetporatlon,  germination,  fermentation,  putrefac-
tion, &c.   It is therefore evident that Bacon regarded
it as the efficient cause of mechanical, chemical and
vital action.  Yet, so far was he from recognizing its
identity with the elementary fire of antiquity, that he
represents heat as a mere effect, condition or property
of other matter.  On the whole,  his views of the ani-
mating principle were less accurate than those of Ser-
vetus and Harvey, Avho maintained that it Avas derived
from the atmosphere by respiration, imparted  to the
blood in the lungs, giving it a bright florid hue, and
as possessing the vigour of heat to produce motion.*
   The vital, natural and  animal spirits of  Descartes
and his  numerous  followers of the seventeenth cen-
tury, were  identical with  the ~^u;j.ara of  Galen,  to
which he referred  the faculties of generating  animal
motion,  sensation  and intelligence, according  to  the
different parts of the system in which they resided; as
the thorax, abdomen, brain, &c.  But so ignorant was
 Galen in regard to the source of animal heat, that he
 sometimes  speaks of it as an inherent  condition or
 property of living  bodies, diffused from the heart
 through the arteries to all parts of the system, in con-
nection  with the pneumata, or spirits ;f  and he sup-

   *  The same active principle was recognized by Dr. Henry More,
 as the spirit of matter, and  by the learned Dr. Ralph Cudworth,
 as the plastic principle of Nature.
   f  In regard to what these spirits are, the  celebrated Harvey
 observes: " Opinions are so conflicting that it is not wonderful that
 they should serve as a common refuge for ignorance; and that when 
448
ETHER OF NEAVTON.
posed that the principal object of respiration Avas to
cool  the  blood.   The same doctrine Avas  taught by
Silvius, Fabricius, Harvey, Bartholine, SAvammerdam,
Morozzo and  Cigna; while  Borelli,  Boyle  and many
others belonging to the mechanical school, down to the
time  of Haller, maintained that animal  heat was pro-
duced by the motion of the blood, and friction of dif-
ferent parts of the  body, because the temperature of
animals is increased by motion and exercise.
   The ether of Sir Isaac  Newton, to Avhich, in various
parts of his later writings, he referred gravitation, co-
hesion, capillary  attraction,  the emission, reflection,
refraction  and inflection  of light, the elastic  force of
gaseous bodies, and the  power of  menstrua to dis-
solve solids, was identical with the Acdsp  of  Hippo-
crates, and the ancient sages of the East.  He  further
suggests, in the  Third Book of Optics, that "animal
motion may be performed by  the vibrations  of  this
ether, excited in the brain by  the power of the will,
and  propagated  thence through the capillaments of
the nerves into the muscles, for contracting and dilat-
ing them."
   It is therefore  evident  that NeAvton did not ahvays
regard attraction and repulsion as ultimate phenomena,
but that he referred all  the operations of nature, in-
cluding animal motion, to what he termed an "un-
known ether," which  I have shoAvn to  be identical

men are at a loss to assign  the cause of any thing, they very com-
monly reply that it is done by the spirits." He adds: " As to those
who advocate incorporeal  spirits, they have no ground'of experi-
ence to stand upon; their  spirits being  synonymous with powers
or faculties." (Works, ed. by Willis, p. 116.) 
BOYLE, HOOKE  AND MAYOW.
449
Avith caloric.  Yet so imperfect were the views of this
great mathematician in regard to the nature of heat,
that he represents it as an effect of  motion and vibra-
tion.  Had he  been aware that the velocity of the
planets through tlieir  orbits is directly in proportion
to the heating poAver of the sun, Avhich varies inversely
as the squares of the distance, he would not have re-
ferred their lasting motions to  a single impulse, ex-
erted through a vacuum.  Or had he known that the
quantity of life diminishes from the equator to the
polar regions, like all  the  mechanico-chemical trans-
formations  of  matter,  he  would not have regarded
comets as destined to supply the planets Avith vitality.
But as he confounded the cause of motion, of climate,
of changes of season, of the growth of vegetation, &c.
with vibrations of an ether Avhich he never identified
Avith any known  agent, it is not very surprising that
his  physical speculations have been  little understood.
  During the  time of Newton,  it was discovered by
the experiments of Boyle, Hooke,  MayoAV, Bathurst
and Henshaw, that during the process of respiration
a portion of atmospheric  air underwent the  same
change as in ordinary  combustion;  by which its elas-
ticity was greatly diminished, and its property of sup-
porting life destroyed.   Mayow  supposed  that a nitro
aerial spirit was imparted  to the blood in the lungs.
But in accordance with the reigning fashion  of the
day, animal heat was referred  to innate powers of the
system, or to motion of the blood, its friction against
the solids, &c.
  From the times of Homer,  Hippocrates, Galen and
Celsus, doAvn to the period of  Harvey and Sydenham,
                        29 
450         STAHL, HOFFMAN  AND CULLEN.

the animating principle was supposed to be conveyed
to all parts of the system Avith  the blood, which Avas
thought to  be the  immediate source of all diseases.
But after the attention of physiologists was awakened
to the importance of the  brain and nerves, by the re-
searches of  Willis, Malpighi  and others, it was main-
tained by Stahl, Hoffman and Mead, that all the func-
tions  of  animal life, whether vegetative  or  sentient,
are immediately dependent  on  the nervous  system;
that some peculiar and refined species of fluid, which
they regarded as identical with the animal  spirits of
the ancients, Avas secreted  by  the  brain, and conveyed to
all parts of the body through the nerves.  It must, how-
ever, be confessed,  that the  neuro-physiologists never
explained what enables the brain to secrete; how the
solids are formed from the blood; what  endoAvs the
blood with the power of  vitalizing all the organs;  in
what way the eggs of animals are hatched by nervous
influence; nor how the life and  growth of vegetables,
including many of the lower orders of animals that
have apparently no nerves, are sustained.
   Yet the celebrated  Cullen represents the brain  as
necessary to the action of the vital principle, and the
primary source of animal motion, Avhether voluntary
or involuntary.   He further  maintained that all dis-
eases should be  referred to some preternatural condi-
tion  of the  nervous system; that cold, miasmata, fa-
tigue, the depressing passions, &c.  diminish  the vital
energy of the  brain, and through  it that of all the
other organs, causing debility and a spasmodic state of
the capillary vessels, as in the cold stage of fevers.
He further maintained that the temperature of animals 
OPINIONS OF HALLER.
451
is in proportion to the quantity of their life, or nervous
energy.  Yet he never explained how animal heat is
generated by respiration; how diminished during the
cold stage of fever, and increased during the hot; why
fever is attended with nausea, headache, pains in the
back, limbs, &c.; nor in what way spasmodic diseases
arise from derangement of the nervous system.  But
I shall endeavour to make it clear in the following
pages, that  the  brain is no more the origin of animal
motion, than the rudder of a steam-vessel is the cause
of its moving power; that as the object of the one is
to guide the direction of the vessel, so it is the  office
of  the  other  to generate  ideas, or  endoAV  the living
machine with sensation, intelligence, volition, &c.
   In accordance with the Newtonian doctrine, that all
 the molecular changes of matter are owing to the in-
 nate powers of attraction and repulsion, Haller referred
 the phenomena of life to irritability and sensibility, the
 first of which was regarded as an inherent property of
 the muscular fibre, and termed vis insita; while the
 other was supposed to reside in the  medullary tissue,
 and was  called the vis nervosa.   But if the muscular
 and nervous  systems be not duly supplied with living
 blood, the vis insita  and the vis nervosa can have no
 existence;  nor  can they  be  supported by the blood,
 unless  the latter  be vitalized  by respiration.  It is
 therefore evident  that these fundamental properties
 of life are derived from the atmosphere, and not inhe-
 rent in  any  part of animal bodies, whether solid or

    With the most distinguished philosophers of ancient
 and modern  times, it was maintained by John Hunter, 
452        MATERIA  VIT^E OF JOHN HUNTER.

that all the phenomena of animal life are  governed by
an independent principle, which he termed the materia
vitce, and sometimes the architect or organ builder. But
so far was he influenced by the neuro-physiology of
Hoffman and Cullen, that in his Treatise on the Blood,
he confounds it with the hypothetical  nervous fluid,
and  even with the  medullary  substance.  He says,
" I consider that something  similar to the materials of
the brain is diffused  through the body,  and even con-
tained in the blood, between which and  the brain a
communication is kept up by nerves:  I  have therefore
adopted terms explanatory of this theory, calling  the
brain the materia vita' coascervata; the nerves corda
Internuncio';  and that which is  diffused  through all
parts of the body, the materia vitce diffusa." (Page 89.)
But, again: he observes that breathing seems to com-
municate  life to the  blood, which imparts it to all  the
other organs; that as the brain and nerves are com-
posed of the same tissue, it  is presumptive proof that
nothing material  is conveyed from one to the other;
but that sensations and ATolitions are only a species of
nervous action.  So  contradictory and unsettled were
all his notions on this important subject, that he again
represents "the stomach as the seat of the materia
vitce, and  thereby the organ of universal  sympathy;"
to Avhich he referred  " the sensations of heat and cold
that attend many diseases."   In another place he con-
founds the organizing principle with " a  certain species
of motion," in the same way that Bacon, Rumford and
others, confounded heat with motion; or  as the disci-
ples of Sir Isaac  Newton have confounded  the cause
of attraction and repulsion with mechanical force.  To 
MATERIA YITM OF JOHN HUNTER.        453
complete the problem of contradictions, Hunter finally
observes, that "life is a property we do  not under-
stand."
  In accordance with the doctrine of Cullen, (av!io re-
jected Dr. Black's theory of respiration as the exclu-
sive source of animal temperature,) Hunter maintained
that "the degree of heat  in animals is in proportion to
the  quantity of their life." (Phil. Trans, vol. lxvi.)   But
it might as  well be said that  the  degrees  of heat
throughout the  earth, from the equator to the poles,
are in proportion to the  quantity of animal and vege-
table life.  Had  this great anatomist known that all
the physico-chemical and vital operations that make
up  the history of our planet are directly in proportion
to the heating power of the sun, he would have recog-
nized caloric as the cause of motion,  and as the grand
instrument of the Deity in all the revolutions of mat-
ter—from the formation of mountains to the  aggrega-
tion of crystals, and the more complicated organization
of  living bodies.   Or had  he known  that the vital
energy  of animals is directly in proportion  to their
 standard healthy temperature, he would not have in-
 verted this fundamental law of physiology.
   In the observations of Hunter on the  animal eco-
 nomy, he recommends to the  attention of philosophers
 a comprehensive inquiry into the laws of heat, as con-
 nected with  all the operations of nature.  And he ob-
 serves in his Lectures  on  the Principles of Surgery,
 that "heat must be regarded as one of the first  prin-
 ciples of action in nature, which unlocks matter, and
 allows  it to act according to its  natural properties;
 that it  is congenial with  the  vital principle, which 
454
BROUSSAIS.
owes its vigour to a due supply of heat; that it is a
sign of strength in the constitution, whereas coldness
arises from Aveakness of the whole constitution."*  And
Broussais observes, that "caloric is the first and most
important of all stimulants; that if it ceases to ani-
mate the economy, others lose their influence over  it;
that all the preservative, recuperative and sanative
phenomena cease; and that caloric brings  into  play
the  unknown  power which constructs the organs."
(Pathol., p. 110.)   Dr.  Dowler, in fact, seems to have
adopted my own views, since he represents caloric  as
the  great  motor of the universe, and  that it ought to
be studied in preference to hypothetical agents or vital
metaphysics. (West. Journ. of Med., June, 1844, p. 447.)
But I have shown that  heat is  not  only the agent
which unlocks  matter, but  that it  is the great bond
of union, without which matter  could have no power
of action.
  When  commenting on  Hunter's theory of life, Mr.
Abernethy observes, that the widely extended research
into all the phenomena of  nature which  the subject
requires, is more adapted to an ancient Greek philoso-
pher, than to one  of the  present day.  He then de-
clares  himself at "a loss to knoAV what  chemists now
  * Following in the footsteps of Hunter, Sir Gilbert Blane ob-
serves, that "the combination of heat with the conservative prin-
ciple, forms the main constituent of simple life." (Medical Logic.)
But, like the vis insita of Haller, the vis medicatrix naturae of
Hoffman and Cullen, the excitability of Brown,  the sensorial
energy of Darwin, and the nisus formativus of Blumenbach, the
conservative principle is a mere refuge for ignorance in regard to
the physical cause of all the vital functions. 
OXYGEN DISCOVERED.
455
think respecting heat—whether they conceive it to be
a distinct species of matter, or mere motion; and that
in this state of perplexity he  could  not  advance one
step  farther than Mr. Hunter had led him."  Alas!
that  great  man left the theory of life in almost as
much obscurity as the chemists have left that of heat,
light  and  electricity; for, notwithstanding his  nume-
rous  experiments on the blood, he never explained the
cause of its coagulation and conversion into the various
tissues.
   Since the  discovery of oxygen by Priestley * and
Scheele, Girtanner, Blumenbach, Richerand and many
other physiologists  in different parts  of Europe,  in-
cluding Dr. Southwood Smith and Dr. Holland, have
maintained it to be "the life-sustaining  principle of
the atmosphere."  But it  is  absolutely  certain that
oxygen exerts no influence Avhatever in n%aintaining the
functions of animal life, unless it undergoes a chemical
change in  the  lungs, by which caloric is evolved and
united with the blood.  Besides, the quantity of life
throughout the earth is not in  proportion to the
amount of oxygen,  which is even more  abundant in
the polar regions than in the climes of perpetual sum-
mer.  It would, therefore, be a waste of time to dwell
on the absurdity of  regarding oxygen  as  the organiz-
ing principle independent of caloric.
  When it was found  that electricity is capable of
causing the muscles of recently killed animals to con-
tract, philosophers began to imagine that this agent
Avas identical with  the unknoAvn  nervous fluid, and
generated  in the brain, which some  haA-e represented 
45G          ELECTRICAL THEORY OF LIFE.

as  a galvanic battery.*  Mr. Abernethy fancied that
it wras  the materia vitce of Hunter; while Lamarck
supposed that the  vital principle  was  composed  of
electricity and light.   But  it is  not  in the  form  of
electricity that the  solar fluid warms and vivifies the
Avorld.   Nor is it in the form of electricity that solar
heat maintains the  fluidity of the ocean, the mobility
of  the air, the transformations  of chemistry and the
growth of plants; or  that animal heat maintains the
fluidity of the blood, the action of the heart, brain and
all the  other organs.   As I  have already proved that
caloric is the active principle in light, and that all the
different forms of electricity are modifications  of this
universal principle, it is needless to  dwell  longer  on
the electrical theory of life.

  *  In a recent work on the Principles of Medicine, by Dr Bil-
ling, the author "tnaintains that "the contractile power of the dif-
ferent tissues is called into  action  by nervous influence, generated
in the cineritious portion of the nervous system, and conducted by
the white medullary part to all the organs; that it is analogous to,
or depends on, if not identical with the electrical principle, or
fluid, whatever that may be; that the energy of parts depends on
a something communicated to them by the nerves, in conjunction
with the brain and spinal marrow;  causing the deposition of new,
and the absorption of old  matter, which keeps up a slow combus-
tion, and produces an extrication of caloric." (Pages IT and 20.)
In other parts of the same work, he  contends that all febrile dis-
eases have their  seat in the cineritious portion of the brain and
nerves; and that convulsions have their seat in the white or medul-
lary part of the same system, whether arising from excessive cold,
irritation of the bowels, the action  of narcotic poisons, the virus of
a rabid  animal, emotions of fear, wounds, &c.;  that hydrophobia
is a leaven which poisons the nervous system; and that the small-
pox virus may produce its effect by  some  chemical or electrical
action, positive or negative, on the nervous tissue. 
OPINION OF ST. AUSTIN.
457
  From the earliest dawn of science in India, Chaldea,
Egypt and Greece, down to this period, the organizing
principle was almost universally regarded as an inde-
pendent, ethereal and  refined substance.  The  same
doctrine was  held by the most  distinguished  fathers
of the  church, who maintained  that the soul, or ani-
mating principle, whether it inhabit the body or not,
is of a corporeal nature.   It was the  opinion of St.
Austin, that whoever denies this, reduces the  soul to
a non-entity,  and thus virtually takes aAvay the proofs
of its existence.   In his treatise, De Quantitate Animce,
he reasons thus:—" Take away extension from bodies
and they will be nowhere, and if they are nowhere,
they will not be at  all."  But since the publication of
Sir Isaac NeAvton's Principia, many physiologists have
maintained that there is no such thing as a primary
and efficient  cause  of power in nature, distinct from
the phenomena produced;  that cause  and  effect are
resolvable into the  mere antecedence and sequence of
events;  or that  Avhat is a cause in one case, is an
effect in another.  Dr. Thomas Brown observes, that
men have not been able to discover the cause of gra-
vitation, cohesion and chemical  affinity, because there
is none except the inherent tendency  of masses and
their  constituent particles to approach one another.
But  it  might as well  be said that there is no other
cause of steam-power  than the inherent tendency of
water to expand into  the  gaseous form, which is ab-
surd, and contradicted by  all experience.  Besides, if
it be true that caloric possesses the power of moving
itself,  and of generating motion in other  bodies, it
must be endowed  with  the essential  attributes of  a 
458
DEFINITIONS OF LIFE.
primary cause.  And if Avhen deprived of this  prin-
ciple the particles of matter become  passive and mo-
tionless, it is clear that, without its agency, they could
have no poAver of approximating, or of receding from
each other.*
  Yet Ave are  told by many of the most distinguished
modern  physiologists that, as NeAvton succeeded in
resolving nearly all the phenomena of nature into the
inherent properties of matter, there is no necessity of
resorting to the agency of any distinct principle as the
primary and efficient cause of animal motion.  In ac-
cordance Avith this view, Bichat  defines "life as the
sum  of  the  functions  that  resist death,"—Cuvier, as
"the combined result of all the organic functions,"—
and Richerand, as "the assemblage of  the  properties
and laws that govern the animal economy."  He says:
"Le mot de  principe vital, force vital, &c. n'exprime
point un etre  existent par lui meme, et independam-
ment des actions par lesquelles il se  manifeste:  il ne
faut l'employer que comme une formule abrege, dont on
  * So far as it was the object of Brown to guard men against the
error of assuming the existence of some occult and immaterial
cause of power in bodies,  of which experience affords no proof, he
was clearly right; for it must be admitted that all causes, whether
material or spiritual,  that  exist in nature, must be a portion of the
divine work.  Newton  carried this doctrine so far as to maintain
the materiality of the Great First Cause; for, said he, "there can
be no virtue without  substance."  (Opticks, book iii.)
  But without transcending the limits of the human mind, it may
be safely affirmed, that whoever denies the existence of any cause
of attraction, repulsion and animal motion, distinct from the phe-
nomena produced, not only rejects the evidence of reason and the
common sense of mankind, but involves the whole theory of nature
in profound obscurity. 
OPINIONS OF DIFFERENT WRITERS.
459
se sert pour designer l'ensemble des forces qui animent
les corps vivans, et  distinguent de la matiere inerte."
(Nouveau Elemens de Physiologie, tome i. p. 80.)  As
to Emanuel Kant's  definition of life, it is character-
ized by the vagueness of transcendentalism in general.
"Life,"  says  he, "is an  internal faculty producing
change, motion and action."  He might as well have
admitted with Mr. Hunter, "life  is a property that we
do not understand."
   Here,  then, as Mason Good observes, "we  have not
only the employment of terms that have no  meaning,
but properties, laAvs and powers without any  source,—
a superstructure without a foundation,—effects with-
out a cause."*
   Similar views have been expressed  by Magendie,
who thinks that "physiology is  now in the same con-
dition that natural philosophy Avas before the time of
Newton, and  only  waits until  a genius of the first
order shall arise to unfold  the  laws of vital force, as
Newton did those of general physics."  More than an
hundred other writers might be quoted who have de-
nied the existence of a vital principle, as maintained
by Hippocrates, Aristotle,  Galen, CelsusJParacelsus,
   * The truth is, that laws necessarily presuppose the  existence of
an agent; for they are merely the  mode  in which it produces effects
in a regular or uniform  manner.  And it might as well  be said that
"murder is the act of murderously killing a man;" that "death re-
sults from a want of vitality;" that "opium induces sleep by means
ofa dormitive property;" that "the heart contracts by means ot a
pulsific virtue;"  or that all the movements of nature are the sum
of the powers that prevent it from falling into a state of quiescence;
as that "life is the sum  of the functions that resist death."  It would
be an  abuse of reason to refute such vagaries. 
460
PRICHARD AND BAXTER.
Servetus,  Harvey,  Van Helmont,  Borelli, Perrault,
Stahl,  Hunter,  Lamarck and Abernethy;  Avhile a
large majority of modern philosophers  have, with an
equal disregard  of the clearest evidence, rejected the
materiality of caloric, electricity and light.
  Dr.  Prichard  objects to the doctrine of a subtile
fluid as the cause of vital action, because he cannot
conceive how it could produce  the wonderful phe-
nomena of animal motion, sensation and thought, un-
less endowed with  intelligence.   This in reality Avas
the opinion of Hippocrates, Galen, Seneca and Virgil,
who maintained that all the operations of nature were
governed  by the immediate agency of mind—"mens
agitat  molem."   The  same doctrine was taught  by
Paracelsus, Van Helmont, Harvey  and  Stahl, who,
with the ancients, seem to have  identified the active
principle in nature with the eternal mind of the uni-
verse.
  The celebrated Baxter denied the  existence of a
subtile fluid as the cause of crystallization and plane-
tary motion, because he  could not conceive how it
could produce such effects, unless it knew what it was
about.  (Immateriality of the Soul, p. 117.)   He there-
fore maintained  the vacuum of space, and referred all
the phenomena of nature to the immediate agency of
the Deity.
  From the  foregoing  brief history, we may readily
comprehend why no modern system of medicine has
maintained  its  credit  above  fifty  years.   Like the
house  in  the parable, that Avas built upon  the  sand,
they  have been defective  at the  very foundation,
Avhich, not being able  to uphold the  superstructure, 
BACON AND AVHEWELL.
461
they have gradually crumbled away, to be  replaced
by others destined to share the same fate.
  The observation of Bacon is no less applicable now
than it was  two hundred years ago:—" Medicine is a
science which hath been more professed than laboured,
and yet more laboured than advanced; the latter hav-
ing been,  in my judgment, rather in circle than  in
progression; for I find much iteration, but small addi-
tion."  Mr. WheAvell affirms, in the last  chapter of his
Bridgewater Treatise, that "Ave have yet to  begin  to
learn all that we are to know concerning the ultimate
laws  of organized bodies."  And he observes, in his
late History of the Inductive Sciences, that " many ana-
tomical truths have  been discovered, but no genuine
physiological principle; that the  notion of life, and of
vital forces, is still too obscure  to be  steadily held;
 and that we cannot connect it distinctly with severe
inductions from facts; that we can trace the motions
 of fluids, as  Kepler traced the motions of planets; but
 when we seek to render a reason for  these motions,
 like him we recur to terms of wide and profound, but
 mysterious  import—to virtues,  influences and unde-
 fined powers." (Vol. hi. pp. 404  and 431.) 
CHAPTER  II.
  "Nil turpius physico, quam fieri sine causa quidquam dicere."—
Cicero.
  " The ultimate purpose of our researches is to penetrate and
lay open the secret springs by which the great system of organiza-
tion, termed nature, is maintained in a state of perpetual activity."
—Lawrence.
                        •
  The  prevalent  doctrine  of  modern  physiologists,
that the phenomena of life are wholly distinct from
those of inorganic  matter, has arisen from our imper-
fect  knowledge  in regard  to  the primary physical
cause of motion throughout nature;  and is refuted by
the fact,  that the amount of vegetable life on our
planet, like  all the mechanical and chemical  trans-
formations that modify its  surface, is  directly in pro-
portion  to the  quantity  of caloric Avhich it receives
from the sun.   For we have already seen that  as the
amount of  evaporation and rain, the magnitude of
rivers, the number of volcanos  and the  elevation of
mountains, diminish from  the equator  to the regions
of lowest mean temperature; so do the number, variety
and magnitude of organized beings.  Let us then reject
the notion of Bichat, that "physics are not accessary,
but foreign to  the science of physiology."  (Life and
Death, p. 83.)
  It Avas observed by the  learned  Tiedemann, that
      (462) 
TIEDEMANN AND MULLER.
463
" the final cause of vital force, like that of attraction,
repulsion, gravitation, cohesion and chemical affinity,
is a secret whose profundity we shall  never be able,
from all appearances, to reach."  (Cornpar. Physiology,
p. 193.)   But we have seen that without the union of
caloric with the particles of ponderable  matter, they
could have no poAvers of approaching to or of receding
from  each other;  and  that the entire extinction of
solar  radiation, if such a thing were possible, would
put an end to the sublime revolutions of the heavenly
bodies, together with all that is beautiful and glorious
in the visible creation.
   The celebrated  Muller observes in a  late work on
the Elements of Physiology, that our knoAvledge of the
vital  principle is not more  imperfect than it is with
regard to the nature of caloric, electricity and light;
 and that the cause of crystallization is no less difficult
 to comprehend than  that of organization.   But I have
 shown that caloric is a self-moving agent and the ac-
 tive principle in light, as in every form of electricity;
 that  it depends wholly on the amount of caloric in
 bodies whether they exist in the solid, liquid or gase-
 ous state; and that the crystalline form of salts, rocks,
 &c. is greatly modified by  the  temperature  at Avhich
 they Avere formed, as in the phenomena of dimorphism.
 Nay  more, that there  are  many  bodies composed of
 the same elements in exactly the same proportions, which
 exhibit perfectly distinct properties when united Avith
 different proportions of  the same active principle that
 transports their particles from one place to another,
 and  arranges  them in  symmetrical forms; that gallic
 acid  is converted into pyro-gallic acid by the addition 
464          CONNECTION OF THE SCIENCES.

of heat  alone;  and  the latter into another distinct
substance by a  further addition of caloric, as in  the
formation of isomeric bodies.
  It has been asserted by innumerable Avriters on phy-
siology, that the phenomena of life are as far removed
from  those  of ordinary chemistry  as the  latter from
mechanics.   But the Great Architect of the universe
has  so completely  connected  all  the  operations of
nature together, that it is often difficult  to draAV the
boundary line betAveen  mechanical, chemical and vital
action.   The mechanical  force of  steam is generated
by the chemical union of caloric with the  particles of
water, to the expansion and contraction of which we
are indebted for all the  phenomena of evaporation and
rain, the nourishment of plants and the sustenance of
animal life.*  The circulation of sap through the ves-
sels of plants is no less the result of attraction than
the absorption of water by a  sponge, or its elevation
in the capillary tubes of dead matter;  but with this
difference, that  the  force  is  much greater in living
vessels, OAving to their extreme minuteness, compared
with  artificial tubes.   The conversion of  sap into or-
ganic molecules, and the latter into woody fibre, bark,
leaves,  floAvers,  fruits and different secretions, is no
less  the result  of attraction  than  the  generation of
water, salts, rocks and  other chemical compounds.
  The first  process of  germination consists in a che-
mical fermentation in the  seed, by \vhich  a portion of

  * And if it  be true, as there  is every reason  to  suppose from
analogy, that  solar light, like that of a lamp or common fire, is
generated by  combustion, all the phenomena of nature must be
referred to chemical action. 
       GERMINATION, GENERATION AND DIGESTION.   465

its substance is converted into sugar and carbonic acid,
while another portion is  changed  into living organic
molecules,  that  are arranged  in  symmetrical order,
corresponding with the parent type from which it
sprung.  The generation of confervae and animal in-
fusoria, during the putrefaction of organic  matter, is
no less the result of attraction than the conversion of
sap into trees, and blood into the structure of animals,
whether produced from seeds and eggs, or without the
concurrence of parents, as maintained by Needham,
Priestley, Ingenhouz,  Monti,  Wrisberg,  Tiedemann,
Miiller, Treviranus and  many other distinguished
philosophers.  The same  is true of the different spe-
cies of entozoa found in the  liver, brain, eyes, veins
and other parts of warm-blooded animals, which seem
to be formed by the immediate combinations of mor-
bid secretions in the parenchyma of their organs,
according to the  observations of Pallas, Miiller, Tre-
viranus, Rudolphi and  many others.   But caloric is
no less  essential  to fermentation, germination, circu-
lation,  nutrition  or  the  generation  of  microscopic
plants  and  animals from  the proximate  constituents
of dead organic  matter, than to the combinations of
ordinary chemistry.
  So far as digestion depends on the solvent poAver of
gastric  juice, it is a chemical process, by which dead
matter  is converted into chyme. And that it is owing
chiefly  to the agency of caloric, would appear from
the fact, that the digestive function in all animals is
performed with a rapidity exactly in proportion to the
amount of their  respiration  and mean healthy tem-
perature, being greater  in birds than in mammalia,
                        30 
466
RESPIRATION.
and very much  greater in both than in cold-blooded
animals, which require many days, and some of them
several weeks to digest a single meal.   We also learn
from the  experiments of  Spallanzani, that the diges-
tive  power of gastric juice  when taken from  the
stomach increases from 50° to 120° F.; and from the
late  researches  of  Dr. Beaumont, that when put in
vials and kept at the temperature of 100°, it converted
food into  a species of chyme that could  scarcely be
distinguished  from what was formed in the stomach,
but required a longer time to produce the effect.  The
fact is, that cooking may be regarded as the initiatory
process of digestion;  for it is  not  only the  softening
of raw animal and vegetable matter by the action of
fire, and thus  preparing it for entering into new com-
binations  in the living body, but greatly changes its
taste, odour and other sensible properties.
   The all-important function of respiration, so essen-
tial to animal life, is, strictly, a chemical process, by
which a portion of atmospheric oxygen  unites with
carbon  to  form carbonic  acid, with  an evolution of
caloric.   Who then can say at what precise  point the
operations of chemistry are merged in the affinities of
life,  as  in germination,  spontaneous  generation,  the
nourishment of plants, &c.; or when the latter  ter-
minate in the actions of ordinary chemistry, as during
the ripening of fruits?
   There is nothing more  calculated to excite our ad-
miration of the infinite wisdom by which the universe
is governed, than  the intimate  relation  that exists
betAveen all its physico-chemical and vital operations
By the mechanical  diffusion of water through  the 
      ULTIMATE ELEMENTS OF ORGANIZED BODIES.   467

atmosphere, organized bodies are supplied with  the
greatest part of their substance.  The carbonic acid
generated by chemical action during the processes of
combustion, fermentation and the respiration of ani-
mals, affords  nourishment to  plants—being decom-
posed in the tissue of their leaves, where crude  sap is
converted into cambium by the evaporation of  water
and the absorption of carbon; then into starch,  sugar,
oils, &c, which in their  turn become the appropriate
nourishment of animals.  It was justly observed  by Sir
Charles Morgan, that " the distinctions Avhich the sub-
tilizing  genius of man has invented to separate  and
to isolate, are contradicted and deranged at every new
step  of  successful investigation." (Philosophy of Life,
p. 62.)

      ULTIMATE ELEAIEXTS OF ORGANIZED  BODIES.

   Among the sixty-tAvo undecompounded bodies, in
dependent of the imponderables, that form  the crust
of the earth, nineteen have been found in plants  and
animals, ten  of  Avhich   are non-metallic,  and nine
metallic;  viz., oxygen,  hydrogen,  nitrogen, carbon,
phosphorus, sulphur, chlorine,  iodine, bromine, fluo-
rine, potassium, sodium,  calcium, magnesium, silicium,
aluminum,  with the more  ponderous  metals, iron,
manganese and copper.   But the most remarkable cir-
cumstance connected with  the chemical constitution of
organized bodies is, that they are composed chiefly of
the most light,  active and mobile species of matter, such
as oxygen, hijdrogen, nitrogen and carbon, the three first
of which are always found in the cjaseous state, when not 
468         ELEMENTS OF MINERAL  BODIES.

united chemically with other bodies;  while their elas-
ticity Is  such  that no mechanical pressure  has ever yet
been sufficient  to overcome it.   Hence it  is that the
atmosphere,  and the waters that  are elevated from
the ocean, which are composed of these  elements, are
in a  state of perpetual motion, circulation and che-
mical combination with  other bodies.*   These, with
carbon, are the basic constituents of organized bodies;
for the sum of the remaining  fifteen  does not exceed
two  or three per cent.  And  that the  staminal ele-
ments of organic matter contain  a larger amount of
caloric around their particles than  an equal weight of
any other known bodies, might naturally be inferred
from  their tendency to assume the  fluid state, their
highly inflammable  properties, their  general activity,
and from the enormous amount of heat evolved during
their combustion.
   On the other hand, the leading characteristic of the
mineral world is, that it is composed  chiefly of metal-
lic bases, which are not only the most dense and gross,
but the most inert descriptions of ponderable matter.
The consequence of  which  is, that  at all ordinary
temperatures  of  the  atmosphere,  they  remain solid
and quiescent, while "the moving waters and the in-
visible air," are continually circulating throughout the
earth, as if impelled by some  spiritual agent.   But if
  * It was long ago said by Aristotle, that the lightest descriptions
of matter are the  most perfect, and  partake the  nature of forms.
As a proof that this is actually the  case, it may  be observed that
the variety of organized species, which are composed of the lightest
elements, is far greater than that of mineral bodies, and they possess
a far more complex structure. 
AFFINITIES OF LIFE.
469
submitted to the influence of intense heat, the  most
refractory bodies are changed to the  fluid state, (the
essential condition of which is mobility,)  and acquire
the power of entering  with great rapidity into new
combinations, as  in  the regions  of subterranean che-
mical  action,  where the rocks  that  form  the  solid
mountains of the globe are aggregated,—and among
the ruins of which  have been discovered nearly all
the precious metals  and gems, including the rich and
sparkling diamond.   The  metallic elements, united
with  various proportions of oxygen, hydrogen,  nitro-
gen, carbon, &c,  constitute the  massy frame-work of
the earth; but they are wholly incapable of forming
organic compounds, and of executing the more elevated
functions of living matter.   It is therefore obvious that
there is a broad line of demarcation  between the che-
mical constitution of mineral and organized  bodies.
   Another  fundamental difference between them is,
that, with the exception of oxygen, hydrogen, carbon
and nitrogen, all the  other elements of  ponderable
matter are capable of entering into simple binary com-
binations only;  whereas  the ultimate  principles of
organic bodies seem to  possess the additional power of
forming ternary  and quaternary compositions.  Thus
oxygen with hydrogen  produces water; with sulphur,
phosphorus, nitrogen, carbon, &c, it forms acids  which
are single binary compounds *  With calcium, sodium,

   * Oxygen enters into the composition of nearly all  bodies. It
constitutes one-fifth  of the atmosphere, eight-ninths of all  the wa-
ters, and about one-third of the solid earth.  But as in the latter
case it is chained down in a state of chemical combination with
metallic and other  gross matters, its active  powers are  kept in 
 470     TERNARY AND QUATERNARY COAIPOUNDS.

 potassium, &c, it makes alkalies that are also binary
 combinations, which, on uniting with the above acids,
 form neutral salts, that must be regarded  as double
 binary  compositions;  while the union of  the  same
 acids AArith simple bodies, such as the pure metals, gives
 a third order of binary compounds, according to  Ber-
 zelius.
   But in the formation of the simplest plant, it has
 been found that at least three elements, oxygen, hy-
 drogen  and  carbon,  are united  together  in a direct
 manner, Avithout  any  previous  binary combination;
 and that the various tissues of all animals (if we ex-
 cept the very lowest species of  zoophytes, the real cha-
 racter of Avhich is doubtful,) are formed by the imme-
 diate union of the same elements Avith nitrogen. From
 the ternary and quaternary combinations of  these ac-
 tive principles in various  proportions, are generated
 all the diversified  organizations that make up the liv-
 ing world, as shown by the analytical researches of
 Thenard,  Gaj'-Lussac,   Berzelius,  Prout,  Thomson,
 Saussure, Berard, Chevreul, Ure and others.  (Tlede-
 mamis  Comparative Physiology, pp.  6,  7.)
   But in addition to  the power of oxygen, hydrogen,
 carbon and nitrogen, to form ternary and  quaternary
 compounds, it is worthy of special notice, that many
 more atoms  of the same elements  unite together in
 forming organic combinations than are found in those
 of inorganic bodies.  For example, Avater is composed

 abeyance.  It also  forms about seven-eighths  of animal bodies,
 and above two-thirds of plants, as may be readily ascertained by a
reference to their elementary composition, and the relative quanti-
ties of water in each. 
PROXIMATE CONSTITUENTS.
471
of one atom of oxygen to one of hydrogen; carbonic
acid, of carbon one atom to tw o of oxygen; and so of
innumerable  other  binary compounds; whereas the
acid,  saccharine,  oily  and  resinous  constituents of
plants, are generated by the immediate union of many
oxygen, hydrogen and carbon atoms.   Starch is com-
posed of twelve atoms carbon, ten of oxygen, and ten
of hydrogen;  sugar of twelve atoms of carbon, eleven
of oxygen, and eleven of hydrogen;  while the oil of
peppermint consists of  carbon  atoms ten, hydrogen
ten, and oxygen one.   The resins and fixed oils con-
tain still higher numbers of the same atoms, as may
be seen by referring to  page 148 of  the  First Book,
where it  has been  shoAvn that this constitutes the
principal  difference between the volatile and more
tenacious compounds of organic  matter.  From which
it is probable that the quaternary unions of  oxygen,
hydrogen, carbon and nitrogen, to form the proximate
constituents of the blood and solid tissues of animals,
 contain still higher numbers of atoms of the same ele-
 ments.   So that whether the affinities of life be OAving
 to the same physical cause which governs those of in-
 organic matter or not, the former evince at once a far
 more complex and refined mode of operation.   Hence
 the beautiful remark of Kielmyer, as cited by Tiede-
 mann, that crystallization represents in  some degree
 the simple elements of geometry; while  in  the pro-
 duction of organized  bodies, nature  has employed a
 high geometry.*____________________
   * It may here be ob^v^thaTsaccharine bodies, including
 gum, starch, lignin, &c, are  formed by the union of oxygen and
 hydrogen in the proportions that form water, with carbon; that 
472        FORCE OF BINARY COMBINATIONS.

   Owing to the more complex affinities by which the
elements of organized bodies are joined together, they
have a greater tendency to undergo what has  been
called  spontaneous  decomposition, than  the  binary
combinations  of  inorganic  matter.   And it would
seem to be a general law of  nature, that the force with
which bodies cohere  together,  is inversely as the number
of elements and atoms of which they are composed. For
example, water is more difficult to decompose than the
deutoxide of  hydrogen;  carburetted hydrogen, than
bicarburetted  hydrogen;  and the latter than etherine.
In like manner, the protoxide of  nitrogen is more dif-
ficult to resolve than the  deutoxide; and so on till we
come to nitric acid, which is composed of five atoms
oxygen to one of nitrogen, and may be decomposed with
great facility.   But I have shown that the quantity of
caloric  around the  particles of alcohol, ether,  nitric
acid, &c, is in proportion to  the number of atoms that
enter into their  composition,  cceteris paribus.  It is
therefore not  true, that the disposition of  organized
bodies to run  into new combinations is OAving merely
to their elements not being united in different propor-
tions, or to their  not being  saturated, as  maintained
by Tiedemann and others; for the elements of sugar,
alcohol and  many  other similar compounds are  as
completely saturated as those of water, carbonic acid,
or the  earths and alkalies,  which  are  so  difficult to
decompose.

the same elements with oxygen in  excess form acids; while with
hydrogen in excess, with respect to oxygen, they afford oily and
resinous compounds.   Yet there is a large class of acids that con-
tain no oxygen, such as the hydrocyanic, the hydrochloric, &c. 
INERTIA OF  MINERALS.
473
  Corresponding with the simple binary composition
of minerals, they are of uniform structure through-
out; and when once formed, their individual existence
depends on the repose of their particles.  What they
are when first aggregated, they remain until destroyed.
They may be  enlarged by accretion, and diminished
by  attrition, but they have  no  organs of  nutrition,
secretion,  or reproduction; no origin by birth, no re-
neAval of  their composition,  and no termination by
death.  Being  composed of the more ponderous ele-
ments, or binary combinations of them, they are  held
together with  great  force,  and  endure for a much
longer time than trees, which consist of ternary  com-
binations  of more active elements.  For the same rea-
son, animal bodies that are  formed of three elastic
gases, united in various  proportions Avith carbon, are
more volatile  and  destructible  than wood, after the
affinities of life have ceased.  In  other words, mine-
rals are more solid and fixed than plants, because they
 are formed of  more gross and inert materials; while
 trees are  more solid and durable than the  animal tis-
 sues, because the first are  composed  chiefly of water,
 with carbon, and the latter of air, water and carbon.
    So essential are fluids to the existence of organized
 bodies, that they constitute nearly the whole of their
 substance during the embryotic state, especially in the
 egg and foetus of animals.  But the proportion of fluids
 to that of solids, varies in different species, and at dif-
 ferent periods of their growth, being about ten to one
 durin- early  life in the human body, and six to one
 in oldVe. According to Richerand, they are  as three
 to one in trees; but they are much more abundant in 
474
COMPOSITION OF THE BLOOD.
the annual and more succulent plants, as also in the
newly formed  parts of trees;  Avhile it is worthy  of
notice, that the affinities of life are always most active
in those  parts which  receive the greatest amount  of
fluids, such as the medullary and muscular tissues  of
animals,  and the soft vascular structure of plants; but
that the  movements of life are slow and  fdeble in the
hard  woody fibre, and almost wholly absent in the
earthy matter of bones.   Fluidity, then, which is only
another  name  for, mobility, is  absolutely essential  to
the manifestations of life.
  According to the latest  analyses of human venous
blood, it  has been found to consist of about 790 parts
of water in  1000, and  the remainder  of albumen,
fibrin, colouring matter,  oily and saline ingredients.
From which it is obvious that as water is composed  of
eight parts by weight of oxygen to one of hydrogen,
and also  forms  about  one-third of the organized  part
of the blood, oxygen must constitute by far the greater
proportion of its substance; the remainder being car-
bon and  nitrogen, with nearly one per cent, of saline
matter.
  From  the ternary and quarternary combinations  of
oxygen, hydrogen, carbon and nitrogen, organic mole-
cules  are generated, Avhich form the proximate consti-
tuents of all living bodies, whether fluid or solid, from
the simplest plant or gelatinous animalcule up to man.
They have been found in  the blood, chyle, chyme,
milk, fat, saliva, bile,  pancreatic and gastric juice, the
seminal fluid, the yolk and  albumen of the egg, in all
animals;  in the sap of plants, and much  more abund-
antly in the cambium, after it has been exposed to the 
      MOLECULES FORMING THE PRIMARY TISSUES.   475

influence of solar warmth Avhile circulating through
the leaves.  They have  also  been discovered in the
albumen of farinaceous seeds and bulbous  roots, the
cells of flowers, and the embryo while forming, accord-
ing to many accurate observers, cited by the  learned
Tiedemann.  As. might  naturally be supposed, these
globules, as they have been  termed, vary in  form,
colour  and  magnitude,  according  to  the species  to
which they belong, and the office they are destined to
fulfil.
   By the arrangement of organic molecules, in series
and aggregates, the primary tissues of all living bo-
dies are generated, in accordance with  laws no less
fixed and definite than those  of crystallization.  The
lowest species of plants and zoophytes, such as fungi,
lichens, alga3 and the gelatinous animalcules, are com-
posed chiefly of cellular tissue, Avhich in the higher
orders of plants is expanded into ligneous fibre, bark,
leaves and flowers.   The cellular tissue also enters so
largely  into the composition of the more perfect ani-
mals, that it has been often represented as the scaffold
of all the organs, and the mould in which their parti-
cles are deposited.  The  osseous, cartilaginous, fibrous,
vascular, serous, dermoid and mucous membranes, are
all regarded as  modifications of this  primary tissue,
which   is formed  chiefly of  albumen,  arranged  in
lamella? and fibres variously  interlaced, so  as to con-
stitute  a net-work of cells,  that communicate with
each other throughout the body.
   But  as the elementary composition of animals is
more complex than that of plants, they present a more
diversified system  of organization,  if we except the 
476     UNION  OF  THE  THREE PRIMARY TISSUES.

lowest species  of zoophytes, which so nearly resemble
the simpler microscopic plants, that some physiologists
have maintained tlieir mutual convertibility into each
other.  For example, in addition to cellular tissue that
forms the basis of plants, and the principal portion of
the higher animals, the latter are composed of mus-
cular and nervous  tissues, by which they are endowed
with the powers of locomotion,  perception  and con-
sciousness.  The muscular fibres are formed of fibrin,
the particles of which  are  arranged in lines that re-
semble rows of globules under the microscope;  while
the nervous tissue is composed of albumen, and cer-
tain oily matters that  contain much hydrogen, and a
little phosphorus,  forming an infinite  number of ex-
ceedingly minute  and  delicate tubes.  (Midlers Ele-
ments of  Physiology, vol. i. p. 599.)
  By the union of these  three primary tissues in va-
rious proportions,  the different complicated organs of
the animal fabric are built up, as the heart, stomach,
intestines, liver, pancreas, kidneys, muscles, ligaments,
tendons, cartilages, membranes, bones, &c;  all of which
are generated from the albuminous, fibrinous, oily and
saline constituents of the blood;  which is formed by
the immediate union of oxygen, hydrogen, carbon and
nitrogen, into quaternary combinations.   Most of the
fluids secreted  by  animals, such as gastric juice, bile,
mucus, pancreatic  and  seminal liquor, are  also quater-
nary compounds.   But they also secrete several combi-
nations that are ternary, as the sugar of milk and urine,
fat, resin and the volatile oily matters termed civit
and castor.  On the other hand, there are many plants
that contain more  or less nitrogen, which  is abundant 
CAUSE OF VITAL  AFFINITY.
477
in mushrooms, and in the vegetable salifiable bases,
morphine,  narcotine,  veratrine, solanine,  delphine,
emetine, quinine, cinchonine and many other like com-
pounds.  From  which it is obvious,  that  the more
complicated organization of animals than of plants, is
not owing  merely to the greater complexity of their
elementary composition, as will further appear here-
after.  Yet there cannot be a doubt, that the structure
and functions of all organized bodies are determined
by the chemical constitution and fundamental proper-
ties of their ultimate elements, which  are modified by
every increase or diminution in the quantity of caloric
around their atoms.
   The great question  that lies at the very foundation of
organic chemistry is,  whether the power of forming or-
ganic compounds, with the aptitude for renewing their
composition by assimilation and elimination, be owlhg
to the same cause which  governs  the affinities of dead
matter, or  to some peculiar principle of a totally distinct
nature, as  maintained by Berzelius,  Tiedemann, Miiller
and nearly all the most distinguished physiologists of the
present day.  Nothing but an earnest  appeal to nature
and a  careful examination of facts can resolve this
difficult problem.
   The learned Tiedemann observes very justly,  that
the difficulty of explaining the phenomena of life by
the laws of physics  may be  oAving to our  imperfect
knowledge of natural phenomena in general.   But
 Miiller contends, that "the power  by which the ele-
ments of organized bodies are united into ternary and
quaternary compounds  in opposition  to the laws  of
 chemistry, is, without doubt, a peculiar  force, or im- 
478
SPONTANEOUS GENERATION.
ponderable  matter, unknown in  inorganic  nature."
Yet he admits in another place, that the cause of crys-
tallization is  not less profoundly hidden than that of
organization.   (Elements of Physiology, pp. 22, 251.)
That the power of oxygen, hydrogen, carbon and ni-
trogen, to form the proximate constituents of living
bodies, is owing to the fundamental properties of these
elements, would appear from the fact, that no others
are capable of entering into ternary and quaternary
compositions; in short, that no  plant  or animal was
ever  formed  or nourished  by  any other elements.
And  that the tendency of dead organized bodies to
undergo decomposition, is owTing to the  same active
principle that enables these elements to form ternary
and quaternary combinations, is proved  by  the cir-
cumstance that  this tendency is augmented by every
addition of caloric, which I have  shown to be not only
the universal bond, but the great  decomposer of all
matter.
  During the decomposition of organized bodies under
the influence  of a  summer temperature, a portion of
their substance enters into binary compounds of water,
carbonic acid  and ammonia.  But during this process,
another  portion of  the same elements  unites to form
the simplest species of microscopic plants and animal-
cules, without the concurrence of parents, seeds, eggs
or the addition of any other principle  than Avas con-
cerned in the  generation of Avater, carbonic acid, &c*

  *  It is related  by Sharon Turner, that in boring for water near
Kingston-upon-Thames, some earth was brought up from a depth
of 360 feet; and though carefully covered with a hand-glass to pre-
vent the possibility of any seeds being deposited on it, was yet in a 
PROGRESSIVE ORGANIC DEVELOPMENT.       479
And as it has been shoAvn that the  form of crystals
depends on the nature  of their atoms,  modified by
the temperature at which  they are  aggregated, so has
it been observed that the specific  character of infu-
soria, generated during the fermentation of albumen,
fibrin, starch,  gluten and other organic compounds,
varies according to the different species of matter em-
ployed.
   It is also said, that there  is  a progressive advance
in the productive power of the infusion, which  at first
produces animalcules of the smaller kinds, that after-
Avards become  gradually larger  and more complex in
structure; that when the quantity of water is small,
and the organic matter  abundant,  there is a predomi-
nance of vegetable production; but that when there
is much Avater, animalcules predominate.   It is there-
fore highly probable, that if all the  plants and animals
that  noAV inhabit the > earth, together with all their
seeds and eggs, were annihilated, other orders, genera
and species, Avould gradually arise, under  the influence
of existing laws.  The  idea that  every  new creation
of organic beings, requires  a  special or  miraculous

short time covered with vegetation. (Lardner, Hist, of the Earth,
vol. i. p. 210.)  If in this case, the vegetation sprang from seeds,
they must have been preserved in a damp soil for more than a mil-
lion of years, which  is incredible.   But  does any one suppose
that the aboriginal generation  of plants is more  miraculous than
their perpetuation by  sexual intercourse ? or that different agencies
 are required to effect  both results ?  Is it strange that our mother
 earth which gives birth to all things under the influence of the
 prolific sun, should cause herbs to spring  from her fruitful bosom
 without seed ?  If not so, how did plants and animals begin their
 existence before there were any seeds or eggs ? 
480       SPONTANEOUS  GENERATION  OF ENTOZOA.

feat of the Deity, is equal to saying  that the universe
requires new  modifications of the plan on which it
was originally constructed, and therefore is imperfect.
   Those simple  organizations termed  entozoa,  gene-
rated in the parenchymatous substance of many ani-
mals,  Avithout  the visible  existence  of any parents,
eggs or  germs, also vary according  to  the  nature of
the animal, and  even of the organ in which they are
formed.*  Nor is there anything more mysterious in
this, than in the ordinary process  of generation, only
that Ave are more accustomed  to  the latter;  or that
specific  contagions  should  be  generated  by  certain
combinations of filth and vitiated animal  secretions,
as  in  gonorrhoea,  lues venerea,  smallpox, &c, that
have the power of propagating themselves in  a  mode
analogous to the  production of fermentation by yeast;
which, according to the observations of De la  Tour,
  * It is said that twelve different  species of entozoa have been
found in man, six in the alimentary canal and its appendages, one
in the lungs, one in the brain, one in the eyes, one in the muscles,
one in the kidneys, one in the ovaries and one in the  skin; while
in the several organs of the sheep, nine species have been  dis-
covered ; eleven in the ox; nine in the horse, hog and fox;  and
eight in the hare.   They have been found in  birds, reptiles,
fishes, Crustacea and mollusca.  (See Fletcher's  Rudiments of
Physiology, part ii. p.  12.)
  They have also been found in the embryons of these animals;
from which it is  maintained  by Pallas, Miiller, Werner, Bloch,
Goeze, Braun, Gr. R. Treviranus, Rudolphi and others, that they
are the products of non-assimilated matters, or morbid  productions
formed in the humours or parenchyma of the organs, in a mode
resembling the generation of infusoria during the  fermentation of
organic matter.  (Tiedemann's Comp. Physiology, p.  40.) 
ORGANIZATION AND VITALITY.         481
is composed chiefly  of organic molecules that have
the faculty of multiplying  themselves in all ferment-
able matters.
  Should it be objected that such molecules, like the
different species of moulds, confervae and animalcules,
can be generated only from matter that has been once
organized,  I  ansAver  that the  elements of oxygen,
hydrogen, carbon and  nitrogen, wherever they exist,
are capable of entering into the universal tide of life;
Avhether locked up Avith rocks,  metals and beds of
coal, in the bowels of the earth, or  floating over its
surface in  the state of air and  water.   When once
formed, the germs of plants  have the power of con-
verting the binary combinations of water and carbonic
acid into ternary compositions of lignin, sugar, starch
and other organic products, which are thus prepared
for  entering  into  the composition  of more exalted
species of organization; while it is certain, that what-
ever the cause of vital action may be, it is incapable
of converting the elements of mineral bodies into the
sap, cambium  and solid structure of plants; or into
chyme, chyle, blood, and the  different organs of ani-
mals.
  Owing to the  comparative inertness of their  ele-
ments, mineral bodies  have  the power  of entering
into binary combinations only, Avhich maintain their
original state of aggregation until destroyed by che-
mical agency, and possess no  internal mechanism for
renewing their composition.   But the essential attri-
bute of the elements of organized bodies is that of
mobility or activity, by which they are kept in a state
                        31 
482          ORGANIZATION AND  VITALITY.

of perpetual transformation, or transition from death
to life, and from life to death.
        " All forms that perish, other forms supply,
         By turns we catch the vital breath and die. "

   Owing to the large  amount of caloric around these
elements, they are enabled to form ternary and qua-
ternary combinations, with the  aptitude for  life;  and
Avhen reduced to the condition of dead matter, they
are constantly entering into  binary combinations of
Avater, carbonic acid, &c, or into the  simplest forms
of living organizations.  But if reduced to a low tem-
perature, all their chemical and vital  affinities cease,
Avhen they assume that condition of repose which
characterizes  the  elements of mineral bodies.   The
sap of plants  is no  longer converted  into cambium,
lignin, bark, leaves, flowers and fruits.  The food of
animals is  no  longer converted into chyme by uniting
Avith  gastric liquor; into chyle by  uniting AArith bile
and pancreatic juice;  nor into blood during the pul-
monary circulation.    But when the  temperature of
the human body is maintained by  respiration at the
normal standard, it exhibits an universe of motion in
miniature.  Like the waters  of  the earth that are
continually passing from  the  ocean by evaporation
and returning to  their source by rivers, the blood is
conveyed with immense rapidity from the lungs and
heart throughout the system, renewing its composition
by the deposition of fresh organic molecules, the cohe-
sion of which diminishes until the cause of force is
expanded by  action;  when they are removed by ab-
sorption, conveyed into the general circulation and 
       INFLUENCE OF CLIMATE ON ORGANIZATION.    483

thence out of the body by elimination.   Not a particle
remains quiescent for any considerable  time, so that
in about forty days, a complete revolution may be
shown to  be effected in its  substance, if we except
the cartilages, bones and teeth, which  last two are
almost wholly destitute of life.  The cellular tissue is
also endowed with a very low degree of vital energy,
compared  with the nervous  and muscular, if we ex-
cept the mucous membranes; and contains much less
nitrogen in its composition.
   That the power of living bodies to renew their compo-
sition  by assimilation, and to reproduce their species by
generation, is governed by the emphatic agency of caloric,
is evident from the fact, that the power of nature to mul-
tiply organic forms is directly in proportion to the tem-
perature of the  earth, from  the  equator  to the  polar
circles.  It is only in the regions  of perpetual  sum-
mer, that  the number of species, variety of structure
and magnitude of form, are  developed in full perfec-
tion throughout the  vegetable world,-—where the air
is perfumed with the odours  of myrrh, sandal,  balm,
frankincense, sugar-cane, coffee, tea, mace, cloves, nut-
meg, cinnamon,  pepper, tamarind,  with innumerable
other  plants that abound with the  most highly elabo-
rated  aromatics  and  precious drugs,—where the fig-
tree,  orange,  lemon, date,  banyan and a thousand
varieties of palms, are loaded with  an  exuberance of
delicious fruits.   But as we  advance to  the middle
latitudes, where  the  mean temperature is from 20° to
30° lower, we find that the more exquisitely organized
vegetation of the torrid zone is, for  the most part, re-
placed by totally  different  orders  and genera, which 
484    INFLUENCE OF CLIMATE ON ORGANIZATION.

diminish in number, variety and magnitude, on to the
polar circles;  where  only fungi,  lichens, algas, the
humbler grasses and  a few other  plants of the  most
simple  structure  are generated during tlieir  short
summer.
   It is also in the tropical  regions  that animals  have
been found in  the greatest number, and where  they
arrive  at the greatest magnitude;   from the ostrich,
cassowary  and condor of Africa and  South America
among  birds, to the  elephant, rhinoceros,  hippopo-
tamus, giraffe and camel, among  mammalia, or the
gigantic  species of the feline  tribe, as  the lion, tiger,
leopard, &c.   But it  is  more especially among the
cold-blooded animals, that the magnitude of the same
species is found  so greatly to exceed  that of such as
inhabit the higher latitudes.  The development of the
crocodile, boa,  anaconda,  the  immense turtles of the
East and West Indies, as of the enormous mollusca of
the tropical seas, and the  mighty forests of India,
Africa and South America, is fostered by the ceaseless
influence of a powerful sun.
   If the whale  and  a few other mammalia  attain to
a great size in high latitudes, it is because  they are
supplied Avith an apparatus for obtaining  caloric from
the atmosphere by respiration, which maintains then
mean temperature about 20°  above that of the earth
under the equator, as will  be noticed further hereafter.
The caloric thus acquired is preserved by means  of a
Avarm fur coat,  or a subcutaneous layer of fat, that in
the Avhale varies from eight to fifteen inches in thick-
ness.   And if there  be  some species of plants  that
remain evergreen throughout the Avinter, it is because
they abound with oily and resinous constituents, Avhich 
        INFLUENCE  OF CLIMATE ON ORGANIZATION.    485

 are bad conductors, and therefore retain  a sufficient
 amount of heat to prevent the  destruction of their
 foliage, but not to maintain their growth.
   Now Avhatever the cause may be by Avhich organized
 bodies are enabled to renew their composition, it must
 determine the actions that modify their structure and
 functions; for the elements of which they are formed are
 the same in all parts of the Avorld, with this prominent
 exception, that within  the tropics they are continually
 receiving from the sun a larger  proportion of  that
 ethereal principle, (whatever men may choose to call
 it,) which preserves all nature in a state of activity.
 The elements of the air, water and crust of the earth
 are the same in South  America as at Melville Island;
 which is also true  of all the  plants and animals that
 inhabit the earth.  The number of species, the mag-
 nitude of their forms and complexity of organization,
 must  therefore be regulated by the energy of the prin-
 ciple that causes their  development, which diminishes
 from the hottest to the coldest  parts of the globe; be-
 cause in the former, the affinities of life are continually
 in action, but suspended for six  or nine months of
 every year, in the middle and higher latitudes.
   The experiments of Decandolle on the  medicinal
 properties of  plants, compared with their  external
 forms and natural  classification, prove that their com-
 position depends  on the vital  energy by which they
 are developed.   From Avhich it follows, that  if the
phenomena that constitute their  groAvth  depend on
climate, it must determine the composition of all their
diversified products.   If the indigenous plants  and
animals of the old world are different from those of
the new in the same latitudes, there is a corresponding 
486
THEORY OF RESPIRATION.
difference of climate and season.   And if the vegeta-
tion west of the  Rocky Mountains be different from
that of the same parallels east of that great chain, it
is because the climate of the western coast of America
is greatly modified and tempered by its vicinity to the
Pacific Ocean, if Ave except the arid plains and valleys
of California.   Owing to  the unequal distribution of
land  and sea, mountains, hills, plains and valleys,
there is an  endless diversity of climate, Avith a corre-
sponding variety of organized beings.

THEORY  OF RESPIRATION, AS CONNECTED WITH ANIMAL
                   TEMPERATURE.

  Nothing  could afford a more striking proof  that
" no genuine physiological  principle has ever yet been
discovered," than the numerous contradictory hypo-
theses now prevailing in regard to the source of animal
temperature;  some maintaining with Black, Crawford,
Lavoisier, Ellis and Dalton, that it is evolved in the
lungs during respiration, by a chemical process, as in
ordinary combustion; others with Bichat, that "it is
a product of all the vital functions."  (Life and Death,
p. 278.)   Within the last twenty years, many have
embraced the theory of Sir Benjamin Brodie, who in-
ferred from his own experiments, that animal  heat is
in some Avay generated by nervous influence, because
mechanical injuries of the brain and spinal marrow
were followed by a reduction  of  temperature.  But it
Avill be seen hereafter, that such injuries, like  the in-
fluence of narcotic poisons, diminish or destroy the
function of respiration;  and it has been proved by the 
DIFFERENT OPINIONS.
487
experiments of Hastings, Holland, Flourens and many
others, that  the reduction of  temperature may be
greatly retarded  by artificial inflation of the lungs
after decapitation, and  division of the eighth pair of
nerves.
  Others maintain, with Dr. Philip, that animal heat
is the result of secretion; while Tiedemann contends
that its evolution is "a vital act, which depends im-
mediately on the process of nutrition, the conditional
and preservative cause of life."  (Compar. Physiology,
p. 247.)   Mr. Mayow says, that physiologists at pre-
sent incline to the opinion that "the  production of
animal heat depends on nervous influence;" but with-
out explaining how and whence the nervous system
obtains it; and  he adds in another  page, that "the
source of vital heat is unknown." (Physiology, pp. 79,
264.)
  With Dulong and Despretz,  Dr. S. Smith regards
respiration as the principal source of  animal tempera-
ture, but thinks there  is reason to  believe that the
remainder  is extricated from the blood  by nervous
influence, as in the process of secretion  and nutrition.
(Philosophy of Health, vol. ii. p.  153.)   Chaussat  con-
cludes, from his own experiments, that the evolution
of heat depends more on the cervical portion of the
spinal marrow or medulla oblongata, than on the brain.
(Ann. de Chim. et de Phys. tome hi.)   And Miiller ob-
serves, that " since all organic processes are dependent
chiefly on nervous influence, it cannot appear wonder-
ful if the reciprocal action between the organs and the
nerves is a main source  of animal heat." (Elements of
Physiology, p. 86.) 
488
THEORY OF EDAVARDS.
   As if with a view of reconciling these  conflicting
hypotheses, Dr. W. F. EdAvards maintains, in a recent
article on animal heat, contained in the Cyclopedia of
Anatomy and Physiology, that it  depends first, on the
condition of the blood; secondly, on  the development of
the nervous system; and thirdly, on muscular cemtrac-
tlon;  because the temperature of animals is in propor-
tion to the richness of tlieir blood, and the degrees of
nervous energy,  muscular  power, &c.   At  the com-
mencement of the  same  article, he  observes that
"Physiologists have  not been able to discover the
cause of animal heat, for the same reason that natural
philosophers have not yet discovered how heat is pro-
duced in the inorganic Avorld."   But if it be true that
caloric is absolutely everyAvhere present, either in a
combined or separate state, and cannot be  traced to
any more comprehensive principle, it must be allowed
to possess  the  essential and efficient attributes of a
primary cause.  Moreover,  I have  proved that it has
the power of moving itself, and of generating motion
in other bodies;  that if the  air, the ocean  and the
solid  ground Avere deprived of this active  principle,
they Avould be perfectly inert  and  quiescent, for the
plain  reason that the volume,  elastic force, mobility
and chemical power of  all bodies are diminished  by
every reduction of their temperature; consequently,
that caloric does not consist in the vibratory motions
of ponderable matter, as supposed by Rumford, Davy,
Young and others, nor in " the successive polarization
of its particles;"  but that it is the cause of vibration,
without which there could be no sound, light, life nor
motion  in  the  universe.  It is, therefore, chimerical 
            THEORY OF SIR CHARLES MORGAN.        489

 to call in question the materiality of the only agent in
 nature that is omnipresent, as it is to speculate about
 its nature or origin, unless we confine our inquiries to
 the mode in which it is separated from other matter,
 and to the mechanical, chemical and vital effects it
 produces.
   Sir  Charles Morgan observes, that "the manifest
 connection  of living  energy with  temperature,  and
 with development of the respiratory function, leads to
 an idea that heat is the specific bond of  connection;"
 but  that "the ignorance in which we are placed in
 regard to the nature and origin of fire, fixes an obvious
 bar  to the  knowledge of the affections  of organized
 beings by  that cause;"  and that "the  influence of
 respiration on life has yet to be sought;"  that  "in
 attempting to extend  the limits of inquiry, the map
 must be traced after  the discoveries of  a Columbus,
 not  covered with an  imaginary Terra  Australis, or
 fancied Atalantis," &c.  (Philosophy of Life, pp. 148,
 156, 384.)   Dr. South Avood Smith also observes, that
 "Avhether the blood acquires something  from the at-
 mosphere Avhich is essential to life, or part with some-
 thing incompatible  with life, is wholly unknoAvn."
 (Philosophy of Health, vol. ii. p. 436.)
  Among those physiologists Avho  regard respiration
 as the source of animal  temperature, it is still  unde-
 cided Avhat proportion of the oxygen consumed is con-
 Alerted into carbonic acid; whether the combination of
 oxygen Avith carbon  takes place in the air-cells of the
 lungs, as maintained by Black, Crawford,  Lavoisier,
 Ellis and Dalton;  or in the general  course of the cir-
culation,  as  supposed by Lagrange,  Hassenfratz,  Ed- 
490        LEADING  POINTS IN THE INQUIRY.

wards  and  some  others.   With the  exception  of
Priestley, the early  experimenters  concluded  that
nearly all  the  oxygen  absorbed during  respiration
was expired in the form of carbonic acid.  But it Avas
soon after discovered by CraAvford and LaA7oisier that
about 25 per cent, of the  oxygen consumed disap-
peared;  from which  they concluded that it  united
with hydrogen to  form water.   Similar  results were
obtained by Sir H. Davy, from numerous experiments
on himself; for  he found that the oxygen  absorbed
was  in  the proportion of 100  to 81*66 of what was
exhaled from the lungs.
  It was also found by Allen and Pepys, that pigeons
absorbed 16 per cent,  more oxygen than they expired
in the form of carbonic acid, and Guinea pigs 20 per
cent.   In the experiments of Berthollet, the difference
was 25 and 30 per cent, in the rabbit and Guinea pig;
Avhile in those of Despretz, it was from 25 to  34 per
cent, in the same species of animals.  But in the cat,
dog and  hawk, Dulong found the difference from 20
to 50 per cent.  (Journal de Physiologie, 1823.)
  Dr. Edwards states, from his own experiments, that
in Guinea pigs and yellow hammers the difference Avas
in the ratio of 100 to 82*26;  while  in puppies it was
as 100 to 53.  He further ascertained, that green frogs
and  lizards consume  much  more oxygen than is re-
turned in the form of carbonic acid;  as  Spallanzani
had found to be the case in many of the lower species
of animals.  (Influence of Phys. Agents on Life, pp. 216,
218.)
  What then becomes of the surplus oxygen?   Does
it unite with hydrogen, as supposed by CraAvford, La- 
         CARDINAL OBJECTS  OF INVESTIGATION.      491

voisier,  Cuvier,  Dulong and Despretz;  or with the
blood, as maintained by  Edwards and many other
physiologists?  Miiller thinks it may combine with
the blood, giving it a bright arterial hue, but not with
hydrogen, because Collard  de  Martigny found that
aqueous vapour  was exhaled from the lungs of ani-
mals when deprived of oxygen.  But this objection is
not well founded;  for if 25 per cent, of the oxygen
consumed by a  healthy man in  twenty-four  hours,
(which is about 45,000 cubic inches, or two pounds in
round numbers,) were to unite with hydrogen, it would
make only nine ounces of water; whereas it is known
that from 18 to 20 ounces are exhaled from the lungs
in that time.  And it might just as  well be denied that
oxygen  unites with the hydrogen of wood in the  pro-
cess of ordinary combustion, as that it does so during
respiration.
   If ever we shall be enabled to reduce the phenomena
of life to the certainty of fixed  principles, it must be
accomplished by ascertaining the elementary composi-
tion of organized bodies, and the  changes they undergo
at every stage of their development; what is added to
our food, during its conversion into chyme, chyle and
blood; what  changes are  effected  on the atmosphere
by respiration; what the  blood  receives and Avhat it
loses, while  passing through the lungs, and during its
circulation through the systemic capillaries; above all,
what enables it to  excite the heart, and maintain the
activity of all the vital functions.  This should  be the
ultimate aim of our researches.   For if all diseases are
OAving to some deviation from the natural state of or-
ganized  bodies, it is clearly impossible to comprehend 
492
THE ANIMATING PRINCIPLE.
the right method of their treatment, without knowing
the conditions of healthy action.
  Let us then agree with Aristotle, that, " if there be
any description of knowledge more high and excellent
than another, it  is that  of the animating principle."
But if the cause  of animal life be obtained from the
atmosphere by breathing,  as taught by  Moses, and
sanctioned by the universal  common  sense  of  man-
kind, it must be a bond fide  constituent of the atmo-
sphere, and not a hyperphysical essence,  as supposed
by some modern  theorists; who have confounded the
physical cause of animal motion with  sensation, voli-
tion and thought, which are operations of  the nervous
system, and not material entities; for  they cannot be
added to, and subtracted from bodies, like caloric, elec-
tricity and other measurable elements.
  It also follows, that if  the  atmosphere be composed
of oxygen, nitrogen, aqueous vapour and carbonic acid,
united  Avith  some still more refined essence, one of
these must be the primary cause of vital action.  And
as it is now well  known that oxygen  is the only gas
capable of supporting life by respiration, the question
arises whether it  produces the effect  by its immediate
agency, or by the evolution of an imponderable fluid,
as during the process of combustion.  But if the num-
ber, diA^ersity and specific character of plants through-
out the earth be determined by the amount of caloric
derived from  the sun, it follows a fortiori that the
vital force of animals, and the development of  their
organization must be regulated by the quantity of the
same agent, which I have shoAvn to be the active  prin-
ciple in light, electricity, oxygen  and all the other 
ARTERIAL AND VENOUS BLOOD.        493
forms of matter.  Yet no regular and systematic at-
tempt has ever  been made to connect the theory of
animal temperature with the laws of life, or the phe-
nomena of sanguification, secretion, nutrition, sensa-
tion, volition and muscular motion.
  If it can be shown that there is more  carbon  and
hydrogen in the venous than arterial blood of all ani-
mals, -they must be given off while passing through
the lungs, because they are found to be diminished im-
mediately afterwards.  And if there be more nitrogen
in the arterial than venous blood of animals, it must
be derived from the atmosphere  by respiration.  But
so far has this department of  organic chemistry been
neglected, that no  one  has ever attempted  to ascer-
tain the relative proportions  of oxygen, carbon, hy-
drogen and nitrogen, in the venous and arterial blood
of different animals, with the view of discovering the
true theory  of respiration.  The consequence of thus
rejecting a whole series of facts has been, that nearly
everything most important to  be known remains still
involved in  deep obscurity, or vitiated  by fallacious
hypotheses.
   That the venous  blood of all animals contains more
combustible  matter than that of the arteries, would
appear from the following results of Michaelis,  ob-
tained by heating with oxide of copper the dry colour-
ing matter,  fibrin and  albumen, separately, of blood
taken from  the calf.  (Schweiggers Journal, vol. liv.)
Nor can there be a doubt, that when a sufficient num-
ber of similar experiments shall have been performed
on  the blood of different  animals, the proportions of 
494
ANALYSIS OF MICHAELIS.
carbon and  hydrogen that  unite with oxygen in the
lungs, Avill be found to vary Avith the kinds of  food.

                        Colouring matter in          Fibrin in
                    Venous blood. Arterial blood.   Venous.   Arterial.
Carbon............................. 53-231     51-382       50-440    51-374
Nitrogen.......................... 17-392     17-253       17-207    17*587
Hydrogen........................  7*711      8-354        8*228     7*254
Oxygen.......................... 21-666     23-011       24065    23-785

                                 Albumen in    Albumen in
                                Venous blood.  Arterial blood.
       Carbon......................."............. 52-650      53-009
       Nitrogen................................. 15-505      15-562
       Hydrogen.................................  7-359       6-993
       Oxygen.................................. 24-486      24-436

   Now if we take the average of the whole it will be
found that the  proportions  are as  follows:

                               Venous blood.  Arterial blood.
       Carbon................................... 156-321      155-765
       Nitrogen.................................  50-164       50-402
       Hydrogen...............................  23-298       22-601
       Oxygen..................................  70-217       71-232

   Similar results have been obtained by  Mulder, who
found the composition of  fibrin from blood of the cow,
as in the next table:
                                Venous fibrin.  Arterial fibrin.
       Carbon.................................... 53-476       53-019
       Nitrogen.................................. 15-295       15-462
       Hydrogen.................................  6-952        6-828
       Oxygen.................................... 24-281       24-691

   So far  as these analyses are to  be relied on, (and
they are  perhaps the most correct of any yet pub-
lished,) they show that the proportions of carbon and
hydrogen are  greater in  venous  than arterial blood;
viz., immediately before than after passing through the 
RESULTS OF  MULLER AND BERGMAN.      495
lungs;  consequently, that they must be there  given
off.  They also show that the ratios of oxygen and
nitrogen  are  greater in  arterial than venous blood.
That a portion of nitrogen is absorbed from the atmo-
sphere and united chemically with  the  blood, might
reasonably be inferred  from the fact,  that there is
much less of it in the food of herbivorous than in that
of carnivorous animals;  as will  be seen when I come
to treat of aliments.
   Now if it be true that animals consume from 20 to
50 per cent, more oxygen by respiration than is re-
turned in the form of carbonic acid, as shown by the
experiments of Dulong, Despretz, Edwards and Trevi-
ranus, Avhat, I repeat, becomes of the surplus oxygen ?
Does it unite with the  hydrogen exhaled  from the
lungs; or with the blood, as supposed by EdAvards and
others?   That it combines  with hydrogen to form
water, and contributes largely to the evolution of ani-
mal heat,  is evident from the  fact, that there is no
other mode of accounting for the disappearance of the
 surplus oxygen or of the hydrogen given off by venous
 blood in the lungs.   Nor has it  ever been proved  that
 the combination of oxygen with the blood is attended
 with an elevation of temperature, unless carbonic acid
 or Avater be formed.  Edwards maintains that carbonic
 acid is formed in the general course of the circulation,
 because  he found it to be exhaled  in notable quanti-
 ties from the  lungs of frogs and young kittens, when
 confined in vessels of pure  hydrogen, and from fishes
 placed in water deprived  of  oxygen.  Miiller  also
 states,  as  the result  of his own  experiments  and
 those of Bergman, that frogs exhale from three-tenths 
496
EXPERIMENTS OF ELLIS.
to ninety-six hundredths cubic inch of carbonic acid in
from six to twelve  hours, in gases that contain no
oxygen;  or nearly as much as they generate  in atmo-
spheric air.  (Elements of Physiologyf p. 339.)
  The objection  to  these experiments is, that they
prove too much, since it is manifestly impossible that
an animal can exist for  any considerable time Avithout
oxygen, except in a torpid state.   That small propor-
tions of carbonic  acid may be exhaled by cold-blooded
animals while confined in an atmosphere of hydrogen
or nitrogen, is evident from the fact, that at  the ordi-
nary temperature of  the atmosphere, water absorbs its
own volume of carbonic acid.  So that as animals are
composed of 80 per cent, of water, it is not very sur-
prising that when deprived of oxygen, frogs should
exhale an  amount of carbonic acid nearly  equal in
volume to that of their Avhole bodies, in the space of
from six  to twelve hours.
  But  it is impossible to. reconcile the results of Ed-
wards, Miiller and Bergman with the experiments of
Mr. Ellis, who found that carbon (not  carbonic acid)
was exhaled from the stigmata of bees  and other in-
sects, after all  the oxygen of the air in  which they
were confined was consumed.  (Inquiries, sections 133,
137 and  671.)  The formation of carbonic acid in the
blood is also disproved by the fact, that variable  pro-
portions of carbon and  hydrogen are given off by ve-
nous blood while  passing through the lungs, as shown
by their diminished quantity in arterial blood, accord-
ing  to  the analyses of Michaelis, already given.
  That different gases may exist in a state of mechan-
ical mixture with the blood, and  be separated from it 
EXPERIMENTS OF MAGNUS.
497
by means of the  air-pump, has been shown  by the
experiments of Magnus, who found the proportions of
carbonic acid, oxygen and nitrogen, in the arterial and
venous  blood of the horse and  calf,  as follows; mak-
ing from  10 to 12 -J  per cent,  of gaseous matter by
volume.
                         HORSE.           CALF.
                     Arterial. Venous.   Arterial. Venous.
     Carbonic acid.................. 17-7   18-8      16-4    16-3
     Oxygen........................  6-8    4-8       6-5     2-8
     Nitrogen.......................  2-5    2-8       4 2     1-9

  These experiments show that there is more oxygen
and nitrogen in arterial  than in venous blood, and a lit-
tle more carbonic acid in the latter.  But if they prove
anything  in regard  to the theory of respiration, it is,
that carbonic acid is not formed in the general circula-
tion.  For if generated in the arterial blood, it ought
to contain more  carbon than venous blood, Avhich  is
not the  case;  and if  in venous  blood, its temperature
ought to be higher than  that of the arteries; for the
obvious reason, that caloric is always evolved during
the formation of carbonic acid.   But the most decisive
proof that the latter is generated in the lungs, and not
in the general circulation, is, that the temperature of
arterial  is higher than that of venous blood, as long ago
observed by Haller,  Black, Plenck and Menzies.
  This  important fact, which was denied by Cullen,
and  overlooked  by nearly all other physiologists, has
been completely established by the experiments of Dr.
John Davy, Magendie and Holland.   In an excellent
paper, recorded in the  Philosophical Transactions for
1814, it was shown by Davy, that in lambs, sheep and
                         32 
498        EXPERIMENTS OF DR. JOHN DAVY.

oxen, the blood is from 1° to 1*5° Avarmer in the caro-
tid arteries and left ventricle of the heart than in the
jugular veins and right ventricle.
   In another  series of observations made  in 1838,
and recently published among other physiological re-
searches, he has shoAvn, that in sheep, the difference
is in some cases 3°.  In one case, he found the tem-
perature of the right pleura 107°, while that of the
jugular vein was 106°.  In another the lung was 108°,
and the rectum 105°.  In a third sheep, the lung Avas
109°, and  the  rectum  106°, the air being at 51° F.
He also found  that the blood of a spaniel bitch was
104° in the right side of the heart, but 107° in the left
ventricle  and  pleura;  thus  demonstrating  that the
lungs have a higher temperature than other parts of
the  body,  which Cullen had ironically said ought to
be the case, if  animal heat were the effect of respira-
tion.*   And as Haycraft, De la  Rive and Marcet had
shoAvn that equal volumes  of the different gases have
the  same  capacity for heat, Davy proved  that it is
nearly  the same in  arterial  and venous  blood; thus
sweeping aAvay all the crude speculations founded on
the  erroneous  experiments of CraAvford, avIio  repre-
sented  the capacity  of oxygen  gas as 4*7, compared
with carbonic acid, which he made 1*6; that of arterial
blood as 1*03, and venous blood as *89.  Yet Dr. Davy
  * It has been absurdly enough maintained, that if the whole of
the caloric were disengaged in the lungs, their temperature would
be so great as to consume them in a short time.  Were it not
known that all the blood, together with the heat which it obtains
in the lungs, is distributed throughout the body every three mi-
nutes, there would be some reason for this objection. 
VIEWS OF MULLER.
499
maintains that animal heat is OAving to the fixation or
condensation of oxygen in the blood, and to the com-
binations into which it enters in the circulation.  (Phy-
siological and Anat. Researches, vol. ii. pp. 171, 212 and
214.)
   Miiller observes, that the formation of carbonic acid
in the capillary vessels of the body  explains why the
lungs are not warmer than any other part of the sys-
tem.  (Elements, p. 333.)   But we have seen from the
reliable  observations  of Davy, that the pleura, sur-
rounding the lungs, and the blood that comes  imme-
diately from  them, are  actually warmer than  other
parts of the body.  And as the fact has been  called
in question by other  physiologists, I repeated  his ex-
periments on sheep and oxen  several times during the
winters of 1839-40, and 1840-41; the result of which
was, that in every trial, the temperature of the lungs
and left side of the  heart Avas from 2° to 3°  higher
than that of the stomach, liver and brain, or the blood
of the vena cava and  jugular  veins.*
   Miiller adds, that  the object of respiration  is evi-
dently the absorption of oxygen into the blood, Avhich
conveys that  gas as a stimulus to the different  organs

   * The  animal was  first knocked down, and the vessels of the
neck divided.  The thorax was then opened, and a small aper-
ture made with  a penknife, into the right ventricle of the heart,
into which the  bulb of a delicate  thermometer was  introduced,
after being put  in warm water, near the temperature of the ani-
mal.   In  two or three minutes, the same process was performed:
on the left ventricle,  and the  difference of temperature noted.
Could the experiment be performed  on animals without first arrest-
ing respiration, it is probable that the difference between the tem-
perature of arterial and venous blood, in large animals, would  be
still greater. 
500
EXPERIMENTS OF BICHAT.
 of the  body;  and secondly,  the removal  from  the
 blood of the carbonic acid which is formed  in the ca-
 pillaries.  (Elements, vol. ii. p. 341.)   But that oxygen
 does not excite the heart to contract,  the stomach to
 digest, the nerves to feel,  the brain to think, and  the
 various organs to perform their respective functions,
 would appear from the experiments  of  Bichat, who
 found that when  injected  into the jugular veins of a
 dog, death speedily ensued;  and it is known that far-
 riers are in the habit of killing horses no longer fit for
 service, by injecting  air into the veins.   Nysten also
 found that when oxygen was introduced  into the ve-
 nous blood of animals, no carbonic acid Avas  evolved,
 although it acquired the scarlet hue of arterial blood.
 And  that atmospheric oxygen is not essential to the
 existence of those  imperfect organizations termed en-
 tozoa, which  are formed in the  brain, liver,  muscles,
 eyes and other parts of  the higher animals, is evident
from  the fact, that it has no access to  them, Avhich is
 also true  in  regard to  the primordial germs of  all
animals.*
  * A decisive proof that the blood of animals is not vitalized by
oxidation and decarbonization, is, that during the respiration of
plants, carbonic acid is absorbed by the leaves and decomposed, its
carbon being retained, and its oxygen returned to the atmosphere,
the purity of which is thus maintained.  Dr. Gilly found that when
grass leaves were exposed to the sun in ajar four hours, the fol-
lowing changes were produced:
  At the beginning of the experi-
ment, there was in the jar:—
  of Nitrogen.................. 10-507
    Carbonic acid............  5-700
    Oxygen..................  2-793
  At the close of  the experiment,
there was in the jar:—
  of Nitrogen.................. 10-507
   Carbonic acid............   -37
   Oxygen....................  7*790
19-000   I                     18-667 
BERZELIUS AND HUNTER.
501
  That a small proportion of oxygen is absorbed by
the blood, and contributes to  its formation, is highly
probable;  but I have proved that by far the greater
part of it unites immediately with carbon and hydro-
gen in the lungs.   If then  it be true, that caloric is
ahvays disengaged during the formation of carbonic
acid and water, and that the lungs are the  source of
animal temperature, the latter cannot  be "owing to
the fixation or condensation of oxygen in the blood,
and the combinations into which it enters in the cir-
culation," as  maintained by Dr. Davy; nor to "the
combination  of oxygen with carbon in the  systemic
capillaries," as supposed by many modern  physiolo-
gists.
   Should it still be urged, that the agitation of venous
blood with oxygen gives it the  arterial colour, I an-
SAver  that  sugar, nitrate of potassa, sulphate of soda,
chloride of sodium, carbonate of potassa, sal ammoniac
and even carburetted hydrogen, (according to Berze-
lius,) produce the  same effect, but destroy its vitality
and power of coagulating.  Moreover, when arterial
blood  is withdrawn  from the  system,  it acquires the
colour and other  properties of venous  blood, without
either the loss or  gain  of ponderable matter.  For it
was found by Hunter, that on tying the carotid artery
of a dog in two places, the blood between the ligatures
soon acquired the  dark venous hue; and by Hassen-

   But that the circulation of sap, and its conversion into the nu-
tritive fluid of plants, is effected  by the agency of solar heat, is
evident from the fact, that neither light, electricity, air, water nor
any other physical agent, will produce these phenomena at a low
temperature. 
502
EDAVARDS  AND PROUT.
fratz, that when confined in glass tubes, hermetically
sealed, it undenvent the  same  change  of  colour as
Avhen placed  in  vacuo,  hydrogen,  nitrogen,  carbonic
acid or common  air.   Miiller admits, that as arterial
is converted into venous blood while passing through
the systemic capillaries, the former ought to contain
principally oxygen, and  the latter carbonic acid in so-
lution.   But we  have seen, from the experiments of
Magnus Avhich he reports, that arterial contains nearly
the same proportion of carbonic acid as venous  blood,
but  the  former a little  more oxygen and nitrogen.
The truth is, that if carbonic acid were formed  in the
systemic capillaries, (as maintained by Edwards, Miil-
ler, Prout  and others,) they  ought to  have  a higher
temperature  than the lungs, for the obvious reason,
that whereA^er oxygen unites with carbon, caloric is
e\Tolved,  Avhether during  ordinary  combustion, fer-
mentation or respiration.  But that the temperature
of arterial blood is reduced, instead of being augmented
in the systemic capillaries, is evident  from  the fact,
that on returning to the right side of the heart, it is
found to have lost from 1° to 3° of caloric, together
with its  bright florid hue, and power of maintaining
the actions of life, just as the steam of an engine loses
its elastic force and the  power of moving the piston,
after undergoing  a reduction of temperature.
  That venous is converted into arterial blood during
its passage through the lungs, was long ago proved by
the experiments of Lower, Mayow,* Hewson, Hunter,

  *  The nitro acrid spirit of Mayow was oxygen, which he calk
"spiritus vitalis igneus."  (Part I,  of Tractus de Sal. Nitro et
Spiritu Nitro Acrio, and Aer Purus Vitalis, p. 281.) 
   CRAWFORD ON  THE INFLUENCE  OF TEMPERATURE.   503

Goodwin and  Bichat, who, in various  species of ani-
mals, observed it  to  pass from the right side of the
heart, through the pulmonary artery, of a dark  hue,
and  return by the pulmonary veins to  the left ventri-
cle, of a bright florid complexion.   It must not, how-
ever, be supposed that the vital properties of the blood
are essentially connected with its colour, which is ab-
sent in insects, in nearly all the lower orders of inverte-
brated animals, and is confined  to a small  proportion
of the blood in  fishes; from Avhich it  would appear,
that colour is rather a concomitant, than an essential
or vital property of the blood.*
   In regard to  the agency of caloric  in producing a
change  of colour,  some interesting  experiments were
performed by Crawford, who found that after immers-
ing a dog, with the exception of his head, in water at
45° F. for fifteen minutes,  his venous  blood was  the
darkest he had ever observed; but on placing another
dog  in water at 114° for thirty minutes,  it Avas  of a
scarlet hue, and  could scarcely be distinguished from
that of  a neighbouring artery.*{•  (Experiments and Ob-
  * It has been recently maintained by Dr. G. 0. Rees, that the
particles of venous blood contain phosphorus, which also unites
with atmospheric oxygen, to form phosphoric acid, which again
unites  with the alkali of the liquor sanguinis, and forms a tribasic
phosphate of soda, that produces the florid hue of arterial blood,
like other salts.
  f He supposed that the dark colour of venous blood was owing
to the  carbon it obtained during  its circulation through the sys-
temic capillaries;  and that by elevating the temperature of  an ani-
mal above the natural standard, this change was prevented from
taking place.   But the experiments of Hunter, Hassenfratz and
others, demonstrate that arterial blood passes into the venous state 
504          INFLUENCE OF TEMPERATURE.

servathns on  Animal  Heat,  pp.  310, 387.)   And Dr.
John Davy states, that there is much less difference
betAveen the  colour of arterial and venous blood  of
sheep when the temperature is 80° or 90°, than during
winter in England, or when the mercury is beloAv 32°.
(Physiological and Anedomical  Researches,  vol.  ii.  p.
140.)  In accordance with  these facts, it may be ob-
served, that after immersion for some time in a cold
bath, the surface of the body assumes a purple hue,
as when  exposed to a very cold atmosphere; but  if
transferred  to a Avarm bath, the skin changes to  a
bright scarlet  colour.   The reason of this difference
is, that the cold  bath  prevents the blood of the  cuta-
neous vessels  from passing freely through the lungs,
where it is arterialized; whereas the warm bath aug-
ments the circulation  in all parts of the body.
  Again, if it were established  that  venous blood  is
brightened by uniting with oxygen, and darkened by
the presence of carbonic acid, the injection of oxygen
into the veins will not support life when the chemical
function  of the lungs is arrested, any more than nitro-
gen, hydrogen or any  other  description of ponderable
matter.   As a further proof that oxygen is not the
agent by which the fluids are formed, and converted
into the  various  tissues by vital affinity, it has no ac-
cess to the germ of the foetus, which is nourished and
without either the loss of oxygen or the gain of carbon.  Magnus
also found, that by depriving venous blood of its carbonic acid, it
is not changed to the scarlet hue of arterial blood.   Moreover, if
the serum be removed from  a clot of venous blood, and the latter
be washed with distilled water, oxygen no longer  imparts to it the
arterial colour, as when it is immersed in serum. 
ERROR OF DR. PROUT.
505
lives before any communication is established with the
blood of the mother by means of the placenta.
  From all  the foregoing facts we are authorized to
conclude, 1. That during the passage of dark venous
blood through  the  lungs, it gives off variable propor-
tions of carbon and hydrogen, that unite  chemically
with atmospheric oxygen to form  carbonic acid and
water, as in ordinary combustion, by which it acquires
an addition of caloric, with a bright florid hue; and
2. That during its circulation through the systemic ca-
pillaries, the caloric obtained from the atmosphere is
transferred to the solids, by which their temperature
and  vitality are maintained, when the blood returns
to the right side of the heart of a dark modena  hue,
having lost its power of stimulating the organs, until
it acquires an additional quantity of caloric from the
lungs.
  Dr. Prout observes, in his late Bridgewater Treatise,
that "the phenomena of life are wholly removed from
the logic of quantity."  But if respiration be the source
of animal life, the phenomena are resolvable into addi-
tions and subtractions of measurable elements; and it
is only because they have not been ascertained with
numerical accuracy, that physiology  has never  yet
been  reduced to the character of an  exact  science.
For  if it be  true  that  the conversion of food into
chyme and chyle is effected  by  its union with gastric
juice, bile and  pancreatic liquor;  that  chyle is trans-
formed into more highly organized particles of blood,
by giving off water, carbon  and  hydrogen, while pass-
ing through  the  lungs, in exchange for which it re-
ceives caloric from  the atmosphere, Avith variable pro- 
506
EXPERIMENTS OF DR. URE.
portions of nitrogen, there is no good reason Avhy the
proportions  of each should  not be  reduced to "the
logic of quantity."
  According to some  recent experiments of Dr. Ure,
caloric enough is evolved during the combustion  of
one pound of charcoal to melt 75 pounds of ice, Avhich
Avould raise 150 pounds of Avater 70°.   Now if Ave sup-
pose that 45,000 cubic inches of oxj'gen are consumed
by a  healthy man in 24 hours, making  about two
pounds  in round numbers;  and  that 40,000  cubic
inches, or a little more than one pound twelve ounces
are expired in the form of carbonic acid, it  must unite
Avith about 12 ounces  of carbon;*  so that if the same
proportion of caloric be  given out  as in ordinary com-
bustion, it ought to compensate  the  loss of 52 i° in a
man weighing 150 pounds.   And if the remaining
5000 cubic inches of oxygen combine Avith one-eighth
its weight of hydrogen, (the proportion of oxygen Avhich
disappears is generally much larger in carnivorous ani-
mals,) it ought to raise the temperature of 150 pounds
of Avater 12°; allowing, Avith Dr. Thomson,  that caloric
enough is evolved during the combustion of one pound
of hydrogen to melt 400 pounds of ice.
   The supposition  of  Dulong and Despretz, that more
caloric is given off by animals than can be accounted
  * Dr. Dalton calculated that the aliment which  he took in 21
hours contained about  1H ounces of carbon; but that the mean
quantity exhaled,from  the lungs did not exceed 10^ ounces,  the
remainder passing off with the other excretions.  He thinks that
of the six pounds of food and drink taken daily by a healthy man,
one pound consists of  carbon and nitrogen, the remainder being
chiefly water.  (Manchester Memoirs, vol. ii. new series; and Ed.
New Phil. Journal, 1832, 1833.) 
HYPOTHESIS OF  DESPRETZ.
507
for by the amount of oxygen absorbed, has been refuted
by Liebig, Avho very justly observes, that while sur-
rounded  by water at 47*5°, as in the experiments of
Despretz, the temperature of the Avater Avas raised at
the expense of the animals, which Avere proportionally
cooled; and that even if the windpipe had been tied,
there Avould have been a rise of temperature  in  the
water Avithout  any combustion  of  oxygen.   Dumas
also observes, that it is the cooling of the animal,  not
taken into the account by Dulong and Despretz, which
expresses the excess of heat that has  been attributed
by them  and other physiologists to a peculiar power
in the system, independent of respiration.
  In regard to the hypothesis of M. Despretz, that
"the small remaining portion" of caloric not accounted
for by respiration, is generated by motion of the blood,
friction, assimilation, &c, I ansAver, that whenever  the
process of  respiration  is arrested, the motion of  the
blood, friction, assimilation, &c. are  no longer carried
on, and that the temperature of the Avhole system falls
rapidly to that of the surrounding medium.
  In reply to the arguments of Brodie, Philip, Tiede-
mann, Edwards and others, who  contend  that animal
heat is generated by nervous  influence, secretion,  nu-
trition, the condition of the blood and muscular con-
traction,  I shall proceed to prove  that the mean healthy
temperature  of all animals is  directly in proportion to
the  amount of their respiration; without which there
could be  no sanguification, secretion, nutrition, nervous
influence nor muscular contraction, and that they ha\Te
mistaken effects for the cause of animal heat. 
CHAPTER  III.
INFLUENCE OF RESPIRATION ON  THE  TEMPERATURE AND
              VITAL ENERGY OF ANIMALS.

  "If errors had not been rooted in men's first notions, some things
justly discovered might have rectified others; but as errors have
been fundamental, and of such a  kind that men have rather  ne-
glected and passed things over, than formed a wrong or false judg-
ment about them, it is no wonder if they never attained what they
never had in view; not arrived at the end they never proposed;  nor
performed the course which they never entered."—Bacon.

   If ever medicine be destined to take its appropriate
rank among the exact sciences, it must be founded on
precise and enlarged views of the cause which governs
all the movements of nature,  including those of the
animal economy.   And  there  is abundant reason to
hope, that when mankind  shall be once  thoroughly
aroused to the importance of throwing off the paralyz-
ing trammels of authority, they will very soon be able
to dispel the numerous obscurities that  have hitherto
retarded the progress of science.  For it is certain that
if the cause of  sanguification,  digestion, secretion, nu-
trition, sensation and muscular motion be derived from
the air by breathing, it must be a positive agent, subject
to the logic of quantity, whatever men  may say about
its mysterious and hyperphysical properties.
   Having already shoAvn that the poAver of the earth
       (508) 
PROCESS  OF LIVING COMBUSTION.        509
to multiply organic forms is regulated  by the amount
of caloric it receives  from the solar fountain, I pro-
ceed to prove that the organizing power of animals, and
the  activity of their respective functions, are directly in
proportion to the  quantity of the same  active principle
derived from the atmosphere by respiration.
  Among all the operations of nature,  there is nothing
more calculated to excite admiration  than the silent,
beautiful process  of  living  combustion; for it is so
immediately connected with that by  which blood is
formed,  that both may be regarded  as one and the
same act.  Every time chyle passes through the lungs,
it gives off carbon and hydrogen, that unite with at-
mospheric oxygen,  by which heat  is  evolved,  and
blood generated.  We have  also seen that  venous
 blood is constantly renovated by giving off what is
 superfluous, and by receiving from the atmosphere what
 is  essential; in short, that  respiration,  sanguification
 and calorification, constitute but one  process.   It has
 been known since the time of Linnaeus and Dr. Black,
 that all the  higher  orders  of animals are warm-
 blooded; that  they have a double heart and a double
 circulation, by one of Avhich their blood is distributed
 throughout the lungs, where it is exposed to the atmo-
 sphere; and by the other, sent throughout the system,
 —that  the  breathing apparatus of birds is larger, in
 proportion to  the size of their bodies, than in any
 other description of animals, extending through all
 the cavities of the  abdomen, and even of the bones;
 that they consume more oxygen, generate more car-
 bonic acid, and have a higher mean temperature.
    Next to birds, mammiferous animals have the largest 
510      TEMPERATURE OF  DIFFERENT ANIMALS.

organs of respiration.  And  although confined to the
thorax, they consist of innumerable cells that present
a vast extent of surface to the atmosphere.  The con-
sequence of which is, that many of them are capable
of maintaining their temperature in the coldest parts
of the Avorld.   Accordingly,  it will be seen by glanc-
ing over the folloAving tables, that the mean tempera-
ture of birds varies from 105° to nearly 113° F. which
is about 28° above that of the tropical regions; while
in mammalia it varies from 96° to 106° in their active
and  healthy state.   But  if Ave descend to  the lower
orders of air-breathing vertebrated animals,  such as
chelonians,  saurians, ophidians  and batrachians, in
which the heart is so constructed  that only a portion
of blood is  sent through  their imperfectly developed
lungs,  we find that  the  power of  obtaining caloric
from the air by respiration is small; that their  tem-
perature rises and falls with that of the surrounding
medium, and rarely exceeds it more than a feAv degrees
in their most  active  condition; Avhile in fishes,  Crus-
tacea, mollusca, annelida  and all  the more imperfect
animals that livTe in water, and breathe by means of
branchiae or gills, it is still less, as may be seen by re-
ferring to the third table.
   It Avas discovered by Lavoisier, more than fifty years
ago, that xavo sparroAvs confined in a vessel of air, gene-
rated more carbonic acid in a given time than a young
Guinea pig under the same circumstances.  And it
has been recently estimated by Treviranus, from the
experiments of different physiologists, that for every
100  grains  Aveight of birds, they generate  in  100 mi-
nutes nearly tAvice as much carbonic acid as mammalia,
and  the latter above eight times more than the  frog, 
TEMPERATURE  OF  BIRDS.
511
as  may be  observed  in  the ensuing table.  (Midler's
Elements,  p. 312.)
                       Oxygen consumed. Carbonic acid exhaled.
                      Cubic inch English.   Cubic inch.
Pigeon................................. 1*14        0-96  Allen and Pepys.
   <<  ................................. 1-58        0-99  Despretz.
Guinea Pig........................... 0-67        0-42  Berthollet.
     <<    ........................... 0-74        0-60  Allen and Pepys.
     «    ........................... 0-68        0-47  Despretz.
Rabbit................................. 0-60        0*44  Berthollet.
Cat..................................... 0-98        0-66  Despretz.
Fr0g.................................... 0-00        0-06  Miiller and Treviranus.

                             TABLE  I.
                      TEMPERATURE  OF  BIRDS.
   Names of the animals.                Temperature of the animals.  Observers.
Bearded Vulture....................................... 112-89° F.      Pallas.
Snow Bunting.......................................... 110-24
Grouse................................................... 108'
Snipe (Lesser Godwit).............................. 108-
Oyster Catcher........................................ 106-
Bullfinch................................................ 108-
Ruff..'.................................................... 108-
Redpole................................................. m'70
       Female.....................................- HO'24
Swallow................................................. m'70
Hawk.................................................... 109*72
Pi(reon ...................................... 106° to 112-75          Holland.
   The same."........................................... 109*37          Despretz.
Sparrow.................Feb.  105°...Apr. 108° to 111-  July.      Edwards.
 a       ™  i                             111-            Dr. J. Davy.
A young Drake....................................... ilJ-                      ■*
         Duck.........................................  11°'
Adult Turkey Cock..................................  1°9'
       Turkey Hen....................................  1°8'
 Fowl, full grown.....................................  108-50
                                          ill-                 "
       two months old...............................  Xl1
 Goose..........................................  107° to HI-
                                          110-                 "
 Guinea Hen............................................
 Common Thrush....................................... 10^               *<(
 Jackdaw................................................
 Screech Owl............................................      _         ^
 r,       n                          ........  108*15         Despretz.
 Common Crow.....................................
 „ „    .                             .......  109*18
 lellow-hammer....................................
       Mean of the whole..........................  109'53 
512
TEMPERATURE OF MAMMALS.
   Nearly all  the foregoing results  Avere  obtained by
introducing the thermometer into the rectum, during
life, or into the blood or entrails soon after death.  It is
also Avorthy of notice, that the temperature of vigorous
young birds  is somewhat higher than that of adults,
as in the duck, and common fowl;  and higher in the
male than female, as in the turkey,  duck  and redpole.
The  experiments of Dr. EdAA ards on  the sparrow, in
connection Avith  those of Dr. J. Davy on the human
subject, Avould further lead  to the conclusion, that the
temperature of all the  smaller  species of animals  is
higher during summer than winter.

                       TABLE II.
                 TEMPERATURE OF MAMMALIA.
Temperature of the animals, .... 96° to 102° F.*	Observers. Davy. it
... 101 to 104-50	
... 103 to 100-	u
............. 105-	ii
102-50 to 103-50 ............. 102-	
............. 101-	<<
... 101 to 102-	,,
............ 103*60	Despretz. Davy. <<
.............102-	
... 103 to 104-	
............ 103-	(<
............ 102-	u
............ 103-	ii
............. 104-	
............ 104-	K
,............ 104-	Pallas.
103-5 to 106-50	Holland.
  * From the observations of Dr. John Davy on one hundred and fourteen
individuals of the human species, of both sexes and of all ages, in various
parts of the world between England and the tropical portions  of the East
Indies, the temperature in the month varied from 96-5° to 102°, and was
generally found to be 1° or 2° higher when and where the atmosphere was
at 80°, than in England during the colder seasons of the year.
   Names of the animals.
Man.........................
Monkey (Sim. Aygulia)
Sheep........................
Spaniel Bitch.............
Cur Dog.....................
Bull Dog....................
Jackal.......................
Common Cat...............
  Thesame.................
Leopard.....................
Goat..........................
Elk...........................
Guinea Pig.................
Common Hog..............
  The same................
Calf...........................
Hare.........................
Rabbit....................... 
TEMPERATURE OF COLD-BLOODED ANIMALS.      513
                      TABLE IL—(Continued.)

   Names of the animals.                Temperature of the animals.
Arctic Fox..............................................106*75*
  The same (the air,—32°)........................ 106-
Female (the air, 26°).................................'104-75
Wolf (the air, 27°)................................... 105-
Ermine................................................... 104-45
Squirrel..................................................102*
Common Rat........................................... 102-
Weasel................................................... 103#
Horse....................................................  99-50
Indian Elephant.......................................  99*50
0x.............................................. 100 to 101-
The Whale...............................................1°2,
Porpoise................................................. 10°"
Polar Bear.............................................. 10°"
Tiger (Ceylon).........................................  98-
Observers.
Fisher.
Pallas.
Davy.
Scoresby.
  ii
Capt. Lyon.
Davy.
                            TABLE  III.

               temperature of cold-blooded animals.
                                  Temp, of the Temp, of the
   Names of the animals.                 medium.     animals.     Observers.
Large tropical Turtle...................... 79*50° F.    84-00°    Davy.
  The same.................................. 80-          88-50      «   •
Common Frog............................... 61*          70'
Active Lizard............................... 74-75        82-61    Czermack.
Green   «   ............................... 61*25        68*50
Spotted  «   ............................... 54'          59"
Chameleon................................... 72-          74-      Murray.
Coluber...................................... 83-          90-      Davy.
A brown Snake............................. 82*50        84-50      «
Adders        ............................ 58-          68-      Hunter.
Boa....................................... 78-          75-      Wilford.
NatrixL^'is'.'.'.............................. ^*          8°- Q    C™k'
Proteus Anguinus.......................... 59-55        68 73
Geometrical Tortoise..................... 61-          86-90    Davy.
  Another....................................  79'          ?J'
Shark..............................inwater 74-75        77*
Bonito (Tunny).............................  80-50___8*________________

  *Infifteen^of^een foxes, the temperature was from 100° to 106*75°,
in the other 98°. {Parry's Journal of a  Voyage, &c, p. 157.)
                                 38 
514
ADDITIONAL OBSERVATIONS.
                 TABLE III.—(Continued.)
                         Temp, of the    Temp, of the '
  Names of the animals.          medium.       animals.    Observers.
Common Trout............................. 56-        58-     Davy.
Flying Fish................................. 75*50      78-      "
Crab.......................................... 51-80      59-     Rudolphi.
Black Snails ................................ 54-        57-      "
EarthWorms....................in a vial 56-        58*89    J. Hunter.
Leeches..........................    "    54-        56-80
                                            (Rdaumer.
                                             (Nat. Hist.
                                             des Insects.)
                                            (Reaumer.
                                             (Nat. Hist.
                                             des Insects.)
                                            fHuber. (Mem.
                                             sur les Ab-
                                             eilles.)
                                            (Huber. (Mem.
                                             sur les Ab-
                                             eilles.)
An Ant-hill................................. 55-40      68-

  After the foregoing sheets were printed, being obliged
to retire into the country for a feAv months, in conse-
quence  of ill-health, brought on by over-exertion of the
nervous system, from too  intense  application  to  the
subject of this Avork—I  embraced  the opportunity of
making some  additional observations on the temper-
ature of such  domestic  animals as came in my Avay.
Most of them were made in the month of August, by
placing the bulb of a medical thermometer under the
forearm, Avhich was gently pressed against the thorax.
They Avere  performed with a vieAv of ascertaining the
influence of season and  of age in modifying temper-
ature.  From which it  will be  seen, that  in some of
the  more  active  mammalia, it  was  higher than  the
average represented in  the second table.   The obser-
vations on  fowls,  ducks and  a feAV other birds, cor- 
               ADDITIONAL OBSERArATIONS.           515

responded with those of Davy and Edwards, therefore
have been omitted as unnecessary.

                       TABLE IV.
   Temperature of a young she-goat, three months old............  107°
   Mother of the same, old, and in poor condition...................  104
   A tame young rabbit, two months old................................  108
   A fine active kitten, two months old.................................  105*5
   A vigorous cat, nearly full-grown....................................  104
   Mother of the kitten, three years old................................  103-5
   Avery old cat, said to be in its nineteenth year..................  102
   An active cur dog, three months old................................  106
   A fine active young horse, four years old...........................  104
   A mare, twenty years of age, (in vaginam)........................  100
   Thus  it would appear, that in the same species of
 animals,  the temperature is higher during youth than
 middle age, still  lower in old age, and higher  during
 summer than at any other season. We have seen that
 Dr. J. Davy found  it higher  in the  human  species
 under the tongue, within the tropical than  the tem-
 perate latitudes.  And I have ascertained by about
 one hundred  observations on  myself, during the last
 eighteen months, that a nicely graduated thermometer
 placed under the tongue, varies from 97° to 100° dur-
 ing Avinter, and from 100° to 102° or 103° occasionally,
 during summer;  while  in April and May, the average
 has been about 100°.*   I have also  found it from 1°
 to 2°  higher  on first awaking in the morning, and
 throughout the day,  than at twelve o'clock  at night,
 when it  has ahvays been  at the  minin^^jxcept
   * On the T8th of Mav, 1840, the temperature of the air was
 above 80° at New York, when that under my tongue and in cur-
 rente urinx was 101°, but the next morning at eight  o'clock the
 temperature of the air,  after a north wind and thunder-storm, had
 fallen to 53°, and that under the tongue was 99°. 
516
SPECIFIC OFFICE  OF  CALORIC
after taking supper, or returning from a brisk walk,
both of which augment the quantity of respiration.
   But what is the specific office of caloric in the ope-
rations of life ? Within the last few years I have often
propounded this question to  various members of the
medical  profession, without  receiving  any better an-
swer, than that it is to keep us warm.   With a vievv of
ascertaining what the uneducated portion of the com-
munity think about it, the question Avas put to a Lon-
don barber:—What is the use of animal heat ? To Avhich
he replied, without hesitation, "to make us live and
grow!"  Surprised at the novelty of this answer,- his
reasons were demanded, when he  again  replied, with
equal readiness, " Without the heat of the sun there could
be no life and growth of plants."  Such is the difference
between the unsophisticated  common  sense of man-
kind, founded on the daily observation  of what is con-
tinually  passing around us in nature, and the  mystic
jargon of books filled with metaphysical speculations
about  "the unknown  vital principle" — speculations
which have  tended only to  divert the votaries  of
science from the  path that leads to  the  acquisition
of positive  and useful knowledge.

    " Some truth there is, but dash'd and brew'd with lies,
     To please the fools, and puzzle all the wise."—Dryden.

   Corresponding with the facts exhibited in the fore-
going  tables, the Avhole organization of birds is more
highly deA^eloped, and their different functions are per-
formed with greater rapidity than in mammalia.  The
stomach is more concentrated, digestion more vigorous,
the heart larger in proportion to their weight, its Avails
thicker,  its pulsations  stronger and   more frequent. 
             IN THE FUNCTIONS OF LIFE.          517

Their blood  is more highly organized,  or  richer in
fibrin and red particles, their secretions more copious,
and  the  renewal  of their composition  by  nutrition
more rapid.  Their bones are harder, their muscles
more firm, and their vital power of contraction greater,
as shown by  the activity of all their movements, and
the immense velocity with which many of them glide
through  the  pathless air to distant regions,  in opposi-
tion to the force  of gravity.  For it is Avell known
that the  haAvk and eagle are capable of flying forty-
five miles per hour, the carrier-pigeon  from fifty to
sixty, and a species of swallow  termed the swift, at
the rate  of ninety miles per hour,—which, if continued
for twelve hours, would make 1080 miles a day.  And
such is the enormous strength of the ostrich, combined
with rapidity of movement, that, if we  are to credit
 the account of Adanson,  as reported by Mason Good,
 it has been known, with a negro on its  back equal to
 double its OAvn weight, which is  about eighty pounds,
 to outrun the  swiftest race-horse.  (Book  of Nature,
 vol. i. 325.)
   So  great  is the power of digestion in birds, that
 common fowls require two and a half ounces of solid
 barley per day, as proved by the experiments of Mou-
 brav; or about one-twentieth of their whole weight,
 supposing the latter  to  average three  pounds.   But
 there is reason to believe, that the smaller and  more
 active species of birds consume a much larger propor-
 tion of  oxygen than  fowls,  geese, turkeys,  ducks and
 other large  birds, especially such as are confined  to
 the surface of the earth.  For if it be  true, as stated
 by Lavoisier, that two sparrows generate and expire
 more carbonic acid in a given time than a young 
518
VITAL ENERGY OF BIRDS.
Guinea pig, they must consume three times the ratio of
oxygen; as the average Aveight of sparrows is about one
ounce, and that of a young Guinea pig about six ounces,
Avhile it is worthy of notice, that they are both grami-
nivorous animals.   In accordance Avith these  data,
which can be  regarded only as approximations to the
truth, Moubray says, that the domestic pigeon requires
one  ounce tAvo drachms  of solid barley per day; so
that if we estimate  the average Aveight of pigeons at
tAvelve  ounces, they  must digest  about one-tenth of
their whole weight every tAventy-four hours.  It there-
fore  follows that, as barley consists of 86*8 per cent, of
solid nutritive matter, and the living body of about
tAventy per cent., the rest  being Avater, the composition
of foAvls is renewed  in a  period not much  exceeding
ten days, and that of pigeons in a much  shorter time,
as might be inferred from the rapidity of their growth,
A\Thich is remarkable in all the feathered tribes.
   The brain and nervous system are also more highly
developed in small than in the  larger species of birds f
especially in the  canary,  bullfinch and several other
songsters, as  in the parrot tribe, and more so in some
  * On the authority of Haller and Cuvier, Mr. Lawrence gives
the weight of  the brain in several species of birds, compared with
that of the whole body,  as follows :—
           .............. 1:  14
           ............... 1 :  25
           ,.............. 1 :  27
           ............... 1 :  27
Red-breast.................... 1 :  32
Canary ...
Sparrow..
Chaffinch.
Fringilla.
Blackbird.................... 1
Falcon........................ 1
Duck.......................... 1
Eagle......................... 1
Goose......................... 1
 G8
102
257
2(50
360
  Nor is it unworthy of notice, that in the ostrich, cassowary, swan,
condor and turkey the relative size of the brain is still less, corre-
sponding with their well-known stupidity. 
REPRODUCTIVE POAVER OF BIRDS.         519
of them than in any other description of animals, not
even excepting man.   Hence  the  remarkable acute-
ness of their senses, their sagacity in foreseeing changes
of Aveather, in  the construction of their nests, and in
providing for their wants.   Hence, also, their delight-
ful genius for  music, the social and almost human
affections of some, including the faculty of articulating
words, together with all those beautiful instincts which
many have justly regarded as a species of inspiration.
But although in a very feAv of them the brain is larger
in proportion to the size of the body than in man, its
convolutions are less numerous, and its frontal  por-
tions less  developed, coinciding Avith the activity, yet
limited range of their intelligence.  Nor is it unworthy
of passing notice, that the pigeon, sparrow, and  some
other among the smaller species of the feathered tribes,
rear from six to eight broods of young every season, in
the middle latitudes, all of Avhich attain their growth
in a few weeks; while the common fowl often affords
one hundred eggs annually, if  well-nourished and pro-
 tected from the inclemency of the weather, or even
 one hundred   and  fifty, in a  few  cases, according to
 Buffon.
   Again,  those mammalia in which the  organs of
 respiration are most fully developed, possess the high-
 est degrees of vital  energy.   For example, the chest
 of the dog, wolf, fox, goat, deer, horse, ox,  sheep, hare,
 rabbit and some other species  of quadrupeds is larger,
 in proportion to the size of the body, than that of man,
 and their temperature several degrees higher,  as we
 have already seen.  The  consequence of which is, that
 they are capable of  resisting much greater degrees of 
520          VITAL ENERGY OF MAMMALIA
cold, and of enduring muscular exertion  for  a much
longer time,Avithout exhaustion*   The thorax of the
greyhound is larger, in proportion to his size, than that
of any other quadruped;  and  it is well known that,
for a short distance, he will surpass the swiftest race-
horse,—that, with  a fair field, he  will overtake  the
hare, fox, deer and rabbit in  a few minutes, during
Avhich his  speed  is equal  to  that of the  Avild-pigeon,
which flies  at the rate  of a  mile  every minute for
several hours.
   The thorax of the  common foxhound  is larger, in
proportion to  his  weight, than that of the ordinary
horse, and he will pursue the  chase for a longer time
without exhaustion—sometimes for above  three hours,
  * When I come to treat on the influence of climate and season,
food and drink, exercise, repose, &c. it will be shown that the lungs
of man and other  mammalia, from the greater necessity of exer-
cising them, are more developed in the higher latitudes than in the
tropical regions,—that they are larger in the dog, wolf, fox, polar
bear, reindeer and  other animals  which inhabit cold climates, in
proportion to the size of the body, than in the elephant, rhinoceros,
camel, tiger, leopard, or even the  lion,—whose temperature, mus-
cular activity and power of enduring cold are proportionally less.
It will also be seen that respiration, the power of enduring intense
cold and  protracted muscular exertion, are greatly diminished by
starvation, and that vital heat is expended  by over-exertion faster
than acquired.  As an example of this, it has been said that 30,000
horses belonging to the French  army perished in one week, chiefly
from cold, during the fatal retreat from Moscow, when the mercury
was only 4° F. below 0°;  whereas it is certain that, when well fed
and not over-exerted, this  noble animal is capable of enduring a
temperature of 36°, and even 40° below 0° F., without house or
clothing. 
IN PROPORTION TO AMOUNT  OF  RESPIRATION.   521
and to the distance of forty or fifty miles.*  As a fur-
ther proof that the vital energy of the hound exceeds
that of the horse, the former requires one and a half
pounds of actual nourishment per day, such  as hard
biscuit and fat, making one-fortieth of his whole Aveight,
which is about sixty pounds.  But the usual allowance
of a common work-horse is equivalent to twelve quarts
of oats per  day;  so  that if a bushel  of oats  average
thirty-seven pounds,f two-thirds of  which, or tvventy-
four and a half pounds, consist of pure meal,  he must
consume above nine pounds of solid food, independent
of chaff; and about one-seventieth of his whole Aveight,
if the latter be estimated  at  seven hundred pounds.
From which it  follows,  that  the composition of the
  * Captain Lyon, when  in the arctic regions, had an Esquimaux
dog, which dragged one hundred and sixty pounds at the rate of six
and two-third miles an hour for seven or eight hours a day.  Such
dogs will draw a heavy sledge  to a considerable distance, at the
rate of thirteen or fourteen miles  an  hour;  and they will  travel
long journeys at half that rate,  each of them pulling the weight of
one hundred and thirty pounds.
  The strength of the elephant is reckoned  equal to that  of six
horses;  but  he  consumes a greater ratio of food, and will carry a
load of three or four thousand pounds.
  f A bushel of oats weighs from thirty-two to forty-two pounds,
(average thirty-seven pounds,) and affords 74*3 per cent, of  actual
nourishment, according  to the analysis of Sir  H. Davy.   The
cavalry allowance in England is four feeds, consisting of eight
quarts of oats every twenty-four hours, and twelve pounds of good
meadow hay, which contains about twenty-five per cent, of nutri-
tive matter,_making in all nine pounds of nourishment.  In  Spain
and Portugal, horses in the army are allowed eight pounds of bar-
ley per day. 
 522        VITAL ENERGY OF THE  RACE-HORSE.

 hound is reneAved in about ten  days, and that of the
 horse in about twenty  days.
   The  capacity of the chest and nostrils of the fine-
 blooded race-horse is also larger, in proportion to the
 size of his body, than  in any other description of the
 horse-kind;  corresponding with  his  great  muscular
 strength and activity.   These conditions are owing to
 the expansion of his lungs, and  the  development of
 the muscular sj'stem by active  exercise, by Avhich he
 is disencumbered of all useless fat; so  that the greater
 part of his blood  and  vital energy are expended  on
 the organs of locomotion.*   Besides, we are informed
 by Darvill, that, Avhile in training, he requires fifteen
 quarts of oats daily, Avhich must afford about twelve

  * For the same reason, the goat, sheep, deer, ox, hog, ass and
many other animals, are  more active in the wild state than when
 domesticated, over-nourished and prevented from taking much ex-
ercise.   The wild buffalo, or bison, is no less  remarkable for the
size of his chest than for strength and swiftness in running, com-
pared with the tame  and  unwieldy ox.  The wild ass, also, is
scarcely surpassed in fleetness by the finest horse, although slow in
his  general movements when  made a mere beast of burden.  But
even then his muscular strength is superior to that of man; for a
small donkey, not exceeding the weight of a large man, will carry
two hundred and twenty pounds a distance of twenty miles a day,
which is  certainly more  than the stoutest porter could perform.
We are, therefore, authorized to conclude, that all animals whose
power of obtaining caloric from the atmosphere by respiration ex-
ceeds that of man, surpass him in the powers of digestion, secre-
tion, nutrition and muscular motion.  The reproductive power of
the  rabbit, hare, cat, dog, hog and other animals of hot temper-
ament, is also greater than in man,—greater in nearly all the dif-
ferent species of birds and mammalia,  especially  those of small
size, during summer than winter, when  they are also less playful
and sprightly. 
      DIFFERENCE BETWEEN  MAN AND THE HORSE.   523

pounds  of  actual nourishment.   It  is, therefore,  ob-
vious, that  a larger amount of carbon and  hydrogen is
given off by the lungs of the race-horse than by those
of the ordinary horse, ceteris paribus,—that he obtains
more caloric from the atmosphere by respiration; that
his blood is richer and more abundant; and that  his
composition is reneAved more rapidly,  or in about
seventeen days.
  Again, that the aggregate vital energy of the horse
is greater, in proportion to  his size, than that of man,
would  appear from  the  following facts:—First, that
his tractive poAver has been found equal to that of six
men, Avhose collective Aveight is about six times 150
pounds, making in  all 900 pounds; whereas  that of
the horse has been  estimated at an average  of only
700  pounds:  Secondly,  that a man in  full  health,
Aveighing 150  pounds, digests  about one and a half
pounds  of  actual nourishment  daily, which  is only
about one  one-hundredth  of  his Avhole weight, and
much less  than Avhat Ave  have seen  to be the ratio
consumed by the horse.   From Avhich it follows, that,
in a state of the most vigorous  health, man requires
only twenty-five days for the renewal of his organiza-
tion, alloAving  that all his  actual nourishment is con-
verted into blood and his  several tissues, before it is
discharged  from the body  in  the form of excretions.
But it remains to be ascertained Avhat proportion of the
food  is consumed in the lungs by combustion, during
the conversion of chyle into blood.   When this ques-
tion is settled, it will probably be found that the com-
position of man is  reneAved in  from 30  to 40 days,
instead of seven years, but  that of birds and the more 
524   RESPIRATION  THE SOURCE  OF VITAL ENERGY.

active mammalia in much shorter periods.  Coinciding
with the above facts, it is well known to medical men,
that  a broken  bone  of  a  healthy  individual, when
rightly set, acquires its former  strength in  about forty
days, more or less,  according to the age and constitu-
tion of the patient.*
   The thorax is larger  in men than in  women, its
mean circumference  being about thirty-six  inches in
the former, and thirty-two in the latter.   It is there-
fore not  surprising that the  blood  of men is  more
highly organized, their muscles more fully developed,
their  brains from  four  to  eight  ounces  larger,  (as
shown by Tiedemann,) Avith a corresponding superi-
ority of  muscular  and intellectual power.  Nor was
there  ever an individual of great vital energy, whether
of the brain, stomach or muscles, without large and sound
lungs, which  are essential to the sanguine  and  heroic
temperament.
   If  Ave descend to the loAver  orders of air-breathing
animals,  whose  mean healthy temperature is  from
30° to  50° below that of birds*f* and mammalia, and
  * But so rapid  is the nutritive or formative  process in birds,
that, when a bone  is broken, it requires only about three weeks to
unite and become  strong, if kept in apposition.  The Vis medi-
catrix Naturae is,  therefore, only another name for the aggregate
vital energy of animals, and  is in proportion to the quantity of
caloric they derive from the atmosphere by respiration.
  ■j* That birds consume at least twenty times more oxygen, in pro-
portion to their weight, than reptiles, would appear from some ex-
periments performed by Dr. Edwards,  who found that a frog was
capable of living above three days when confined in a vessel con-
taining sixty-four  cubic inches of  common air; (with a solution of
pure potassa for absorbing the carbonic acid exhaled,) whereas, un- 
       RESPIRATION A MEASURE OF VITAL ENERGY.    525

falls to that of the surrounding medium during winter
in the higher latitudes, we shall find that their poAvers
of digestion, circulation, sanguification, secretion, nu-
trition  and  muscular motion, are exceedingly low,—
that  the lungs,  heart, stomach, brain,  muscles  and
other  organs,  are  imperfectly  developed,  compared
with the whale,  dolphin, porpoise  and  other cetacea,
which  have large lungs,  abundance  of rich arterial
blood, and,  like all warm-blooded animals, an highly
organized stomach,  heart, brain and muscular system.
The truth is,- that scarcely any part of reptiles is more
than half formed; while some of their organs  may be
said to exist  in a merely rudimentary state.  Correspond-
ing with the obtuseness of their senses, and the low
grade of their intelligence, it has been observed by
naturalists,  that  the brain of a crocodile twelve feet

der the same  circumstances, a yellow-hammer of the same weight
lived only one hour.  Nor can there be a doubt that many of the
smaller birds  devour more food in one day  than reptiles of the
same size in twenty.   For it is well known, that frogs,  toads, sala-
manders, tortoises and many other reptiles, are capable of living
several weeks without food, or suffering any material diminution of
weight, and that serpents are often many weeks in digesting a sin-
gle meal.  Spallanzani relates  an instance of one that was three
months in completing the digestion of a fowl.   He also found that
in snakes, the  process was more rapid in June, when the tempera-
ture was 82°, than in April when at 60°.   Hence the slow growth
of all cold-blooded animals, compared with birds and mammalia.
Nor  can there be a doubt that the muscular power of  the latter is
from ten to twenty times greater than that of reptiles, cseteris pari-
bus,—for example, that in a horse weighing  700 pounds it is  ten
times greater than  in a tropical turtle of the same  weight, and
twenty times greater in a sparrow than a frog. 
526   RESPIRATION A MEASURE OF VITAL ENERGY.

long, and of a serpent eighteen feet long, does not ex-
ceed from one to two ounces in Aveight.
   If  we descend the scale of organization from  rep-
tiles to fishes, Crustacea, mollusca and other animals
Avhich breathe with gills instead of  lungs, and  live
constantly  in  water, which  contains  only about one
per cent, of free oxygen by volume, we  find, that al-
though formed of the same elements, animated by the
same principle, and constructed  after the same model,
as the highest species, they resemble abortions, compared
with the finished  beauty of form  exhibited in birds and
mammalia.   For example, the heart  of  fishes is ex-
ceedingly small, its Avails thin, its pulsations sIoav and
languid, the arteries small and few, the blood pale and
watery, the muscles flaccid, the  bones soft or replaced
by cartilage, while the  brain consists of a few small
knots or ganglions, with a corresponding defect of the
senses.*   And notwithstanding  they move with great
velocity through water, it is owing  to the density of
that medium, by which they are enabled to propel
themselves  onward by a small exertion of vital force;
nearly all of which  is  expended on the muscles em-
ployed  in locomotion.   But  as  Cuvier observes,  they
are soon  exhausted  by exertion, which is true of all
cold-blooded animals.
   As a further proof that the aggregate vital energy of
all animals  is directly in proportion to the development

  * The eyes are without lustre, the organs of hearing scarcely
distinguishable, and so imperfect are those of voice, that they have
no power of uttering sounds, but vegetate  in  perpetual  dumb si-
lence, with scarcely the animal desire of sexual communion, or the
slightest regard for their offspring. 
RESPIRATION A  MEASURE OF VITAL  ENERGY.   527
of their breathing apparedus, it may be added, that by
means of stigmata or holes, arranged along their bo-
dies, and minute vesicles for conveying air throughout
the system, the active insects are more fully supplied
with organs of respiration than  any other description
of animals, not excepting birds.  As  an  example of
the large amount of oxygen they consume, Spallanzani
found that a caterpillar generated more carbonic acid
in a given time than a frog, and butterflies still more.
Corresponding also with the facts exhibited in Table
III.  p. 513, Ave  learn  from the  experiments  of Mr.
Newport, recorded in the Phil. Transactions for 1836-7,
that Avasps, hornets,  beetles,  moths and  some  other
insects, have a much  higlier temperature than that of
the surrounding  air, and  that it is always in propor-
tion to the quantity  of oxygen  they consume by re-
spiration, which is augmented by exertion, and dimi-
nished by repose.
   In accordance with the above  facts, and with all the
analogies  of nature,  the Avhole organization of  the
higher insects is very complex  and refined.   For, al-
though like all invertebrated animals, they have  no
brain in the head, nor central sensorium, they are sup-
plied Avith a  series of  knots  or ganglions, extending
along the interior of their bodies, and connected with
each other by nervous cords; Avhile it is known that
some of them are covered over with eyes.  Hence the
extreme acuteness of their senses, and the wonderful sa-
gacity displayed in the economy  of bees, ants and many
other species of insects.  The honey-bee has, to a cer-
tain extent, the same emotions of fear, anger, revenge
and affection, as man.   It  also  remembers, compares 
528
ORIGIN  OF  INSTINCT.
and  reasons; for, while disporting in the joyous sun-
shine, and culling sweets  from the flowery fields, it
looks forward to a change of  season, avoids the ap-
proach of rain, wind and other injurious conditions of
the Aveather; while in the construction of its honey-
cells it exhibits the perfection of mathematical skill.
  We are told that all this is mere instinct, because it
is not improved by education.   But if we admit that
bees construct  their cells with  as much art the first
day  of  their commencing  to  labour, as  after three
years of experience, and  that  they do  it  by instinct,
must not the latter depend on the peculiar  organiza-
tion of their  nervous  system?  And  if  within  the
limited range of their appointed labours, they operate
with more consummate skill, without education and
experience, than man, it is because they are employed
on only a few objects, to which they are adapted by
their organization, and directed by a species of phy-
sical necessity,  arising from their wants; just as birds
of passage are directed by their sensations to  seek
warmer climates on the approach  of winter,—or for
the same reason that the eye of the eagle can discover
small objects at a great distance, and that the sense
of smell is more acute in the common hound, than in
any  other description of  animals,  viz., because  the
optic and  olfactory nerves are  larger, and expanded
over a greater extent of surface.  Descartes  gave the
true theory of instinct, when he said that  " the lower
animals do many things better than ourselves,—not
because they are  endoAved  with more reason, but that
nature acts in them according to the structure of their
organs."  (De Methodo.) 
     MECHANISM AND MUSCULAR POAVER OF INSECTS.  529

  As an example of the complex mechanism of the
higher insects, Ave are informed that Lyonet discovered
4061 distinct muscles in the Gossus, while in the cater-
pillar state.  And as an  example of the prodigious
muscular power of the more perfect insects, Richerand
states, that the common grasshopper has been known
to leap two hundred times its oavh length; while there
is reason to believe, that in proportion to his size, the
flea is still more active and strong.   The muscular
power of insects is  still more remarkably shown by
the fact that  a small number of bees Avhile suspended
from the limb of a tree Avill  support for some time a
swarm of several thousand, whose aggregate Aveight is
equal to from three to six  pounds.
34 
CHAPTER  IV.
  A  FURTHER INQUIRY INTO THE PHYSICAL  CAUSE OF
                   VITAL  ACTION.

  "In physiology, what a vast advance would that  philosopher
make who should establish a precise, tenable and consistent con-
ception of life."—Whewell.

  As in every department of human knowledge one
radical  error leads to others in endless sequence, it is
not surprising that erroneous views  in  regard to the
cause of vital action  should have involved the whole
science  of medicine in a maze of perplexity and un-
certainty.   The  fatal  consequences  of ignorance in
regard to what the living principle is, and hoAV it ope-
rates, may be traced  in the unsettled opinions Avhich
everyAvhere prevail concerning the essence of fever, its
causes and  its treatment,  a state of things that calls
loudly for reform ab origine.
  In all attempts to improve the science of physiology,
it should be our leading object to discover the primary
physical cause of animal  motion;  and whether it re-
sides in the blood, as  maintained by Moses, Hippo-
crates and all the ancients; or in the nervous system,
as supposed by the great majority of modern authors.
Until these fundamental  questions  are  decided, the
theory of life, health and disease, must continue in-
\rolved  in profound darkness.  Nor  is it less certain,
      (530) 
PRIMARY SEAT OF VITAL ENERGY.
531
that the Avhole theory of nature must remain a sealed
book, so long as attraction, repulsion, chemical affinity,
polarity, irritability and  sensibility, are  regarded as
ultimate phenomena,  or confounded  with primary
causation.   It  is therefore high time  that we  should
look beyond the surface  of things to  the mainspring
of all power, Avhether in living or dead matter.
  In accordance with the  universal belief of antiquity,
it Avas maintained by the illustrious Harvey, that what
the  Romans termed color vitalis,  is the primary  and
immediate cause of the  heart's action, and of vitality in
the blood, which he describes as the common bond of union
among all parts of the living body.  "In quo, vegeta-
tive et sensitiATae operationes primo elucent,  cui calor,
primarium et immediatum  animse instrumentum, in-
nascitur, qui corporis  animseque commune vinculum
est,—et quo vehiculo  anima omnibus totius corporis
partibus influit."  (Op. Omnia, p.  388.)  He further
maintained  that the animating principle is a finite
portion of the  uni\7ersal spirit that actuates all crea-
tion.
  But this simple and rational  doctrine Avas destined
to be superseded by the speculations of Willis, Baglivi,
Hoffman, Gaubius and Barthez, Avho confounded  the
animating principle Avith  some unknown  hypothetical
fluid, supposed  to  be  generated  in the brain, from
Avhich it was conveyed  to  all parts of the body by
nerves.  According to Stahl, the organizing  principle
Avhich he termed the Anima, is endowed with  intelli-
gence, and corresponds to the  <ZW'C of  Hippocrates,
with this exception, that  Stahl  regarded it as  an  im-
material essence. 
532         PRIMARY SEAT OF VITAL ENERGY.

  It was also maintained by the celebrated Boerhaave
that all the operations of the  living body are governed
by the agency of an uniArersal catholic fluid, the most
subtile and elastic principle in nature, termed by the
Greeks and Romans Anima Mundi.  But  he supposed
that the action of the heart, stomach and other invo-
luntary organs is owing partly to the influence of arte-
rial blood, and partly  to the agency  of a nervous fluid,
generated in the cerebellum;  while the voluntary mus-
cles derive their power from the influence of a nervous
fluid  secreted in the  cerebrum, as first  suggested by
Willis.   And so confused Avere his  notions in regard
to the source of animal  heat, that with Bacon, Boyle,
Borelli  and  other mechanical physiologists, he repre-
sents it  as an effect of the heart's action, friction and
motion of the blood, because when the circulation is vigor-
ous, the body is warm,  but cold when it is languid* (In-
stitutions in Physic,  pp. 16, 61 and 116.)
  Although it must be confessed that this logic is not
precisely after  the  manner of Euclid, it is not a bad
specimen of what may be found in the works of many
distinguished modern philosophers,  who have equally
confounded cause  and effect.  Sir Isaac Newton him-
self has fallen into a like error, when he says that
"animal motion may be performed by vibrations of the
ether, excited in the bredn by the power of the will"  But
  * He further maintained, like Hoffman, that every variety of
fever and inflammation is owing to a deranged condition of the
blood, and its too slow or too rapid movements, as during the cold
and hot stages; that all spasmodic affections are owing to a vigor-
ous influx of nervous influence into the muscles, and paralysis, to a
stoppage of that influx.  (Op. cit. pp. 216, 250.) 
LEADING DOCTRINES  OF  CULLEN.         533
Iioav can  the brain Avill, unless  previously vitalized?
And if the will depend on the  activity of the brain,
how can it be the cause of vibrations in the ether, or
of any species of cerebral motion?  Is it not manifest,
that sensation, memory and volition are mere modes
of action of the living nervous system?  For, when
life ceases, they are Avholly  extinguished, therefore,
like the mind itself, cannot be  regarded as material
entities, (as they have neither extension, solidity, nor
any other properties of tangible  matter,) but as effects
of the same  cause  that generates attraction, repulsion,
vibration, chemical affinity and all the motions of pas-
sive matter.
   But it  was reserved for the  celebrated Cullen  to
erect on the ruins of nearly all that was true in the
medical doctrines of antiquity, one  of the most vision-
ary systems ever invented by the subtilizing genius of
man;  and Avhich has exerted an astonishing influence
in retarding the progress of sound practical knoAvledge.
Although he admits that all the phenomena of health
 and disease must  be referred to the moving powers of
 the animal economy, he maintains  that digestion, cir-
 culation, secretion, nutrition, sensation  and muscular
 motion, including the generation of animal heat, are
 owing to the agency of a "subtile and elastic principle*

   * But if caloric, in some of its forms, be the  cause of all elas-
 ticity, it must be the very same principle which  Cullen terms  the
 nervous fluid, and describes as the prime mover in the animal eco-
 nomy   Yet so little  did he know in regard to the origin and use
 of animal heat, that,  in his Institutions of Medicine, he speaks of
 it "as  probably the effect of the motion of the  blood, because in
 dying animals the heat grows less as the motion of the blood grows 
534
LEADING DOCTRINES OF CULLEN.
inherent in the  medullary substance of the  brain;  and
which he termed tJie nervous fluid, or the nervous power,
—that this fluid or power is the prime  mover In  the ani-
mal body, and determines the activity of all the organs,
whether voluntary or involuntary,—that  as it appears
only in the living, and  disappears entirely in the dead
state of the body, it must be regarded as the vital prin-
ciple,"—and  that it regulates not only the various de-
grees of muscular strength, but the quantity,  quality
and distribution of the fluids, with  every variety of
temperament. (Materia Medlca, pp. 55, 88 and 99.)
   In accordance with this hypothesis, he taught that
all medicinal and morbific agents exert their influence
primarily on the nervous system, and not through the
medium of the  blood, as maintained from  the  days of
Hippocrates  down to the time of Harvey.  And it is
remarkable that he should haAre rejected the humoral
pathology, on the ground of our ignorance in  regard
to the office of blood in health, and of the changes it
undergoes in disease.
   The supposition that nervous influence is  indispen-
sable to muscular contraction, Avas long ago disproved
by the experiments of Haller and Fontana, Avho found,
that when the chest of an animal was laid open, and
the nerves going to the heart were stimulated, its con-
tractions were neither  accelerated nor renewed Avhen
at rest.   And Dr. Philip has since demonstrated, that
even the voluntary muscles retain their irritability as

less; and when  at death it ceases altogether, the heat ceases also
in  a very short time."  That such a sentence should  have been
written by Cullen after he had been made acquainted with the dis-
coveries of Dr. Black, is almost incredible. 
DR. PHILIP.
535
long after their nerves have been divided as when left
entire,—that chemical stimulants which  excite them
to contract Avhen applied immediately to their fibres,
produce no effect when applied to their nerves  alone.*
Yet the  majority of modern  physiologists who  have
not adopted  the views  of Cullen, maintain with  Haller,
that all the phenomena of animal life may be referred
to  tAvo fundamental properties, irritability  and sensi-
bility, the one inherent in the muscular fibre, and the
other in the medullary tissue.   But as these  proper-
ties cannot  exist in any part of  the body before it is
  * He says, that "the power of the muscular fibre is a property
depending on the mechanism of that fibre, and in no degree directly
depending on the nervous power."  Yet he maintains that "animal
heat must be ranked among the secretions :" that it is evolved from
the blood like the various secretions, by nervous influence, because
the temperature of animals is reduced by injuries of the brain, spinal
marrow and division of the vagus or eighth pair of nerves, and their
secretions diminished; as if the cause of muscular contraction were
different from that of secretion.  In another place he observes, "we
have reason to believe that nervous influence is the galvanic fluid,
collected by the brain  and  spinal marrow, and  sent along  the
nerves." But he says  again, that "neither nervous influence  nor
galvanism  can excite the actions of animal life, except in parts
endowed with the vital principle, whether the latter be something
superadded to bodies,  or only a peculiar  arrangement  of their
parts." (Experimental Enquiry, pp. 156, 219, 248, 265, 267, &c.)
  It is painful to trace  the flounderings and contradictions of so
great an experimenter as Dr. Philip, who has overlooked the  ad-
mirable precept of Newton, that no more causes of natural things
ought to be admitted, than such as are true and sufficient to explain
the phenomena.  For  if neither galvanic electricity nor nervous
influence can excite the actions of life in parts not endowed with
the vital principle, why admit them as causes of secretion and the
evolution of animal heat ? 
536
THEORY OF BICHAT.
formed, it is self-evident that they are secondary effects
of the organizing principle; while it is equally mani-
fest, that the vital attraction, the vital affinity and the
vital contractility of Dr. Alison are modifications of one
and the same  poAver  by Avhich  the  blood  is formed,
united Avith the different organs, and the whole main-
tained in a state of activity.
   The  theory  of  Bichat was  only  a modification  of
that proposed  by  Cullen; for he referred the contrac-
tile poAver of the heart and  all the involuntary organs
to the ganglionic system of nerves, which he regarded
as the source of organic or unconscious life,—(corre-
sponding with that of plants,  the  vital and natural
functions of the ancients, and  those  termed vegetative
by Harvey;) while he supposed that the brain, spinal
marrow and their nerves Avere the organs of sensation,
perception and  the power of regulating the movements
of the voluntary muscles. The objections to this theory
are—1. That contractility is a property of all  living
matter, including every description of plants, and even
the medullary tissue; for the brain undergoes contrac-
tion and expansion during violent emotions or active
thinking.   2. That all the operations of life, Avhether
Aroluntary or involuntary, are organic. 3. That among
all the loAver orders of animals which have neither
brain nor spinal marrow, but  only ganglionic nerves,
and some of them  only a single cord extending along
the body, as in the earth-worm, there  is not a single
species destitute of sensibility, consciousness and voli-
tion; for the lowest Avorm seeks nourishment, and re-
coils from the approach of harm: while the more active
insects are endowed Avith far higher degrees of intelli- 
          OFFICE OF THE GANGLIONIC NERA-ES.      537

gence than  many animals  Avhich have a brain and
spinal marrow,—with emotions  of loA^e, anger,  fear,
and  perhaps,  to a certain  extent, the sentiments of
justice and benevolence.
  Thus it is, that without  resorting to the cruel ex-
periments of vivisection, (Avhich  ahvays deranges the
natural state of the functions, and has led to so many
erroneous conclusions,) we  learn by a simple appeal
to comparative physiology,  that the office of the gan-
glionic nerves is identical with that of the brain, spi-
nal  marrow and their nerves.   For, as Cuvier  truly
observes,  by comparing the structure and functions of
different  species, in which  "nature  adds to,  or sub-
tracts from, each  of  their different parts, just as we
might wish to do  in  our laboratories, and shows her-
self the results of such additions and subtractions,"
we may easily ascertain the specific office of any one
organ.  We may obtain responses from nature by put-
ting her  to the torture; but, like the prisoner  Avhen
submitted to the rack, her answers are often fallacious.
The truth is, that the brain may be regarded as a large
ganglion, or concentration of nervous matter, of Avhich
the spinal  marroAV is a mere continuation;  and  the
nerves  of both, as expanded branches, with which the
ganglions in  the  higher animals are connected; and
the object of which is to endow the involuntary organs
 Avith so much sensibility as may be requisite  to their
 Avell-being.   But  as the heart, stomach and all  secre-
 tory organs are excited to action by the  stimulus of
 blood, there is no necessity for their being subject to
 the commands of the sensorium commune, like the loco-
 motive muscles, or even the sphincters of the bladder 
538             VIEWS OF CUVIER AND

and rectum.   Let us, then, reject the doctrine of Miil-
ler, that "the ganglia are the centres of organic life;"
and that "the cerebro-spinal system alone is capable
of exciting voluntary motion."  (Elements  of Physi-
ology, pp. 734, 934.)
  The celebrated Cuvier seems at one time to have
aimed at more enlarged views of the animal  economy;
for he observes that the vital  energy of  animals, and
the development of their organization, are in propor-
tion to the amount of their respiration.   But, like his
illustrious  predecessor, John Hunter, he  Avas so com-
pletely  fettered  by  the  preATailing  doctrine  of  the
schools, that in his introduction to the Reguc Animal.
he says that, "as the heart, stomach  and other invo-
luntary organs are  affected by the nervous  system, it
is probably the source of their contractile power." And
again:  " as all the animal fluids are derived from  the
blood by secretion, there  cannot be a doubt that  the
nervous fluid is secreted by the medullary matter, from
which  it is conveyed to all parts of the body by  the
nerves."
  The  fundamental error of regarding the brain, or
any part of the nervous system, as the source of vital
energy, Avill appear evident from the following unde-
niable facts:—1.  That life exists throughout the vege-
table Avorld, and in many species of the lower animals
termed  zoophytes, polypi, entozoa, &c. in Avhich  not
the slightest trace  of nervous  matter has ever been
discovered; consequently, that all those physiologists
who have regarded nervous influence as the source of
vital energy, have vainly endeavoured to explain an
universal by a partial fact.  2. That the germs of all 
OTHER PHYSIOLOGISTS.
539
 the higher animals are developed and endowed Avith
 vitality, before  any  part of the nervous  system is
 formed; consequently, that the latter must be a se-
 condary effect or product of the organizing principle.
 3.  That the aggregate vital  energy of  animals is
 directly in proportion to the quantity of their respi-
 ration, or of caloric that passes through their tissues,
 and bears no uniform relation to the  development of
 the brain and  nerves.   4.  That the nervous system,
 like all the other organs, is formed from, and vitalized
 by, the  blood, which is formed in the lungs  by  the
 same  active  principle that  causes the seeds of plants
 to germinate, and the germs of animals to unfold from
 a simple albuminous mass into highly organized bodies.
   Yet we are told by Tiedemann, "that the develop-
 ment of the  locomotive organs is in proportion to that
 of the nervous system." (Compeer. Physiology, p. 182.)
 And  Mr. Mayow says, that "the nervous system de-
 termines the rate at which each function proceeds,  the
 quantity of secretion and the frequency of involuntary
 motion."  (Outlines of Physiology, p.  264.)   Again,
 Magendi  observes, that  "we are totally ignorant in
 regard to the cause of muscular motion, but must seek
 for the impulse which sets our various tissues  in mo-
 tion, in the  nervous system."  (lectures on the Nerv.
 System.)  Dr. Edwards also maintains, that "the pre-
 dominance of the nervous system  in warm-blooded
 animals renders  all parts of the body more excitable,
 giving the greatest energy to the nutritive functions."
 And Sir Charles Bell observes, in his late work  on the
Nervous System, that "vital power is possessed through
the agency of nervous matter, diffused through all ani- 
540
VIEWS OF BILLING AND
mals, from the simplest up  to  man."  (1836, p. 17.)
Dr. Billing also maintains, that " the nervous system
regulates and supplies all the organs Avith energy, and
that without nerves there is no organic contractility."
(Principles of Medicine.)  And  Miiller contends, that
"the organs of animals manifest as great a dependence
on nerves, as plants  do on light."   (Op.citat, p. 43.)
In the  same strain, Ave are  told by Mr. Earle, that
"the agent AArhich causes animal heat, the fluidity of
the blood, and maintains all the functions of life, is
something which  proceeds  from the brain, along the
spinal  marrow to the extremities of the nerves; and
that animal heat is as much to be considered a  secre-
tion  as  bile, saliva  or gastric juice."  (Neio Expos, of
the Nerv. System, p.  137.)
  As if to fill up the measure  of  our astonishment,
Edward Johnson  observes,  that the heart and all the
other organs derive their poAver of action from a fluid
brought to them by  the nerves from the  brain, by
whose  action that  fluid is produced,—that wherever
there is an artery, vein  or absorbent, there must also
be a nerve  to enable  these vessels to convey their
fluids, &c.  But, as  if conscious that all this  amounts
to nothing in the way of explanation, he says again:
"If you ask me  for the cause of the  first life, I an-
SAver your question  by another:—What is the cause of
gravitation, chemical  affinity, &c. but the  Causa Cau-
sarum? the Deity  himself?"   (Life, Health and Dis-
ease, pp. 66-72.)
  But why should I quote further examples of a doc-
trine Avhich  is taught by nearly all modern physiolo-
gists, and by some  of them carried even farther than 
OTHER PHYSIOLOGISTS.
541
was ever contemplated  by Cullen?   Having already
shoAvn that nervous influence  is not the cause, but a
secondary effect of  vital energy,  it may be right to
show, by a brief reference to comparative physiology,
that the muscular strength  and locomotive power of
animals  are not in any proportion to the development
of the nervous system.   As a striking example of this,
the  brain of man is perhaps fifty times larger than
that of  the ostrich, which is no  less remarkable for
stupidity, than for its prodigious muscular power; for,
if we are to credit the accounts of travellers in Africa,
it has been knoAvn to surpass, with a full-grown negro
on  its back,  the fleetest race-horse.*   She does not,
however, seem to be ignorant of the fact, that her eggs
may be hatched by the agency of  solar heat, indepen-
dent of  nervous influence,  when buried in the  hot
sands  of Senegal,  where she  sits  on them only at
night.f
   The brain of the  greyhound, like that  of the fox,
hare, rabbit, goat, deer and many other  species of
  * It is said of the ostrich in the Book of Job, chap, xxxix. verse
17, that  "God hath deprived her of wisdom, neither hath he im-
parted to her understanding."
  f A similar view has been recently advanced by Dr. Draper of
New York;  for  he  says that "the beams of the sun are the true
nervous principle in plants;" that to the yellow ray is assigned
their nutritive processes, to the blue their movements. But unfor-
tunately for  this latter hypothesis, if kept  in air of the  proper
temperature, all  the movements of plants,.including the decompo-
sition of  carbonic acid by their leaves, their circulation and nutri-
tion are carried on in the midst of profound darkness, if we except
the process by which their colours are produced.  (See Phil. Mag.
for August, 1844, p. 104.) 
•342
RELATIVE SIZE OF THE BRAIN
 mammalia, is exceedingly small:  but as he is made up
 chiefly of lungs, blood and muscles, he is the SAviftest
 of all runners except the ostrich.  The brain of the
 horse and ox varies in Aveight from  one pound four
 ounces to one pound seAen ounces; while that of man
 varies from three pounds two ounces to four pounds
 six ounces.   Yet the muscular power of the horse is
 equal to that of six men.  Besides, if the brain were
 the source of vital  energy, such men  as Bacon, Shak-
 speare,  Newton, Milton, Franklin, Napoleon, Byron
 and all  others that  have large heads,  ought to possess
 the energies of life  in the highest degree;  whereas it
 is certain, that, in men of genius, the  poAvers of diges-
 tion,  secretion, nutrition and muscular motion,  are
 generally inferior to what they are in  individuals of
 the athletic temperament, who are often remarkable
 for  the  smallness of their heads, and a deficiency of
 intelligence.
  According  to  Rudolphi, the brain  of a  full-grown
 Greenland Avhale, (Balenet Mysticetus,)  seventy-five feet
 long, weighs only five pounds ten ounces four drachms.
 But as the cetacea  have large lungs, and a tempera-
 ture that varies from 100° to 104°, with a correspond-
 ing amount of rich red  blood, the muscular poAver of
 the Avhale is  equal  to  that of several hundred  men.
John  Hunter states, that, from the capacity of the
heart and aorta, from 80 to 120 pounds of blood must
be discharged by the left ventricle at each contraction.
The weight of  this enormous animal has been esti-
mated at 140,000 pounds; and it has been said that,
Avhen of the largest size, it has afforded above 20,000
pounds of oil.  We have no accurate information in 
IN DIFFERENT ANIMALS.
543
regard to the weight of the brain in the sperm whale,
which  measures  eighty-four feet in  length,  and  is
larger  than  the  Balena  Mystlcetus.   But Mr. Beale
states,  that the cranial cavity of one, fifty-eight  feet
six inches long, measured  fourteen inches  in width,
ten inches in length, and nine inches in depth; that
the  spinal canal, Avhich is  of a triangular form, mea-
sured ten inches in Avidth at the base, Avhere connected
Avith the brain, and  eight inches  in  depth;  but only
seven inches wide, and  six and  a half  deep, at  the
seventh dorsal vertebra, from which  it diminished to
the termination.*
   Should  it be urged  that  the brain of the elephant
Aveighs from eight to  ten pounds, I  ansAver, that his
muscular poAver is far inferior to that  of the  horse, ox,
dog, wolf,  deer and other mammalia, in  proportion to
their size.  So that, notwithstanding  the absolute size
of the  brain is larger in the whale and elephant than
in man, it is A^ery much  smaller, compared with the
  * The most remarkable fact connected with the  natural history
of the cetacea is, the length of time they are capable of remaining
under water.  Mr. Beale says, that the male sperm whale continues
below the surface  from one hour to seventy, and even eighty mi-
nutes, when he rises and breathes  for ten minutes; but  that the
female remains only twenty minutes below and four minutes above
the surface.  (Beale on the  Sperm Whale, p.  45.)  The means by
which they are enabled to effect this, exhibit a striking  adaptation
to the medium  in which they exist, and  doubtless depend on the
vast amount of blood contained in the numerous convolutions of
vessels found in the thoracic and abdominal cavities, as first noticed
by Hunter,—all of which is vitalized during the  short time  they
remajn above water, by a rapid process of breathing, and thus pre-
pared to maintain the activity of their  functions from twenty to
sixty, and even eighty minutes, while in search of food in the depths
of the ocean. 
544          RELATIVE  SIZE OF THE  BRAIN.

magnitude of the body, and its superior frontal por-
tions less perfectly developed.   The consequence of
which is, that, in the range of their intellectual facul-
ties, they are as far inferior to man  as they are his
superiors in muscular poAver.  And although the brain
of the canary, sparroAV and  chaffinch,  be  larger, in
proportion to the size of the body, than in  any other
animated beings  Avith  Avhich Ave are acquainted,  its
convolutions are  much less numerous  than in man,
and the intellectual portions less fully developed, com-
pared  with  the inferior and posterior compartments.
But  the muscular poAver of these birds  is not greater,
in proportion to their Aveight, than that of the pigeon,
Avhose brain, compared Avith the Avhole body, is in the
ratio  of one to ninety;  while in man the  average
ratio is as one to forty), excepting idiots, in which it
is often not much larger than in infants, according to
the measurements of Tiedemann,) but varies with the
different degrees  of obesity, and diminishes Avith old
age.    We are, therefore, authorized to  conclude, that
the intelligence of animals is directly in  proportion to
the development of their nervous system, caeteris paribus;
but that their powers of digestion, circulation, secretion,
nutrition, absorption, muscular motion and cerebration,
depend on the  amount  of caloric  they derive from the
atmosphere by respiration*
  The specific office of the brain, spinal marrow and
  * So far is it from being true that the brain is the source of vital
energy to the other organs, that when snakes, eels and other cold-
blooded animals are  decapitated, the trunk remains  alive much
longer than the head.  And Whytt states, that Redi extracted the
brain from a tortoise, which afterwards lived  from November until 
SPECIFIC OFFICE OF  THE BRAIN.          545
their nerves, including those of the ganglionic system,
is  to endow animals  with  sensation, perception,  me-
mory, volition, instinct and all the attributes of mind,
—to direct  the various movements of  the body, but
not to supply the moving power,—to generate ideas,
but  not organic  products.   It is  very  true,  that  the
nen^ous system is far  more  highly developed in warm
than in cold-blooded  animals; but we  shall see  pre-
sently, that this is owing  to the greater  activity of
nutrition in the former.  It is also very true, that when
the nerves  going to a voluntary muscle  are irritated,

the following May, but lost the power of vision and hearing.  (Es-
say on Animal Motion, p.  386.)
   It is also evident, from the experiments of  Flourens,  that in the
highest orders of animals, the cerebrum is not essential to respira-
tion, which is governed chiefly by the eighth pair of nerves, that
arise from the medulla oblongata.  For  he  found that, when the
cerebrum of a chicken was removed, it remained in a healthy state
for ten months, and even  grew fat on being  daily crammed with
food,—that, when thrown  into the air, it exerted its wings, as if
endeavouring  to fly, but lost the power of vision, hearing, tasting,
smelling, the feeling of hunger, sexual desire, memory, comparison,
and,  to a great extent, all  its sentient faculties.  Yet  we are in-
formed by Magendie, that  after the cerebrum, cerebellum and all
parts of the brain above the medulla oblongata, were removed from
a hedgehog, the animal retained, in a low degree, the sense of feel-
ing, smelling  and consciousness,—uttered cries when its whiskers
were plucked,  and made repeated  efforts with its forefeet to get rid
of the annoyance.   Volkman also found, that, when a decapitated
frog  was irritated with a hot  iron, it leaped forward, as if  con-
scious of pain.  We further learn, from the experiments of Granger
and Barron, that, after the  brain was removed from a young puppy,
it made efforts to suck,—thus showing an imperfect power of voli-
tion. (Med. Gazette, April 13, 1839.)
                            35 
546
SPECIFIC OFFICE  OF THE
contractions are  produced, and that, Avhen divided, it
can no longer contract in obedience to the commands
of the will.   But if the locomotive organs be not sup-
plied with arterial blood, the}7 become cold, insensible
and paralytic, AvhateA^er the condition  of the brain
may be.  And if the blood  be not supplied continually
with  caloric by respiration, it cannot  excite the brain
to think and  will, the nerves to  feel, the  muscles to
contract and the glands to  secrete.*

  * In his late History of the Inductive Sciences,  Mr. Whewell
observes, that  " the phenomena of the nervous system bring us in
a striking manner to the passage  from the physical  to the hyper-
physical sciences;"  and he adds, that "the  nervous fluid can
neither be mechanical, chemical nor physical,—that  it must cease
to be a fluid before its motions can become sensation and thought."
(Vol. iii. pp. 422-430.)  But if  the nervous fluid be neither me-
chanical, chemical nor physical, it must be a non-entity, or a meta-
physical phantom, and should therefore be  excluded  from the
inductive  sciences.,  "What  can we  reason  but from  what we
know ?"  Yet  Mr. Earle has described the circulation of the ner-
vous fluid with as  much confidence as did Harvey that of the  blood.
Dr. Alison also maintains, that " vitality has no  connection whatever
with the notion of mind as distinguished from  matter." And even
Lord Brougham has so far forgotten himself as to  hazard the asser-
tion, that "mind has no necessary connection with sensation."  But
it might as well be said, that motion has no connection whatever
with matter, as that mind has no necessary  connection with the
vitality of the  nervous system, or with sensation;  for it is self-evi-
dent that,  in our  present state of existence, there can be no percep-
tion, memory, comparison or vouq, without sensation, and no sensa-
tion without life; consequently, that all the phenomena  of mind
are strictly physiological.  And  it is only when we attempt to
speculate  about  the operations of the soul, independent of matter
and of all corporeal organization, that we  lose  ourselves  in the
labyrinth of the hyperphysical sciences, among what Lord  Bacon 
WHOLE  NERVOUS SYSTEM.
547
  It has often been asked, what is the use of nerves
in parts not subject to the will?  I answer, that with-
out nerves in the stomach, we could not  be informed
by the sense of hunger, when and how much nourish-
ment to take; that Avithout  nerves, the  heart, liver,
bowels  and  other viscera,  could not warn  us  of ap-
proaching disease by the sensation of pain, nor direct
in the  employment  of  suitable remedies.  Through
the  agency of nerves distributed  to the respiratory
muscles, we are enabled  to  regulate the process of
breathing, and thus to obtain the  principle  of life
from the atmosphere.   To this act, the infant is first
prompted by the painful sensation of a pressing vital
want, which forces the little being to utter a cry, when
the lungs expand for the reception of air, and all his
embryo faculties are exalted.  This half unconscious
feeling continues to operate throughout the remainder
of  existence, and when  all  the outward senses are
steeped in  oblivion; for "not even in sleep is will re-
signed," as  proved  by the fact  that respiration still
goes on, though somewhat diminished, while all the
higher functions of the brain are  suspended.   Hence
it is, that when the vagus  or eighth pair of nerves is
divided, the  process of breathing is diminished, the
temperature  of the body reduced, sanguification, se-
cretion, nutrition, &c. impaired,—or even wholly sus-
pended by destruction of the brain and spinal  marroAv
—simply because respiration is a voluntary  process,
 and  the primary function of life, on which  all the

calls "the idols of the Den."  The genesis of  all mental phe-
nomena must be sought in our organization, and that of  organiza-
tion in the union of spirit and matter. 
548       VITAL OFFICE  OF ARTERIAL BLOOD.
others depend.  Division of the nerves  going  to the
stomach,  pancreas, kidneys and  other  glands, does
not prevent them from secreting their respective fluids;
but if cut off from the  supply of living  blood  by di-
viding or tying their arteries, the powers of secretion,
nutrition,  sensation and motion, are wholly suspended.
  The sensorium may be compared to the commander
of an army, whose office it is to direct its movements;
but the moving  power resides in the army and  not in
the general.   The  external senses may also be com-
pared to the sentinels which give information of what
is going on, while the nerves operate as messengers
that convey orders from the chief to the ranks, and
bring back information in regard to their condition.
So long as the commander fulfils his duty, the  e\*olu-
tions of the army are performed with order and intel-
ligence; but should he  be slain or wounded, and  his
place not be taken by  another chief,—or should  his
means of  communication with his subordinate officers
be cut off, the operations of the  army become irregu-
lar, confused and inefficient, because no longer guided
by  superior intelligence.  In like manner, Avhen the
sentient power of the brain has been destroyed by
suffocation, strangulation or a violent concussion, the
locomotive muscles contract spasmodically, because no
longer directed by the organ of thought.
  So far is the brain from being the source of moving
power in  the animal  economy, that arterial blood is
more essential to its vitality than to any of the other
organs; for if  the carotid  and  vertebral  arteries be
divided or tied, it  dies almost immediately,—and long
before the heart and other muscles cease to contract. 
VITAL OFFICE  OF ARTERIAL BLOOD.        549
The reason of which is, that the brain is supplied with
five or six times more blood  in proportion to its  mag-
nitude, than the general system—corresponding Avith
its  exalted vitality, and the  important office it has to
perform as  the  organ  of  mind, by which we are en-
abled to hold communion Avith the external world, and
to enjoy Avhatever is beautiful or excellent in the uni-
verse.   For  the same  reason, birds die much sooner
after  decapitation or  the  privation of oxygen, than
mammalia, and the latter than cold-blooded animals.
In other Avords, it is  because arterial blood is  more
essential to  the vitality of the brain than  to any of
the other organs, that it dies in a few moments  when
deprived of  that fluid, or when the latter is no longer
 arterialized  by respiration;* whereas  the contractile

   * For example, when the smaller birds are deprived of  oxygen,
 or  the vessels that supply the brain with blood are divided, they
 become insensible in 40 seconds.   When insects are smeared over
 with varnish, so as to prevent  respiration, they die almost imme-
 diately, as shown by the  experiments of  Treviranus; the more
 active mammalia in about one minute,—whereas in man, sensibility
 remains for about one minute and a half, after the process of breath-
 ing has been arrested by exposure to mephitic gases, strangulation
 from hanging  or drowning, as found by the experiments of Good-
 wyn  and Bichat.  But when reptiles and fishes are deprived of
 oxygen, or the great vessels are divided, they often maintain a low
 degree of vitality for several hours, and even for several days when
 the energy of  their functions has been diminished by external cold.
 We also learn from the researches of Legallois and Edwards, that
 puppies  kittens and other mammalia that are born with  the eyes
 closed (and in which the function of respiration is so imperfect as
 to resemble that of cold-blooded animals,) may be resuscitated after
 remaining above half an hour under water. The rationale of which
 is  that in proportion to the vital energy of animals, is the rapidity 
550        VITAL OFFICE  OF  ARTERIAL BLOOD.

power of the  muscles remains for a long time, and is
not wholly extinguished until the body becomes cold,
as shown by the rigidity or stiffening that takes place
after death.
   This brings us to one  of  the most important laAvs of
the animal  economy, which, when fully understood,
Avill  unfold  the rationale  of spasmodic  diseases, and
lead to the true method of curing, or rather of pre-
venting  them—viz.,  that the duration of life in any
fart of the body, when deprived of arterial blood, or the
animating principle, is  inversely  as the quantity of
blood rcqulreel to  maintain its activity.   The conse-
quence of this law  is,  that whenever  the chemical
function  of the lungs is  diminished, and the vital pro-
perties of the blood are  impaired, the voluntary power
of the brain  ceases  to operate some time  before the
moving power of the muscles, which contract without
its orders, and therefore  in  a convulsive manner.   The
more suddenly the power of the brain is arrested, the
more decided  and energetic is the spasmodic action,
Avhich always follows decapitation, excessive and rapid
hemorrhage, strangulation, the action of hydrocyanic
acid and other narcotic  poisons, the inhalation of me-
phitic gases, and Avhatever pre\rents the arterialization
of the blood.   It is  therefore  manifest, that convul-
sions are owing chiefly to  diminished power of the
brain,  (Avhich cannot direct  the  locomotive organs
with  intelligence, unless supplied Avith  good arterial

of its expenditure in maintaining their activity, and  the necessity
of its renewal by respiration, which is therefore  less essential to
mammalia than to insects and birds, and still less essential to the
imperfect vitality of cold-blooded animals. 
THEORY OF SPASMS AND LOW SPIRITS.      551
blood,) and not to the  " influx of a nervous fluid into
the muscles," as  supposed by Boerhaave,—nor to " a
preternatural energy  of  the cerebral  functions," as
maintained by Bichat,—nor to some peculiar condition
of the ganglionic nerves,  as imagined by others.
   The true  theory of  all spasmodic diseases must be
sought  in a  loss  or deficient supply of animal heat,
diminished circulation and a vitiated condition of the
blood, by which  the brain and nerves are prevented
from guiding and restraining the actions of the volun-
tary muscles,—as in the convulsions of hysteria, the
contortions  of chorea, the more obstinate spasms  of
tetanus, hydrophobia, epilepsy and  cholera,—or the
cramps that often follow immersion in cold water, and
the universal tremours which attend the cold  stage of
fever.  When I come to treat of these maladies  in
 detail, it Avill  be seen that the  immediate  exciting
 cause of all such actions, is deficient vitality of the
 blood, which in  all the  worst  forms of cholera, epi-
 lepsy,  apoplexy  and  even  ague,  presents  the dark
 venous hue in the arteries.   And although still ade-
 quate to maintain the contractile power of the mus-
 cles, it can no longer endow the brain with  sensorial
 energy to control their  movements.   So greatly are
 the vital properties of the blood deranged in the latter
 stages of tetanus and hydrophobia, that when drawn
 from the body it refuses to coagulate, as we are  in-
 formed by  Cullen, Magendie and other  accurate ob-
 servers  The object of the  physician should therefore
 be, to restore its healthy properties by pure  air, arti-
 ficial inflation of the lungs, the warm bath, when the
 circulation  is languid, genial tonics and suitable nou- 
552       THEORY OF SPASMS  AND LOAV SPIRITS.

rishment.  A still more  Important  requisite is, to pre-
vent  that fatal condition of the blood which constitutes
the leading symptom of all malignant diseases; for Avhen
it has been once thoroughly disorganized, the springs
of life are vitiated at the fountain head.
   As the nervous system is more readily deranged by
morbific agents, than any of the other organs, so are
its functions  most easily deranged  in men whose ner-
vous  organization is highly developed, by AvhateAer
diminishes the quantity  of respiration,  or impairs the
vitality of the blood,—whether it be impure air, defi-
cient or improper nourishment, too little or too much
exertion,  intemperance,  the depressing emotions, &c.
Hence it is, that in all ages, men of genius  haATe been
subject to fits of great  mental depression, or  hypo-
chondria,—a  disease that belongs  especially to  the
poetic temperament, and is perhaps common to  all
individuals whose vital  energy is not equal to their
boundless sympathy with nature, and burning inten-
sity of desire to  render their felloAv-beings  wiser and
happier.  Such were Dante, Petrarch, Tasso, Luther,
Melancthon,  Kepler, Shakspeare, Pascal, Milton, NeAA*-
ton, Johnson, CoAvper, Burns, Rousseau and Byron, with
many other " kings of thought and song,"—Avho in the
midst of ad\7ersity, affliction and persecution, became
immortal lights in  the firmament of mind,  that shall
shine brighter and brighter, until knowledge shall lie-
come the uniA'ersal  inheritance of mankind, and ban-
ish innumerable  evils that noAV exist in the Avorld,—
the greater portion of which are OAving to  ignorance in
regard to the  physical and moral laAvs of the universe. 
PLURALITY OF THE NERVOUS FUNCTIONS.     553
But, alas! how many brave  spirits have perished  in
the conflict Avith prejudice and blind custom!
  The most important  discovery ever  made  in the
physiology of mind, Avas the plurality of the cerebral
functions by Dr. Gall and his disciples, who have de-
monstrated  that  the perceptive, reasoning and moral
faculties in  man, depend on the anterior and superior
portions of the  brain;  and the propensities or pas-
sions, as they have been called by metaphysicians, on
the lateral,  inferior and  posterior divisions of the sen-
sorium.   Whether the numerous subdivisions of these
more general ones have been accurately ascertained,
must be  determined by a  more  extended induction
from facts.   When physiologists shall have traced the
connection  betAveen the nervous organization of  all
animals in Avhich it exists, with the various degrees of
their intelligence, passion and instinct, the mysteries
 of the nervous  system will be resolved, and the phy-
 siology of mind be transferred from the  hyperphysical
 to its appropriate rank among the exact sciences.
   In regard to the double function of the nerves, it
 was long ago taught by Herophilus and Erasistratus,
 that some are designed  for sensation alone, and others
 for the purpose of regulating the voluntary move-
 ments of the body.  This  theory has been submitted
 to the test of experiment by the late Sir Charles Bell,
 Ma-endie, Mayow,  Miiller  and  other  physiologists,
 who, although  they differ on  some  points, maintain
 that the nerves arising  from the  posterior portions of
 the spinal  marrow, including the optic and olfactory
 nerves, branches of the  fifth, seventh, eighth and ninth 
554     PLURALITY OF THE  NERVOUS FUNCTIONS.

pairs, are destined for sensation;  Avhile those arising
from the anterior portions of the  spinal marrow, like
the third, fourth, sixth,  and branches of the  fifth,
seventh, eighth and  ninth, are regarded as voluntary
or motory, and wholly destitute of sensibility.
   But as  yet, the discrepancy between the results of
different experimenters, and even of the same  indi-
viduals, leave it more than doubtful Avhether  there be
any such  thing as insensible nerves.   For Magendie
has arrived at the conclusion from  more recent ex-
periments, that  "the roots of the sensitive and motor
spinal nerves are equally sensible when they are both en-
tire.   But if the sensitive nerves be cut, the motor
immediately lose their sensibility.  And if the motor
nerves be cut  across at the middle of their roots, the
end which remains attached to the spinal cord is per-
fectly insensible, but the other end (next the ganglion)
preserves  an extreme sensibility."  (Medico-CMrurgical
Review, No. 62, p. 577.)  Some physiologists maintain
that the anterior spinal root is slightly sensitive, owing
to an anastomotic filament Avhich  it derives from the
posterior root.  Nor is it easy to comprehend  how im-
pressions conveyed to the  brain through the external
senses could be transmitted  to the voluntary muscles
so as to direct their movements, if wholly destitute of
sensibility.  And although it is highly probable, that
one set of nerves may perform the office of conveying
information to the sensorium, and another set that of
transmitting it to the locomotive organs, it is manifest
that without sensation there could be no  conscious-
ness, memory  and volition, all of which  must there-
fore be modifications of one and the same power, dif- 
PLURALITY OF THE NERVOUS FUNCTIONS.     555
fering, hoAvever, according to the various parts of the
nervous system in which it is exerted.
  For example, there is a striking difference between
the sensations of feeling, hearing, seeing, smelling and
tasting.   Yet they are all excito-motory, and may be
resolved into the tactual agency of material particles.
The auditory nerves are excited  by the tactual influ-
ence of the atmosphere in a state of vibration, exerted
on  the tympanum, by which  an endless diversity of
words of definite  meaning are conveyed to the senso-
rium commune, and the voluntary organs directed hoAV
and when to move.   Seeing is  produced by the tactual
agency of light on the optic nerve, and the* visual im-
pressions are transmitted to  the  locomotive  organs.
And so of feeling, taste or odour, all of which  are spe-
cifically different sensations, that are modified in a vast
 variety of ways,  by the particles of material bodies
 acting on the nerves of feeling, taste and smell.  But
 how is it possible  that any set of nerves  could  trans-
 mit  these different  sensations,  if not endowed with
 sensibility?   And if such Avere proved to be the case,
 I should still maintain, that unless duly supplied with
 arterial blood, they could be  neither  sensitive nor
 motory.
    In regard to the office of the  spinal marrow,  a new
 theory has been proposed by  Dr.  Marshall Hall, who
 admits with other physiologists, that the brain and ite
 nerves are for the purpose of endowing animals with
 sensation, perception, judgment, memory and volition;
 but  maintains that in the functions of the true spinal
 marrow there is no  sensation,  no consciousness, nothing
 psychical.—-that it presides over respiration, degluti- 
556
CALORIC THE PRIMARY CAUSE
tion, nutrition,  reproduction and the  action  of the
sphincters,—that it is the source of animal life, gives
tone to the  muscular  system,  and  is the seat of all
convulsive diseases;  and yet that it is, in a peculiar
sense, the seat of the appetites and passions.* (Memoirs
on the Nerv. System, p.  70;  Lancet, February, 1835,  p.
686.)  It Avould be useless to attempt a formal refuta-
tion of a theory that  contradicts itself, and Avhich  is
in fact unanswerable, because unintelligible. For if it
be true, that in the functions of the spinal marrow
there is no sensation  nor consciousness, hoAV can it  be
the seat of the appetites and passions ?   Or if respira-
tion and the action of the  sphincters be  not  subject
to the voluntary poAver of  the brain, why is  it that
during apoplexy, coma, typhus and concussion of the
brain, respiration is nearly suspended, and the sphinc-
ters so far relaxed that the discharges are involun-
tary?
   Whenever the temperature of  warm-blooded ani-
mals is reduced 20° or 30° beloAV the natural standard,
by surrounding them  with ice-cold Avater, the  blood
loses its florid hue, the surface becomes purple or livid,
the  action of the heart languid, the secretions  are  ar-
rested, the brain refuses to  perform its office, and the
voluntary muscles are  seized Avith spasms, or become
paralytic, Avithout the loss of  oxygen, electricity  or
any other agent, except caloric; and if kept long  in
this situation, the heart ceases to beat, the crimson

   *  But in the Lancet of November 21, 1840, he informs us, that
 "life results from the pressure of  arterial blood within the vascular
 structure of the different organs; or that life, in a word, is arterial
 blood." 
OF ANIMAL MOTION.
557
tide of life to run, and all the powers of motion are at
an  end.  The  graceful form of the rounded  limbs is
exchanged for sharp or prominent angles, the cheeks
become pale  and shrunken, the lustre of the speaking
eye is  gone,  the brightness of fancy is quenched, and
the " thoughts that wander  through eternity" are lost
in  the  night of death.
   What then would be  the effect of immersing  the
human body in a bath of mercury, at the temperature
of  30° below 0° ?   One  spasmodic  effort would close
the scene,—and  there would not be a drop of living
 blood  in  the  system*   Where  then would be "the
 vital spark of heavenly flame,"—the Archeus of Para-
 celsus, the  animal  -pints of Descartes and others,—
 the pneumatical body of Bacon,—the ether of NeAvton,
  * An answer to the above question has been recently attempted
by Dr. N. S. Davis, in an article on the Philosophy of Medicine,
published in the New York Journal of  Medicine, in  184t.
After taking to himself no small share of credit for "avoiding the
effort so often made  in vain  to find  out the nature of the vital
principle," he observes in  a tone of triumph, that "life would be
extinguished quite  as soon by plunging a man in a bath of mer-
cury at the temperature of 662° above, as at  30° below 0° :  and
if the latter experiment proves that caloric is the life-supporting
agent, the former must prove it equally the life-destroying agent."
Unfortunately for this ingenious logic, it proves too much ;  for if
raised to 662°, steam would cause the boiler to burst, and the mo-
tion of the machine would be arrested, with as much certainty as
if the fire were removed  from the furnace.  It follows therefore,
according to the reasoning of Dr. Davis, that caloric is not the
cause of motion in  the steam engine, Q.E.D.  I marvel that he
did not represent caloric as the principle or cause of death; since
there is an  excess of heat in  nearly all febrile and inflammatory
diseases. 
558
IMPORTANT QUERIES.
—the  anima  of Stahl,—the  nervous fluid of Willis.
Baglivi, Hoffman and Cullen,—the irritability of Glis-
son,—the vis insita and vis  nervosa of  Haller,—the
materia vitce of John  Hunter,—the  vis vitce of Goert-
ner,—the excitability of BroAvn,—the nisus formativus
of Blumenbach,—the sensorial power of Darwin,—the
organic spirit of Pring,—the conservative principle of
Blane,—and the vis medicatrix naturae of so many au-
thors?  Would this  sudden loss of motion, sensation
and intelligence be owing to the abstraction of some
unknown hyperphysical entity, or  of that  spiritual
fire which actuates the universe ?—

          Warms in the sun, refreshes in the breeze,
          Glows in the stars, and blossoms in the trees !

   If then it be true, that the quantity of life through-
out the earth be in proportion to the heating poAver of
the sun, what, I repeat, is the use of animal heat?  Is
it not  the essential character of a vera causa, that its
poAver should be proportional to the effects it produces,
and that  the latter should cease in its absence ?   Is it
philosophical to assume the existence of any more
causes than are sufficient to explain the phenomena?
Or if  an  immaterial and unknoAvn principle of life be
still admitted, will it explain anything in the absence
of caloric?   It is impossible to blink these questions,
or to resist the conclusion  they naturally force upon
the common sense of every unbiased mind, that caloric
is not only the cause of all  excitement, but directly
or indirectly, of excitability,—that it  is not only the
most  potent and universal stimulant  in nature, but
 the cause of  sensitiveness. 
CAUSE OF THE HEART'S  ACTION.        559
  Let us  noAV  proceed to  trace the natural order in
Avhich the different functions depend on each other,
and  the manner  in which all the organs  are united
into  one harmonious system.  As it is already under-
stood that the action of the heart is owing to the same
cause on which all the moving  powers of  the animal
economy  depend, I shall proceed to show that  it is
derived from the lungs by respiration, to which all
the other functions are subordinate, and not from an
inherent property of the muscular fibre, as  maintained
by Haller;  nor from an inherent propulsive force, as
maintained by Tiedemann.
   It Avas long ago  ascertained  by Hunter, that after
the  heart of a recently killed dog had ceased to con-
tract, its  pulsations might be many times  renewed by
artificial  inflation  of  the  lungs, at intervals of  eight
and ten minutes—a fact  which has been since veri-
fied by the  experiments of Brodie  and many others.
Bichat was  also  fully aAvare that respiration is essen-
 tial to  the movements of the heart; but so confused
 were his notions, that he observes, in his Researches on
 Life and Death:  "the heart  ceases to beat when the
 chemical function  of the lungs is arrested, because^
 black blood  is not  of  a nature to keep up  its  action."
 Again, it is said by  Miiller, that "the nature of the
 cause of the heart's  action cannot be  determined  in
 the present  state  of our knowledge." (Elements,  p.
 188.)
   It is generally admitted by physiologists, that blood
 is the proximate exciting cause of the heart's action.
 But that the caloric evolved  in the lungs  enables it to
 produce  this effect, is evident from the fact, that when 
560             MUSCULAR CONTRACTILITY.
removed  from the body, and even deprived of blood,
its contractions may be many times reneAved and sus-
pended, by successive elevations and reductions of tem-
perature, Avithout  the  influence of oxygen, electricity
or any other known agent.  As  an example of this,
it was observed by Bacon, that the heart of a criminal
Avho had been executed for high treason, Avhen throAvn
into the fire, contracted with such force as to leap up
seven or eight times, to the height of about eighteen
inches  at first.   (Hist, of Life and Death.)  It was
also  ascertained  by John Hunter, that when  three
pieces of muscle were taken from the neck of a  re-
cently killed  sheep, and  placed  in Avater at different
temperatures, they contracted sooner and more firmly,
in  proportion to the quantity of heat  applied.*  Nor

  * With  a view of ascertaining the correctness of his results, I
took three pieces of muscle from the neck of a sheep just bled to
death, each of them an  inch and a half in length, and put them
into separate vessels of  water,  at temperatures of  80°, 110°  and
120°, when the one in the first vessel contracted one-third of an
inch in three minutes ; the second, one-half an inch, and the third
three-quarters, in one minute and a half.  The experiment  was
then varied by placing another piece of the same dimensions in a
freezing mixture at 17°, when it scarcely contracted at  all, and
was quite frozen in seven minutes.  But when transferred to water
 at 120°, it slowly shortened from one and a half to half an  inch.
 In accordance with these facts, it was found by Mr. Clift, that by
 the application of hot water, the heart of a carp was made to  con-
 tract eleven hours after decapitation ;  and that the muscles  of
 another carp were thrown into a state of violent contractions by
 the same means, for hours after the brain and spinal marrow had
 been destroyed.  Similar results were obtained by Mr. John Mar-
 shall, at my request, in 1840.   For he found that, forty-five minutes
 after the  vessels of the neck of a tortoise had been divided, the 
CAUSE OF CONTRACTILITY.
561
was he ignorant that the blood itself Avhen removed
from  the body, and  therefore from all nervous influ-
ence,  undergoes  contraction,  as  in  the  process  of
coagulation; and that this contraction is hastened by
an elevation of temperature.   Yet it seems never to
have  occurred to this great  man, that caloric is the
active principle in the blood; nor that if the temper-
ature of the whole earth were reduced to 32° for any
considerable time, there could not be a vestige of life
on its surface.
   Corresponding with the  large  amount of  caloric
derived  from  the atmosphere by the respiration of
birds, the pulsations  of the  heart are stronger  and
more frequent than in mammalia, cceteris paribus,—
varying from  one hundred and ten, to  one hundred
and fifty, and even two  hundred per minute in the
smaller  and more  active  species.  So rapid  is  their
circulation,  that when the vessels of the neck  are
 divided, nearly all their blood escapes in  about half a
 minute;  but  requires from  one and a  half to two
 minutes, in the dog, sheep, deer, hog and other mam-
 malia : whereas in  man, whose mean temperature is
 several degrees  loAver, the  pulsations of the heart are
 less vigorous and frequent.  For it has been found to

 pulsations of its heart were augmented from nineteen to thirty-six
 per minute, on raising its temperature from that of his room to
 90°;  that on applying water cooled down to 60°, they were re-
 duced to seven beats, but augmented to fifty-two on raising the
 water to 106°, and again  reduced to twenty-two per minute, on
 cooling the water to 90°.  The heart was then removed from the
 body and exposed to the alternate influence of warm and cold
 water, with similar results, which were also observed on the heart
 of a salamander.
                           36 
562
INFLUENCE OF  TEMPERATURE
discharge about tAvo ounces  of blood from the ven-
tricles at each beat, more or  less,  according to the
energy of the constitution, size of the organs, &c.;  so
that if it contract seventy  times per minute, it fol-
lows, that from twenty to thirty  pounds of blood, or
all which the body contains, must circulate through-
out the lungs and general system in from two to three
minutes.
   But so  languid is the circulation in reptiles and
fishes, that when decapitated or deprived of the heart,
their  cold,  pale,  watery and  imperfectly  organized
blood, oozes out by drops; and is often many hours m
escaping from the system in  sufficient quantity to de-
stroy  life,  especially during cold Aveather.*   Again,
whenever the temperature of the  human body is raised
above the  natural standard by immersion in the hot
bath,  the pulsations of the heart are augmented from
 seventy or  eighty to one hundred  and forty or more
 per minute, which is  also  the  case during the hot
 stage of inflammatory  fever.   On the other hand,

   * Caldesi  found that  the heart of a  tortoise contracted from
 thirteen to twenty times per minute ; while Wilford observed that
 in the boa, the pulsations  varied  from  fifteen to twenty-five per
 minute;  and Fontana found them from ten to fifty in the frog.
 But their number and force depend on the temperature of the sur-
 rounding medium.  For at 47°, Spallanzani observed the heart of
 a  serpent to perform ten  or  twelve beats; but twenty-eight or
 thirty beats  when the air was at 65° and 10° ; while others have
 found that on the approach of winter, they are sometimes reduced
 so low as one beat in two  minutes.  And Dr. Whytt states, that
 on raising the temperature of a frog to that of the human body,
 its pulsations augmented  from  twenty-five to eighty-seven  per
 minute. 
ON THE CIRCULATION.
563
when reduced below the natural standard, as during
the cold stage of fever, or by immersion in the cold
bath, the force and frequency of the heart's action are
greatly diminished.   For example, it was observed by
Dr. Currie, that on plunging a patient in water at 36°,
his temperature soon fell to 87°, when the pulse be-
came nearly extinct.   So greatly is the pulmonary
circulation paralyzed in such cases, that  very little
carbon  and hydrogen are given off  in  the air-cells of
the  lungs; the supply of animal heat  by respiration
is nearly suspended;  and if the circulation be not
speedily restored by the  warm bath, the  patient re-
mains chilly for two  or  three  days, even  before an
ordinary fire.
   The  same thing  occurs  during  asthma, and that
congested state of the lungs Avhich exists in the early
stages of tubercular consumption.   It  has also been
observed, that during the cold stage of cholera, and
some of the more malignant forms of algid fever, the
temperature is often reduced from 10° to 20° below
the normal standard, when the blood,  even in the ar-
 teries,  assumes  a dark venous hue, and the general
 circulation  is so far diminished, as to resemble the
 languor of cold-blooded animals, with a frightful pros-
 tration of all the vital functions.   In all cases of lan-
 guid circulation, from whatever cause produced, we
 should apply that remedy on which its healthy vigour
 depends.  By means of the warm bath, we can arouse
 the circulation of the whole system;  and when the
 stagnant blood is dark coloured, we can change it to a
 bright florid  hue, accelerate  its passage through the
 lun&-s  and thus augment the function of respiration; 
564   CIRCULATION OF THE  CAPILLARIES AND  VEINS.

as will  further appear when  I come  to  treat of  its
therapeutical agency.
   It  now remains to  inquire what impels the blood
through the  arterial capillaries, and causes its  return
through  the A^eins  to the  right side  of the  heart.
Magendie  and many  other  physiologists maintain,
that  both are owing to  the  heart's action  alone,
because they  are diminished  whenever  the  arteries
which  supply  them Avith blood are secured by  liga-
tures.   But  Avhen the arteries are tied, not only is the
supply cut off, but the blood  no longer  receives the
vitalizing influence of  respiration.   That the office of
the heart is to  convey blood  from the lungs to the
arterial capillaries, cannot be doubted; but that it is
not any further  essential to the capillary circulation,
Avould appear from the following facts:—1. That the
circulation  of sap in plants,* and of blood through

   * I have been told that caloric cannot be the only cause  of cir-
culation in  plants, because the sap rises more rapidly in spring than
 summer; which is  true enough.  But this is owing first,  to the
 empty state of their vessels and cells, induced by the long absence
 of sap; and secondly, to its rapid expenditure in the formation of
 leaves and  flowers, on first beginning to rise. For the same reason,
 when the lacteal  absorbents have been completely emptied by fast-
 ing, they take  up chyle more rapidly that when in a state of reple-
 tion- while it  is certain that when dry, the earth absorbs water far
 more rapidly  by capillary  attraction, than when saturated by re-
 peated heavy rains.   The above objection is therefore without any
 solid foundation.   Nor has it ever been proved that the capillary
 circulation of  animals is owing to contraction  of their minute ves-
 sels.  And it has been observed by Wedemeyer, that when  they
 were made to  contract by the injection of alcohol or vinegar into
 them, the  flow of blood through them was retarded.  The  only 
      CIRCULATION OF THE  CAPILLARIES AND VEINS.  565

many of the loAver animals which have no heart, is
active during summer, checked by cold nights, and
wholly arrested during winter:—2.  That the circula-
tion of chyle  through the  lacteals,  and of  lymph
through the absorbents,  is obviously  independent of
the heart's action;  and like that of the blood, is in
proportion to the  healthy temperature of  animals;
being more rapid in birds than in mammalia; languid
in cold-blooded animals;  and  suspended in all by in-
tense cold, or by arresting the  supply of caloric by
respiration:—3. That after decapitation and removal
of the heart from rabbits, or placing a ligature around
the aorta, the blood has  been seen with a good micro-
scope, to move with considerable velocity through the
capillaries of the mesentery  for thirty-five minutes,
and in one case for an hour and a quarter, as  proved
by the experiments of Dr. Philip:—4.  That in many
cases after death, and  apparent cessation of the heart's
action, the large arteries  have been  found  empty;  all
their blood having been  conveyed to the veins by ca-
pillary  attraction: and, 5.  That after the  amputation
of a limb, and the stoppage of its capillary circulation,
the motion of its blood  may be restored, and carried on
with  considerable activity for fifteen  minutes, by the
application of heat, as proved by the experiments of
M. Guillot.  (Journal  de Physiologie, tome  xi. p. 170.)
   It has been urged by De Saussure, Decandolle, Tiede-
mann and others, that the circulation in plants and

view then which seems capable of explaining the phenomenon, is
that of an attraction  between  fluids and solids, whether we call it
capillarity,  endosmose, exosmose,  vital affinity or by any other
name. 
 566      CIRCULATION IN  PLANTS AND ANIMALS.

 animals must be owing to a different cause from that
 of ordinary capillary attraction,  because Avhen their
 vessels are divided  during the living state, sap and
 blood continue to flow from them; Avdiereas the fluids
 draAvn up by small tubes of glass  and other dead mat-
 ter are not expelled  from their upper orifices.   But it
 should be observed,  that the force of capillary attrac-
 tion, cceteris paribus, is always inversely as the dia-
 meter of the tubes, which in most of our experiments,
 varies from the one-twentieth to the  one-hundredth of
 an inch; whereas the intestines  and capillary tubes
 in the tissues  of plants and animals ha\^e diameters
 from ■j-sV-ff to sosu of  an inch,  according to recent  ob-
 servations with the microscope.  Hence the great force
 with which the sap  issues from the  stump of  a cut
 grape-vine, as  shown by  the  experiments of Mirbel
 and Hales, who found it equal to the pressure of 34
 and 38  inches  of mercury.*   And such is the vis a
 tergo generated by the capillary circulation of chyle
 and lymph through the absorbents, that when the tho-
 racic duct of a dog is secured with a ligature below
 the subclavian vein,  it has been known to burst from
 the  pressure.   This  has been proved by the experi-
 ments of Home,  Autenrieth,  Tiedemann and  Carus,
 cited by Miiller.  (Elements, vol.  i. p. 284.)    In  all

  * It has been  long known, that  when a  plant is put  in  the
 ground, its roots will extend only in the direction in which they can
 obtain nourishment; and  that when placed in a dark room, with a
hole in the wall to admit light, it gradually extends or grows in
that direction.  Nor is the latter fact more surprising, than that
solar influence should be the cause of  growth throughout the vege-
table creation. 
         CIRCULATION IN PLANTS AND ANIMALS.      567

such cases, the vis a ter go is generated by virtue of an
attraction between fluids and their containing vessels;
the former being plus, and the latter minus.  The or-
ganic particles of blood are forced through the pores
of the  systemic capillaries, and  combined with the
several  tissues, by virtue of the same attraction.  And
it has been found  that the worn-out  particles of the
solids are  not taken  up by the mouths only of the
lymphatics, but are  absorbed by  the pores of  their
coats; and finally, that neither in plants nor animals
is any contraction of their capillaries essential to their
circulation. 
CHAPTER  V.
THEORY  OF  DIGESTION,  SANGUIFICATION,  COAGULATION,
   SECRETION, NUTRITION, MUSCULAR MOTION,  SENSATION,
   ETC.

  "The  idea of vital forces may gradually become  so clear and
definite as to be available in science, and future generations may
include in their physiology propositions  elevated as far above the
circulation of the blood, as the doctrine of universal gravitation
goes beyond the explanation of planetary motion by epicycles."—
Whewell.

   In accordance with the  prevalent doctrine of  the
schools, Dr. Prout maintains, that  "the true  and le-
gitimate  object of inquiry for the physiologist ought
to be, not what the vital principle is, but what  it does,
just as  the laws and effects of gravitation are legiti-
mate objects of inquiry, though Ave know nothing, and
probably never will  know  anything of the principle of
gravitation." (Application of Chemistry to Physiology.)
Such, however, ay as not the opinion of Sir Isaac New-
ton, Avho made repeated  efforts to ascertain the cause
of gravitation, cohesion, chemical affinity and animal
motion, all of which he referred to one and the same
cause.   Yet it is maintained by Berzelius, Tiedemann,
Miiller, Liebig and more than an hundred other physi-
ologists of the  nineteenth century, that  "the vital
principle is a poAver distinct from all the other powers
      (568) 
VARIOUS THEORIES  OF DIGESTION.        569
in nature;" Avhile Dr. C. Holland adopts the hypothesis
of Bichat, Richerand,  Magendie,  Prichard, Fletcher,
cum multis aliis, that "life is not a simple principle,
but the result of compound principles and actions, per-
vading and common to  every part of nature."   (Laws
of Organic and Animal Life, p.  355.)   Alas!  the con-
tradictions  and mysteries of science *are scarcely less
perplexing and prejudicial to the interests of mankind
than those of  metaphysics and scholastic divinity.

       "For 'tis not only individual minds
        That habit tinctures, or that interest blinds;
        Whole nations, fool'd by falsehood, fear or pride,
        Their ostrich heads in self-illusion hide."
                                         Thomas Moore.

   The earliest theory of digestion that has come down
 to us is that of Hippocrates, who regarded it as a spe-
 cies of concoction analogous to the  ripening of fruits
 by solar  heat.*   The same view was  adopted by Ga-

   * Plato also, in the Timxus, represents  heat as the cause  of
 digestion, of the diffusion of blood throughout the body, of nutri-
 tion and growth, which he attributed to the union of similar parts,
 that have an affinity for one another.  (Chap. 5*7.)  Aristotle like-
 wise  declares expressly, in  his Treatise on the Soul, that heat is
 the cause of concoction. (Lib. ii. c. 4.)  The doctrine of the early
 Greek physicians, that food is cooked in the stomach, was rejected
 bV Asclipeades,  who maintained that  the process is merely one of
 solution into very minute parts.  (Le Clerc, Hist, de la Medecine,
 p 408 )  But solution is only an effect of heat,  or a stewing  pro-
 cess    According to Erasistratus, digestion is a triturating  or
 grinding process, performed by a contraction of  the stomach on its
 contents   It was in reference to these  ancient  theories, that  Dr.
 James Gregory said to his class: "Gentlemen, some tell us the
 stomach is a stew-pan; others, that it is a mill; and others again, 
570
VARIOUS THEORIES OF DIGESTION.
len, and taught by nearly all his successors, down to
the time of Paracelsus and Van Helmont, who referred
it to the agency of an acid liquor, under the control
of the  Archeus, which was supposed to be  endowed
Avith intelligence, to direct the stomach when to allow
its contents to pass into the duodenum, to  give  the
alarm and cause it to expel Avhatever is noxious, and
to preside over all those actions of the living body that
constitute  the vis  conservatrix  naturer.   But I have
already shown that  the  Archeus was  only another
name for the Ooatc, of  Hippocrates; while it is equally
evident, that  the fermentation and maceration of the
chemical physicians were  merely different names for
coction,  which means  an action  produced by caloric,
from coquo, to heat, to boil, to cook, to digest, to ripen,
&c.   With the exception of the mechanical physicians,
who maintained that digestion is the result of tritura-
tion by the coats of the stomach, the chemical theory
prevailed  until the time of  Boerhaave, who,  like a
genuine eclectic, referred  it to the  united agency of
gastric liquor, nervous  influence and animal heat.
  Since the time  of  Boerhaave,  physiologists  have
generally maintained  that food  is converted  into
chyme by the solvent power of gastric  juice, but un-
der the immediate influence of "the unknown vital
principle," which some have identified  with the  un-
knoAvn  nervous fluid, and others with the equally
unknown electric  fluid.*  That nervous  influence is

that it is a fermenting vat.  But I say, gentlemen, ii is a sto-
mach."  Whether this facetious account of the matter was intended
to silence inquiry, is left to the decision of competent judges.
  *  Those who have  adopted the electrical theory of life, have
vainly attempted the explanation of one mystery by resorting to 
VARIOUS THEORIES OF DIGESTION.         571
not essential  to the  process, (further  than  as it go-
verns the voluntary function of respiration,)  has been
sufficiently  proved by  the  experiments  of  Brodie,
Magendie,  C. Holland,  Mayer, Brachet,  Leuret and
Lassaigne, who have shown that in the horse, dog and
rabbit, the nerves going to  the stomach may be di-
vided Avithout arresting  the secretion of gastric juice,
or seriously retarding the process of digestion.
   Nor have Ave  ever had the slightest proof that elec-
tricity is essential to the process;  for the experiments
of Dr. Philip have been repeatedly proved to be falla-
cious, and therefore require no comment.*   But that

another.  And  so highly developed is the organ of wonder, com-
pared with the reasoning faculties, that  in all  ages the mass of
mankind seem to have entertained a profound reverence for what
they did not understand, as if simplicity were not the highest attri-
bute of excellence, beauty and truth.  It is also gratifying to the
selfish pride of inferior minds, to perceive that there are mysteries
which reduce the loftiest intellects to an equality with themselves.
With  such persons, the simplicity of a new discovery derogates
from its importance, being apparently so clear  and obvious, that
they only wonder how it ever could have escaped their own sagacity.
It has been supposed that during respiration, the blood acquires
electricity, which is distributed by the pneumogastric and sympa-
thetic  nerves to the great nervous centres, which, becoming thus
charged, excite the action of  any organ, by giving a spark  to the
nerve that supplies it.  But in the new experiments of Person and
Miiller, no signs of electricity could be detected by the finest gal-
vanometer in a nerve, at the moment when some charge,  consequent
on its  irritation, and transmitted along it, was exciting a muscle to
contract. (Alison's Outlines of Physiol, and Pathol, p. 117.) The
fact is, that all nerves are bad conductors of electricity,  as Bischoff
has shown.
  * The impression that electricity is in some way connected with
digestion and all other vital phenomena, has been inferred from the
fact, that the gymnotus, torpedo and  silurus, have the power of 
572
THEORY  OF DIGESTION.
 caloric is  the  principal  agent  on Avhich the solvent
 power  of gastric juice depends, would appear from  a
 variety of considerations.   1. We have  seen  that di-
 gestion is far more  rapid  in birds than in mammalia,
 and more rapid in the latter than in cold-blooded ani-
 mals.   2.  It has  been proved by the experiments of

 communicating an electrical shock; and that after having imparted
 several shocks, the power of digestion is greatly diminished.  But
 the  circumstance alone of this power being confined to  a very
 small number of animals, and  these of a low grade in the scale of
 organization, proves that it is not essential to any of the vital func-
 tions.  Like the  nauseous  secretion of the pole-cat, and  that of
 some insects, it was doubtless intended by nature merely as a means
 of defence.   Besides, electrical fishes  have  always been found in
 warm climates, and cannot exert their peculiar faculty when ex-
 posed to a low temperature.  It was observed by John Hunter,
 that the  electric columns of the torpedo were largely supplied with
 blood-vessels, and  he found that they were not essential to any of
 the processes of life except the  preservation of the electrical  power.
 Dr. Davy observed that the electric columns are connected with the
 organs of respiration.    It was also the opinion of  Humboldt, that
 the electrical power of the  animal is  proportional to the activity
 of respiration and nutrition.  It may therefore be inferred, without
 departing from the rules of philosophic induction, that such ani-
 mals have the power of converting at will a portion of the  caloric
 obtained by respiration into the temporary form of electricity.  Nor
 is this more strange than that the caloric of  atmospheric vapour
 should be discharged in  the concentrated form of lightning.   Some
 have supposed that the lungs  are positive, and the stomach nega-
 tive;  while others have prescribed  copper and zinc filings, with
 dilute nitric acid, with a view of supplying the patient with galvanic
 electricity.  But, as Prof. Schcenbein observes: " So long as we are
 without an  exact idea of what  electricity is, the different modes of
its development will, of  course, be incomprehensible, and we shall
scarcely be  able to  say  anything upon the  cause  of animal elec-
tricity, however carefully the structure of the fish may be  studied."
 (Noad's Lectures, p. 251.) 
THEORY OF DIGESTION.
573
Dr. Beaumont, that Avhen gastric juice is taken from
the stomach, and kept in vials at the temperature of
the body, it  converts aliment into chyme; but that
Avhen kept below the temperature of 40°, it produced
no further change than so much water.   3. That the
digestive  power of man is in proportion to the quan-
tity of his respiration, which is augmented by mode-
rate exercise and  agreeable  emotions, but diminished
by repose and the depressing passions.  4. That when
the circulation is weak, digestion is wholly arrested by
taking large quantities  of  cold  drinks, which often
produce  flatulence, colic  and nausea.  The danger of
drinking cold Avater when exhausted by over-exertion,
is well known in warm climates, where it often de-
stroys life suddenly.  Dr. Beaumont  states, that on
giving to St. Marthi a gill of water at 55° when the
stomach was empty, its temperature was reduced from
99° to 70°, at which it  stood for a few minutes, and
did not regain its normal standard until thirty minutes
had elapsed.  Cholera morbus, gastritis, enteritis, dys-
entery and  diarrhoea, are often  produced by  cold
 drinks, ice-creams, &c, during hot weather.
   The next step  in  the process of assimilation, by
 which aliment is prepared to nourish the solids, takes
 place in the duodenum,  where the albumen, oily mat-
 ter, and white  globlues  of chyme  are converted into
 chyle, by uniting with  pancreatic juice and a  very
 large proportion of bile; while the resinous or bitter
 portion  of the  latter  combines with the excrementi-
 tious part  of the aliment, to be  conveyed into the
 intestines,  being never found  in  the  luteals.   But
 Avhenever the chemical function of the lungs is greatly
 diminished, and the temperature of the body reduced 
574
CHYLIFICATION.
from 5° to 10°,  as  during the cold  stage  of  many
fevers;  or even 20°, during the later  stages of malig-
nant cholera, and in those algid forms of disease termed
cold plague, the  secretion of gastric liquor, bile, pan-
creatic  juice,  urine,  perspiration and other animal
fluids, is almost wholly suspended.
   During the progress of chyle through the duodenum
and lacteals to the thoracic duct, it becomes further
and further organized, or assimilated to the nature of
blood.  For it has been found that, besides albumen,
oily matter and  Avhite globules, it contains more or
less fibrin, that coagulates  slowly.   But it is not until
it passes  through that Avonderful laboratory of life
termed  the lungs, that it assumes the colour and vital
properties of blood, which contains the proximate con-
stituents of all  the  organs ready  formed, including
most of the secreted fluids.  By giving  off variable
proportions of carbon  and hydrogen, that unite with
atmospheric oxygen, caloric is evolved, and a portion
of nitrogen absorbed, by  Avhich chyle is  transformed
into living  blood of a bright  scarlet hue, its temper-
ature elevated  from 1° to 3° in  the  higher animals,
and its  solid particles  augmented  from three to four-
fold, according  to the analyses of Vauquelin, Tiede-
mann, Gmelin,  Reuss and Emmert.
   How  transcendently beautiful is the mechanism by
which grass, corn, fruits and a multitude  of aliments,
all differing in their composition, are thus converted
into the constituents of animals,  endowed  with the
power of renewing tlieir  organization and  of main-
taining  the activity of all their functions !   The  art of
man has  scarcely yet succeeded in ascertaining the
proximate constituents of gastric juice,  bile, pancreatic 
CHYLIFICAT10N.
575
liquor, chyme, chyle and lymph.   How then is it pos-
sible  that he should imitate the exquisitely refined
chemistry of nature by which blood is formed?  We
have not even approached  the perfection  of  that
amazing  process of living combustion, by  which the
temperature of animals is maintained at an uniform
standard,*—much less the admirable provision of na-
ture by which just so much  carbon and hydrogen are
given off in  the  lungs, and just so much  nitrogen
absorbed, as are requisite for the formation of blood.
Nor  is it possible to rival the chemistry of life,  so as
to  produce blood,  bile  and  gastric juice, without a
special mechanism for the purpose, such as that of the
lungs, liver and stomach.
   But that the caloric obtained from the atmosphere
by respiration  is  the organizing principle by which
blood is formed, would appear  from all  the analogies
of nature.  In the first place, if it be true, that solar
caloric is the cause of organization and growth through-
out  the  vegetable world, animal heat must  perform
the same office in the higher grades of existence.  As
the  abundance, diversity and  richness  of vegetation
 depend on the  mean temperature of climates, so will it
be seen from the table, constructed from the  analyses
  * By the discovery of such a method, including the combustion
of all that valuable fuel which now passes off in the form of smoke,
four-fifths of the capital now wasted in the creation of artificial
warmth would be saved.  And could we devise a method of con-
veying caloric through our dwellings, in a mode  resembling that
by which it is diffused through every part of the body from the
lungs,  in combination with arterial blood, the saving would be
still further increased, an equable temperature  maintained,  and
many of the diseases that afflict the human race be prevented. 
576
SANGUIFICATION.
of Prevost and Dumas, Denis, Le Canu, Berzelius and
Marshall, that the ratio of solid organic matter in the
blood  of  different  animals  is  in  proportion to  the
quantity of their respiration and mean healthy tem-
perature, cceter is paribus,—being greater in birds than
in mammalia, greater in the latter than in reptiles,*
and greater in reptiles  than  in  fishes.   In accordance
with this fact, we learn from the accurate researches
of  Dr. John Davy, that the specific gravity of  the
blood  in these four  classes, varies in  the  folloAving
proportions:—
                                Arterial.       Venous.
       Turkey..........................'..........  1061          ----
       Lamb......................................  1047         1050
       Dog........................................  1048         1053
       Frog........................................  1040         ----
       Codfish....................................  1034         ----

   But there is reason to believe from the experiments
of  Denis,  Le  Canu, Marshall  and  others,  that  the

  * Prevost and Dumas  found the blood of a tortoise, which had
been five months in a state of lethargy, to contain 15*06 per cent.
of solid matter, owing, as they rightly supposed, to the loss of a
large proportion of water by exhalation or transudation.   And it
will be seen hereafter, that owing to the same cause, (transudation
of serum or water,) the proportion of red particles is greater in
many cases of malignant  cholera, than during the most vigorous
state of health.  (Examin. du  Sang,  Ann. de Chim. et de Phys.
vol. xxiii.)   But Mr. Marshall was so kind as  to perform some
analyses at my request, which show that the blood of the tortoise,
while in a state of activity, does not afford above eight per cent, of
solid particles, and that of the salamander about 7 "54. It may there-
fore be presumed, that the blood of all young birds hatched with-
out feathers, and of mammalia born with the eyes closed, whose
power  of maintaining their temperature by respiration, is for some
days very imperfect,  is less highly organized than at later periods,
corresponding with the feebleness of all their vital functions. 
SANGUIFICATION.
577
ratio of fibrin and red particles, is higher in the blood
of birds and mammalia, than was represented by those
of Prevost and Dumas.  For on evaporating a mix-
ture of arterial arid venous blood of healthy pigeons
to perfect dryness, by means of the moderate temper-
ature, produced by a water bath, as in the process of
Prevost and Dumas, Mr. Marshall obtained 20*41 per
cent, of solid  particles.  There is  also reason to  be-
lieve, from the analyses  of Denis, that the blood of
the  more active mammalia when  in health and well
nourished, is more highly organized than that of man.
For with  Prevost, Dumas and  Le Canu, he found the
latter to average about 13 per  cent.; while the blood
of the dog, calf, bullock and horse,  afforded the mean
of 16*40 per cent, of fibrin and hgematozin;* as might
be  inferred from the size of their lungs,  mean tem-

  * Denis also found the blood of individuals with broad  chests
and great muscular power, to  contain from fourteen to eighteen
per cent,  of fibrin and red particles;  whereas in those of narrow
chests and feeble constitutions, they  varied from eight to  eleven
per cent.   And as might be supposed from the larger size of the
thorax in man than woman, his blood is richer in organic particles,
in the ratio of 13*24 to 11*59, according to M. Le Canu. (Etudes
Chimiques sur le Sang Humain, par Louis Rene Le Canu.)  Co-
inciding  with these  facts, M.  Quetelet represents the lumbar
strength of the male as greater than that of the female, during
the early periods of life, in the ratio  of three to  two; and after
full growth, nine to  five ; while at fifty years of age, it is one-
third less in both.  And it will be  seen hereafter, that whatever
diminishes the process  of respiration, whether a diseased state of
the lungs, (as in asthma, pneumonia  and  phthisis,) low diet, loss
of blood, the  depressing  passions, or protracted disease of any
description, impairs the process of  sanguification,  with all  the
energies of life.
    b                      37 
578         CONSTITUTION  OF THE  BLOOD IN
perature, and power of digestion, which I have shoAvn
to be greater than in man, cceteris paribus.   In accord-
ance with the above facts, Denis found the proportion
of fibrin in the  mixture of arterial  and venous blood
of the fowl, to  be twelve  parts  in 1000;  Avhile  in
venous  blood of the horse, it varied from five to six,
and in  that of man, from 2*9 to  4*3.   He further
states, that  the ratio of red particles in  the human
species  augments from infancy up to the adult state,
but  diminishes  after  the  age of forty, up  to seventy.
(Recherches Experimentales sur le Sang Humaln, etc. par
Prosper. Denis.)
Table Representing the Relative Proportions of Dry Coagulum, Albumen of
      Serum, and Water, found in the Blood of different Animals.
 Names of Animals.      Coagulum.
Pigeon, (venousblood.)... 15-57
Do. art. and venous........ 20-41
Hen, venous blood......... 15-71
Do. art. and venous........ 1610
Duck, venous............... 15-01
Raven, venous............... 14-66
Simia Calitriche, venous.. 14-61
Man, venous................. 12-92
Do. vena port ee.............. 11-44
Maximum in Man, v...... 1484
Do. in AVoman, venous.... 12-99
Average in Man, venous.. 13-24
Do. in AVoman, venous.... 11-59
Sang. tem. in Man, v...... 15-85
Maximum do. venous...... 18-87
Lymph, temper, venous...  9-27
Do. minimum, venous.....   6-33
Guinea Pig, venous........ 12-80
Dog, venous.................. 12-38
Horse, venous...............   9-20
Calf, art. and venous......   9-12
Sljeep, venous...............   9-35
Albumen		
of Serum.	Water.	Experimenters.
4-69	79-24	Prevost and Dumas.
4-69	79-69	Marshall.
6-30	79-99	Prevost and Dumas.
4-50	77-00	Denis.
8-17	76-52	Prevost and Dumas.
5-64	79-70	a a
7-77	77-60	<< <<
8-69	78-39	u
8-44	80-14	a it
6-76	77-86	Le Canu.
7-84	79-03	"
7-81	78-93	<<
7-96	80-43	<<
4-85	76-92	Denis.
5-23	73-30	<<
5-90	82-00	i<
5-40	86-90	t<
8-72	78-48	Prevost and Dumas
6-55	81-07	« <<
8-97	83-79	a a
8-28	82-60	(« <<
7-72	82-60	!< t<
 
DIFFERENT ORDERS OF
ANIMALS.           579
Albumen		
of Serum.	Water.	Experimenters.
6-76	79-40	Marshall.
5*25	81-44	t<
4-60	78-00	Denis.
6-30	77-50	a
5-00	76-30	n
6-00	78-65	n
6-50	75-50	n Le Canu.
6-90	85-02	Marshall.
6-16	86-80	«
4-64	88-46	Prevost and
7-25	86-37	"
9-45	84-60	ii
6-87	88-62	•'
 Names of Animals.      Coagulum.
Do. art. and venous........ 13-84
Three Kittens a day old.. 12-95
Young Puppies.............. 16-90
Calf three weeks old...... 15-80
Bullock two years old..... 17-40
Horse......................... 15-30
Do............................... 16-80
Sheep, venous............... 16-36
Do. art....................... 17-07
Land Tortoise, a. and v...  8-02
Salamander, do.............  7-54
Frog...........................  6-90
Trout.........................  6-38
Eel.............................  6-00
Loach ........................  4-81

   From the analyses of PreA^ost and Dumas, Berzelius,
Marcet, Denis,  and  his  own, M. Le  Canu  represents
the venous  blood of man as composed of  the following
constituents:—

    Dry crassamentum............................... 130-8453
    Albumen of serum..............................  67-8040
    Salts,* oily, extractive and other matters  10-9800 I
    Water............................................... 790-3707/"

                                       1000-0000,

   He also estimates the  crassamentum as composed of

    Albumen.........................................  125-6373  ")
    Fibrin............................................   2*9480f j-in 1000 parts.
    Colouring matter..............................   2-2700  J

  *  The proportion of salts in the blood, depends on the quantity contained
in the aliment: and it has been found that above one-half of them consists
of chloride of sodium, if we except the  salts of lime, which enter into the
composition of bone.   But the office they perform in the functions of life is
not well understood.   Nor have the proportions of oily, phosphuretted and
extractive matters, found in the blood, been ascertained with precision.
  f  From twenty-two observations, he found the proportion of dry fibrin to
vary from 1-360 to 7-235 in 1000 parts of human venous blood. 
580
CONSTITUTION OF THE BLOOD  IN
   From which it AArould  appear, that the organic  par-
ticles of blood are composed chiefly of albumen, with
a  small proportion of fibrin, both of Avhich  are radi-
cally identical, according to Denis.   As an example of
the  highly complex character of their proximate  con-
stituents, we are informed  by Liebig, on the authority
of Mulder, that the equivalent of  albumen, as it com-
bines with oxide of silver,  is 7447, and that  of  fibrin,
as it combines with hydrochloric  acid, the oxides  of
lead and copper—6361.*  (Organic Chemistry,  vol. i.
p. 339.)
   The  blood of all animals  is  formed  from  the same
primitive elements; but as the different orders obtain
various quantities of caloric  from  the  air  by respira-
tion, its organic particles vary in form and magnitude,
being elliptical in birds, and larger than in mammalia,
yet  larger  in reptiles, fishes and other  cold-blooded
animals than in  either.-}-   The  consequence of which

  * Liebig observes, that the readiness with which the complex
molecules of organic matter decompose, is owing to the large num-
ber of atoms that enter into their composition, and the numerous di-
rections in which their attractions operate, (page 323.) But I have
shown that the tendency of the primitive atoms to unite into com-
plex  molecules, depends on the  quantity of caloric  around  their
particles, as no other elements except oxygen, hydrogen, carbon
and nitrogen,  are capable of entering into such complex combina-
tions. (See page 471.)
  f Hence it is, that when the blood of mammalia is injected into the
veins of  birds, the latter die in a very short time, and vice  versa;
while the blood of reptiles and fishes is  rapidly fatal to  all the
higher animals, in which the extreme capillaries  are so  small, that
they cannot be seen without a good microscope; but they may often
be discerned with the naked eye in cold-blooded animals.  In regard
to the colour of the red particles, nothing has  been clearly ascer- 
DIFFERENT ORDERS OF ANIMALS.          581
is, that  their Avhole organization exhibits correspond-
ing variations.   Nor is this more  strange, than that
the  form  of  crystals, and the  chemical properties of
many bodies  composed of  the same  ponderable ele-
ments in the  same  proportions, should vary according
to the temperatures  at which  they are produced, or
the quantity of caloric around their particles, and the
number of  atoms that compose these  particles.  For
it is self-evident,  that whatever the organizing  princi-
ple  may be,  it must determine the composition and
arrangement  of the  molecules that form  any part of
the  body,—modified, however, in an endless variety of
ways by surrounding circumstances.

tained, except that it is owing to an envelope surrounding white
nucleii, from one-third to one-fourth the size of the blood corpus-
cles, according to Hewson;  and which he supposed to be identical
with the white globules of chyle.  Some have referred their red
colour to the  presence  of carbon,—others to iron or its oxide, be-
cause found united with the red particles, (in  the ratio of about
two drachms  to 30  pounds of blood,) or of 5*6 parts of the pure
metal in  10,000 parts  of blood.  But as both of these substances
are found in chyle, which is white, and as the  colouring matter of
the blood has been obtained entirely free from iron, we must  look
for some  other explanation, connected more immediately  with the
function of calorification. For it is evident that the depth of colour
is in proportion to the mean temperature of animals, being brighter
in birds than  in mammalia, yellowish in reptiles and still paler in
fishes, if we  except the tunny tribe, (and a  few others,) whose
breathing apparatus is very extensive for their class; while in ani-
mals of a still lower grade, it is without any colour.  In fact, Galen
tells us, that  like Plato and Aristotle, Praxagoras of  Cos, (the
master of Herophilus, and one of the first of the medical sect called
Dogmatists,)  maintained that the aliments we consume  undergo
various changes in the  vessels, according to the different degrees of
heat which they contain. (Galen, De Natural. Potent., L. ii.) 
582
THEORY OF INCUBATION.
  That caloric  is the cause  of sanguification, Avould
further appear from the fact, that it  is the  obvious
agent  by Avhich the eggs of birds, reptiles,  insects,
fishes  and all  other animals, are gradually changed
from the state of a semi-fluid  germ into blood  and the
various organs of Avhich they are composed,—Avhether
derived from the sun, by which the lower animals are
hatched,—from ordinary combustion,  as in  artificial
incubation, or supplied  by the natural  temperature of
the parent, as in  the  ordinary process  of hatching
birds.   Dr. Theodore Schwann Avas convinced  by a
series of his OAvn experiments, that when surrounded
by an artificial temperature at the  proper standard, the
development of the germ can proceed to  a certain ex-
tent without oxygen, Avhile surrounded  with hydrogen
or nitrogen, but not if exposed to carbonic acid.   And
some  recent  experiments of  Mr.  Towne, recorded  in
the fourth volume of the Guys Hospital Reports, Avere
by many persons thought to prove, that oxygen is not
essential to the early development of the chick in ovo.
For he found that  after eggs were surrounded Avith
strips of thin and dense paper, dipped in albumen, and
then smeared over Avith varnish,  the process of incu-
bation Avent on  without interruption, till the  tAvelfth
or thirteenth day, Avhen kept at the temperature  of
100°;  and that the allantoid membrane was perfectly
formed.*

  * But in his able Lectures on Generation, (published in the
Lancet, 1840,) Mr. Owen states, that when a solution of  acetate of
lead was introduced through an opening at one extremity of the
shell, which was then carefully luted, covered over with paper
dipped in albumen, and smeared with varnish, as in the experiments 
THEORY OF INCUBATION.
583
   Dr. South-wood  Smith maintains,  that  chyle and
venous blood are converted into the arterial state,  by
parting with carbonic acid and water in the lungs;  in
exchange for which, they receive oxygen and nitrogen.
Miiller also contends, that  "oxygen  combines  imme-

of Mr. Towne,—patches of  black pigment, or sulphide of lead,
were discovered on the internal surface of the shell, after exposing
the egg for some time to the influence of sulphuretted hydrogen.
He therefore contends that this gas must have found  its way
through the different layers of paper  dipped  in albumen,  because
they were changed  yellow; and that air may percolate the coating
of varnish, and afterwards find its way to the internal parts of  the
egg through the layers of paper.   I have  also  observed that  the
blood going to the respiratory membrane is of a dark venous hue,
and returns of a scarlet colour,—proving that, to a certain extent,
it undergoes the same change as while passing through the lungs,
after leaving the shell.  But we are greatly in want of additional
experiments for ascertaining with precision, what amount of car-
bonic acid is thus generated and exhaled through the pores of  the
shell during the various  stages of incubation,—in short,  what is
gained  and what is  lost. Wagner states, that during the first week,
the egg loses five  per cent, of its  weight, thirteen  per cent,  the
second Aveek, and sixteen per cent, during the third week.  (Ele-
ments of Physiology, p. 129, trans, by Willis.)  This loss of thirty-
four per cent, is doubtless  owing  to the exhalation  of water,  and
to the giving off of carbon and hydrogen, that unite with the oxy-
gen absorbed, by which the albumen of the egg is converted into
blood,  in the  same  way that chyle is changed into blood by giving
off water, carbon and hydrogen, while passing through the lungs,
viz., by the creative process of living combustion.  Since  the first
edition of this work was printed, Baudrimont and  Martin  Saint
Ange have announced as the result of their experiments, that dur-
ing incubation, the small red globules do not appear in  the em-
bryo, nor is the latter  developed unless there be an absorption of
oxygen through the  shell,  and an exhalation  of carbonic acid.
(Matteucci, Phenom. of Living Beings, p.  139.) 
584
THEORY OF FCETAL DEVELOPMENT.
diately Avith the blood, and  enables  it to excite  the
various tissues."  But if oxygen were the animating
principle, it ought to excite the heart and other mus-
cles to contract when removed  from the body, which
is not the fact; for when reduced to  the temperature
of 32°, it produces no more effect upon them than so
much carbonic acid.   And  although electricity excites
contractions for a short time, they are spasmodic, and
its influence is exceedingly partial, compared with  the
same agent in the form of  caloric.
  Moreover, it has been  fully established by recent
researches into  the phenomena of  generation  and
growth of the embryon, that  in no  case is arterial
blood  transmitted  from  the  mother to  the foetus
through  the vessels  of  the  placenta,  which serves
chiefly as a reservoir of nourishment,  supplied by  the
mother, absorbed by the vessels of the foetus, and con-
verted into blood that is wholly different from that of
the mother,—in short, that the embryon is nourished
by the transudation of arterial  blood  from the vessels
of the mother.  According to  Miiller, the colour of
foetal  blood is the same in both arteries  and veins.
This much may be asserted with confidence, that it is
not by means of oxygen, or any other ponderable gas,
that the  proximate constituents of the egg  are con-
verted into the blood and different organs of the chick;
and that  as the germ of viviparous  animals is formed
from an  albuminous secretion,  before  any connection
is established with the circulation  of the mother  by
means of the  placenta, it can receive  no oxygen from
the maternal blood;   consequently, that  it  must  be
deAreloped  by means of the same life-giving element 
ARTERIAL AND VENOUS BLOOD.         585
(Zwi}<popoi>) that  actuates  the universe, and fills it
with beautiful creations;  that  causes the  germina-
tion of plants, the circulation of sap, and  its conver-
sion into the various constituents of their substance
while passing through  the lea\res, (where oxygen is
not absorbed but given off;) and by which the Egyp-
tians annually produce one hundred millions of poultry
from one hundred and fifty millions of eggs,  placed in
a few large ovens.  Should it still be urged that oxy-
gen is indispensable  to animal  life, I answer, so is it
to the movements of  the steam  engine, because  by its
chemical union with carbon and hydrogen in the fur-
nace, as in the lungs, the moving principle is evolved;
and, because like carbon, hydrogen and nitrogen, oxy-
gen is an essential constituent of animal bodies.
   During the passage of dark venous blood through
the lungs in combination with  chyle  and lymph, re-
ceived from  the  thoracic duct,  its temperature is ele-
vated, its colour  changed  to a bright  florid  hue,  and
its vital  properties exalted.  It has also been proved
by the experiments of Prevost and Dumas, Denis, Le
Canu, Mayer, Autenrieth and Letellier, that arterial
contains a larger proportion of organic particles than
venous blood; as might naturally have been inferred
from the obvious fact, that during every circulation of
the former through the general system, a portion of
them is transferred to the solids, which are nourished
at the continual expense of arterial blood.   The rela-
tive proportions of fibrin contained in the arterial  and
venous blood of different animals, are  stated by Miil-
ler, on the authority of Berthold, as follows:— 
586
THEORIES OF ANIMAL HEAT.
                               Arterial.     Venous,
      Dog............................................. 666        500
      Sheep.......................................... 566        465
      Cat.............................................. 521        474
      Goat........................................... 429        366
  Dr. John Davy observes, that "the use of the red
particles,  according  to  the views of Hunter,  seems
to be connected less Avith nutrition than Avith action,
and more Avith  the  production  of animal heat, than
perhaps Avith any other function."  That they do ac-
tually afford a large proportion of combustible matter
before they are  in a condition to nourish the  tissues,
is evident from the fact, that  haematin contains  a
much larger ratio of carbon than albumen or fibrin;
Avhich excess of carbon unites with atmospheric oxy-
gen in the lungs, Avhere animal  heat is evolved  and
imparted  to the blood, carbonic  acid, urea  and other
inorganic products formed, before they can pass out of
the body in the form of excretions.
  Dr. Edwards  also maintains, that the temperature
of animals  depends greatly on  the prorjortion of red
particles in their blood, because the' lower orders, in
Avhich  it consists chiefly of water, are cold-blooded.
But this is only one among a thousand examples that
might be adduced, of the manner in Avhich men have
inverted the laAvs of nature, or confounded cause and
effect.   For as  the  mechanical  physicians,  including
BoerhaaAre  and Haller, regarded animal heat as an
effect of the heart's action, motion of the blood  and
its friction  against the  solids; so did Sir H. Davy re-
gard it as "a  result of all the  changes and organic
actions  that take place in animal bodies."  And so
effectually has  the chemical theory of respiration been 
DEFINITIONS OF LIFE.
587
shaken by his denial that caloric is a material agent,
that Mason Good " omits the consideration of it," while
he defines " respiration as the act of receiving oxygen,
and throwing out carbonic acid."
  In a recent course of lectures, published in the Lan-
cet of 1840, by Mr. Ancell, the author maintains that
animal heat  results from "the molecular vital actions
continually going on between the red  particles  and
the liquor sanguinis."  We are also told by Dr. Dick-
son, in  a late work termed Fallacies of the  Faculty,
that " animal heat results from the constant mutation
and motion of all the organs"—which is only another
mode of expressing the opinion of Sir H. Davy, and
of Bichat, Avho represents it as "a product of all the
vital  functions"—with  this  difference, that Dr. Dick-
son refers  the mutation and motion of all the organs
to electricity;  but AAithout  explaining  the origin or
modus operandi of this  mysterious agent.   Alas!  it is
much easier to expose, than to  reform, the errors of
the faculty.   Nor  is it any  definition of life to say
with Sir H. Davy, that "it consists in a series of cor-
puscular changes"—and Avith Dr. Roget, that "it con-
sists in  a series of actions  and reactions,"—Avithout
explaining the cause of these corpuscular changes, ac-
tions and reactions.
   In regard to all the  above hypotheses, I answer,—
we might  as well suppose that the temperature and
power of steam are owing to the movements of the
engine, as that animal  heat depends on the action of
the heart, friction, &c;  that  the  temperature of  boil-
ing water, and its conversion into the elastic or gase-
ous state,  result from the vibratory or rotary motions 
588
VITALITY  OF  THE BLOOD.
of its particles,—as that  "animal  heat results from
the molecular vital actions of the  blood;"  that  the
temperature of spring, summer and winter depends on
the actions Avhich make up the movements of chemis-
try, geology and life—or that  the caloric perpetually
radiated from the sun into the planetary spaces, and
again returned to the fountain from which it sprung,
depends on the motions of the  hea\^enly bodies,—as
that "animal  heat  results from  the constant motion
and mutation  of all the organs."*
  If the vitality of the blood had not been recognized
by all antiquity, and sanctioned by the universal com-
mon" sense of  mankind, down  to  the time of Harvey
and Willis, it would  still  be evident  from the well-
established fact, that all the organs are formed imme-
diately  from it; and that whenever  its supply is  cut
off, they cease to live.   It is therefore  clear, that all
the phenomena of the animal economy, whether in
health or disease, must depend  on the conditions of
this  important fluid, which, in  accordance Avith  the
doctrine of Hunter, Bordeu termed liquid flesh,—and
that a complete knowledge of its vital properties is
essential to any sound or  rational system of medical
theory and practice.   It was justly observed by  the
celebrated Boyle, that "to mind  the  solid parts of  the
body, and overlook inquiry into the fluids, especially
the blood, were little less improper in a physician than

  * It was maintained by  Anaximenes  that the heat of the sun
was generated by his rapid motion, the cause of which motion,
however,  was not explained.  But the modem  discovery, that the
sun is stationary, having only a slow motion upon his axis, has en-
cumbered this ancient theory with still more serious difficulties. 
COAGULATION OF  THE BLOOD.          5gQ
it would be in a vintner to  be very solicitous about
the structure of his  cask, and  neglect the considera-
tion of  the wine contained in  it."  (Essay on Human
Blood.)
  One of the most important facts connected with the
vital properties of the blood,  is the process of coagula-
tion by  Avhich its fibrin becomes solid, when remoA^ed
from the vessels, and unites  the red particles  into a
mass of greater or less density.   But the cause of this
change  remains an unresolved  problem.   As it must
always have been known that inorganic fluids become
solid  under the influence of cold, it was maintained
by Hippocrates and Aristotle, Harvey and Sydenham,
that the coagulation of blood is owing to  the  loss of
animal  heat.   For the  first time  in the history  of
science, this error was refuted by Hewson, who found
that the process was  always  retarded by cold, and
hastened by  increase of temperature.  He therefore
concluded, that it was owing  to the influence of atmo-
spheric  air.  But as it was  observed by Spallanzani
to take  place within the cellular tissue when extrava-
sated, removed from the circulation, and not exposed
to the air, he inferred that it was owing to the cessa-
tion of its motion.  This opinion has also been refuted
by  the  fact,  that coagulation  cannot be  wholly pre-
vented by agitation of blood out of the body.  Yet it
would appear from the experiments of Magendie, that
it is greatly retarded by the natural movements of the
circulation; for, when  he connected a dead tube  at
the temperature of the  body, with the extremity of a
divided artery  of a living animal, the blood  sent into
it remained fluid while  kept  in motion by the  heart's
action. 
590           COAGULATION OF  THE BLOOD.

  Some  have ascribed the process of coagulation to
the escape of  carbonic acid, and others to the loss of
nervous  influence, or to the death of the blood.  But
it is now fully established, that it is not prevented by
the presence of carbonic acid, nor when placed in vacuo.
And that it is not owing  to the loss of vitality, is evi-
dent from the fact, that in the latter stages  of  the
most malignant diseases,  the blood remains fluid after
death.    What, then, is the rationale  of coagulation?
To  this  important query physiologists have hitherto
offered no satisfactory reply; and  Dr.  John Davy ob-
serves, that it must still be  regarded as "one of  the
many mysteries of nature;" that " all we know is, that
from a fluid state, the fibrin becomes solid, entangling
a portion of red particles  and serum." (Anat. and Phy-
siological Researches, vol.  ii. p. 2.)
  The leading  facts connected with  the theory of
coagulation may be reduced  to the following propo-
sitions :—
  1. That the contractile power of the blood, when
removed  from the  body, like  that of the  muscular
fibres, is in proportion to the quantity of respiration,
mean healthy temperature and  aggregate vital energy
in the different orders of animals; being greater in
birds  than in mammalia, and  greater in the latter
than in reptiles and fishes.
  2. That as the temperature  of arterial  is  higher
than that of venous  blood, so does  the former coagu-
late more quickly and firmly than the latter.*
  * We also learn from the experiments of Hunter and Thackrah,
that arterial resists putrefaction longer than venous blood.  And
Bellingeri  states, that while the former is positive, the latter is in 
THEORY OF COAGULATION.
591
  3. That  as the vital energy of animals is  ahvays
diminished by reducing their  temperature below the
natural  standard, so is the coagulation of the blood
retarded  by the  same means, and wholly prevented
by long-continued cold.*
  4. That  the blood of individuals  belonging to the
sanguine or dynamic  temperament, coagulates sooner
and more  firmly than in such as are of a weak  or
phlegmatic constitution;  while  its contractile power
is diminished  by whatever  impedes the  function of
respiration, as in phthisis, asthma, disease of the heart,
the cold stage of fever, and all maladies of long stand-
ing, by which the powers of life are greatly reduced.
   As a proof of the first proposition, and  correspond-
ing  with the highly  organized state of the blood in
birds, together Avith its bright florid hue, we are  in-
formed by  Denis, that when poured from  the  divided
vessels of a decapitated fowl,  it coagulated almost  in-

a negative state  of electricity. However this may be, they are
certainly plus and minus in relation  to temperature, or  the quan-
tity of caloric in each, while circulating through the body.
  * Sir Charles Scudamore found, that human blood which began
to solidify in four minutes in air at 53°, uuderwent the same change
in two minutes and a half at 98°, and in one minute at 120°; again,
that blood which coagulated firmly in five minutes at 60°, required
seventy minutes to become solid when reduced to the temperature
of 40°.   Nor is it true, as stated by Mr. Ancell, on the authority
of Mr. Prater, that when blood is suddenly raised to  140° and 150°,
its power of coagulation is destroyed; for in numerous experiments
 of my own, it took place rapidly in the blood of sheep at all tem-
peratures, from 110° up to 150°, and almost instantaneously, when
the cups in which it was received were placed in  water at 180°,
 owing, doubtless, in the latter case, to solidification of its albumen,
 which takes place immediately at temperatures above 156°. 
592
THEORY OF COAGULATION.
 stantaneously, and formed a A7ery firm clot.  Dr. Davy
 also states, that he observed the  blood  of a  fowl  to
 become  solid in less than  a minute  at  the ordinary
 temperature of the  air; but Avhen suddenly cooled  to
 40° by  means  of ice,  in something  less than three
 minutes. (Op. cit. p. 76.)  He also found that the arte-
 rial blood of sheep and lambs coagulates  much sooner
 than that drawn from the veins.*  And it is generally
 knoAvn that the blood of dogs, sheep, rabbits and other
 mammalia, whose temperature is higher  than that  of
 man, becomes solid  in a shorter time; or in from one
 to three  minutes in the former, and in from two to five
 minutes  in the latter, during health.
   Having ascertained that a mixture of arterial  and
 venous blood of ducks  and  fowls began to  solidify
 almost immediately, I performed the following experi-
 ment,  Avith a view of discovering how far the  process
 might  be modified  by reducing the  temperature of
 animals.   For this purpose, a healthy pigeon was im-
 mersed in Avater at 47°, Avith the exception of its head,
 when a thermometer in recto,  fell from 108° to 74° in
 tAvelve minutes, and the poor bird presented all  the
 symptoms of approaching convulsions, coma and death.
 In  this state -it was decapitated, and  its  blood made
 to flow into three saucers, one of Avhich was placed in
 water  at 130°, another in water at  110°, while  the
 third was exposed to the temperature of  the room at
 about 60°,—when the blood in the first saucer began
 to solidify in three minutes, that in the second in four

  * The same thing has been observed in the blood of birds  and
 other mammalia, by Denis and Berthold; which I have  also re-
peatedly witnessed in the slaughter-house. 
THEORY OF COAGULATION.
593
minutes, and that in the vessel at 60° but slightly in
seven minutes.  Nor is it  less worthy of notice, that
when the blood of another pigeon was treated in the
same manner, but without previously reducing its tem-
perature,  it coagulated sooner at 110° than at 60°,
sooner at  130° than at either; and more firmly in five
minutes, than the blood of the other pigeon at the ex-
piration of  thirty minutes.  Nor is it more strange
that caloric should  determine both the fluidity  and
coagulation  of blood, than  that  attraction and repul-
sion, contraction and expansion, should be modified
effects of  one  and the same physical cause.
   In another set of experiments, I found that when
half an ounce of blood from the divided vessels  of the
neck in a healthy sheep was put  in a small tin cup,
and surrounded with a freezing  mixture of snow and
common salt  at 17°, it began to coagulate slightly in
two minutes and a half, increasing slowly till the end
of five minutes, Avhen the clot Avas very loose and im-
perfect; soon  after which it began to congeal, and was
quite frozen in  fifteen minutes.   In another experi-
ment, the same  quantity of blood  was taken from the
carotid artery of a vigorous sheep,  (whose temperature
was 106° in the left ventricle of the heart, and 104°
in the right side,) and placed in a tin cup, surrounded
with a freezing mixture at 0°, when it began to solidify
just perceptibly in three  minutes, and was quite frozen
in six minutes.   After remaining in this state above
an hour, it was  gradually thawed  by exposure  to the
atmosphere, which  was  at 51°,  and formed  a loose
coagulum.  In a third experiment, three half-pint cups
were filled Avith blood from the neck of another sheep,
                        38 
f
 594           THEORY OF COAGULATION.

 one of Avhich was placed in Avater at 130°, another in
 water at 100°, and the  other exposed to the air at
 51°; when they all began to coagulate  in about one
 minute and a half, but that in the  cup at 130° con-
 tracted more firmly in two minutes, than either of the
 others in five minutes.
   Corresponding with the fact established by Hunter,
 that the  ears of rabbits, the combs of cocks  and the
 extremities of other  animals, may be rigidly frozen,
 and afterwards restored to life, when gradually sub-
 mitted to the influence of warmth, it has been demon-
 strated  by the experiments of Hewson, Thackrah,
 Davy, Magendie and  Prater that the blood of animals
 may be  repeatedly frozen, and afterwards coagulate
 when thawed.  Hence it is that hybernating animals,
 including reptiles and other cold-blooded species, after
 being frozen for months, as in the higher latitudes, are
 restored to activity by the returning power  of solar
 warmth.  The influence of caloric on the coagulating
 power of the  blood is further illustrated by the follow-
 ing observations of Dr. John Davy, who found that the
 blood of a tropical turtle, whose temperature was 91°,
 coagulated firmly in about two minutes; while that of
 another turtle, whose  temperature was 84*5°, required
 five  minutes  to become solid;  and that of another,
 whose temperature was 58°, required thirty minutes
 to coagulate firmly.   (Anat.  and Physiological Re-
 searches, vol.  ii. p. 10.)  Mr. Marshall also found that
 the blood of a tortoise whose temperature was 55°,
 that of the room  being  58°,  began  to coagulate  in
 eighteen minutes, and became solid in one hour and
forty-five minutes.   But that Avhen raised to the tern- 
THEORY  OF  COAGULATION.
595
perature of  110°, (falling to  80°,) it began in nine
minutes and a half,  and was completed in  twenty-
three minutes and a half.   He further observed, that
when raised to 130°, it did not commence before thir-
teen minutes  and a  half had elapsed, and was com-
pleted in one hour.
   It is therefore  evident that, within certain limits,
the coagulating power of blood is augmented by rais-
ing its temperature above, and diminished by reducing
it below the natural standard.   As a further proof of
this, it is stated by  Miiller, that during winter, the
blood  of frogs coagulates very imperfectly.   And  I
may add, from several observations of my own during
the Avinter of 1840-1, that blood of the eel and several
other species of fish, requires from ten to fifteen and
sometimes thirty minutes to coagulate in a very  im-
perfect manner.   Let  us then reject the assertion of
Magendie, that "blood coagulates alike at all temper-
atures  from 10° to 156° F."   The  truth  is, that not-
withstanding  the vast number of  experiments  per-
formed by this celebrated physiologist, he seems never
to have inquired hoAV far the process of coagulation is
modified by the  difference  between  warm and cold-
blooded animals*
  * Yet we are greatly indebted to  him  for the light which his
researches have shed on the influence of various medicinal agents
on the vital properties of the blood, many of which, that are con-
stantly employed in practice, disorganize its particles, and diminish
or prevent its coagulation, out of the body.  For example, he has
shown that sulphuric, nitric, hydrochloric, oxalic, hydrocyanic,
phosphoric, arsenious and  many other acids, in small proportions,
either prevent  or retard its solidification,—that it is retarded by
solutions of opium, belladonna, strychnia, nicotine, sulphate of mor- 
596
THEORY OF COAGULATION.
   That coagulation is a vital process, analogous to that
by Avhich blood is converted into the different organs,
and OAving to the same cause  which enables the mus-
cles to contract, was fully recognized by John Hunter,
who  demonstrated, by an  admirable series of experi-
ments, that when effused into healthy divided parts,
it becomes penetrated with innumerable vessels  that
may be injected by injecting the neighbouring arteries,
—causing wounds  to heal  by the first intention, and
plugging up divided vessels.*  He also  maintained
with  HeAvson, that the process of coagulation is accele-
rated by an increase of temperature, and retarded by
cold; that  the  colour and  coagulating poAver of  the
blood are more expressive of disease, than is any other
part of the  animal  economy.   (Treatise on the Blood,
phia, digitalis, aconite, hemlock, tartarized antimony, bichloride of
mercury, nitrate of copper and by nearly all the neutral salts, ex-
cept in very small proportions, although most of the latter change
it to a florid hue; and that while some of the above medicines pre-
cipitate the albumen of the blood, others dissolve its fibrin.   Ma-
gendie has also  shown, that  by injecting seven grains  of oxalic
acid into the jugular vein of  a dog, he was attacked with difficult
breathing, small  and frequent pulse, prostration of strength, fol-
lowed by coma and death in a few hours; and that the same fatal
effects were produced by injecting an ounce of the mildest neutral
salts into the veins. (Lancet for 1839.)
  * We  also learn from the researches of Prevost and Dumas, that
when a small quantity of blood from a living animal is immediately
placed between thin pieces of talc, the red particles may be  seen
with a good microscope  to arrange themselves in lines, or series
and aggregates, that resemble chaplets of beads—a process which
must be  regarded as an imperfect species of organization, and as
the result  of its  last remainder of vitality. (Ann. des Sciences
Naturelles, tome xii.) 
THEORY OF COAGULATION.
597
&c. vol.  i. p. 135.)   But he was wholly mistaken in
supposing that  coagulation  is  prevented in cases of
sudden death  from  lightning, violent emotions of the
mind, the more  active poisons, and exhaustion  from
excessive muscular exertion,  as has  been recently
proved by the accurate researches of Dr. John Davy.
   At the same time, it is certain from the experiments
of HeAvson, that the coagulating powrer of the blood
is diminished  in all cases of congestion, intermittent
fever, pneumonia, consumption, rheumatism and vari-
ous other modifications of disease, by which the general
forces of life are seriously impaired,—and that the pro-
cess is delayed, in such cases, for ten, twenty, thirty or
even ninety minutes.   It  is very much protracted in
cases of apoplexy, epilepsy, concussion of the brain, suf-
focation, strangulation, violent  emotions of fear and
other depressing passions,* or Avhatever diminishes the

   *  It is very well  known, that in cases of fright, the powers of
life are remarkably diminished.   That this  is owing to  partially
suspended respiration, on which the vital properties of the blood
depend, is evident from the coldness of the extremities, languor of
the circulation, paleness of the skin  and darkness  of the  blood,
when drawn from a vein.   In all such cases, the voluntary power
of the brain is more or less impaired by the shock, and its command
over the  lungs so far diminished, that their chemical function is
greatly interrupted, when  they fail to  arterialize the blood in a
proper manner.   Accordingly it was  observed  by  Hewson, that
whenever the pulmonary circulation is much impeded, the blood
first drawn did not  coagulate for ten or fifteen minutes;  but that
after the congestion of the weakened and  overloaded capillaries
was removed by taking away a few ounces of blood, it flowed from
the orifice more freely, changed from a dark to a bright florid hue,
and coagulated  in from three to five minutes.   It  has also been
observed by others, that blood which  exhibits a  bluish tint while 
598
THEORY OF COAGULATION.
chemical function of the lungs, and consequently, the
vital properties of the blood, or the process by which
it is organized.   We also learn from the researches of
Denis, Le  Canu and other physiologists, that in all
chronic  diseases, such as chlorosis, scrofula, diabetes,
scurvy, diarrhoea, &c. the blood coagulates sloAvly and
imperfectly, Avhile in the worst forms of typhus, yellow
fever, plague, malignant cholera, tetanus and hydro-
phobia, it scarcely coagulates at all, toward their fatal
termination.  And  it is worthy of notice here, that
during  pregnancy,  by which a portion of the  vital
energy of the mother is expended in support of the
foetus, her  blood coagulates more slowly than  at other
periods,  giving time for the red particles  to subside,—
thus causing the fibrin  to  contract by itself on the
surface,  and to present  the appearance  of a whitish
crust, termed the buffy coat, which is generally Avit-
nessed in  the  blood drawn during nearly all cases
attended with slowness of coagulation, excepting those
that are marked by a great loss of vitality, and general
prostration of the system.
  It has been  maintained  by many physiologists, in-
cluding  Scudamore  and  Miiller, that the relative pro-
portion  of fibrin in the blood is  augmented during
inflammation, and that  this is the cause of the buffy
coat,—an opinion Avhich has been completely refuted
by Dr. John Davy, who has shown that healthy blood

flowing, always coagulates more slowly than usual, and afterwards
exhibits the buffy coat. I have further observed, that when chickens
and rabbits are decapitated under the influence of fright, the blood
is more dark than usual,  and requires a much longer time to coagu-
late. 
THEORY OF COAGULATION.
599
 contains more fibrin than the blood in cases of inflam-
 mation.   But  although he  admits that "very buffy
 blood is very slow in coagulating," and that in healthy
 blood the process is rapid, he maintains with Hewson,
 that in  some cases,  owing  to a  thinness, tenuity or
 liquidity of the fibrin, the red  particles may subside
 from one-eighth to one-fourth of an inch in two mi-
 nutes, and sufficiently to cause  the buffy appearance.
 (Anat. and Physiological Researches, vol. ii. pp. 43—6.)
   The true state of  the  facts is, that  in all cases of
 protracted disease  in which the chemical function of
 the lungs is seriously deranged,  the proportion of both
 fibrin and  red  particles is more or less diminished, as
 proved by Denis and  Le  Canu,  and the process of co-
 agulation retarded; while it is equally certain, that in
 the early stages of acute inflammatory affections, which
 are marked by augmented respiration and evolution of
 heat, there is an increased amount of fibrin generated,
 —doubtless for the same reason that it is more abund-
 ant in the blood of birds than that of mammalia, and
 more so in the  blood of the latter than in that of cold-
 blooded animals, viz., increase of temperature, circula-
 tion, &c.
   In opposition to the well-established fact, that in
 persons  of the  sanguine  temperament, Avith a broad
 and full chest, the blood coagulates quickly and firmly,
 as in all  the more powerful mammalia, and still more
 so in birds, whose vital energy is vastly greater, cceteris
paribus, while in persons  belonging to the phlegmatic
 temperament, and in the various species of cold-blooded
 animals,  the process  of coagulation is imperfect,—it
 has  been  recently maintained  by Mr.  Ancell  that 
600
THEORY OF COAGULATION.
"blood coagulates most rapidly in Aveak animals, in
weak states of the constitution, and in diseases of de-
bility"—that " when the blood is a long time in coagu-
lating, its contractile poAver  is strong, corresponding
with the vigour of the constitution."   (Lectures on the
Blood, Lancet, Jan. 1840.)
  This extraordinary statement, so inconsistent Avith
the analogies of nature,  and  which  the intelligent
author has offered as a general axiom, seems to have
been founded on the observations of Hewson, Dr. Davy
and  others, that  the  blood of animals exhausted by
excessive hemorrhage, and by long-continued muscular
exertion, coagulates much sooner  than  Avhen taken
from the vessels in a healthy state.  In regard to the
cause of this apparent exception to the general laws
of physiology, no adequate explanation  has been of-
fered.  All parties agree, that it  is a beautiful  pro-
vision of nature to arrest hemorrhage,  by plugging up
divided vessels.   When it was proved by the analyses
of Prevost, Dumas,  Magendie, Denis  and Le Canu,
that the proportion of fibrin is ahvays diminished by
loss of blood, the rapidity of its  coagulation was re-
ferred  by some to an excess of  serum, or of saline
matter.  But Ave  have seen that in cases of protracted
disease, the serous portion of the blood is augmented
in relation  to the quantity of fibrin and red particles,
while its coagulation  is both slower and weaker than
in health.
  The fact is, that although  the  blood of an animal
exhausted  by over-exertion, like  the  last running of
blood in cases of excessive  hemorrhage, coagulates
almost instantaneously, the crassamentum is  always 
RIGIDITY AFTER  DEATH.
601
loose and infirm.  There is reason to believe, that the
rapidity of the  process is OAving partly to diminished
motion and vitality of the blood; and  that, like the
rigidity of the muscles after death, it depends on the
last remains of contractility, as will appear from the
following facts.  In the first  place, it is well  known,
that when blood is extravasated, and its  motion ar-
rested,  as in  uterine  hemorrhage, and  in cases  of
ecchymosis,  it  very  soon  coagulates, although sur-
rounded with living parts;  Avhile it is equally certain,
that the action of the heart and general activity of the
circulation, are greatly diminished by loss of blood.
Secondly, it is  well knoAvn to butchers, that in ani-
mals exhausted by over-exertion, rigidity of the mus-
cles comes on much sooner after death, and their blood
coagulates much more rapidly, than if slaughtered in
vigorous health. I have also observed that in a sheep
which had been exhausted by travelling  to  market,
the extremities Avere cold, the circulation exceedingly
languid, and the muscles stiff, even before death.   In
accordance with this fact, I found that when an  ounce
of its  blood was received from the divided vessels of
the neck, it became solid in half a minute.  It is  there-
fore probable, that when the motion and vitality of
the blood are thus diminished, the process of coagula-
tion may actually commence, though imperceptibly, before
it leaves the vessels;  (just as water begins to congeal
insensibly at 39°, but  does not become solid till  re-
duced to  32°;)  and for the same reason that the muscles
become stiff before death.
  It is stated  by Richerand  and Orfila, that in cases
of sudden death while in  the full vigour of health, 
602
RIGIDITY AFTER DEATH.
caused by suffocation in the mephitic gases, the tem-
perature  and flexibility of  the muscles  remain for
several  hours after death.  And it is  certain, that
whatever may be the cause of the roideur cealeiverlque,
—AAThether mechanical, chemical or vital—and Avhether
it be owing to coagulation of the blood, as supposed by
Orfila, Beclard and Treviranus—the  contractility of
the muscles  continues only so long as their tempera-
ture remains above that of the surrounding medium,
and Avholly ceases Avhenever the body becomes cold,—
for  if the limbs be  then flexed, they do not again be-
come rigid.   Bichat asserts, that after death, the ces-
sation of absorption  is simultaneous Avith the  subsi-
dence of animal temperature.   And Magendie says,
that it  goes  on for a considerable time (two hours)
after death.   Miiller relates on the authority of Nysten
and Sommer, that rigidity begins in fifteen or twenty
minutes after death from lingering maladies, in Avhich
the powers of life have been greatly exhausted—that
it commences sooner  in infants and very old people
than in robust constitutions, or in such as have been
carried off by violence  in  the  full vigour of health,
Avithout loss  of blood,—in which it does not come on
for  several hours after the circulation has ceased, and
remains for a proportionably longer time.   It has been
also said, that after death from  exposure to intense
cold, (in which the rigidity commences before death,)
it is completed very soon  afterwards—and that in  a
case of tetanus, the spasmodic contractions passed im-
mediately into the rigidity of death.   But that it con-
sists of the last remainder  of vitality, is evident from
the fact,  that it ahvays disappears before putrefaction 
THEORY  OF NUTRITION.
•  603
begins, and its duration is shortened by whatever di-
minishes the previous forces of life.
  In accordance with the opinion  of many modern
physiologists, Cuvier  represents the process of nutri-
tion, by which blood  is converted into  the different
organs,  as  the  greatest  mystery of life.   And  Sir
Charles Morgan observes, that "the  conversion  of
arterial blood  into venous blood is a process involved
in the deepest obscurity"—that "whether  any single
element is  abstracted, Avhere the change takes place,
or whether the  alteration depends  upon a change of
disposition in all the elements among themselves, can-
not even be guessed."  (Philosophy of Life, p. 145.)
  But we have already seen, that during the passage
of dark venous blood through the  lungs, in combi-
nation with chyle and lymph, variable proportions of
carbon and hydrogen are given off, and unite with at-
mospheric oxygen, in exchange for which caloric is
received, with more or less nitrogen, according as the
aliment contains more or less of that element,—that
during the transition of blood through the pulmonary
tissue,  its  temperature is elevated  from 1° to  3°, its
colour  changed  to a  bright florid  hue,* its  specific

  * Hippocrates  seems to have been fully aware, that the temper-
ature is higher in the left ventricle of the heart and aorta, than in
the right ventricle or vena  cava.  He  also observes, that the heart
is the well-known fountain of the aorta, which is connected with
the lungs by the  trachea, which he regarded as the upper extre-
mity of the aorta.  (~epc 4>Xe(3wv, i. ii—~spc Apxcov, vi.—nept Kapdcyjq,
vii. viii.)  But so little did this greatest of  the ancient physicians
know in regard to the  true theory of respiration and sanguifica-
tion,  that he speaks of the  former as a cooling process; while he
referred the dark  or livid colour of what we call venous blood, to 
604
THEORY  OF NUTRITION.
gravity diminished, the  proportion of  its organic par-
ticles augmented, and all  its vital  properties exalted.
In this  state, it excites the left ventricle of the heart
to contract, by which it  is impelled into the ultimate

the  contraction  of the heart, and the  rubicund or  florid hue of
what is now called arterial blood, to its dilatation.  And so little
did he know in regard to the office of the brain, that  he represents
the  mind  (rviop.7]) of  man  as seated in the left ventricle of the
heart.  But as  Pythagoras, Anaxagoras, Democritus and Hera-
clitus, regarded  the brain as the organ of mind, it  may well be
doubted whether Hippocrates was the  real author of the treatise
ascribed to him,  on the heart.  Galen also observes in his treatise
on the use of the pulse, that on opening the ventricles of the heart
of an animal, especially the left one, if the  finger is immediately
introduced, the heat is then felt to be greater, and continues longer,
than in other parts—Page  810.    (Cox's Epitome of Hippo-
crates and Galen, page 536.)  He further states, in his Finitiones
Medicse, when explaining the difference between a  vein and an
artery, that  the  latter contains  less blood, (which is more atten-
uated,) but more spirit, is  more warm, and endowed with a pul-
sating motion. (Cox's Inquiry  into the Claims of Harvey, page
124.)  It  is therefore evident,  that  without the aid of thermo-
meters, the anciente had discovered the important  fact that arterial
is warmer than venous blood.   But although he speaks of respira-
tion as essential to life, and superior in the importance of its func-
tion to the stomach, or even the brain, he  seems to  have had but
vague, erroneous and contradictory  views on  the subject; for at
one time he represents its  object to be the conservation of the in-
nate heat of the blood, while at another time  he  describes the
air inspired as intended to ventilate  and cool  the blood.  In Bis
treatise on the doctrines of Hippocrates and Plato,  he represents
the liver  as the organ of sanguification,  and the  origin of the
veins. (Cox, op. cit. page 541.)   It  is therefore manifest, that his
physiology of respiration and sanguification was not much better
than bis knowledge  of anatomy.   As for Aristotle, he maintained
that the blood is warmer in the right ventricle of the heart  than
in the left. (Le  Clerc, page  211.) 
THEORY  OF  NUTRITION.
605
tissues of the whole body, where the  caloric just re-
ceived in the lungs, together with a portion of arterial
blood, percolate  the delicate coats  of  the capillaries,
unite Avith the solids  by .vital  affinity, and  form the
various secretions by glandular action.
   As proofs of what has just been stated, the temper-
ature, vital activity and renovation of all the organs,
are constantly  maintained at the expense of  arterial
blood, during its conversion  into  the venous state,
while passing through the systemic capillaries, where
its temperature is reduced, the  number of its organic
particles diminished,  and its  power of sustaining the
 healthy state of the different functions is greatly im-
 paired,—when it returns to the lungs for a  fresh sup-
 ply  of organic  particles and  of living  fire.   If the
 temperature of the blood were  not raised above that
 of the solids while passing through  the lungs, there
 could be no transition of caloric from  one to the other
 —no combination of  its proximate constituents with
 the membraneous, bony, muscular and nervous tissues.
 Nor could chyle and venous blood be converted into
 the  arterial state, without  giving off carbon  and hy-
 drogen in the lungs, by which caloric is evolved, the
 temperature of the blood elevated and its composition
 renewed.*                 ___________________
 "T77is^tlierefor7^no7true^7s maintained by Dr. John Davy,
 that "the object of respiration is  to introduce oxygen into the
 blood, and separate carbonic acid from the blood"_that<< animal
 heat is owing to the fixation of oxygen in the blood in the lungs,
  and to the combinations  into which it enters in the circulation in
  connection with the different secretions and changes essential to
  animal life "  For if it  be a fact, which he has clearly demon-
  strated  that the temperature of blood is elevated  while passing 
606
THEORY OF NUTRITION.
    Should it  be urged,  that  arterial contains  more
 oxygen than venous  blood, I reply that the difference
 is very small, and wholly disappears in the lungs, on
 giving off carbon and hydrogen, Avhere venous becomes
 arterial blood,—that although it be true that the lat-
 ter has been  found to contain a little more oxygen,
 and the former a little more carbonic acid, as observed
 by Magnus, those gases  exist in  a state of merely
 mechanical mixture, and not as organic constituents
 of the  blood.   Besides, it  has been shown  by the
 microscopic observations  of Miiller and others,  that
 the form  and  magnitude of the red  particles are the
 same in arterial as in venous blood.  Nor has there
 ever  been  the  slightest  proof that  oxygen  causes
 arterial blood  to unite  with the  solids while passing
 through the systemic capillaries,—nor that carbonic
 acid is  there  received, as it changes to  the  venous
 state.   We  are then  bound to conclude that the dif-
 ference  betAveen arterial and venous blood is  owing
 chiefly to the  greater amount of caloric and organic
 matter in the  former.  It has  also been shoAvn  in a
 preceding chapter,  (page 502,)  that  when the blood of

 through the lungs, and diminished while passing through the gene-
 ral system, animal heat  must be evolved in the pulmonary air-cells,
 where the carbonic acid is generated, and  there unite with the
 blood, from which it is given  off to the different organs.   Nor is
 it true, as  maintained by Dr. Stevens, that arterial blood is changed
 to  the  venous state, by acquiring carbonic  acid in the systemic
 capillaries, and again arterialized by the attraction of atmospheric
 oxygen for carbonic acid,  and the abstraction of the latter in the
 lungs,—much less, that arterial blood owes its colour and  vital
properties to the salts contained in the serum ; because they exist
in chyme and chyle, which are white. 
THEORY OF NUTRITION.             607
a living artery is confined betAveen  t\vo  ligatures, or
in glass tubes hermetically sealed, it assumes all the
properties of venous blood, without the  loss of  any-
thing except caloric.  Moreover, it is manifest, that if
the  composition  of the solids be  renewed, and their
temperature  maintained, at  the expense of arterial
blood, while the latter is changed to the venous state,*
and deprived of its nutritive properties, there is  no
conceivable method of explaining the  transmutation
of one into the  other, without admitting, that nutri-
tion consists  in  the transfer of vital heat and organic
particles from arterial blood to the solids.
   The principal mystery connected with the process
of nutrition, is  the law of elective  affinity  by which
the  proximate constituents of the blood  unite Avith the
respective  tissues.  Some light is thrown on this pro-
blem by the fact that the bud of one fruit when grafted
on the tree of another, retains its original specific cha-
racter; shoAving that the sap of the tree  into which it
was inserted, is changed on coming  into  contact  with
the  graft.   And so of morbid animal growths.   This

  * Physiologists have often asserted, that the paralyzing  influ-
ence of venous blood when  sent to the  brain, stomach and other
organs, is owing to some poisonous property which  it acquires while
circulating through the capillaries.   But that its fatal influence is
merely negative, owing chiefly  to  the loss of  vital  heat in the
ultimate tissues, and not to any positively noxious  influence,  would
appear from  some experiments of Dr. Kay, (recorded in the 28th
vol.  of the Med. and Surg. Journal,) who found that after  a limb
had  been paralyzed by depriving it of arterial blood, its contrac-
tility was partially restored by the  influx of fresh  venous blood,—
which was doubtless owing to the fact, that fresh venous blood con-
tains more caloric than the solids, even at the same temperature. 
608
THEORY OF SECRETION.
much, however, is certain, that if the temperature of
the blood be not raised above that of the solids, there
could be no transition of caloric from one to the other,
—no combination of fibrin with  the muscles,—of al-
bumen,  oily, phosphuretted  and other  matter, with
the  brain  and nerves,—of albumen with the mem-
branes,  ligaments  and cartilages,—nor  of lime with
the bony textures.  The proof of which is, that after
the temperature of  arterial blood has been reduced to
an  equilibrium with  the solids, and  its properties
changed to the venous state, it  fails  to nourish the
brain, nerves, muscles and other tissues,—to maintain
their temperature and  specific modes of action, and to
elaborate  the  various  secretions.   The inference is
therefore obvious, that animal heat is the agent by
which these vital affinities are produced and the ac-
tivity of the various tissues maintained.   Nor is this
any more remarkable, than that the chemical union of
water Avith the aromatic constituents  of  tea, coffee
and  many other bodies, including the various salts,
should be owing to the transition of caloric from one
to the other.   Nor is it more strange, that the caloric
disengaged in  the  lungs during respiration, should
there convert  chyle into blood,  than  that the same
active principle should cause  oxygen and hydrogen to
unite in the formation of water, or that solar caloric
should determine  all  the chemical  and vital trans-
formations of the vegetable world.
  Moreover, that animal heat is the  ceiuse, and not
the effect of secretion, as maintained by Philip and
many others, Avould appear from the folloAving unde-
niable facts:—1. That the secretion  of perspiration is 
THEORY OF SECRETION.
609
much more  copious during summer than winter, and
in tropical than  in the higher latitudes;  while it is
known to be greatly augmented by the high artificial
temperature of glass-works, foundries, &c. ;* and  that
sweating  is the  natural termination of the hot stage
of fever.  2.  That in cows, goats and other domestic
animals the secretion of milk is more abundant during
summer  than Avinter, especially in cold climates,  and
that the  growth of all young animals is greatly re-
tarded by cold weather, unless  they be protected by
 suitable  shelter.   3.  That the menstrual secretion, like
 that of the skin, is checked by exposure to cold damp
 air, getting  the feet wet, by wearing too thin garments,
 and by Avhatever causes the abstraction-)- of vital heat
 from  the system more rapidly than it is obtained by
 respiration; or  whenever the latter  process is  dimi-

   * Dr. Southwood Smith found, that workmen who are exposed
 to the intense heat  of the London gas-works, lose from two to five
 pounds of perspiration in the space of one hour, twice a day, mak-
 ing the aggregate  from four  to ten pounds,—during which they
 consume  enormous quantities  of malt liquors.  (Philosophy of
 Health, vol. ii. p. 396.)                              .
   f The  menstrual secretion also diminishes from the tropical re-
 gions  where  it amounts to twenty-four ounces, more or less, to the
 warm climate of Greece, where, according to Hippocrates, the ave-
 rage is twenty ounces;  whereas in the middle latitudes of Europe
 and America it does not exceed six or eight ounces and not above
 three or four in the polar regions.  As might be inferred from this
  difference, the women are said to be more voluptuous in warm than
  in temperate, and least so in frozen climates, where sensibility is at
   ero   ffippicrates observes,  that among the Scythian women, the
  menses flow but rarely, in small amount, and that they are not
  fruUful;  while the wild animals are small and few in number. (On
  Airs, Waters and  Places.)
                             39 
610     THEORY OF SECRETION AND NUTRITION.

nished by the depressing emotions of grief, fear and
anxiety, which  are attended with  cold  extremities,
languid circulation and a general loss of vital energy.
4. That as  the  quantity of secretion throughout the
vegetable world  is always in proportion to the heating
influence  of the sun, and wholly arrested during win-
ter,—so are  all the secretions of animals during health,
in proportion to the amount of caloric  they derive
from  the  atmosphere by respiration, and Avholly ar-
rested or greatly diminished whenever  the temper-
ature of the body is reduced much below the normal
standard  by immersion  in cold water, or during the
cold stage of fever, cholera, &c.  5. That if the tem-
perature  of blood be  not  raised above  that  of the
solids, it cannot excite  the stomach to secrete gastric
juice, nor any of the  other  glands  their  respective
fluids.
  Again,  that neither  secretion nor nutrition depend
on  nervous  influence,  is evident from the fact, that
the germs of all animals are generated by secretion,
and developed by nutrition, before any part of the
nervous system is formed, as stated in the preceding
chapter, page 538.  Yet we are informed by Dr. Roget,
in an article on  Animal Physiology, contained in the
Library of Useful Knowledge, p. 92, that "the nervous
system  exerts  a certain action  upon  the blood, by
which are maintained the  secreting and other assimi-
lating processes, a disengagement of caloric produced
and the temperature necessary to  animal health sus-
tained."   He also adds in his elaborate  Bridgewater
Treatise, that "not only muscular contraction, but the
organic affinities which produce secretion, and all those 
THEORY OF SECRETION AND  NUTRITION.     6H
unknown causes which effect nutrition, development
and growth of each part, are placed under the control
of the nervous power."  (Vol. ii. p. 357.)
  Similar views have been offered by Tiedemann, who
observes, that "perhaps an imponderable fluid, resem-
bling galvanic electricity, is generated in the nerves,
which causes changes in the blood, passes through the
delicate net-Avork of the glands, and renders them capa-
ble of secreting, as supposed by Wollaston, Berzelius,
Brodie, Philip  and others."  (Comparative Physiology,
p. 207.)*   And so far has Dr. South wood Smith been
fettered by this obscure hypothesis, that in his excel-
lent  work  on the Philosophy of Health, he represents
" the repulsive power of the blood on which its fluidity
depends, as a vital endowment, derived, probably, from
the organic nerves, so  abundantly distributed to  the
coats of the blood-vessels;" while in another place he
maintains that "secretion  is effected by  means of the
electric fluid, conveyed to the different organs by the
ganglionic  nerves."-j*   And although he  admits that
the temperature of arterial is somewhat  higher than
that  of venous blood, he observes that the difference
is so slight, that in the general theory of animal heat
it may be disregarded.  (Vol. i. p. 347; vol. ii. pp. 147,
213, 326.)

  * As to M. Matteucci, he maintains that "the  nervous fluid is
not caloric nor electricity, but that it is produced by the chemical
action of nutrition." (Comptes Rendus, March 15, 1841.)
  f In a late work by Rudolph Wagner, he observes, that "the
final cause of the secretion of gastric juice lies in the nature of the
animal organism, and  is unknown to us." (Elements of Physiology,
part ii. p. 346.) 
612         THEORY OF MUSCULAR FORCE.

   Is  it then possible that physiologists are in doubt
whether the fluidity of the blood is owing to the same
cause which determines the fluidity of the ocean ?  Or
is it  possible  that the Author of Nature Avould have
ordained  that  the temperature of arterial  should be
higher  than that of venous  blood,  if  the  difference
were not  essential to the well-being of the animal eco-
nomy?  The truth is, that this "slight difference" consti-
tutes one of the most important facts connected with the
whole theory of physiology, pathology and therapeutics.
In accordance Avith  the views of the  ancients, Avho be-
lieved Avith Homer, that  "strength  is derived from
spirits and from blood,"—it  is now completely esta-
blished,  that  the contractile  power of the muscles,
whether voluntary or involuntary, is directly in pro-
portion to the quantity of arterial blood with which
they are supplied, and  the rapidity of its circulation
through them.  But that cedoric is the spirit on which
its power of maintaining their nutrition and strength de-
pends, is manifest from the facts already stated, that if
the temperature of the blood be not raised above that of
the solids, while passing through tlie  lungs where it is
formed, it cannot unite with their substance; and that
whenever the  general  system is reduced below  the
natural standard  by the abstraction of its vital heat,
or  by a deficient supply of it by respiration, all  the
energies of the  animal machine  are proportionally
diminished.
   On the other  hand, whenever the temperature of
the living body is  raised much above the  natural
standard by the external action of caloric, so that  the
solids are brought nearly  to an equilibrium with that 
THEORY OF VITAL DYNAMICS.
613
of the arterial blood, the operations of secretion and
nutrition are  nearly suspended, and  all the energies
of life proportionally diminished.  The reason of which
is, that under such circumstances, there is very little
caloric transferred  to  the solids in combination Avith
the blood, which, therefore, returns to  the right side
of the heart,  of nearly  the  same temperature, florid
hue and quantity of organic particles, as when it left
the lungs.  Hence it is, that when the system is raised
above  the  natural  standard, as during immersion in
the hot bath, or surrounded by an atmosphere from
five to ten  or  more  degrees above the healthy temper-
ature of the body, as in the tropical portions of Africa,
India, New Holland  and  South America during the
heat of the day,—all the poAvers of mind and body
are prostrated, attended with syncope, apoplexy,  and
frequently  death, if not relieved by cooling  ablutions
by Avhich the  system is reduced to its natural plus and
minus condition of arterial blood and of the solids.
For  it  is a certain fact, that without this essential
condition,  none of  the vital functions could be long
carried on.
   The dynamical agency of caloric is not more essen-
tial to the movements of a steam engine than to the
muscular poAver of animals and the  activity of all
their functions.  In both cases, it is obtained by the
combustion of carbon and hydrogen.  In the former,
it is  evolved  in the furnace,  communicated to the
boiler,  where  it unites  with water,  and converts  it
into an elastic gas, which, by acting  on the piston,
sets all parts  of the machine in motion,—whereas in
the latter,  it  is disengaged in the lungs, Avhere it  con- 
614        DYNAMICAL AGENCIES OF CALORIC

verts chyle and lymph into the proximate constituents
of blood, and raises its temperature, by Avhich the heart
is excited to contract, and send the \dtal stream to all
parts of the animal  system.   And as the  power of
steam to move the piston is destroyed on  parting with
its caloric in the condenser, so is that of arterial blood
to maintain  the  action  of  the heart, stomach, brain
and  voluntary muscles  diminished  or destroyed  by
parting with the caloric it receives in the lungs, while
passing through the ultimate tissues of the body, which
cannot  be nourished and vitalized by dark  venous
blood,—for  the  simple  reason, that its  temperature
has  been reduced to an  equilibrium with that of the
solids,  and its Adtal prorjerties impaired, until again
renovated by respiration.
  Thus it is  manifest, that when stripped of all hypo-
theses,  and  reduced to its  utmost simplification, the
science of animal physiology may be reduced to a very
small compass,—that a difference between the temper-
ature of arterial  blood and that of the solids is abso-
lutely  essential  to  all the  phenomena of life,—that
the transformation of blood into the different organs
depends on the same attraction of fluids for solids that
determines the growth of plants, and the capillary cir-
culation in  animals that haATe no heart, like that of
the lacteal and lymphatic absorbents. But Avhy should
I waste time in maintaining a doctrine that requires
only to be once fairly stated, to give  it the force of a
self-evident truth? I answer, that such is the influence
of "stone-blind custom,"  in obscuring the perceptions
of mankind, that they generally disregard the plainest
facts, when  not in accordance with  established sys- 
IN LIVING AND  DEAD MECHANISMS.
615
tems, however unsatisfactory the latter may be,—that
it is therefore often necessary to insist upon the clearest
propositions,—to add "line upon line, and precept upon
precept," until the light of common sense shall pene-
trate the  thickest crust of prejudice, and dispel the
mists of error that have so long dimmed our intel-
lectual  vision.   But what shall Ave say of men who
wilfully close their eyes to the azure heaven, the shin-
ing  sun and the growing corn?  who "grope in the
noon-day  as in  the night," and  dig their way in the
dark like  a mole, until  they lose the poAver of vision?
Alas! this is their condemnation, that light has come
into the world, and they reject its revelations.
   The finest specimen of mechanism ever yet devised
by the  skill of man is the steam engine, which is des-
tined to augment the power of producing wealth and
happiness an hundredfold.  But as the grandest inven-
tions of human genius are only feeble imitations of
nature, (Avhich  Plato beautifully  termed the art  of
 God,) the process of living combustion is absolutely
perfect, and the power thus obtained, applied with
the  admirable wisdom and efficiency that characterize
all the operations of the Divine  Architect.   For, in
addition to the large  amount of caloric that is wasted
by imperfect combustion in the  furnace  of  a  steam
engine, including what is lost by radiation, or passes
off with  smoke, there is  a great  loss of power, owing
to its being applied  only to  the  piston; whereas, in
the  animal machine during health, and where the cli-
mate is temperate, there  is no waste of caloric, which
is conveyed  and applied directly  to every part of the
body, in combination  with arterial blood, by which 
616        DYNAMICAL AGENCIES  OF CALORIC

the composition and vitality of all the organs are re-
neAved, while they are endowed with the faculties of
motion, sensation and the exalted attributes of intelli-
gence.
  As an example of the difference between the dyna-
mical effects of ordinary combustion and that of the
living frame, we are informed by Mr. Thomas Wick-
stead, that during the  consumption of one hundred
pounds of small Newcastle coal, in the furnace of the
best  Cornish steam engine, a power is generated equal
to the  elevation of from 82,000,000 to  113,500,000
pounds  a foot  high,  making an  aA^erage of  above
97,500,000 pounds, or nearly double that of Watt's
engine with the same amount  of coal.   But accord-
ing to  the mean result of experiments performed by
Emmerson, Desaguliers,  Bolton  and Watt, Smeaton,
Bevan, Wood, Tredgold and Leslie, as reported in the
Journal of the Franldin Institute, the tractive poAver of
a first-rate English  dray-horse is equal  to the  eleva-
tion  of 16,500,000 pounds a foot high in eight hours,
when fully exerted.  Yet  a horse, living on  twelve
pounds of farinaceous food per day, cannot consume
above six pounds of carbon  and hydrogen by respira-
tion  in  tAventy-four hours,  and  perhaps  about thfee
pounds  during  eight hours vigorous exercise.   From
which it follows, (if these data be an approximation
to the truth,) that thirty-three such horses would con-
sume about one hundred pounds of carbon and hydro-
gen by respiration in eight hours; and that they would
generate an aggregate force equal to the elevation of
550,000,000 pounds a  foot high, or above five  times
that  which is created by the combustion of one hun- 
IN LIVING AND DEAD MATTER.
617
dred  pounds of  coal  in the  furnace  of  a Cornish
engine.*
  It has been also ascertained by experiments in Eng-
land, that a man Avorking on  a treadmill for eight
hours, will elevate 1,500,000 pounds  one foot high,
and that a  Cornish steam engine  will perform  the
same work  by the  expenditure of one  and  a  half
pounds of coal.   If, then, Ave suppose that by such
exercise the  respiration of man is doubled beyond the
average, he would expend about six ounces of carbon
and hydrogen in eight hours; from which it follows,
that  the same  amount of  combustion in the living
body Avill generate about four times as much power
as a steam engine.
  In every description of mechanism, the power generated
is always directly in proportion to the quantity of the im-
pelling agent, cceteris paribus.   As the velocity  of a
steam car depends on the amount of caloric communi-
cated from  the furnace to  a given quantity of water
in the boiler, and thence to the piston, so is the loco-
motive power of  animals determined  by the amount
  * Since the first edition of this work was printed, many experi-
ments have been performed in Germany, France and other parts of
Europe, from which it appears, that an average-sized horse con-
sumes about 6*40 times more oxygen than a man;  or, in  the ratio
of 6504 to 1015 grammes in twenty-four hours.  Dumas has  also
calculated, that from 1000 to 1200 grammes of carbon would be
burned in a steam engine while carrying a man from  the level of
the sea to the summit of Mont Blanc; whereas a man would make
the ascent on foot in two days, by consuming 300 grammes of car-
bon. (See Matteucci on the Physical Phenomena of Living Beings,
pp. 152,  325;  London ed., 184T.) 
618            EXPENDITURE OF  CALORIC.
of the  same actiATe principle imparted to blood in the
lungs, and thence  to every part of the  body.   Nor is
this any more remarkable,  than  that the  velocity of
planets through  their orbits, like all  the changes and
transmutations which make up the history of chemis-
try and geology, should  be  directly in  proportion  to
the heating influence of the sun.
   But as it is an universal law of nature, that the cause
of force is always expended in producing motion, the
caloric  which is  employed in  uniting the  proximate
constituents of blood Avith the different organs, and  in
maintaining  their  healthy activity, is carried off and
removed from the system,* with a rapidity correspond-
ing Avith  the energy of the  brain, muscles, stomach,
&c. until the vital affinities by AArhich  the molecules of
  * The  caloric conveyed to the different glands in combination
with arterial blood, and in elaborating the various secretions, is
also expended by their action, when it passes out of the body with
the exhalations from the skin, lungs  and kidneys, or from the sur-
face by radiation.   Were it not for this rapid expenditure of blood
and vital heat, the temperature of birds would be far higher than
it is, and their blood proportionally richer in organic particles; for
we have seen that they consume at least double the ratio of oxygen
and of aliment as the same weight of mammalia.  But as the  func-
tions of circulation, secretion, nutrition  and muscular motion are
more energetic in birds, their blood and animal heat are transferred
to the  solids, and expended in maintaining the renewal of  their
composition and vital force with such  rapidity, that their mean
temperature, and the ratio of organic particles in their blood, are
not  much higher than  in mammalia.   For the same reason, the
temperature of a man with large thorax and sound lungs, does not
much exceed that of one with a narrow chest, diseased lungs and
imperfect  respiration,—because in the former it is more rapidly ex-
pended by secretion, nutrition, sensation and locomotion. 
COMPOSITION AND DECOMPOSITION.       619
arterial blood are transferred  to, and kept in a state
of combination  Avith, the solids, is gradually dimi-
nished, and finally dissolved—when, having performed
the office of renewing the structure and vitality of the
different tissues, they successively fall from their places,
and are taken up by the lymphatic absorbents, which
convey them into the general  circulation as worn-out
materials,  to  be again  renovated in the lungs, and
finally removed from the system by the several emunc-
tories;  while  their  places are immediately taken by
fresh organic particles  that are continually supplied
from the living  fountain of arterial blood.
   Thus we  perceive, that  the vital energy of the
brain, nerves, stomach,  muscles and all  other parts of
the body, is maintained by the successive additions of
neAV matter, which no sooner unites Avith the different
tissues, than it  begins to die;—that when the caloric
by which the particles of arterial blood are united with
the solids, is expended  by their action, their vital at-
traction begins  to diminish;—that  no healthy indivi-
dual preserves  his  absolute identity for a single mo-
ment;—that  every part of the  body is in a state of
perpetual  motion, and transition  from life to death, of
organization  and disorganization, renovation and dis-
solution;—that whenever the worn-out particles are
not replaced by new and living  ones, emaciation en-
sues and  all the powers of life decay;—in short, that
whenever the process  of nutrition is arrested, death
 speedily closes the scene.             ^         _
    It has been repeated an hundred times by different
 physiologists, that the  affinities of  life are superior to 
620          THEORY OF VITAL ATTRACTION.
those of dead matter.*   That this is actually the case,
would  appear from the rapidity with Avhich  birds and
mammalia convert the constituents of dead matter into
blood and their respective tissues;  and from the fact,
that  a  strong man has been known to lift about ten
times his own A\Teight from the  ground, in opposition
to the  force  of gravity,—while  the cohesion  or con-
tractility of  a living muscle is about ten times that of
a dead one, cceteris paribus.^  But I have shown that
  * It is also maintained by nearly all physiologists, that the cause
of vital  action is different from that of chemical affinity, cohesion,
&c. because we cannot combine the elements of oxygen, hydrogen,
carbon and nitrogen, so as to form the proximate constituents of
organized bodies.  But Liebig informs us, in his late excellent work
on the Application of  Organic  Chemistry to Agriculture, that
urea, allantoin, formic acid  and  oxalic  acid, which are products of
vital action, have been formed out of the body by chemical action.
I have shown, however, that the principal difference between the
operations of ordinary chemistry and those of life is, that the latter
are more complex.   They are also more energetic and exalted in
animals than in plants, because in the former the  organizing prin-
ciple is continually renewed. The truth is, that we cannot combine
the elements of oxygen and  hydrogen together, so as to form water,
any more than we can form blood,  or any other organized sub-
stance, but only bring the materials of which they are composed
together, while nature performs the rest.
  f  The manner  in which the  contractile power of a muscle is
maintained by the perpetual influx of arterial blood, and diminished
by cutting  off the supply, may be partially illustrated by the me-
chanical process of moistening a dry rope with water,  which causes
it to  contract with such force as to raise an immense weight from
the ground, until the water is expended, when the weight descends.
The reason of which is, that the particles of the rope have a stronger
attraction for those of water than for each other without the inter-
vention of a liquid.  And  such is the vast force with which water 
THEORY OF VITAL AFFINITY.
621
this poiuer depends on the rapidity with which the com-
position of the part is renewed by fresh arterial blood,
and is in proportion to the amount of caloric that passes
through it from the lungs in a given time.   For exam-
ple, it  is because  more  caloric  is received from the
atmosphere, and more blood generated in the lungs, of
warm than of cold-blooded animals, that  the  compo-
sition of the former  is  renewed more rapidly, their
organization  more highly  developed, their powers of
resisting the ordinary forces of affinity much greater;
and it  is because  the nutritive process is  more  rapid
in birds than in mammalia, that the muscular power
of the former so greatly exceeds that of the latter.
    So long as  any part  of the body is supplied with
 good arterial blood, and Avith a copious Aoav of animal
 heat, by which its particles are united with the solids,
 and  kept in  a state of perpetual motion, chemical de-
 composition  is prevented.  Nor can the blood  undergo
 coagulation while in this state of motion and perpetual
 renovation.   But whenever the process of nutrition is
 greatly diminished, as in scurvy, typhus, yelloAV fever
 and  other malignant diseases termed putrid, chemical
combines with dry wood, that by introducing dry wedges into the
crevices of huge rocks, and keeping them moist, these may be rea-
dily split open.  Humboldt, Cuvier and some other physiologists,
have maintained, that muscular contractility is generated by the
perpetual coagulation of fibrin.  And it must be confessed, that
this explanation is a very near approximation to the truth; for it
certainly does depend on the union of fibrin with  the muscular
tissue, during which it becomes solid, as in the process of coagula-
tion  ' But they seem not to have had the slightest suspicion that
caloric is the cause of both coagulation and nutrition; nor that the
cohesive power of all the organs is diminished by its expenditure. 
622           THEORY OF VITAL  COHESION.
action commences, even before the entire extinction of
vitality.*   If then it  be true, that the vlt<d force  of
animals in health, and  their power of resisting the laws
of dead matter, be in proportion to  the  quantity of ca-
loric that unites with their tissues, what shall Ave say of
those  physiologists who  have written so many works
on  medical science, without  even  attempting  to ex-
plain the office of heat in the economy of life, or what
the blood receives while passing through  the  lungs,
and Avhat it loses while  circulating  through the ulti-
mate tissues of the body?
  The wonderful activity and flow of spirits that cha-
racterize the period of youth, are owing to the rapidity
of nutrition and growth.  Like birds, children are in
a state of perpetual  motion  during  health;  and not-
Avithstanding the smallness of their locomotive organs,
many of them  will run for hours AAithout exhaustion.
For the  same reason, the power of resisting  the vari-
  * The extravasations of blood that take place during scurvy,
the latter stages of typhus and other malignant diseases, including
the serous portion of the blood effused in dropsy, and which forms
the rice-water discharges of cholera, are owing to the broken-down
condition of the solids, and diminished cohesion of the capillary
vessels, at a time when the nutritive process is  nearly suspended.
The cold sweats that  precede death are owing to the same cause.
But Galen explains them by saying, that the innate heat is nearly
overpowered by the humours which engender the disease.  The
effusion of blood  and serum into the ventricles of the brain in
many cases of apoplexy is not the cause, but an effect of weak-
ened cohesion of the vessels, which also  constitutes the  hemor-
rhagic and dropsical diatheses.   In cases of chronic inflamma-
tion of  the brain and other organs, their texture becomes softened
in proportion as the nutritive process is diminished. 
SEVEN AGES  OF MAN.
623
ous causes of disease is greater during youth  than at
any other period of life; for it  has been ascertained,
that from the fifth to the sixteenth year, fewer deaths
occur  in  England than at any  other age.   But after
the completion of growth, or Avhen nutrition  and ab-
sorption become equal, all the functions of life  are per-
formed with less rapidity, Avhile fatigue is much sooner
induced by muscular exertion.   And as old age comes
on, the lungs diminish in volume, respiration, sangui-
fication,  circulation, secretion, nutrition and  all the
operations of life become languid, the extremities cold,
the skin dry and harsh,  the hair gray or white, the
muscles stiff, the eyes dim, the mind feeble, and "man
hastens to his long home."*
   In the  theory of nutrition Is to be sought the proximate
cause  of  all diseases, from the simplest state of inflam-
 mation to general fever, consumption,  dropsy, tetanus
 and other spasmodic affections.  For if the blood be the
 fountain of life, from which all the organs  are imme-
 diately formed, it  folloAvs, that  whatever  impairs its
 natural properties, must derange the nutritive process
 by Avhich the  healthy condition of the body  is main-
 tained.  Nor is it possible that  disease of the stomach,
  * In a fragment preserved by Philo, and ascribed to Hippo-
crates the life of man is divided into seven ages; the first of which
includes  the period of infancy, from birth to the end of seven
years; the second, or that of boyhood, extends to the  fourteenth
year;'that of adolescence to the twenty-first year; that of youth
till twenty-eight, or full development of the whole body; that of
perfect manhood until forty-nine; that of seniority until fifty-six,
when  old age commences.  (Opera Hippocratis, vol. i. p. 315.
Vander Linden edition.) 
624
THEORY OF FEVER.
brain or any other organ, could exist for any length of
time, while supplied with an abundance of good arte-
rial blood;  for if the latter be sound  and  healthy, so
must be its products.
   But if its natural condition be so far deranged, that
its power of uniting with the solids, and of maintain-
ing the various secretions, is seriously diminished, a
portion of the caloric obtained  by respiration, that is
transferred to the solids during  health, and expended
in carrying  on the various functions, is given out in
the free  state, or rather  accumulates  in the  blood,
causing a preternatural eleA^ation of temperature, and
loss of  poAver in the general system.  In other Avords,
so long as the balmy vital  heat received in the  lungs
is  employed in combining  the proximate constituents
of blood Avith the solids, and in elaborating the various
secretions, the temperature of the body remains at  the
natural standard; all the functions are performed with
healthful regularity, and  there is no  preternatural or
morbid accumulation of  heat.*  Here then is ei key to
  * Similar effects may be traced in the phenomena of nature on
a grand scale.   For example, so long as the caloric received from
the sun  is employed  in combining with water, and converting  it
into vapour, which is carried off to colder regions by winds, the
atmosphere is  kept at a moderate temperature, even during sum-
mer.   But when the atmosphere is saturated with vapour, and its
circulation ceases, as during the calm that precedes a thunder-
storm, the  earth becomes feverish, (from an  accumulation of ca-
loric, which is no longer carried off in the combined state,) and
oppressively sultry over large sandy plains, where there is no water.
Besides, a large proportion of caloric is employed in the operations
of  universal chemistry, and  the growth of  plants, without which it
would accumulate in the atmosphere in the free state, and render it
oppressively warm. 
THEORY OF FEVER.
625
the whole theory of fever, which depends essentially on a
diminution and  derangement of the formative process,
as shown by the rapid emaciation that tahes place during
its progress, and which always terminates on the restora-
tion of secretion  and nutrition.
  The truth  is, that all constitutional diseases  are
OAA^ing to some  alteration of the  blood, and derange-
ment of its vital properties, which are impaired by
whatever seriously diminishes the functions of respi-
ration, seeretion and nutrition.   If the  capillaries of
the lungs be paralyzed by the inspiration of cold air,
less  carbon and hydrogen than  usual are given off,
less animal heat evolved, the temperature of the blood
is reduced, its due arterialization prevented, its healthy
properties so far deranged, as to diminish its power of
uniting with the solids, and of maintaining the various
secretions.  The consequence of which is, a congestion
of blood in the lungs; and  if the  latter state remain
for any length of time, there is a stagnation through-
out the systemic capillaries, so long as the chill con-
tinues.  During this  state, the  transition of  caloric
from blood to the solids is greatly diminished.   But as
the  function  of respiration, though greatly impaired,
still continues to go on, the caloric thus evolved  and
imparted to the blood, gradually raises its temperature
above the natural  standard, by which  the  action of
the  heart is  augmented, until the obstruction  in the
systemic capillaries is overcome,  and the  superfluous
caloric is transferred to the solids, or carried off by the
different emunctories, when the  fever subsides.
   If the  blood be not constantly depurated  by the
elimination of  sweat, urine and  other excrementitious
                          40 
626
THEORY OF FEA'ER.
matters,  its vital properties are impaired, and  the
springs of life vitiated at the fountain head.  For ex-
ample, if there be three pounds of water exhaled from
the skin  every twenty-four hours, and perspiration be
checked  by exposure to cold, the chemical and vital
character of the blood must be more or less changed,
unless prevented by a copious flow of  urine.  ,Or  if
the amount of carbon and hydrogen exhaled from the
lungs be  greatly diminished, as during the cold stage
of all maladies, the blood is no longer renovated as in
health, but becomes grumous and dark  coloured, and
loses the power of  uniting  with the various tissues.
It has also been found, that when the kidneys are ex-
tirpated,  the animal  is seized with difficult respiration,
shivering,  fever, vomiting,  purging,  typhoid  symp-
toms, coma, and dies in from ten to thirty hours, or a
few days at most; urea is found in the  blood after
death. (Midler's Elements, p. 151.)
   What  then must be the result when nearly all the
worn-out or effete matter of the body, including  the
poisonous drugs so often introduced into it by  physi-
cians, are retained in the blood, as when the excretions
are arrested?   Has  anything noxious been absorbed
into the blood through the lungs or from the stomach ?
It must be carried off by the emunctories before health
can be restored.*  Nor is it  possible to overcome any
derangement of the  solids, and bring the system back
to its healthy state,  without following the indications

  * I once saw a well-marked fever produced in a healthy child,
six years old, by a teaspoonful of hive syrup, which was intended
to prevent  a threatened attack of croup.  The fever followed in half
an hour after the medicine was taken. 
THE VIS CONSERVATRIX NATURE.        627
of nature by restoring the action of the emunctories,
and thus improving the vital properties of the blood.
Whenever circulation and nutrition are greatly dimi-
nished in  any part of the body, its  texture  is very
soon removed  by the absorbents, causing an ulcer or
abscess, which can be restored only by the formative
process, or by the deposition of  new matter  termed
granulations, that fill up the cavity.   Has a bone been
broken or attacked with necrosis?  It can be united,
and  the loss  repaired, only by the  nutritive process.
Or has the whole body  been wasted by disease to a
mere skeleton?  It can be restored to its natural and
healthy condition only by the same process.
   The  celebrated vis  conservatrix  naturce  of Stahl,
 Gaubius, Mead, Cullen and many other authors, is only
a general term  designating the natural  action of all the
organs;  and is in proportion, to the amount of respirei-
tion, sanguification, secretion  and nutrition.  Hence it
is, that a broken bone unites much  sooner in  birds
than in mammalia,—sooner in youth  and adolescence
than in old age, and always sooner in persons of large
chestand sanguine temperament, than in such as have
a small  thorax, imperfect lungs or  feeble and phleg-
matic constitutions.   But whenever the vital proper-
ties of the blood are impaired, and  the formative pro-
cess  diminished, whether from disease of the lungs,
the  respiration of impure air, exposure to cold, over-
exertion of body or mind, imperfect nourishment, ex-
cessive  medication  or the  depressing  emotions,  the
power of resisting the various causes of disease, (the
vis conservatrix naturce,) of uniting wounds, and re-
 storing lost parts, is proportionally reduced.  Nor is it 
628
GENERAL ANALOGIES.
p>ossible that any general disease could exist so long as
the blood Is constantly renovated by respiration, and de-
purated by excretion  from the lungs, skin,  kidneys
and boAvels.  In fact, the very existence of man, like
that of the entire universe, is preserved by a continual
creation.  Nor is it unAvorthy of notice, that the forma-
tion of blood is immediately connected with the pro-
cess of combustion, by Avhich caloric is  evolved, and
all the operations of life carried on.   The process of
oxidation by which rocks,  salts and other bodies are
formed, is also one of slow combustion, by which sub-
terranean heat is evolved, A^olcanos, earthquakes and
hot springs produced, and islands, mountains and con-
tinents gradually raised from beneath the ocean.  The
decay of dead animal and vegetable matter is equally
a process of combustion, by which  new  combinations
are created.  Lastly, all artificial light and  heat are
obtained by the  same process,  which  is doubtless
the origin  of solar radiation;  so that all the opera-
tions of the  material universe are  ultimately resolv-
able into combustion, Avhich depends on the agency of
heat.
   The circulation of  arterial  blood from the  heart
throughout all parts of the animal frame is somewhat
analogous to the distribution of water from the ocean
through the atmosphere by evaporation: and the re-
turn of  the same water to the fountain whence it
sprung, by innumerable rivers, resembles  the return
of venous blood to the heart.   The deposition of sedi-
mentary rocks from a state of solution in the Avater of
lakes and seas,  is also somewhat analogous to the pro-
cess of nutrition,  by Avhich the  composition of animals 
GENERAL ANALOGIES.
629
is reneAved; while the  removal of the effete portions
of the body by absorption and  elimination, is similar
to the wearing away of mountains, hills and elevated
plains, by the corroding action .of running water and
chemical decomposition.
  If then it be true, that  the  aggregate vital  energy
of animals and the development of their whole organi-
zation, are in proportion to the quantity of caloric they
derive from the atmosphere by respiration, it must be
the cause of their  vital activity and growth.  Or if
the faculty of sensation be annihilated by the abstrac-
tion of animal heat from the nervous system, it must
be  the sentient  principle.  And  if  the  velocity of
planets through their orbits diminishes in proportion to
their distance from the sun, it is self-evident that their
lasting motions would very soon come to an  end, in
the total absence of  solar radiation.   But as their cen-
trifugal force is maintained by the perpetual radiation
of caloric from the centre toward the circumference of
the system, so is  the centripetal force by which they
are preserved in their respective orbits, maintained by
the unceasing  flow  and pressure of  the  same great
ethereal tide to the  solar fountain from which  it ema-
nates.
  Again, if it  be true, as I have demonstrated, that
the mobility and organizing power of matter are in
proportion to the quantity of caloric around its atoms,
and that these powers are diminished  by every ab-
straction of caloric, or reduction  of  temperature, it
follows, that  in the  total  absence or privation  of that
principle, (if such  a condition were possible,)  the
atoms of ponderable matter would be perfectly inert, 
630
THE PRIME MOVER.
and there could be no attraction, repulsion, contraction
and expansion of matter.
  It was nobly said by Bacon, that " the highest am-
bition  of man  should be  the discovery of some one
thing by which all others might be discovered;" and
that " science, rightly interpreted, is the knowledge of
things through their  causes."  Nor can there  be  a
rational  doubt, that a  complete knowledge of the
Prime Mover would afford  a key by which to unloose
the seals of the book of nature, and open  the gates
that lead to the inner temple of her most hidden mys-
teries.   But owing to the paralyzing influence of cus-
tom, prejudice of education and a dread of encounter-
ing the throned opinions of the world, few have had
the boldness to  inquire with unreserved freedom into
the primary cause of phenomena.   The consequence
of which has been, that the  strength of many an in-
tellectual giant has been wasted in fruitless efforts.
 
 
 
MAR 2 9  1960
 
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