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THE PHILOSOPHY
EXPERIMENTS L < "HE JJISTRY
IN TWO  VOLUMES-.
          BY JAMES  CUTBCJSH,
I'roA-ssor of Chemistry, Mineralogy, and Natural Philosophy in
      St. John's College, Pliiladelphia, President of the
          Columbian Chemical Society, &c. &c



                   VOLUME I.
        PHILADELPHIA:

PUBLISHED BY ISAAC PEIRCE,
   NO. 3, SOUTH  FOURTH STREET.
      Merritt, Printer, Watkin's-alley.
1813. 
District of Pen-i ,;,;\ama, to ?;•*'„' ;

  BE IT  REMEMBERED,  that on the fifth day of December
in the thirtv-scvenlh  year  of the  Independence of the United
States of Amelia,  A. J). 1812, ISAAC PEIRCE, of the said Dis-
trict, hath deposited in this  office, the title  of a book, the  right
whereof he claims as proprietor, in the words following, to wit:

   The  Philosophy of Experimental  Chemistry.   In  two
     volumes.   By James Cutbush, Professor  of  Chemis-
     try, Mineralogy, and Natural Philosophy in St. John's
     College,   Philadelphia, President  of  the  Columbian
      Chemical  Society, &c. life.

  In conformity to the act of the Congress of the United States,
  uitled, " An act for the encouragement  of learning, by securing
the copies of maps, charts, and books, to  the authors and proprie-
tors of such copies during the times therein mentioned.   And
also to the act, entitled, "An act supplementary to an act, entitled,
" An act for the encouragement of learning, by securing the copies
of maps, charts, and books, to the authors and proprietors of" such
copies during  the time therein mentioned," and extending the
.jenefits thereof to the arts of designing, engraving, and etching
  islurical and otlier prints."
                                       D. CALDWELL,
                         Clerk of the District of Pennsylvania 
              TO'THE







    PROFESSORS AND STCDENTS







              OF THE







UNIVERSITY OF PENNSYLVANIA,







             AND THE







  TRUSTEES OF ST. JOHN'S COLLEGE,







          THIS WORK,







           IS RESPECTFULLY DEDICATED







                        BY







                     THE AUTHOR.
 
 
CONTENTS  OF  VOLUME  I.
PART  I.
PAGt
   1
PART  II.
Of chemical affinity

Of light      -             •                            33
                       PART  III.
Of caloric      ------     54
                       PART IV.
Of the gases in general    -       -      -           -    82
Section I.   Of the preparation of oxygen gas    -    -     85
      II.   Of the preparation of carbonic acid gas     -    89
      III.   Of the preparation of gaseous oxyd of carbon    91
      IV.   Of the preparation of hydrogen gas    .     -    92
       V.  Of the preparation of sulphuretted hydrogen gas 93
      VI.  Of the  preparation  of  light  carburetted  hy-
             drogen gas       -      -      -     -      95
     VII.   Of the  preparation of heavy carburetted  hy-
             drogen  gas       -     -      -      -    97
    VIII.   Of the preparation of arseniurettedhvdrogen gas 98
      IX  Of the preparation of phosphuretted hydrogen gas 99
      X.  Of the preparation of ammoniacal gas    -     101
      XI.  Of the preparation of sulphurous acid gas  -    ib.
     XII.  Of the preparation of nitric oxyd gas     -     103
    XIII.   Of the preparation of azotic gas       -       104
    XIV.   Of the preparation of  nitrous oxyd gas    -     106
    XV.  Of the preparation of muriatic acid gas    -    108
    XVI.  Of the  preparation  of oxygenized  muriatic
             acid gas         -      ...     109
   XVII.  Of the preparation of fluoric acid gas.    -     111
                       PART V.
Of the properties of the gases        -       -            112
Section I.   Of oxygen gas    -                          112
      II.  Of carbonic acid gas      -      -      -      120
      III  Of gaseous oxyd of carbon    -     -     -     125
     IV.  Of hydrogen gas               -     -        123
      V-  Of sulphuretted hydrogen gas    -     -      136
     VI.  Of light carburetted hydrogen gas     -    -    241
    VII.  Of heavy carburetted hydrogen gas      -      144
    VIII.  Of arseniuretted hydrogen gas      •     .     146
     IX.  Of phosphuretted hydrogen gas     -     -     149
      X.   Of ammoniacal gas                  >         152
     XI.  Of sulphurous acid gas                  ♦      157
                          A  2 
CONTEXTS
Sect.XII. Of nitric oxyd gas
    XIII. Of azotic gas
    XIV. Of nitrous oxyd gas
    XV. Of muriatic acid gas
    XVI. Of oxygenized muriatic acid gas
   XVII. Of fluoric acid gas
                      PART  VI.
Of atmospheric air.

Of water
PART  VII.
Of simple combustibles
Section I.  Of carbon
      II.  Of phosphorus
      III.  Of sulphur
      IV.  Of boracium
      V.  Of hydrogen
PART  VIII.
Of alkalies
Section 1.
      II.
      III.

Of earths
Division I.
Section I.
      II.
      III.
      IV.
Division II.
Section I.
      II.
      III.
     IV.
      V.
PART  IX.
Of potash
Of soda
Of ammonia
PART  X.
 Of alkaline earths
Of lime
Of magnesia
Of ban tes
Of stroutian
 Of the earths
Of alumina
Ofyltria
Of glucina
Of zirconia
Of silica
proper
Of soaps
Section I.
      n.
     HI.
PART  XI.
          Of alkaline soaps
          Of earthy soap*
          Of metallic soaps
                      PART  XII.
Of stone ware
                      PART XIII.
Oi glass     .
                      PART XLV.
Of hydrosulphurets                '  .
 161
 169
 172
 178
 182
 193

 198

207

 224
 224
 235
 246
 253-
55.5

256
259
275
281

289
295
295
 505
 310
316
 319
319
326
328
330
332

o35
335
339
341

342

 348

 353 
INTRODUCTION.
A.LTHOUGH  there are many excellent works  on
chemistry calculated for the student as well as for the
professional chemist, yet, considering that they are
either too extensive or elementary, the idea of a work
embracing the most important matter of each, together
with all the modern discoveries and improvements of
the science, suggested itself to the author; while, there-
fore, in the formation of a book of this kind, the  lead-
ing doctrines were kept in view, he considered, that as
chemistry is a science founded wholly on facts, the sub-
ject would be the better treated in experiment, ration-
ale, and remark.
  He would not presume to point out defects in  any
 hemical  work;  as every treatise possesses merit
either in  the plan,  arrangement, number of facts, or
subject matter.  Nor would he say, that,  to the student,
this work was better calculated than any other.  It may
be remarked, however, that every department is treat-
ed with that extent which a book of this size  admits,
in order to embrace the subjects of  chemistry, as well
the practice as the rationale, in experiments, theory,
and observations.   By this means  particular  experi-
ments, either  in relation to some chemical fact, pre-
paration, characteristic property, or remarkable  phe-
nomena,  become familiar; and when they tend to any
useful application, particularly to the arts, their impor-
tance is pointed out.  The design of the work, there- 
Vlll
fore, will appear on inspection.  We have in the Eng-
lish language  several valuable and extensive works on
chemistry, besides a  number  of elementary treatises.
The works of  Thomson  and Murray do honour to
these philosophers, and  to  the  country which gave
them birth.  In the  French,  many  valuable systems
and  journals of chemistry  have appeared.   In  the
German  also,  several treatises  have been  written,
which possess an equal share of merit.
   In the  United  States, since  the introduction  of
science,  it is by no means surprising  that chemistry
should have been so zealously cultivated; as it opens
an extensive field for  contemplation and study, and as
its application to the arts  and  manufactures is impor-
tant, it promises to be of the most essential advantage
to all classes of the community.
   The well informed people of America, who happily
constitute the majority, have appreciated the value of
knowledge; and we  hope that the time will soon  ar-
rive, when chemistry will  become  a general  study
throughout the  union.  Several  original works  have,
accordingly, appeared, and some editions of European
treatises  have  been published  with revisions,  correc-
tions, and additions by our countrymen.  The Chemi-
cal and Economical Essays of  Pennington, the edition
of Chaptul enlarged by the late James Woodhouse,
M. D. professor of  chemistry in the  University  of
Pennsylvania, that of  Henry's  Chemistry by professor
Silliman, of Yale College, with some others, evince,
not only  the learning and talents of our countrymen,
but a growing taste for the encouragement of learning,
and the acquisition of chemical knowledge.  Besides
these, in  the Transactions of our societies, and in  the
Journals, or periodical works, several valuable papers
have appeared.   The genius of the medical students of
the University of Pennsylvania, in particular, has been
shown  in  a number of excellent Inaugural Disserta-
tions ; some of  which have added to the improvement
of chemical science. 
IX
     The first teacher  of  chemistry, was Dr. Benja-
  min Rush, now professor of the Institutes and Prac-
  tice of Physic, and of  Clinical Practice in the Univer-
  sity of Pennsylvania.   He may be justly  styled the
  father  of chemistry in America.   He commenced a
  course of lectures on this science in the then college
  of Philadelphia; and  although chemistry at  that day
  may be said to have been in its infancy, yet the Doctor
  did honour to the chair,  the  school, and his  country.
  We now speak of him  only as a chemist.  We do
  not mean to recount his worth, nor his talents; they
  are sufficiently known.   But we mean to say, that he
  then published a syllabus of his course, which embraced
  all the discoveries of  the time ; that he made a num-
  ber of chemical investigations, with an accurate ana-
v  lysis of the mineral waters of Bath (to the  truth of
  which  the author can attest by  his own experiments)
  as well  as of other waters; and that he made a care-
  ful analysis of Dr. Martin's celebrated cancer powder,
  an  account of which may be seen in his works.  He
  was followed in  that chair,  which  he  resigned, by
  Dr. Caspar Wistar,  now  professor of Anatomy,
  who filled  it with perfect satisfaction.  Dr. Carson
  then succeeded,  but he died, I  believe, soon  af-
  ter he  was appointed.   He was followed by Dr. Hut-
  chinson, who also gave satisfaction: to him succeed-
  ed  Dr.  Woodhouse, who,  as an  experimenter,  was
  unequalled,  and after him, the present professor, Dr.
  John Redman  Coxe, whose talents are well known.
     The advancement of chemistry in our city, as well
  us of medicine and philosophy generally, is also indebt-
  ed to other institutions.   The American Philosophical
  Society, which was formed out of two literary  societies
  that had previously existed, in the year 1769, who have
  already  published  several volumes of Transactions ;
  ihe College of  Physicians,  which was  instituted in
  1787, who have also published; the Medical Society
  formed  in  1771; the  Chemical  Society, under  the
  patronage of Doctors Seybert and Woodhouse, which
  has since been dissolved;  the Linnean Society,institut-
  ed under the presidency of the learned Dr. Benjamin 
X
   Smith Barton;  the Columbian Chemical Society,
   formed principally in 1811, by Dr. Thomas D.  Mit-
   chell, and George F.  Lehman; the  Medical Ly-
   ceum; the Academy of Natural Science, instituted by
   Dr. Jared Troost; all show  the  zeal  for  useful
   knowledge, and philosophical inquiry.
     Other institutions, for promoting literary subjects
   generally, have also been  established.
     Dr. Joseph Parrish was the first who delivered  a
   private course of chemistry in Philadelphia.   He was
   succeeded in the  same establishment by  Dr. Edward
   CuTBUsH,and the author, in the winter of 1810, and after-
   wards by the  Doctor alone.   For the  introduction  of
   popular chemistry, the citizens of Philadelphia arc also
   indebted  to Doctors  Rogers and Jones, and to Mr.
   Benjamin Tucker, who have taught  chemistry with
   much zeal and talents.
     The school establishment, formed out of the Luther-
   an congregation  of  the  church of St. John,  have,
   agreeably to their plan, instituted  several professor-
   ships, prior to the enlargement of that seminary, one
   of which, that of chemistry, mineralogy, and natural phi-
   losophy, they have conferred on the author. He is there-
   fore  engaged in delivering a course on these sciences.
   Nor  can  we in justice pass over other institutions of
   chemical science.   Thomas Cooper, Esq. professor of
   chemistry in  the college  at Carlisle, Pennsylvania,  is
   one of those to'whom we are indebted for the promo-
   tion and  cultivation of this science.   Since  the esta-
   blishment of medical schools, besides the University of
   Pennsylvania, which  reflects so much  honour on our
   country, the institution of professorships of chemistry
 ,. has formed a necessary appendage.  In the University
V  of Maryland,  Dr. De Butts, with honour to himself,
   and  credit to  the  school,  fills  the professorship.
   In Columbia  College, New-York, Dr. Stringham;
   in the College of Physicians  and  Surgeons Dr. Mac
   Nevan, and in the Medical  Institution of the same
   city,  Mr. John Griscom ; who are distinguished for
   their talents   in   the  cultivation  of  chemical sci-
   ence. 
XI
  With respect to the cultivation of science, and the
formation of the juvenile  mind, a considerable defect
has existed in the education of youth. ^ That, while the
intellect is in the act of formation, as ideas are acquired
through  the  medium of the senses, such studies or
branches of knowledge should be preferred, whose ef-
fects are the  most extensive, and whose application is
the most useful.   The  honourable Dr.  Samuel L.
Mitchill, professor of Natural  History  in the Uni-
versity of New York, in a letter whichthe author had the
honour of receiving from him, gives a preference to
the improvement of morals, and the cultivation of the
physical  and  natural  sciences, to the classical  course
of dead languages, and the fabulous zoology,  terres*
trial and celestial, with which those tongues abound.
Among these studies, as one of the  physical sciences,
the Doctor recommends chemistry.
   The improvement of education, by the  introduction
of the physical  sciences,  has within a few years been
attended to;  and since the introduction of the Pestallo-
zian system,* the  attention of the public mind has
been drawn to this laudable endeavour.   It would be
an  injustice  to  my feelings, while  on this subject,
were I to omit to mention the zeal, talents, and indus-
try of several of our countrymen in this undertaking.
The establishment of a society in this city for the pro-
motion  of a  Rational System of Education, under the
presidency of John  Goodman,  Esq. is one of those
attempts to bring about a reformation in school educa-
tion ;  and among the number who have  largely  con-
tributed  to this subject, I would mention with pleasure
the names of John Greiner and Daniel  Braeuti-
gam, whose talents and knowledge have added conside-
rably towards the improvement.

  * The  system taught by Mr. Neef appears to be a modifica-
tion of Pestallozian, if we may judge from some European publi-.
cations. 
   DESCRIPTION OF THE FRONTISPIECE.

  In order to conduct a number of experiments on a
small scale, a lamp furnace is indispensably neces-
sary.  It consists of a brass rod, fastened to a piece of
metal, furnished with rings of different diameters, and
thumb screws, to  raise or lower  the lamp and rings
when in use.   By  this furnace  evaporation, diges-
tion, solutions sublimation, distillation, and other pro-
cesses, which require a low temperature, may be per-
formed. 
THE PHILOSOPHY
of'1
EXPERIMENTAL  CHEMISTRY.
                  PART  I.

          OF CHEMICAL AFFINITY.

  Experiment  1.   If  equal  parts,  by weight,  of sul-
phur and mercury be introduced into a crucible, and in
this situation exposed to a sufficient heat;  a compound      «
will be formed, called sulphuret  of mercury.
  Experiment 2.   Mix together sulphur and potash, and
throw them into water; the  sulphur will separate.   If
the same articles be put into a crucible and melted, and
then thrown into water, the sulphur, as well as  the
potash, will he dissolved.
  'Rationale.   In the first  experiment we have an  in-
stance of chemical action, as well as of single affinity,
for the sulphur and mercury would remain separate if
heat  was not  applied.   In consequence of this agent,
they unite into an uniform whole, totally inseparable by
mechanical means, and possessing  characters distinct
from either of its constituent parts.
                        A 
                         2

   In the second experiment, the union of sulphur with
 potash is effected by heat;  for if a sulphuret was  not
 formed, no solution of the sulphur would take place.
 Hence it is, that chemical action is the consequence of
 a power, without which it could never ensue, and with
 which it always acts in unison ; this power is affinity.
   Remark.   Chemistry is a science, which has  for its
 object to discover the constituent principles of bodies,
 the result of ihc various combinations, and the laws by
 which those combinations are affected.   Its operations,
 being either analytical or synthetical, consist of  com-
 position,  or decomposition.   The laws which  govern
 chemical changes have been resolved into those  of at-
 traction or affinity.  Affinity of composition or chemical af-
finity differs from  that of  aggregation,  or  cohesion or
 corpuscular attraction, by acting upon matter of a differ-
 ent kind; or by taking place between the ultimate con-
 stituent  parts of bodies, producing by  its action, sub-
 stances possessing properties frequently very  different,
 and  sometimes contrary to those of  the  constituent
 parts.
   There are several  circumstances to  be. considered
 in these inquiries, as
   1.  In  what  manner chemical affinity takes place ;
   2.  In  what  proportion bodies are  susceptible  of
 combining;
   3. Under what conditions;
   4. With what degree of force they unite.
   These inquiries, however, will be  more fully dis-
 cussed in future.
   While the attraction of aggregation  exerts its  influ-
 ence upon large masses, chemical affinity acts precise-
 ly on the reverse.  That power which tends to preserve
 the  annual and diurnal motion  of the  earth, and the
 planets, in order, Newton demonstrated was attraction.
 This acts at sensible distances, while chemical affinity
 acts at insensible distances.
   Chemical affinity has the following character:
   1.   It acts only at insensible distances, and of course
 affects only the particles of bodies. 
3
  2.  Its force is always the same in the same particles,
but it is different in different particles.
  3.  This difference is modified  considerably by the
mass.   Consequently, in every instance in compelling the
affinities of two bodies for a tlvrd, a more feeble affinity, in
one of the two compa  ed, will be found to be compensated by
increasing its quan'tii-j.
  If A  have a greater affinity for C than B has, if the
mass of B, be greatly increased while that of A remains
unchanged, B becomes  capable  of taking part of C
from A*.  Barytes,  for instance, has a stronger affinity
than potash for muriatic acid; but, if a  combination of
baryteg and muriatic  acid, be boiled in  contact with a
large quantity of potash, the potash will detach a part
of the muriatic acid from the barytes, in direct  pro-
portion  to its quantity.    According to  Berthollet,*
the  absolute weight  of  any  body, multiplied  by  its
affinity,  constitutes its mass; and  bodies  act  not  by
their affinities, abstractly considered, but by their mass; a
larger  mass compensating a weaker affinity.   There-
fore, in the opinion of Berthollet, affinity is not elective,
according to the old doctrine of professor Bergman, and
never occasions decomposition, but only  combination.
The decompositions which take place, are attributed by
him to  other causes, such as insolubility, elasticity, 8tc.
In the old doctrine, affinity is el, ct-.ve, that is, if A has a
stronger affinity for O than  B has; and  if O  be com-
bined with B, forming a compound which we represent
by O B, A, upon being mixed with this compound, has
the  property of separating B  completely from O, and
taking  its place, so as to form a compound, O A, while
 B is entirely disengaged.   Though the observations of
 Berthollet, no doubt, are founded in truth, for which he
has the concurring testimomy of experiment, yet we
 are  inclined to believe, that some  parts of his doctrine
 require additional proof to render them perfectly ad-
 missible.

            * Researches into the Laws of Affinity. 
4
   In the experiments already given, the sulphur and
mercury unite, and form a compound differing from
either the sulphur or the mercury. This takes place by
virtue of single affinity.
   In the second  experiment,  the action  of  heat also
promotes  chemical affinity.   The  sulphur  then, is
united with the potash,  by single affinity, forming sul-
phuret of potash, a compound which is soluble in water.
Other experiments will be given hereafter.
   What is termed the laws of chemical affinity are
formed  out of a great number of facts, which are the
result of certain invariable phenomena, namely,
   1.  Chemical affinity can ensue  between a number
of bodies, simple  or compound, and unite them chemi-
cally into one whole.
   2.  The efficacy of chemical affinity is in an inverse
ratio to  that of corpuscular attraction.
   3.  The agency of chemical affinity, is influenced by
temperature; its  action is either accelerated, retarded,
prevented,  or rendered efficacious.
   4. Chemical affinity is accompanied by a change of
temperature at the instant of its action.
   5.  The agency of chemical affinity existing between
two or more bodies, may be dormant, until it is called
into action by the interposition of another body, which
frequently exerts no energy upon any of them in a se-
parate state.
   6.  The ratio of the energy of chemical affinity act-
ing between  various  bodies, is  dift'erent in different
substances.
   7.  The agency of chemical affinity, is either limited
or unlimited, in certain bodies: in other words, chemi-
cal affinity is capable  of uniting bodies in definite, or
indefinite proportions.     #
   8.  The energy of  chemical affinity  of  different
bodies,  is  modihed in proportion to  the ponderable
quantities of the bodies placed within the sphere of ac-
tion.
   It may not be  improper to  add, that Mr. Davy has
ascertained that all bodies,  which have  a chemical affi- 
5
nity fov each other, are even in opposite states of elec-
tricity, and that the natural affinities may be destroyed
or modified,  by inducing a change in the electrical
states of bodies by artificial means.
  Experiment 3.  Eight parts of bismuth, five of lead,
and three  of tin, melted in a crucible, affords an alloy
which melts at 212°.   A tea spoon formed of this me-
tal will melt in boiling water.
  Experiment 4.  Two parts of lead, three of tin, and
one of mercury, form a compound,  which melts at a
heat even less than boiling water.
  Experiment 5.  Equal parts of lead, zinc, and bismuth',
combined in  the same manner, may be kept in fusion
over a lamp.
  Rationale.  In  these experiments the  metals  have
their  capacity for caloric altered, and  produce com-
pounds, whose characteristic properties are different)
from those of their constituent parts.   They are intend-
ed to prove the truth of law 1.  Other proofs might al-
so be adduced.
  Experiment 6.  Mix together supertartrate of potasfi
with carbonate of potash, in a mortar, no action will en-
sue ;  add  warm water, and an effervescence will im-
mediately take place.
  Rationale.  This  experiment is in  proof of law 2, in.
which chemical action takes.place only on the addition
of water, which brings the particles into contact.  The
tartaric acid, of the supertartrate, unites with the potash
added, whilst the carbonic acid, of the carbonate, takes
the gaseous form.  The compound formed, is the neu-
tral tartrate of potash.   Tin and nitrate of copper will
also exhibit this law.
  Experiment 7.  Equal parts oimuriate of ammonia and
carbonate of magnesia,  mixed together with six parts of
water, and exposed to the ordinary temperature of the
atmosphere,  will  mutually decompose each other.
  Experiment 8.  But if  equal quantities of muriate of
magnesia and carbonate of ammonia be exposed to a tem-
perature of 200°  in about four parts of water, the pro-
                         A 2- 
6
 ducts will be muriate of ammonia aftd carbonati:
 of magnesia.
   Rationale.   These experiments are in proof of law 3.
 At the ordinary temperature of the atmosphere, muriate
 of ammonia and carbonate of magnesia decompose each
 other : the muriatic acid of the  muriate of ammonia,
 will pass to the magnesia, forming muriate of magnesia,
 and the carbonic  acid of the carbonate of magnesia will
 unite with the ammonia,  and form carbonate of am-
 monia.  In the second experiment, in which muriate of
 magnesia and carbonate of ammonia are concerned, the
 increment of temperature  produces a  decomposition.
 The muriatic acid of the muriate, unites with the am-
 monia of the carbonate of ammonia, and forms muriate
 of ammonia, whilst the  carbonic acid of  the carbonate,
 unites with the magnesia of the muriate of  magnesia,
 and  produces carbonate of magnesia.   Consequently,
 by an increase of temperature, the affinity of composi-
 tion is changed, and the products are muriate of am-
 monia and carbonate of magnesia. Other experiments,
 proving the same fact, will be noticed hereafter.
   Remark.  The proofs of  law 4. will be found in the
 experiments on heat.
   Experiment 9.  Mix iron filings and water together,
 no action will ensue,  but add sulphuric acid, and the
 filings will be dissolved.
   Rationale.  In this c.-.se the sulphuric acid promotes
 the chemical action.  If iron filings  were introduced
 into concentrated sulphuric acid, no action would  take
 place; but on the addition of water, a violent efferves-
 cence would result.  In the latter case, the water is the
 coni.'i i m  necessary to accelerate  the chemical action.
 As soon  as the sulphuric acid  comes in contact  with
 t?ie iron filings and water, or as soon as the  water is
 atfded to the  sulphuric acid and iron filings, decompo-
 sition commences. The oxygen of the water, oxydizes
 die metal, which  is then taken up by the acid, whilst
We hydrogen of the water is set at liberty. 
7
   Experiment 10.  Make a solution  of  silver in nitric
 acid, it will form a nitrate of silver;  to  which add
 mercury, and the silver will be precipitated.
   Experiment 11.  To the fluid of the last experiment,
 which is now a nitrate of  mercury, introduce a
 piece of sheet lead; the lead will be dissolved, and the
 mercury become precipitated.
   Experiment 12.  To the fluid of the last experiment
 which is now a nitrate of lead, introduce pieces of
 copper.   The lead will be precipitated, and the  copper
 take its place.
   Experiment 13.  To  the result of the last experi-
 ment, which is  now a nitrate of copper, immerse
 pieces of sheet iron, and the copper will be precipitated.
   Expe-riment 14.  To the fluid which  now remains,
 add zinc  in pieces, and the iron will  become precipi-
 tated.  The fluid is now a nitrate of zinc.
   Experiment 15.  If to the nitrate of zinc of the last
 experiment,  carbonate  of potash  be  added, the  zinc
 will be separated, and the potash take its place, forming
 NITRATE OF  POTASH.
   Rationale.  In all these experiments, which are in-
 tended to illustrate law 6th, we  are presented with the
 changes  which  bodies undergo from  one state to an-
 other,  when  under the operation of  chemical  action.
 Although,  agreeably  to the  old doctrine of affhuty,
 elective attraction is  the  cause of these changes, yet
 according to the theory of Berthollet there is not a
 total transfer of the base, but that  a  division is made
 between  the  two opposite attracting substances, in a
 compound  ratio  of the relative force of affinity  and
 quantity of each.
   It is plain, however, that if the doctrine of professor
 Bergman, as  it stands, be adopted, the mercury has a
 greater affinity for the nitric acid than the silver, lead
 than the  mercury, copper  than  the lead,  iron than the
 copper, zinc than the  iron, and  potash a  still stronger
 affinity.  We ought to remark, however,  that these
 affinities, with an exception to the last, are affected also
by corresponding affinities for  oxygen; for all metals. 
8
previously to solution, must be oxydized, either before
or in the act of solution: and, of course, when the metal
is precipitated, its oxygen, which was necessary to its
solution, must be transferred to the other metal, which
is to take its place.  But in the last experiment a mu-
tual decomposition ensues; the nitric acid  unites with
the potash, whilst the  carbonic acid combines with the
oxyd of zinc, which is precipitated.
   Experiment 16   Alcohol, when mixed with water, will
combine with it in any proportion.
   Remark.  This experiment is in illustration of law 7.
   Experiment 17.   Take one  ounce  of  muriatic acid,
dilute  it with water, and add by degrees some chalk, or
magnesia, either a  super muriate  or a muriate  of
lime, or magnesia, (if it be used) will be formed, ac-
cording to the quantity added.
   Remark.  When the acid will dissolve no more, it is
said to  be saturated.
   Rationale.   This is a combination of lime, or magne-
sia, with  muriatic acid :  if  a  smaller portion  than is
necessary to saturate the  acid be added, it  forms a su-
persalt; if the combination is at its maximum, the result
is a neutral salt.  If more chalk, or magnesia,  is used
than is necessary to complete the saturation, instead  of
being taken up, it will fall to the bottom.   It is on this
account, that water can dissolve only a certain quantity
of salt, spirit of wine a certain quantity of rezin, &c.
   Remark  Chemical affinity  is of  three  kinds, viz.
simple  affinity, compound  affinity, and  disposing  affinity.
That power, which tends to preserve the  component
parts of a body in union, is called by Mr. Kirwan the
quiescent affinity, and, on the  contrary,  the attraction
which tends to destroy the original compound, is called
the divellent affinity.
   Experiment 18.  Put acetate of potash into a retort,
pour muriatic acid upon  it, and apply heat; acetic
acid will be expelled.
   Experiment 19. If nitric acid be added to the  residue
of the last experiment, and heat applied, the MuaiATfc 
9
acib will be  disengaged, and the nitric acid take its
place.
  Experiment 20.   If sulphuric acid be now added, and
heat again applied, the nitric acid will  be expelled,
and the sulphuric acid remain in possession of the alkali.
  Rationale.  These changes take place in  consequence
of simple affinity, as  follows:  The acetic  acid  is
united with the potash by virtue of chemical affinity.
When it  is exposed to  heat in  contact with muriatic
acid, the  former combination is destroyed,  and a new
one, composed of muriatic acid and potash, is formed.
The potash has, therefore, a greater affinity for muriatic
acid, than it has for the acetic.   When nitric acid  is
added to the  muriate of potash, thus formed, the mu-
riatic acid in like manner is expelled, and  a nitrate  of
potash remains.  When this is treated with sulphuric
acid, the nitric acid is disengaged, and  a compound
consisting of sulphuric acid and potash  is the result.
Thus the acetate of potash,  is  finally converted into
the sulphate of potash.
  Experiment 21.   Dissolve the compound last formed
in water, and add thereto a solution of acetate  if lead, a
decomposition will take place;  on filtering  the liquor
and evaporating it, acetate of  potash (provided all
the sulphate was decomposed) will be reproduced.
  kationale.   This effect  ensues in  consequence  of
double or compound affinity,  which will be  presently
noticed;  suffice it to add, that the acetic acid is trans-
ferred from the lead to the potash.
  Experiment 22.   If into a solution of sul/ihate of am-
monia, there be poured nitric acid, no decomposition  is
produced ; but if a solution of nitrate of potash be poured
in, we obtain by evaporation two new bodies, sulphate
of potash and nitraie  of  ammonia.
  Rationale.  In this experiment,  the addition of nitrate
of potash decomposes the sulphate of ammonia, by com-
pound affinity. The sulphuric acid possessesa  stronger
affinity for the potash, than it has  for the ammonia, con-
sequently, sulphate of  potash is first formed.  The
nitric acid in its  turn  unites with the ammonia* and 
10
forms nitrate  of ammonia.   The sulphuric acid then
attracts the potash, and the nitric acid attracts the am-
monia.  As both salts  are  soluble,  they  produce no
visible phenomena;  but on  evaporation,  the  laws of
crystallization separates them in separate states.
  Experiment 23.  If into a solution of sulphate of zinc,
a piece of lead be immersed, no effect will follow ;  but
if to a solution  of sulphate of zinc, acetate of lead in
solution be  added, an  immediate decomposition will
result, and one of the products be precipitated.
  Rationale. In  this  case the sulphuric acid of the sul-
phate of  zinc  passes to the  lead, for which it has an
affinity, while the acetic acid of the acetate  of lead
unites with the zinc,  and constitutes the  acetate of
zinc, which remains in solution.       •
  The following scheme will exhibit the changes that
occur in this experiment :
                    Acetate of Zinc.
                _______________A
Sulphate of   C z[nc and      Acetic acid  | acetate
zinc, consist-  < SuI  h  add    and lead     ^ of lead .
mg of        L___l_______v__________J
                    Sulphate of Lead.
  The original compounds are included in  the vertical
brackets; and the horizontal brackets points out the
new ones, viz.  acetate of zinc  and  sulphate  of lead.
The  point of the bracket turning  upwards  denotes
that the acetate  of  zinc remains in  solution; and, by
that of the lower one  being directed  downwards, it  is
meant to express, that the sulphate of lead falls  down,
or is precipitated.
  As it respects the opinions of Berthollet on the sub-
ject of double affinity,  it  appears that it is equally in-
fluenced by the circumstance of ejuantity, with those of
single affinity.
   Experiment 24.  Add the solutions of sulphate  of soda
and nitrate  of lime  together, a mutual  decomposition
will ensue.
   Rationale.   In this  case, as in the  former, a double
exchange of principle  takes place: the sulphuric  acid. 
11
passes to the  lime, forming sulphate of lime, and the
nitric acid passes to the soda, and produces nitrate of
soda.
  Remark.  In order to shew in what manner the terms
quiescent and divtllent affinities arc applied, and, conse-
quently, the force of attraction, (provided the theory
be true, which however has been modified) let vis in-
troduce the following diagram.
 Original Compound.
________A__________
Soda
Result.  J 7 Divellent
Nitrate^
of soda.
8  Sulphuric acid
Attractions g £ 13
  Result.
[Sulphate
i  of lime.
Nitric  acid  ^
Lime.
"V-
                 Original Compound.
                  Nitrate" of Lime.
  If, to separate the acid from  the  soda, we add some
lime, in order to make it  combine with the acid, we
shall fail in our attempt, because the soda and the  sul-
phuric acid attract each other by  a force, which is (by
way of supposition)  represented by the number  8 ;
while the lime tends to unite w ith this acid by an affinity
equal only to the number 6.   It is plain, therefore, that
the sulphate of  soda  will not be decomposed,  since a
force equal to 8 can not be overcome by a force equal
only to 6.  Again, if we attempt to decompose the salt
by nitric acid, which tends  to  combine with soda, we
shall be  also  unsuccessful, as  nitric  acid unites with
the alkali by a force equal  only to T. But, if nitrate 
12
 of lime be added, the constituents of which arc united
 by a power equal to 4, a decomposition will ensue; be-
 cause the numbers 8 and 4 shew, that  the sum is less
 than 8 and 6, which represent the degrees of affinity of
 the two new compounds, that will  in consequence be
 formed.
   Experiment  25.  Pour a little water into a vial con-
 taining about an ounce of olive  oil, and shake them to-
 gether, no union will take place ; but if caustic potash
 be now added, and the vial shaken, a combination will
 be formed.
   Rationale. In  this  case the alkali promotes the union
 of the oil and water, serving as a bond as it were between
 the two ; the compound, thus formed, is the soap ok
 potash, or soft  soap.
   Remark.  This effect is produced by disposing affinity,
 in which two  bodies, having  no tendency to unite of
 themselves, combine  in consequence of the addition of
 a third substance.  If to the compound, so formed, an
 acid be added, the disposing affinity  is destroyed, be-
 cause the acid and alkali unite,  and  the oil and water
 are separated.
   Experiment 26.  Proceed as in the last experiment,but
 with the addition of caustic soda, the compound result-
 ing therefrom will be of a firmer consistence, and, if
 exposed to the air, will  gradually become hard, form-
 ing the soap of  soda, or hard soap.
   Rationale.  The same affinity takes place in this  as in
 the other experiment.
   Experiment  27.  Pour oil on water, no  union will
 ensue; but add liquid ammonia, and the oil will become
united with the water, as in the former experiments,
 forming the soap of  ammonia, or volatile liniment.
   Rationale.  The same as the preceding.
   It may not  be improper in this place to offer some
remarks  on affinity as it  respects gases,  liquids, and
solids.
   The mutual  mixture, which some of the gases exhi-
bit when brought into contact with each other, is similar
to what happens  when liquids are mixed together.  Mr, 
13
©alton observes, that this effect is owing entirely to the
difference between the size of the particles of different
gases.  Several  gases  again,  when  mingled  together
lose their former state of existence,  and new  products
possessing peculiar  properties  are   generated.   The
following are examples of this kind.

                                       Products.
~         -iv              C nitrous acid.
Oxyeren with nitrous eas      <  .       . ,
   ;&               °        £ nitric acid.
                 f~vapour       liquid ammonia.
                 j muriatic acid  muriate of ammonia.
 ,       .    .,   J fluoric acid   fluate of ammonia.
Ammonia with <    ,   •    • ,    .       c
                 j carbonic acid  carbonate ot ammonia.
                 | sulphuretted  hydrosuiphuretof am-
                 L_   hydrogen     monia.
   Other gases are united only  under  particular cir-
cumstances, as by co nbustion, passing them through a
red heat,or by the electric shock.  Amo.ig these are,

                                      Products.
               "hydrogen       water
                di'ionic oxyd  carbonic acid.
                azote           nitric acid.
                muriatic acid   oxvmuriat'c  acid.'
Oxviren with J        ■ •      ,  •           •  •
   Jb         j oxymunatic     hyperoxymunatic
                  acid            acid.
                sulphurous acid  sulphuric acid.
                r.itrous oxyd    nitric acid.
   When  gaseous bodies  unite, they unite  either in
equal bulks of each, or two  or three p«rts by bulk of
one, unite with one part by  bulk of  the oilier, as  ap-
pears from the following table.

Compounds.                   Constituents by bulk.
Muriate of ammonia    100 ammoniacal    100 nuir. acid gas
Carbonate of ammonia  100 do.           100 carb. acid gas
Snbca'bonate of ammo.  100 do.           50 do.
Water               10) K; drog-en gas  50 oxygen
Nitrous nxvd         K0 azotic gas     50 do.
Nitnc oxyd           100 do.           50. do.
                         B 
14
Compounds.

Nitric acid
Nitric acid
Ammonia
Sulphuric acid
Oxymuriatic acid gas
Carbonic acid
       Constituents by bulk.

100 azotic gas     200 oxygen
200 nitrous gas    100 do-
100 azotic gas     300 hydrogen
100sulphurous acid 50 oxygen
300 muriatic do.   100 do.
100 carbonic oxyd 50 do.
  Some gases have the property of mutually  decom-
posing each other, as
Oxygen with phosphuretted hydrogen.
                       "ammonia.
                        phosphuretted hydrogen.
                        hydrogen.
                        carburetted hydrogen.
Oxymuriatic acid with <| carbonic oxyd.
                        olefiant gas.
                        sulphuretted hydrogen.
                        sulphurous acid.
                        nitrous gas
                            C nitrous gas.
Sulphuretted hydrogen with ^ sulphurous acid>

  On the contrary, in some, decomposition is  effected
by combustion ; of this description we may reckon
              f sulphuretted hydrogen.
              j carburetted hydrogen.
             ■^ olefiant gas.
                vapour of ether.
                alcohol.
                    'hydrogen.
                    phosphuretted  hydrogen.
                    sulphuretted hydrogen.
            ,   . ,   ) carbonic oxyd.
Nitrous oxyd with <^ carburctted hydrogen.
                   j olefiant gas.
                   | vapour of ether.
                   ^alcohol.
„t-   •      j  -.,    ^ hydrogen.
Nitric oxyd with    i   t .         -j
x         '          I sulphurous acid.
 ,  ,       . ,   C sulphurous acid.
Hydrogen with  ^ carDonic acid.
Oxygen with 
15
                      f carburetted hydrogen.
Vapour of water with ■< olefiant gas.
                      (_ muriatic acid
  As it respects the combination of gases with water,
it appears that Mr.  Dalton has made a happy generali-
zation of his experiments, in  which he conceives that
the degree of absorption of the following gases  is in
this order, namely,  of
Carbonic acid         "j  watgr absorbs its own  bulk
Sulphuretted hydrogen V       _,
Nitrous oxyd          J       lJ
Olefiant gas                l-8th its bulk = ^
Nitrous gas              "j
Oxygen gas              !  water  absorbs l-27th =
Phosphuretted hydrogen  f    -^
Carburetted hydrogen     J
Azotic gas     ~\
Hydrogen     y water absorbs l-65th  = Jj
Carbonic oxyd  J .
   Combination of a gas with water, according to the
experiments of Dr. Henry, may be  facilitated by  pres-
sure, and in  this way water may be  made to absorb any
quantity of a gas whatever.  The following table  will
shew the  bulk  of  each gas  absorbed  by one ounce
measure of water.   It must be observed, however, that
as the temperature  increases, the absorbability of the
gases by water diminishes.
       Oxymuriatic acid           1.5  +
       Sulphurous acid            3.3
       Fluoric acid                175 -f
       Muriatic acid               516
       Ammoniacal gas            780
  As an increase of bulk ensues, when a cubic inch of
water is saturated with  these gases,  the  following  table
will exhibit  the magnitude of water when thus  satu-
rated, supposing the original bulk to have been 1.
                ("oxymuriatic acid   1.002 -j-
0 .   .  ,   . ,   j  sulphurous acid     1.040
Saturated  with  <^    v.  ■    ..       . „nr.
                j  muriatic acid       1.500
                ^ammoniacal        1.666 
16
   It appears, therefore, that the water undergoes an
 expansion, so that the density of the gases absorbed is
 not so considerable as what would be supposed.
   The  i\ul  densities  of these gases in water, in the
 order above  named, are as follow:
              1.5
             31.7 — 33 nearly
           344.0 = 73
           468.0 = 83
   A number of other circumstances, on the affinity of
 gases with water, with each other,  Sec. will be  consi-
 dered hereafter.
   As to the  combination of liquids with  each other;
 some liquids will mix, and of  course  combine in any
 proportions,  as
                         {alcohol. ,^,
                         nitric acid.
                         sulphuric acid.
           Alcohol with ether.                      l
           Sulphuric acid with  nitric acid.         J
                             {petroleum.
                             volatile oils.
                             fixed oils.
           Volatile oils with  J P«~«eum.
                              ( volatile oils.
   When these liquids are mixed they form a homoge-
neous compound.  An evolution of heat, consequently
a certain degree of condensation takes place on mix-
ture.
   Other liquids, again,  unite only in  certain  propor-
tions, as
                       f ether.
           Water with < volatile oils.
                       (oxymuriate of tin.
                         f volatile oils.
           Alcohol with -i petroleum.
                         (jmosphuret of  sulphur.
           Ether with 5 vo,ali!e °Us;
                       £ petroleum, Sec. 
17
  Of the liquids, which do not combine in any sensible
degree, are
                      f petroleum.
           Water and < fixed oils.
                      (_supersulphuretted-hydrogen.

           Fixed oils and  J^er^&c.
  As it respects the combination of solids, the follow-
ing table will exhibit some substances which will unite
with  each  other in any proportion whatever, by the
agency of heat:
  Sulphur with phosphorus.
  Carbon with iron.
  Metals with most metals.
  Protoxyd of antimony with sulphuret of antimony.
  Earths with earths.
  Earths with some metallic oxyds.
  Some earths with fixed alkalies.
  Fixed alkalies with solid oils.
  Solid oils with each other and with bitumen.
  Other bodies, however, combine only in determinate
proportions, as
                         ("metals.
           „ . ,     • t  j some metallic oxyds.
           Sulphur with <j earths

                         Infixed alkalies.
                            f carbon.
           Phosphorus with <  metals.
                            (^ some earths.
                       f alkalies.
            Acids with ■< earths.
                       ^metallic oxyds.
  On the combination of acids with alkalies, earths and
metallic oxyds, a  vast number  of experiments have
been made, in  order to ascertain  the  proportion in
which their constituents combine.
  In the following table,  which exhibits the general
results of these experiments, the  numbers  represent
the weight of the different at ids and bases, which neu-
tralize each other respectively:
                        B 2 
18
Acids.			
Sulphurous	50	Barytes	63
Oxalic	39.5	Strontian	. 37
Nitric	34	Potash	38
Sulphuric	31	Soda	23.3
Phosphoric	22	Lime	21.8
Muriatic	18	Magnesia	17.6
Carbonic	16.5	Ammonia	9.00
Phosphorous	16		
  Suppose, for instance, that a combination  of sulphuric
acid and soda is to be formed; it is evident, from the
table, that 23.3 parts of soda added to 31 of sulphuric
acid will saturate each other.
  I have before  observed, that the doctrine of  elective
attractions, on which the  whole system of Bergman
is founded, has been considerably modified by the ex-
periments and observations of  Berthollet, and accord-
ingly a new system framed.  All those cases of chemi-
cal affinity,  which  either  really or apparently contra-
dict the general laws, which are called einomalies, may
be reduced to two classes ; viz. those depending on the
variable force of affinity itself, and those occasioned by
the action of opposite attractions.  We have already
illustrated this position by experiment.
   As the tables of chemical decompositions, commonly
called tables of affinity, may prove useful, we shall here
insert them with some corrections.
■& 
19
TABLES OF SIMPLE AFFINITY, OR  CHEMI-
           CAL DECOMPOSITIONS.
  Oxygen.
Carbon^
Charcoal,
Manganese,
Zinc,
Iron,
Tin,
Antimony,
Hydrogen,
  Oxygen.*
Titanium,
Manganese
Zinc,
Iron,
Tin,
Uranium,
Molybdenum,
Tungsten,
   Carbon.
Oxygen,
Iron,
Hydrogen.
  Nitrogen.
Oxygen,
Sulphur,
Phosphorus,
Hydrogen.
Phosphorus, Cobalt,
Sulphur,
Arsenic,
Nitrogen,
Nickel,
Cobalt,
Copper,
Bismuth,
Caloric,
Mercury,
Silver,
Oxyd of ar-
  senic,
Nitric oxyd,
Gold,
Platinum,
Carbonic ox-
  yd,
Muriatic acid,
White oxyd
  of Mangan-
  ese,
White oxyd
  of Lead.
Antimony,
Nickel,
Arsenic,
Chromum,
Bismuth,
Lead,
Copper,
Tellurium,
Platinum,
Mercury,
Silver,
Gold.
  * Vauquelin's Table of the affinity of the metals for oxygen,
according to the dimculty with which their oxyds are decom-
posed by heat. 
20
TABLES O? SIMPLE AFFINITY CONTINUE*.
Hydrogen.	Sulphur.	Potass, Soda, and
	Phosphorus.	Ammonia.
Oxygen,	Potass,	Acids. Suphuric.
Sulphur,	Soda,	— Nitric,
Carbon,	Iron,	— Muriatic,
Phosphorus,	Copper,	— Phosphoric,
Nitrogen.	Tin,	— Fluoric,
	Lead,	— Oxalic,
	Silver,	—- Tartarous,
	Bismuth,	—• Arsenic,
	Antimony,	— Succinic,
	Mercury,	— Citric,
	Arsenic,	— Lactic,
	Molybdenum.	— Benzoic, — Sulphurous, — Acetous, — Mucous, — Boracic, — Nitrous, — Carbonic, — Prussic, Oil, Water, Sulphur.
Baryta.	Strontia.	Lime.
Acids Sulphuric	, Acids. Sulphuric	Acids. Oxalic,
— Oxalic,	— Phcsphoric,	— Sulphuric,
— Succinic,	— Oxalic,	— Tartarous,
— Fluoric,	— Tartarous,	— Succinic,
— Phosphoric,	— Fluoric,	— Phosphoric,
— Mucous,	— Nitric,	— Mucous,
— Nitric,	— Muriatic,	— Nitric,
— Muriatic,	— -uccinic,	— Muriatic,
— Suberic,	— Acetous,	— Suberic,
— Citric,	— Arsenic,	■— Fluoric,
— Tartarous,	-— Boracic,	— Arsenic,
 
21
TABLES OF SIMPLE AFFINITY CONTINUE©.
     Bary'a.
Ac'ds.  Arsenic,
 — Lactic,
 — Benzoic,
 — Acetous,
 — Boracic,
 — Sulphurous,
 — Nitrous,
 — Carbonic,
 — Prussic,
Sulphur,
Phosphorus,
Water,
Fixed  oil.
    Magn°sia.
Acids. Oxalic,
 —  Phosphoric,
 —  Sulphuric,
 —  Fluoric,
 —  Arsenic,
 —  Mucous,
 —  Succinic,
 —  Nitric,
 —  Muriatic,
 —  Tartarous,
 —  Citric,
 —  Malic,
 —  Lactic,
 —  Benzoic,
 —  Acetous,
 —  Boracic,
 —  Sulphurous,
 —  Nitrous,
 —  Carbonic,
 —  Prussic,
Sulphur.
     Strontia.
Aciel.s. Carbonic,
Water.
      Lime.
Acids. Lactic,
 — Citric,
 — M.lic,
 — Benzoic,
 — Acetous,
 — Boracic,
 — Sulphurous,
 — Nitrous,
 — Carbonic,
 — Prussic,
Sulphur,
Phosphorus,
Water,
Fixed  oil.
    Alumina.           Silica.
Acids  Sulphuric, Fluoric acid,
 — Nitric,      Potass.
 ■— Muriatic,
 — Oxalic,
 — Arsenic,
 — Fluoric,
 — Tartarous,
 — Succinic,
 — Mucous,
 — Citric,
 — Phosphoric,
 — Lactic,
 — Benzoic,
 —  Acetous,
 — Boracic,
 — Su.phurous,
 — Nitrous,
 __ Carbonic,
 __ Prussic. 
22
TABLES Of SIMPLE AFFINITY CONTINUED.
 Ox. of Platinum.
 ------ Gold.
Ether. Gallic acid
Muriatic,
Nitric,
Sulphuric,
Arsenic,
Fluoric,
Tartarous,
Phosphoric,
Oxalic,
Citric,
Acetous,
Succinic,
Prussic,
Carbonic.
Ox. of Silver.   Ox. of Mercu y.
Ammonia,
 Oxyd of Lead.
Gallic,
Sulphuric,
Mucous,
Oxalic,
Arsenic,
Tartarous,
Phosphoric,
Muriatic,
Sulphurous,
Suberic,
Nitric,
Fluoric,
Citric,
Gallic acid,
Muriatic,
Oxalic,
Sulphuric,
Mucous,
Phosphoric,
Sulpiiurous,
Nitric,
Arsenic,
Fluoric,
Tatarous,
Citric,
Lactic,
Succinic,
■ Acetous,
Prussic
Carbonic,
Ammonia.
 Oxyd of Copper.
Gallic,
Oxalic,
Tartarous,
Muriatic,
Sulphuric,
Mucous,
Nitric,
Arsenic,
Phosphoric,
Succinic,
Fluoric,
Citric,
Lactic,
 Gallic acid,
 Muriatic,
 Oxalic,
 Succinic,
 Arsenic,
 Phosphoric,
 Sulphuric,
 Mucous,
 Tatarous,
 Citric,
 Malic,
 Sulphurous,
 Nitric,
 Fluoric,
 Acetous,
 Benzoic,
 Boracic,
- Prussic,
 Carbonic,

   Oxyd of Arsenic.
 Gallic,
 Muriatic,
 Oxalic,
 Sulphuric,
 Nitric,
 Tartarous,
 Phosphoric,
 Fluoric,
 Succinic,
 Citric,
 Acetous,
 Prussic,
  • Omitting the oxalic, citric, succinic, and carbonic, and add-
in % sulphuretted hydrogen after ammonia. 
23
TABLES OF SIMPLE AFFINITY CONTINUES.
  Oxyd of Lead.   Oxyd of Copper.   Ox. of A'senic.
Malic,           Acetous,         Fixed alkalies,
Succinic,        Boracic,--------------
Lactic,           Prussic,          Ammonia,
Acetous,        Carbonic,---------■■"'
Benzoic,--------------Fixed  oils,
Boracic,         Fixed alkalies,---------.......
Prussic,---------------Water.
Carbonic,        Ammonia,
Fixed  oils,      Fixed oils.
Ammonia.

 Ox. of Iron.
Ether  Gallic,
Oxalic,
Tartarous,
Camphoric,
Sulphuric,
Mucous,
Muriatic,
Nitric,
Phosphoric,
Arsenic,
Fluoric,
Succinic,
Citric,
Lactic,
Acetous,
Boracic,
Prussic,
Carbonic.
 Ox. of Tin*
Gallic,
Muriatic,
Sulphuric,
Oxalic,
Tartarous,
Arsenic,
Phosphoric,
Nitric,
Succinic,
Fluoric,
Mucous,
Citric,
Lactic,
Acetous,
Boracic,
Prussic,

Ammonia.
 Ox. of Zinc.
Gallic,
Oxalic,
Sulphuric,
Muriatic,
Mucous,
Nitric,
Tartarous,
Phosphoric,
Citric,
Succinic,
Fluoric,
Arsenic,
Lactic,
Acetous,
Boracic,
Prussic,
Carbonic,

Fixed  alka-
   lies,
Ammonia.
 Ox. of Ant.
Gallic,
Muriatic,
Benzoic,
Oxalic,
Sulphuric,
Nitric,
Tartarous,
Mucous,
Phosphoric,
Citric,
Succinic,
Fluoric,
Arsenic,
Lactic,
Acetous,
Boracic,
Prussic,

Fixed  alka-
  lies,
Ammonia.
• Bergman places the tartarous before the muriatic. 
24
      TABLES  OF SIMPLE A
Sulphuric acid. Sulphurous acid
  Prussic*       Succinic^
FFINITY CONTINUED.
. Phns.phoric acid. Phosphorous
Baryta,
Strontia,
Potass,
Soda,
Li:<ie,
Magnesia,
Ammonia,
Gluci: a,
Gadolina,
Alumina,
Zirconia,
Metallic ox-
  yds.
Baryta,
Lime,
Potass,
Soda,
Strontia,
Magnesia,
Ammonia,
Glucina,
Alumina,
Zirconia,
Metallic ox-
  yds.
 Ca.honici
Baryta,
Strontia,
Lime,
Potass,
Soda,
Ammonia,
Magnesia,
Glucina,
Alumina,
Zirconia,
Metallic ox-
  yds,
Silica,
   acid.
Lime,
Baryta,
Strontia,
Potass,
Soda,
Ammonia,
Glucina,
Alumina,
Zirconia,
Metallic ox-
  yds.
              Fluoric Acid.
Nitric Acid.  Boracic —||
Muriatic—.§  Arsenic —■*$
              'Eungstic —.
Baryta,
Potass,
Soda,
Strontia,
Lime,
Magnesia,
Ammonia,
Glucina,
Alumina,
Zirconia,
Metallic ox-
   yds.
Lime,
Baryta,
Strontia,
Magnesia,
Potass,
Soda,
Ammonia,
Glucina,
Alumina,
Zirconia,
Silica.
Acetous Acid. Oxalic Acid.
Lactic    —. Tar tar os—.
Suberic •—.** Citric  —.ft
              Lime,
              Baryta,
              Strontia,
              Magnesia,
Baryta,
Potass,
Soda,
Strontia,
Lime,
Ammonia,
Magnesia,
Metahic ox
   yds,
Glucina,
Alumina,
Zirconia.
Potass,
Soda,
Ammonia,
Alumina,
Metallic ox-
  yds,
Water,
Alcohol.
  • "With the omission of all after ammonia.
  | Ammonia should come before magnesia, and strontia, gluci-
na and zirconia should be  omitted
  + Magnesia should stand above  ammonia, and alumina and si-
lica shouid be omitted.
  § Ammonia should stand above magnesia.
  || Silica should be  omitted, and instead of it water and alcohol
be inse.-ted.
  ^f Kxri-pt silica
  **  With the omission of strontia, metallic  oxyds, glucina and
zirconia.
  f\ Zirconia after 
^J
       lABLES OK SIMPLE AFFINITY CONTINUED.

  H nzoic  Cam'tiioric .,.   , ~.,   ,,  ,  ,  Sulphuretted
   Arid.      Acid.    h:xed0ll<  -Alcohol.   Hydrogen.
White ox-Lime,     Lime,     Water,    Baryta,
 yd of ar- Potass,     Baryta,    Ether,    Potass,
 senic,    Soda,      Potass,    Volatile   Soda,
Potass,    Baryta,     Soda,       oil,      Lime,
Soda,     Ammonia, Magnesia, Alkal. sul- Ammonia,
Ammonia, Alumina,  Oxyd   of  phurets  Magnesia,
Baryta,    Magnesia,  Mercury,          Zirconia,
Lime,               Other me-
Magnesia,            tallic ox-
Alumina,             yds,
                     Alumina,

  As the tables  of  affinity stand, it is obvious  that in
the case  of sulphuric acid,  either zirconia,  alumina,
ammonia, magnesia,  or  lime will decompose the me-
(allic salts, in which, according to  Bergman, the elec-
tive attraction is stronger for the acid ; and if to any of
these new compounds, either soda, potash, strontia, or
barytes  is added, they  will severally decompose the
new salt or salts.
  Dr. CJren observes,*  that all attractions in the  dry
way, or by  heat, when  one substance is  separated in
the elastic form, though called simple imply a  double
affinity,  in which caloric constitutes the fourth mem-
ber, and do not  belong to simple affinity.
  For instances where muriatic acid  is  expelled from
muriate of soda, in the dry way, by means of phospho-
ric acid, he remarks that it  cannot be. called a simple,
but must be called  a  double affinity; because two new
combinations are formed, phosphate of soda and mu-
riatic acid  gas,  though in similar cases  only one sepa-
ration should take  place.  Nor is  it material whether
the  caloric be applied from without, or whether it be
already  a constituent part of one of the bodies submit-
ted to the operation.
* Gren's Chemistry.
        C 
  The cases of affinity, which  take  place  in  the  drj
way, as it is called, in which heat is  the  decomposing
power, appear to be  subject in some degree to  the
objections, on  the theory of elective attractions, given
by Berthollet.  It is unnecessary, therefore, to annex a
table of affinities by heat, as our knowledge  of these
operations  is but  partial, and  little utility can arise
from them.  One or two examples may prove useful.
  In the  preparation  of  corrosive sublimate,  a double
decomposition, by fire, takes place, as  will appear in
the following diagram.

New Compounds.   Muriate of Soda.   New Compounds.
Muriate of J Muriatic acid     Soda     / Sulphate of
mercury,  j Sulphuric acid    Mercury | soda.
                Sulphated Mercury.

  Therefore, on  exposing a  mixture of sulphate of
mercury and muriate of soda to heat,  the  sulphuric
acid quits the mercury and passes to the soda, forming
sulphate of soda, which  remains at the bottom of the
subliming vessel, whilst the  muriatic  acid unites with
the mercury, and sublimes into a muriate of mercury
Or, if an  alloy of gold and copper be exposed to heat
with sulphuret of antimony (crude antimony) a sulphu-
ret of topper, and an alloy of gold and antimony will
be produced, as follows.

New Comp.   Alloy of Gold and Copper.    .Yew Comp.

Sulphuret  j Copper    Gold       1 Alloy of  gold
of copper.   | Sulphur    Antimony  f and antimony.

             Sulphuret of Antimony.

  The following cases of mutual decomposition, which
take place either  by  simple or compound affinitv, are
extracted from Duncan's Pharmacopen. 
CASES Ol MUTUAL DECOMPOSITION.
1. FROM SIMPLE AFITNITY.
Sulphate of potass
           soda
           ammonia
           magnesia
Supersulphate of alumina
Nitrate of potass
          ammonia
Muriate  of baryta

           soda
           lime
           ammonia
Phosphate of soda
Subborate of soda
Nitrate of silver
Acetite of lead
Sulphate of mercury
Soap of potass
Soap of soda
, ith Muriate of baryta.
—  Nitrate of potass.
—  Muriate of soda.
—  Carbonate of potass.
—  Muriate of lime.
—              baryta.
—  Phosphate of soda.
—  All the sulphates and
      nitrates.
—  Carbonate of potass.
—  Subborate of soda.
—  Carbonate of potass.
—  Muriate of ammonia.
—  Carbonate of potass.
—  Muriate of soda.
—  Citrate of potass.
—  Muriate of soda.
—  Muriate of soda.
—  Sulphate  of lime.
2.  FROM COMPOUND AFFINITY.
Sulphate of baryta
Sulphate of baryta
           potass
           soda
Muriate of baryta
Muriate of lime
Phosphate of soda
Acetite of lead
Acetite of lead.
with Carbonate of potass.
 —             soda:
 — ' Muriate of lime.
 —  Muriate of lime.
 —  Phosphate of soda.
     Subborate of soda.
     Carbonate of potass.
                 soda,
                 ammonia.
 —  Carbonate of ammonia.
 —                lime.
 —  Sulphate of zinc.
 —  Nitrate of mercury. 
23
  It is to  be understood, that in the terms of mutual
decomposition from simple affinity, and mutual  decom-
sition from compound affinity, the following difference
exists.  That in simple affinity, when two bodies unite,
inconsequence of their 7mm/k«/attraction alone, whether
these bodies be themselves simple or compound, and
even  although, in the latter case,  it be attended with
decomposition, it differs from compound affinity in this
particular;  that in the latter there is  more than one
new combination, and when the new arrangement would
not have taken place, in consequence of the attraction
tending to  produce either combination singly.
  The doctrine of Berthollet has lately been called in.
question, and a system of chemical combination pro-
posed by Mr. Dalton, and also by Dr. Wollaston, found-
ed  on the opposite principle  to him, that bodies  unite
in proportions, rendered determinate by the immediate
exertion of their mutual attractions.*
  As it respects the precipitation of metals from their
solution, agreeably to the tables of affinity,  an example
of which is given in page 7, it appears that Mr. Syl-
vester has  rendered it probable, that these precipita-
tions are occasioned by the galvanic action of metals
on each other.  Volta has shown that metals  differ in
the avidity with which they absorb electricity, and that
when two  metals are placed  in contact and separated,
the one becomes plus, and the other minus electrified.
It has also  been shown, that when metals are in differ-
ent states  of electricity, and  properly  arranged, they
decompose water, and produce all the other phenome-
na of galvanism.  Mr. Sylvester, therefore, concludes,
that it is the  hydrogen  evolved that produces the re-
duction of  the metal.t  If this opinion  be correct,  the
order of affinity should be, not as it respects the metal
for oxygen, or acid, but for electricity.
  Certain  substances only can be thrown down or pre-
cipitated.   The agent that effects this change is called

  * See Murray's Supplement to the first edition of a Svstem ef
Chemistry; also Phil. Trans. 1808.
  j Nicholson's Journal, v. xiv. p. 94. 
29
a precipitant,  and the body thus separated is called a
precipitate   By precipitation the earths and metallic
oxyds, and such acids as are nearly insoluble  in water,
may be separated; while the alkalies and soluble  acids
cannot be precipitated.  When a base is  employed to
precipitate a soluble acid,  the substance  thrown  down
is always a compound consisting of the acid united to
the  base employed.   Accordingly,  the acid  is some-
times completely separated, and sometimes not, which
depends on the energy of the base employed, and  the
degree of insolubility of the salt formed.   In the case,
however, of a neutral salt being used as a precipitant,
the  precipitate is composed of one of the ingredients
of the precipitating salt, united to one ingredient of the
salt  in solution.  Therefore such salts are employed as
are known to form insoluble compounds  with the acid
or base which we wish to throw  down.  The separation
is complete when the new salt formed is completely in-
soluble.  Neutral salts perform their office much bet-
ter than either the acid or base : thus sulphate of soda
will precipitate barytes from its solution  much better
than sulphuric acid, and alkaline carbonates will throw
down the earths  with  much more facility than the al-
kalies in a pure state.  Hence it is, that this superiori-
ty is owing partly to  the  combined action of the acid
and  base.
   Dr. Thomson justly remarks, that precipitations take
place, not because the salts are insoluble in water, but
because they are insoluble in the particular solution in
which  the precipitate appears.  Now if  this solution
happens to be capable of dissolving any particular salt,
that salt will  not precipitate,  even though it be insolu-
ble  in water.  Hence  the reason why precipitates so
often disappear when there is present in the solution
an excess  of acid, of alkali,  8cc.
   Precipitation is, therefore, effected by lessening the
quantity of the solvent by evaporation, by diminishing
its powers, as by reduction of temperature, or dilution ;
or, by the addition of  some  chemical agent. In the
latter case we have seen, that the agent, or precipitant,
either combines  with  the  solvent, and  precipitates the
                          c  2 
30
\ulvend,  or forms  itself into an  insoluble compound
with some constituent of the solution.   It may not be
improper  to  enumerate a  few of the  precipitants:
Thus tartaric acid is a precipitant for potash, sulphuric
acid for barytes and strontian, oxalic acid for  lime,
phosphoric acid for magnesia, ammonia and  prussiate
of potash for yttria and glucina, hydrosulphuret of pot-
ash for zirconia, ammonia for alumina, sulphate of iron
and nitrate of  mercury for gold, muriate  of ammonia
for platinum, muriate of soda for  silver and mercury,
prussiate of mercury  for palladium,  iron for copper,
succinate of soda, prussiate  of  potash, and tincture of
galls for iron,  zinc and oxymuriate of mercury for tin,
-.ulphate of soda for lead,  carbonate of potash, 8cc. for
zinc, water and muriate of soda for bismuth, water and
hydrosulphuret of potash for antimony, water for tellu-
rium, hydrosulphurets for arsenic, nitrate of lead for
chromic acid,  prussiate of potash for uranium, muriate
■ )f barytes for sulphuric acid, nitrate of lead for sul-
phurous acid,  muriate of lime  for phosphoric, fluoric
and oxalic  acids, sulphuric acid for boracic acid, mu-
riatic acid for benzoic and suberic acid, sulphate of iron
for succinic acid, acetate  of lead  for moroxylic  acid,
acetate of  barytes for mellitic acid, potash for  tartaric
acid, acetate of lime for citric and saclactic acid, bary-
tic water and lime water for  carbonic acid, solutions of
ead for sulphuretted hydrogen, Sec.   These and other
reagents, or precipitants, will be  described  in the course
of the work, in which their application to the purposes
of analysis, or  chemical investigation, will be  particu-
larly noticed.   The combination of acids with alkalies,
earths, and metallic oxyds form salts,  which are either
soluble, partially  soluble, or insoluble. As a knowledge
of these facts are interesting,  the reader may find an
extensive  table  in Thomson's  System  of Chemistry,
vol. 3d. p.  672.
   Different salts  separate either spontaneously, or on
evaporation, according to the order of their solubility.
Those which are  insoluble, of  course precipitate, and
those which are the least soluble crystallize first when
 he solution is evaporated.   When two salts are mixed 
31
together, on evaporation and crystallization, the result-
ing salts, thus formed, are much  influenced by the
proportions of the ingredients.   One example of this
kind, extracted from Berthollet's table, will be suffi-
cient.
  Experiment 28. Mix a solution of equal parts of nitrate
of lime and sulphate of potash, a precipitate of sulphate
of lime will be formed;  on separating it by the filtre,
and evaporating the liquor, the product  of the first
evaporation will be nitrate of potash and some sul-
phate of lime ; the second evaporation will yield a little
SULPHATE OF POTASH.  But,
  Experiment 29.  If one part of nitrate  of lime and two
parts of sulphate of potash  are used, sulphate of lime
will be precipitated as before, and sulphate of lime and
nitrate  of potash will be the products of the first eva-
poration, and nitrate of potash, sulphate of potash, and
sulphate of lime, the product of the second.
  Crystallization is a species of  precipitation, in which
the parts of the solvend, on separating  from the solu-
tion,  assume certain determinate forms.   Three condi-
tions  are  necessary to crystallization, viz. that when
acted upon by the attraction of aggregation, the inte-
grant particles should have a tendency to arrange them-
selves in a determinate manner ; that they be disaggre-
gated, so far as to possess sufficient mobility to assume
their particular arrangement;  and that the causes dis-
aggregating them be  slowly and  gradually removed.
According to Mr. Hauy  there are only three forms of
;.he integrant particles.

   1. The parallelopiped.
   2. The triangular prism.
   3. The tetrahedron.
   It is by the union of  these  particles in particular
ways that  the  great diversity of crystallizations take
place.  The primitive forms have been reduced to six :

   1. The parallelopiped.
   .2. The regular tetrahedron.
   'i. The octahedron with triangular faces. 
32
   4. The six sided prism.
   5. The dodecahedron terminated by rhombs.
   6. The dodecahedron with isoscelles triangular faces.
   Bodies in the  act of crystallization always  imbibe
more or less water, which  is a  necessary constituent
of the crystal;  hence it is termed the water of crystalli-
zation.  When the  crystallized body is exposed to heat,
and frequently  to the air, it loses its water of crystalli-
zation, becomes opaque, and falls into powder.   When
a crystal undergoes this change  in the air, it is  said to
effloresce; if a  saline substance  absorbs moisture and
"hereby becomes fluid, it is said  to deliquesce. 
PART   II.
                    OF LIGHT.

   Experiment. 1.  Let  the rays of light pass through a
 hole  in a window shutter, in a darkened  room, on a
 glass  prism, placing  it parallel to the horizon, with its
 axis perpendicular, so as to receive the beam of light;
 the light will thus be decomposed into seven parts, viz.
 red, orange,  yellow, green, blue,  indigo, and
 violet.
   Rationale.   As light  consists of seven primitive co-
 lours, in this experiment it is resolved into its princi-
 ples,  in the order above stated.  As none of these rays
 can be further decomposed, and as they always produce
 the same colour,  they  are called original or primitive
 colours.   On turning the  prism slowly upon its axis,
 the refracted light  upon  the  opposite wall will first
 descend and  then  ascend between  the  ascent and de-
 scent ; that is, where the spectrum is stationary the prism
 is to be fixed. The first effect is the refraction of light, or
 the light is bent out of its original course, because,
 according to the laws of optics, the light  passes from
 one medium into another of a different density; it con-
 sequently assumes a new direction ; hence it is said to
 be refracted.  The refraction, therefore, is in the order
 of the experiment, and in passing through the prism,
 the light appears in its  primitive colours.
   Remark.  The science of optics consists of a body of
 facts, which relate to the phenomena of the movement
 of light, its  reflection and  refraction, for upon the re-
flexibility  andt refrangibility of light, is founded  the
 tt! sco/tc, microscope* spectacles, and a number of other 
34
optical instruments.  See  Adams's Philosophy, New-
ton's Optics, &c.
  The decomposition of light is the cause of many na-
tural and other phenomena.   In the rain  bow, cascades
and fountains,  if  properly situated  during the  sun's
9hining; the  halo  which sometimes  surrounds the
moon ; and the colours observed on soap bubbles, are all
occasioned  by the refrangibility  of the rays  of light.
The appearance of  the sky at certain  times  owes its
phenomena  to the  same cause.  The  rays  of light,
are refrangible in the order  in which  they appear in
the solar spectrum, the  red is the least, and the violet
ray the most refrangible.  The analysis of light  may
be accomplished in  the following manner:
  Experiment 2.  Let the light of the sun  pass through
a hole of the  T^th  of  an inch in  a dark room ; and
placing a screen at the distance of six inches within the
room, let the middlemost part of that light pass through
a smaller hole in the screen; the object of which is to
prevent, in  a  great measure, the  indefinite light, or
penumbra on the sides of the prismatic spectrum. Let
that li^ht fall perpendicularly upon a convex  lens, at
the distance of about ten feet, by which means an image
well defined of the sun will be formed upon the screen
placed at a  proper  distance from  the  lens:  but, if  a
prism be situated close to the lens, so that the light,
after having passed  through the lens, may pass through
and  be refracted by  the prism,  then  a coloured
spectrum   well  denned  will be  formed upon the
screen.
  Sir Isaac Newton  demonstrated, that  if the spectrum
be divided  into 360 parts, the rays of light would bear
the following  proportions to each  other: viz. red 45,
orange 27, yellow 48, green  60, blue 60, indigo 4J, and
violet 80.
  Experiment  3.  If the bulb of a sensible thermometer
be moved, in succession through the different coloured
rays, they will be found to  communicate the greatest
heat in the red rays, next in the green ; and so onf
in a diminishing progression, to the ^iolet. 
3.5
  Rationale.  This experiment tends to show, that heat
and light are not present, in a corresponding degree,
in different parts of the solar spectrum ;  for, generally
speaking, those rays illuminate most  that have least
heating power.  Whether this is owing to the  respec-
tive affinities of the particular ray for coloric,or whether
it be owing to its capacity for heat, or to a certain state
in which that phenomena ensues, or to any other cause,
is at present not ascertained. But certain it is, that the
experiments of Dr. Herschel have  proved, that the
rays towards the middle of the  spectrum passes the
greatest illuminating power, and those at  the extremity
the least.
  Remark.   It has been also ascertained, that there are
insensible rays which possess considerable heat; for when
the thermometer is removed entirely out of the confines
of the  red ray, but with its ball still in the line  of the
spectrum, it rises  even higher than in  the red rays, and
continues to rise till removed, half an  inch beyond the
extremity of the red ray.
  In making this experiment,  the air  thermometer
should be preferred.
  On the contrary, beyond the confines of the spectrum
on the other side, or a little beyond  the violet ray, the
thermometer is  not affected.
  It is remarkable, that there  are other rays, also invi-
sible, of a different kind, which exert edl the chemical
effects of the rays of light, and sometimes with more
power.  If muriate of silver be  exposed to these rays,
it will, like  in  the solar rays, become changed from
white  to  black.  The  rays of the prism, it must be
recollected, have this power in  a greater  or  less de-
gree.  Thus, the blue  rays  effect a change  of the
muriate  of silver  in  fifteen  seconds, which the red
requires twenty minutes to accomplish.  Hence it ap-
pears, that the solar beams  consist of  three distinct
kinds  of rays;  of those  that  excite heat and produce
oxydizement; of illuminating rays; and of deoxydizing
rays.
  Solar light, being a compound  of three distinct kind
of i ays, when exposed to the prism is decomposed, on 
:3t>
account of the difference in the refrangibility of these
rays.   The calorific rays, or those which produce heat,
are the least refrangible; the deoxydizing rays are the
most refrangible;  and the colorific rays, or those which
give colour, possess a  mean degree of refrangibility.
Hence the rays in the middle of the spectrum have the
greatest illuminating power, those beyond the red end
the greatest heating power, and those beyond the violet
end the greatest deoxydizing power; and the  heating
power on the one hand, and the deoxydizing power on
the other, gradually increase as we approach  that end of
the spectrum where the maximum of each  is concen-
trated.  Dr. Herschel found, that the heating power of
the violet,  green, and red rays are to each otlier as the
following  numbers :
    Violet = 16, green = 5C4, and red = 55.
  Phosphorus introduced into the nys beyond the red
extremity, is  heated, smokes, and emits white fumes;
but these are presently  suppressed, on  exposing it  to
the deoxydizing  rays,  which exist  beyond  the   violet
extremity.
  There has, however been some objections against the
deoxydizing theory, as there arc a few exceptions to the
doctrine ; for an account of which consult the papers of
Dr. Wollaston.
  It has been supposed, that three  of  the prismatic
colours, the red, yellow, and blue, were simple; and
that the other four formed each of the contiguous ones;
that is, the orange from the red and yellow, the green
from the yellow and blue, the indigo from the blue and
violet, and the violet from  the indigo and red.
  Colours  are all formed in the solar light;  the various
tinges resulting from the absorption of some  of the rays
of light, and the reflection  of others.*  Blue, red, and
yellow, in  dying, are the fundamental colours,- by com-
bining these, on the stuffs, rarely in the bath, the various
hues are obtained.  In  order, in the next place, to con-
sider the theory of c Jours, in the production  of various

  *  See a Theory on the Formation of Colours in the American
Philosophical Transactions, by Dr. Conover. 
bV
hues, by the mixture of colourless fluids, the following
experiments  may be adduced, which were invented by
Mr. Tielebein.
  For this purpose the  following articles are necessary.
  No. 1. A solution of acetate of lead, prepared by dis-
solving  two drams of the acetate ofleadin twelve ounces
of distilled water.
  2.  A  solution of carbonate of potash, obtained by dis-
solving  three ounces of the carbonate of potash in twelve
of water, and proceeding as before.
  3. A  solution of  corrosive muriate of mercury, consist-
ing of twenty grains of the corrosive muriate, dissolved
in twelve ounces of water.
  4.  A  solution of two ounces of sulphate  of iron  in
twelve ol water.
  5.  Acidulous  solution of sulphate of iron,  composed of
an ounce of sulphate of iron, and twelve of water, mixed
with an  ounce of the next solution, No. 6.
  6. An ounce of sulphuric acid, mingled with twelve of
water.
  7. Dissolve one dram of acetate of copper in twelve
ounces  of water, and add one dram ol nitric acid.
  8.  Concentrated liquid ammonia.
  9.  Sulphurous acid.
  10. Tincture of roses, prepared by infusing red rose
leaves in sulphurous acid.
  11. Tincture of red cabbage leaves,  prepared in the
same manner.
  12. Tincture of galls,  prepared  by digesting half an
ounce of gall-nuts  in twelve ounces of water, and add-
ing one dram of nitric acid to the filtered solution.
  13. Diluted  solution  ol prussiate of potash.
  14. One dram of  mercury  dissolved in  an ounce  of
moderately strong nitric acid, with  the addition of an
Ounce of water.
  Experiment 4.  Mix  three parts of  No.  1, acetate  of
lead, with one of No. 2, or solution of carbonate of pot-
ash, and a milk white  will be produced.
  Rationale.  The acetate of lead and carbonate of pot-
ash are  mutually decomposed;  the acetic acid unites
with the potash,  forming acetate of potash, which re-
                         D 
38
mains in solution, whilst  the carbonic acid combiner
with the lead, and forms  carbonate of lead, which is
precipitated.
  Remark.  Whiteness is always  compound; all  the
primary colours are  necessary to its constitution ;  and
its appearance is owing to a copious reflection of all the
rays of  light.
  Experiment 5.  If four parts of No. 14, nitrated  mer-
cury, and one of No. 2, or carbonate of potash, are added
together; a yellow precipitate will be formed.
  Rationale.  In this experiment the nitric acid  of  the
nitrate of mercury, unites with the  potash, forming ni-
trate of potash, which remains in solution, and the car-
bonic acid of the carbonate  of  potash, combines with
the mercury, and forms a carbonate of mercury, which
is precipitated of a yellow colour.  As the carbonate of
potash used in the experiment is, more properly, a sub-
carbonate, the mercury is precipitated with an excess
of base, forming a subcarbonate  of mercury.
  Experiment 6.  To the yellow precipitate  of the  last
experiment, add No. 6, diluted  sulphuric acid, and the
whole returns to its  limpid  state.
  Rationale.  In  this case, the  sulphuric acid decom-
poses the carbonate of mercury, carbonic acid is disen-
gaged, and the mercury is taken up.
  Experiment 7. If a few drops of No. 6, diluted sulphu-
ric  acid, be added to No. 10, or tincture of roses,  a car-
mine colour will appear.
  Rationale.  The original colour is discharged on add-
ing the diluted acid,  which takes the place of the  sul-
phurous acid, and consequently heightens the colour.
  Experiment 8.  If  to the  carmine colour, thus pro-
duced, sulphurous acid be added  in a sufficient quantity,
the colour will disappear.
  Rationale.  In this  case, the sulphurous acid  repro-
duces the original colour, in consequence  of uniting
again with  the colouring matter.    This presents us
with an additional proof of the theory of Berthollet on
chemical attraction.
  Experiment 9.   If to a few drops of No. 6, diluted
sulphuric acid, No. 11, or tincture of cabbage be  added,
a blood red colour will be formed. 
o'J
  Rationale.  On  the principle, that acids have  the
quality of heightening the colour of some vegetable
substances, as is the case with the colouring matter of
the red cabbage, the application of the tincture of cab-
bage, as  a  test for acidity is founded.   The  acid un-
questionably acts, by changing the affinities of the rays
of light  for the  colouring matter into  a  new  order,
agreeably to the theory already i oticed.
  Experiment  10.  On adding  No. 9, the liquid will
become again colourless, as in a former experiment.
  Experiment  11.  If three parts of No 10, tincture of
roses, be added to one of No. 1,  or solution of acetate of
lead, a grass green  colour will be produced.
  Rationede.  In thrs case a change in  the colour, as
well as  a  partial  change in the bodies  themselves
ensues, and the new  affinities for the rays of light  are
such, as to cause the green ray,according to Berthollet,
to be reflected to our optics.
  Experiment  12.  Add  No. 6, or diluted sulphuric acid
to the product of the last experiment, and the  mixture
will become red.
  Rationale.  Here a change again  ensues, which is
owing to the acid, and causes a corresponding change
in the rays of light, the result being the production of
a red colour.
  Experiment  13.  On adding No. 9, or sulphurous acid
to the result of the last experiment, the fluid will return
to its former limpid state.
  Rationale.  Here the  sulphurous acid  disposes  a
new arrangement of affinities for light, and the whole
is changed into a limpid state.
  Experiment  14.  If three parts of No. 11, or tincture
of red cabbage leaves be  mixed with one of No. 1, or
solution of acetate of lead, a light green will be pro-
duced.                        ^
  Rationale.  The cause  is the same as  in some of the
preceding experiments, as it respects the rays of light;
but as the  different shades of colour are produced by
the absorption of some and the reflection of other rays,
in such a manner as  to constitute those  colours, it fol-
lows, that several changes are necessary previously to 
4L>
the formation of mixed colours.  The  production of
brilliant colours, the blushing  beauties of the rose, and
the modest blue of the violet;  the pellucid stream, the
green sea, the white froth, the dark pool,  the azure  sky,
the varying colours of the pigeons' neck, the opal,  Sec.
are owing to the different refrangibility of light.  Some
rays, therefore, are absorbed, or enter into substances,
whilst others are  reflected ;  hence the diversity of co-
lours.   A red body, for instance, reflects the red rays,
while  it absorbs  the rest; a green reflects the  green
rays, and perhaps also the blue and the yellow, and ab-
sorbs the rest, &c.  Hence  also in the compound co-
lours,  in the operations of dying,  a scarlet is composed
of red and yellow, green of blue and yellow, violets, pur-
ples, and lilacs of  red and blue.*
   Experiment 15.  Mix three parts of No. 7, solution
of acetate of copper, with one of No. 8, or concentrat-
ed liquid ammonia, and an ultramarine blue will be
obtained.
   Rationale.   In  this experiment the  acetate of copper
is decomposed ;  the acetic acid unites with the ammo-
nia forming an acetate of ammonia, at the  same  time
:iii oxyd of copper is precipitated : this is then dissolv-
ed by another portion of the ammonia, and forms  am-
moniaret of copper, which is held in solution along with
the acetate of ammonia.
   Experiment 16.  If three parts of No.  11,  tincture
of red cabbage, be mixed with one of  No. 2, or solution
'f carbonate of potash, it will form  a dark blue ; and
if No. 6,  or diluted sulphuric acid be now  added, the
colour will be changed to a ruby red.
   Rationale.  The  sulphurous  acid of the  tincture
unites with a portion of the  potash, and another part of
the carbonate of  potash changes the tincture to a blue,
which is again changed to red on the addition of sul-
phuric acid, in consequence of a neutral compound of
acid and alkali being formed,  and the  excess of acid
acting on the colouring matter of the cabbage.

  * See Berthollet on Dying, and Bancroft's Philosophy 0f Co-
tours.                                        J    'v 
4 •'.
   Experiment If.   If equal quantities of No. 5, solu-
tion of sulphate of iron, and No.  13, solution of prussi-
ate of potash, be mixed, a blue colour will result, and
prussiate of iron be formed.
   Rationale.   In this case a double decomposition en-
sues ; the sulphuric acid of the sulphate ol iron unites
with the potash, forming sulphate of  potash, and the
prussic acid combines with the oxyd of iron, and forms
a blue precipitate, or prussiate of iron.
   Experiment 18.   If equal quantities of No. 7, ace-
tate  of copper, and No.  11, or tincture of red  cabbage
leaves, be added together, a violet colour will be pro-
duced.
   Rationale.   In this case  the acetate  ef  copper acts
precisely as  the acetate of lead,  except that in the
change, a violet colour js formed.
   Experiment  19.   When  three parts of No. 11, are
mixed with one of No.  4,  tincture of red cabbage, and
sulphate of iron, the result will be a pitch black co-
lour.
   Rationale.   Here the  action of sulphate of iron is dif-
ferent from that  of  acetate of lead or copper, in  as
much as the colour produced is of a perfect black.   In
this  experiment  all  the rays  of  light  are  absorbed.
From the nature of the cause, the fluid would remain
black if no body was  presented, which could change the
existing affinities of the rays of light for the colouring
matter  thus  altered. No part, or ray, of the light is
suffered to be reflected, but refracted in ; hence black-
ness is the consequence.
   Experiment 20.  Three parts of No. 12, tincture of
galls, mixed with one of No. 4, or solution  of iron% pro-
duces an ink black.  No.  6, or diluted sulphuric acid*
again renders it limpid, and  the addition of No. 13,
turns it blue. •
   Rationale.  In this experiment the gallic acid of the
tincture of  galls unites with the  iron  of the sulphate
of iron,  and  forms gallate of iron, which  is black;  on
adding sulphuric acid  this combination  is destroyed,
and  sulphate of iron reproduced, which is limpid; and
on adding prussiate of potash the sulphate is decom-
                         d 2 
42-
posed, and prussiate  of  iron formed,  which  is blue.
During these changes the rays of incidental light obey
their own laws.
  Remark.  The application of chemical tests, or re-
agents,  is founded in a great degree upon the colour
which they produce when added to liquids ;  for  the
bodies held in solution are detected by the  reagent,
only as it respects their appearance or habits when  the
particular reagent is  added.  These phenomena  are
governed by the same laws as  in the experiments al-
ready given:  hence, as the appearances  under the same
circumstances are precisely the same at all times, che-
mical  tests have  been justly called the " compass by
which the chemist steers."   Thus, if to an ore  suppos-
ed to  contain  iron, we add muriatic acid, and dissolve
it;  and add to this solution either tincture of galls, or
prussiate of potash, a black colour will  be produced in
the first case, and a blue one in the last, similar to  the
last experiment.  We infer, therefore, the existence of
iron.
  While we are on the subject of colours, it may  not
Le improper to introduce the following  table. 
43
Colour of the Precipitates thrown  down from Metallic  Solu-
               tions, by various Re-agents.
Metals.	Prussiated alkalies.	Tincture of Galls.	Water im-pregnated with Sul-phuretted Hydrogen.	Hydro-Sul-phurets.
Gold	Yellowish-white.	Solution tur-ned green. Precipitate brown of re-duced gold.	Yellow.	Yellow.
Platina	NTo precip.; but an o-range co-loured one by pruss. of mercury.	Dark-green, becoming paler.	Precipitated in a metallic state.	
Silver	White	Yellowish-brown.	Biack.	Black.
Mercury	White changing to yellow.	Orange yel-low.	Black.	Brownish-black.
Palladium	Olive.* Deep orange.+		Dark-brown.	Dark-brown.
Rhodium	No precip.			No precip.
Iridium	No precipi-tate. Colour discharged.	No precipi-tate. Co-lour of so-lutions dis-charged.		
Osmium		Puiple, changing to deep vivid blue.		
* Chenevix.                          f Wollaston. 
44
Colour of Precipitates from Metallic  Solutions, L?c.  Co:
                           tinued.  '
Metals.	Prussiated Alkalies.	Tincture of Galls.	Water im-pregnated with Sul-phuretted Hydrogen.	Hydro- Sul-phurets.
Copper	Bright red-dish-brown	Brownish.	Black.	Black.
Tl. Green , j salts. ,ron-1 2. Red I. salts.	White, changing to blue. Deep blue.	No precipi-tate. Black.	Not precipi-. tated.	Black.
Nickel	Green.	Grayish-white.	Not precipi-tated.	Black.
Tin	White.	No precip.	Brown.	Black.
Lead	White.	White.	Black.	Black.
Zinc	White.	No precip.	Yellow.	White.
Bismuth	White.	Orange	Biack.	Black.
Antimony	White.	A white ox-yd merely from dilu-tion.	Orange.	Orange Blackish. Yellow. Black
Tellurium	No precip.	Yellow.		
Arsenic	White.	Little change.	Yellow.	
Cobalt	Brownish-yellow.	Yellowish-white.	Not precipi-tated.	
Manganese	Yellowish-white.	No precip.	Not precipi-tated.	White.
H rome	Green.	Brown		Green. j
Molybdena	Brown.	Deep-arown.	Brown.	J
 
45
i'olour  of Precipitates from Metallic  Solutions, l?<;.  Coh
                       tinned.
Metals.	Prussiated Alkalies.	Tincture of Galls.	Water im-pregnated with Sul-phuretted Hydrogen.	Hydro-Sul* phurets.
Uranium	Brownish-red.	Chocolate.		Brownish-yellow.
Tungsten				
Titanium	Grass-green, with a tinge of brown.	Reddish-brown.	Not precipi-tated.	Grass-green.
Columbium	Olive.	Orange.		Chocolate.
Tantalium				
Cerium		Yellowish.		Brown, be-coming deep j^reen.
  Experiment 21.  Make a  decoction, or infusion of
madeler in water, and add a solution of alum ; the  co-
louring matter will be gradually precipitated  in the
form of a lake.
  Rationale.  The colouring matter of vegetables, be-
ing precipitated in a variety of cases, by the agency of
certain saline and metallic solutions, it follows, that in
this case the colouring matter  is precipitated in com-
bination with alumine, and forms a  lake.   The  colour
of the lake produced is owing,  as in  other cases, to the
reflection of certain rays.  If a  small quantity of potash
be added, the alumine or  earth of alum, will be sepa-
rated in a larger quantity.
  Experiment 32. If to an infusion of cochineal, a solu-
tion  of tin  be  added, the colouring matter will be 
46
 heightened, and precipitated in union with a portion of
 the metal, forming the carmine of the  shops.
   Rationale.   In this as in the other experiments, the
 colouring matter itself, as well as the rays of light, arc
 decomposed, so far at least as to produce a crimson co-
 lour, which is a combii ation of a part of  the  oxyd of
 tin with the colouring matter.
   Remark.  Other lakes may  be obtained of different
 colours, by the  substitution of different  dye woods;
 thus alum decomposed by potash, in a decoction of
 quercitron bark, yields a bright yellow ; with  oxyd of
 tin all the shades, from a pale lemon colour to a deep
 orange ; and with oxyd of iron  a drab colour is  produc-
 ed from the same wood.  Thus also, a combination of
 red oxyd of iron with the gallic acid and tan, is the prin-
- cipal black colour, which has therefore the same basis
 as common writing ink.
   Experiment 23.  Make a decoction of cochineal, and
 immerse into it a piece of cloth; on washing it the co-
 louring matter will disappear-
   Experiment 24.  To the remaining  decoction  add
 supertartrate of  potash, and a  portion of nitro-muriate
 of tin ; now immerse a cloth in this mixture, and it will
 impart a permanent scarlet colour.
   Rationale.  A decoction of cochineal, therefore, will
 leave only a fugitive  stain  on  a piece of cloth,  which
 is evident in the first experiment; but in that portion
 of the  decoction, which contains the  supertartrate of
 potash and nitro-muriate of tin, the colouring matter is
 rendered fixed,  or  permanent.  The nitro-muriate of
 tin and supertartrate  of potash are here decomposed ; a
 nitrate and muriate of potash is formed, whilst the tar-
 taric acid of the tartrate combines with the tin, and pre-
 cipitates the colouring matter on the cloth, at the same
 time the incidental light imparts colour to the  preci-
 pitated colouring matter,  which has thus entered the
 cloth.  Other experiments of  a like nature, together
 with observations on dying, with   an examination of
 the  theories and  opinions of chemists, will be given in
 the  course of the work. 
47
  Remark.  It would'be irrelevant to our plan to en-
ter  into a detail of the effects of  light on vegetables
and animals ; a few experiments, however, on the agen-
cy of light on  metallic oxyds and acids, may, with pro-
priety, be introduced in this place.
  Experiment 25.  Take muriate  of silver, wet it, and
expose it to the light; in  the course of a few hours the
upper suiface will be blackened.
  Rationale.   The deoxydizing power of light has  al-
ready been noticed.  The'light will exercise  no power
but at the surface, where the muriate will be found to
be reupproarhing to the  metallic  state.   It  appears,
therefore,  that oxygen is absolutely  carried off  from
the oxyd in the state  of oxygen  gas, this gas* being
composed of oxygen, caloric, and light; and in this  re-
spect has  a greater affinity  for the  oxygen than the
metal.
  Experiment 26.  Cover white paper, or leather, with
a solution of nitrate of silver,  place it behind a painting
on glass,  and  expose it  to the  solar  light;  the rays
emitted through differently painted surfaces  will pro-
duce distinct tints of brown or black, sensibly differing
in intensity, according to  the shades of the picture  ; and
when the  light is unaltered the colour of the nitrate
becomes deepest.
  Remark.  This effect takes place on the same  prin-
ciple ; and is  a plan  invented by  Mr. Wedgwood  for
copying paintings  upon glass, and making profiles of
figures.   For  particulars, see the Journals of the Royal
Institution, No. 9, p. 171.
  Experiment  27.  Into a solution ol muriate of gold
introduce a piece of charcoal,  and submit the vessel
with  its contents to the rays of the  sun.  The metal
will be reduced, and the  charcoal  gilt.
  Rationale.   In this experiment,  as in the preceding,
the effect is owing to  the  deoxydizing  power of the
sun's rays: the oxygen is taken off by  the light, and
the metal remains on  the coal.   The oxygen which
oxydized the metal in  the act of solution,  being  thus
abstracted, it follows that the  metal is no longer chemi-
cally combined with the acid. 
48
  Experiment 28.   Expose a ribbon, wet with a diluted
solution of muriate  of gold, to the sun, the gold will
be revived as in the last experiment.
  Remark.  This experiment is stated by count Rum-
ford,  in his Philosophical Papers, vol. i.   The count
found that if magnesia was wetted with the  solution of
gold, and exposed in the same manner, it would change
to a purple, and then to a crimson colour.   If the rib-
bon, however, be first dried after it has been moistened,
and then exposed, no change takes place.
  Experiment 29.   If a slip of ivory be immersed for
a few hours in a solution of pure nitrate of silver,  then
taken out and exposed in water to the rays  of the sun,
it will in a few hours become black.  On rubbing it the
black will be  changed into a  metallic surface, the
silver being revived.
  Remark.   The effect is the same as  in the other ex-
periments.   This process, invented by count Rumford,
is for the purpose of silvering ivory.   All metallic ox-
yds are affected,  more or less, in the course of time, by
the sun's rays.
  Black oxyd  of mercury, prepared  by decomposing
the sulphate of  mercury by  pouring  ammonia on it,
when exposed to the rays of light rapidly parts with its
oxygen, and is converted into fluid quicksilver. Many
other bodies are  also affected by light.
  Experiment  30. Expose concentrated nitric acid in a
white bottle half filled, to the rays  of the sun, at the end
of some days the white  acid will  be converted into an
orange coloured and fuming one, and the  bottle  will
become filled with red vapours ;  this  is the nitrous
acid.
  Experiment 31. Take  the  acid,  thus coloured, and
remove it to a dark place;  in the  course  of time it
will change into the pale acid, or nitric acid.
  Rationale.   In  the first  experiment the light  sepa-
rated a part of the oxygen from the azote, as nitric acid
is a compound of oxygen and  azote, in consequence of
which nitric oxyd or nitrous gas is evolved,  part  of it
however remains in the acid, to  which its colour is
owing; but, when the light is withdrawn, as in the se- 
IV
cond experiment, the  nitric oxyd is gradually  decom-
posed, or rather oxygen unites with it, and  converts it
into nitric acid.
  Remark.   If oxygenized  muriatic acid  is exposed
to the sun's rays,  it suffers decomposition, and consid-
erable quantity of oxygen  gas may be easily obtained.
See oxygen gas.   Certain  bodies  have the property of
absorbing the rays of light; of retaining them for some
time, and of again evolving them unchanged,  and un-
accompanied with sensible heat.   Thus  according to
Du Fay, a diamond exposed to the sun,  and  immedi-
ately covered with  black wax,  will shine in the  dark
on  removing  the wax at the  expiration of several
months.  Bodies  gifted with this property are called
solar phosphori.    The eyes of cats, owls, and  seve-
ral  other animals, are formed so  as to collect light,  to
enable them to find food in the dark.  This accounts
for  the light emitted by snow.   Thus snow is a natural
solar   phosphori.   So also is, occasionally,  the sea
when agitated; putrid fish have  a similar property;
and the glow worm belongs to the same class.   These
phenomena are independent of any thing  like combus-
lion ; for artificial  phosphori after being exposed to
the light and placed in vacuo^ will also emit it.   Light-
wood  is  also a phosphori ;  for some  woods  possess
this property, at a period when they are about to un-
dergo decomposition.
  Experiment  32. If pieces  ol sulphate of barytes are
made red hot, in  a covered crucible, for a  few minutes,
and then  pulverised and  sifted;  and  this  powder
made  into a paste with a little mucilage of gum arabic,
and divided  into  cakes or pieces of the thicknesss of a
quarter of an inch, and gradually exposed to a violent
heat among charcoal,in a wind furnace, the bolognian
phosphorus will  be formed.  When this is  exposed
to the light, and  then taken to the dark, it will  emit
light for some time.
  Rationale.  In this case, however, the  light  is emit-
ted  partly in consequence of its absorption, and partly
from the decomposition of oxygen gas.    When sul-
                         E 
jU
phate of barytes are exposed in contact with charcoai:
as under the above circumstances, a partial decompo-
sition of the sulphuric acid of the  sulphate of barytes
takes place.  At a high temperature, the ignited char-
coal possesses a greater affinity to the oxygen  of sul-
phuric  acid  than  the   sulphur;  the  result of this
union is carbonic acid.   A part of the  sulphur thus
separated from the sulphuric acid, unites with the ba-
rytes, and forms sulphuret of barytes, which is known
to have the property of absolving oxygen to the repro-
duction of  sulphuric acid.  This effect then, may  be
partly considered a species of slow  combustion,  in
which oxygen is absorbed, and caloric and light given
out, the oxygen gas being decomposed.
   Experiment 33.  Put oyster shells into a crucible, cal-
cine  them by  keeping them in a good  coal-fire, for
about an hour.  To three parts of the lime, thus made,
add one of flowers of sulphur, and place  the whole in
layers, in a crucible, tightly. Remove it to the fire, and
keep it red-hot for about an hour and  a half.  When
it is removed and  cool,  select the brightest part for
use.  This is the canton's phosphorus.   After ex-
posure to light for  a few  minutes,  and  then put in the
dark, light  will be evolved as in the last  preparation.
This should  be kept in  a wide mouth vial, and well
closed.
   Rationale.   A   sulphuret  of lime is  formed in this
process.  It  is necessary from some cause or other to
employ the oyster shell.  In this as in the former, oxy-
gen gas is  decomposed.
   Experiment  34. Dissolve lime in nitric acid ;  when a
neutral compound is formed, evaporate it to dryness,
and expose it, well rammed in a crucible, to the  action
of heat, where it is to  be kept till the whole mass be-
comes liquid.  Pour this mass into an iron pot, previ-
ously heated,  and the  phosphorus of Baldwin will
be formed.  Preserve the mass  in vials.  After being
exposed to the sun for a few moments, this preparation
affords a beautiful light in the dark. 
51
  Rationale.  This  phenomena  is  owing to no other
cause, than the previous absorption of light.
  Remark.  Several substances when exposed to an
elevated temperature, are  converted into solar phos-
phori.  Such as all neutral salts with a base ol barytes,
magnesia,  carbonate of magnesia,  sulphate and carbonate
of lime,  sulphate  and carbonate  of strontian, sulphate of
potash, alumine earth, fluate of lime, zeolite, some metallic
oxyds, phosphate  of  lime, cotton wool, different combina-
tions of  earths, linen and woollen, hair powder, saw dust,
wax and oils, animal fats, isfc.
  Experiment 35.  If one part  of powdered muriate of
ammonia,  and two of  powdered lime be  introduced in-
to a red-hot crucible, and kept hot till the mixture be-
comes  fluid, the phosphorus  of  homburg is pro-
duced.   See to  Accum, p. 167.
  The  preparation is to be poured into a heated iron
pot,  then broken into pieces, and preserved in a well
stopped vial.
   Rationale.   In  this  process  the muriate of am-
monia  is decomposed ; the muriatic acid unites with
the lime, forming muriate of lime, and the ammonia is
disengaged in the state of gas.   The muriate of lime
is, therefore, a Baldwin's phosphorus.
   Remark.  If the substance obtained, after the prepa-
ration of liquid ammonia, by the decomposition of  sal
ammonia  with quicklime, be melted with a  sufficient
degree  of heat, Homburg phosphorus will also be form-
ed.   In this case the  same  substance, viz. muriate of
lime is  used ; for in the other experiment, the muriate
of lime  is formed during the operation.
   Homburg's phosphorus or pyrophorus which is the
same, emits light   when it is struck by a hard body.
When  a  red-hot poker is  dipped into  the fused sub-
stance,  and  rubbed after it is cool with another piece
of metal, it becomes luminous and evolves sparks and
light.
  Flints and other  siliceous stones, borax, sugar, bon-
net-cane, tremolite, phosphate of lime, black-jack, gums, re-
sins, &c. give out light more or less by attrition.  Some
substances emit light in contact with acids.   We have 
52
 stated already, that various animal and vegetable sub.
 stances were solar phosphori.   The shell fish  called
pholas, the medusa phosphorea, and  other molluscs, the
fulgora, or lantern fly, the lampyris  or glow worm, the
 scolopendra electrica,  the cancer fulgens,  peat earth, the
 medullary substance of the brain of human beings ;  all
 emit light under certain circumstances.  In  the  opi-
 nion of Dr. Holme,* he believes that light is a constitu-
 ent part of many animals,  particularly  of  the marine
 fishes.  This subject  is treated  at large in Thom-
 son's Chemistry, vol. i. p. 413.  But in many cases light
 <s only emitted at  the commencement of putrefaction.
 This phenomena has often been witnessed.
   Experiment 36.  Put  four drams of the flesh  of the
 herring, or mackarel, into a  vial  containing about  two
 ounces of sea water, or  of pure water holding in solu-
 tion half a dram ol common salt, or two drams of sulphate
 (f magnesia ; remove the whole to a dark room,  in the
 i ourse of three days a  luminous ring will appear on
 the surface of the  liquid ; on  shaking  the  vial, the
 whole becomes luminous.
   Rationale.  This experiment  is in conformation  of
 what has  been said on this subject.  Dr. Thomson con-
 dudes from this and other experiments, thatlight con-
 stitutes a part of these substances,  and that  it is the
 first of the constituent parts, which makes  its  escape
 when the substance containing it is to be decomposed.
   Remark.   When the liquids  are frozen, the  light dis-
 appears, but is again emitted as soon as they are thaw-
 ed.  A moderate heat increases the luminousness, but
 a boiling  heat extinguishes it altogether.  The light is
 extinguished also by water, lime water,  water impreg-
 nated with carbonic acid gas, or sulphuretted hydrogen
 gas, fermented liquors, spirituous liquors, acids, alkalies
 and water saturated with a variety of salts; but light ap-
 pears again when these solutions arc diluted with water.
 The light produces no sensible effect on the thermom-

   * Phil. Trans. 1800. p. 161.  See also a paper of Mr. Canton's
 in the same v. orkjix. 446. 
/
53
eter.    The  absorption  of light  by vegetables, an
important subject in vegetable physiology, enables us to
explain the reason why plants become  pale and white
in the dark, and green in the light.
  Experiment 37. Into a tea cup or plate, put one dram
of fresh prepared  calcined magJiesia, and add  at  once
half an ounce of sulphuric acid, and heat and light
will be evolved.
  Rationale.   It  would be  more philosophical to con-
clude, that in this experiment, the phenomena was pro-
duced by the sudden conversion of latent into sensible
heat, and at the same time light was evolved. -
  Remark. As to the relative intensity of light emitted
by luminous bodies, various contrivances  have  been
used to determine it.   Instruments for this  purpose
are called photometers, of which the best are  those of
count Rumford,  and Mr. Leslie.  For particulars  on
this subject  consult Rumford's Philosophical Papers,
1802. p. 270.
                         E 9. 
PART III.
                   OF CALORIC.

    We canonlyobtain a knowledge of what is understood
 by the terms hot or cold, through the medium of senses..
 The ideas of heat or cold are perceptions thus acquired,
 which indicate only a certain state in which  we  find
 ourselves, independent of any exterior object.   Sensa-
 tions, therefore, which are prodoced by external agents,
 as heat, in the instance  before us, are attributable to
^causes, and these causes  produce  certain consequences.
 Hence it is, that  we apply the terms hot or cold to the
 substances themselves.   If a  body communicates  heat
 to the system, in a perceptible manner, we call it  hot;
 but if it produces the contrary effect we  call it cold.
 That which produces  the sensation of  heat is called
 caloric, or matter of heat; the abstraction of which,  con-
 sequently, produced cold.
    Experiment 1.   If steel be struck with a flint, a  con-
 siderable  degree of heat will be produced,  which is
 evident from the ignited particles thrown off.
    Rationale.   In the production of heat  by percussion
 or collision, a temporary condensation of the body struck
 ensues, which causes the evolution of heat, and, in this
 instance, melts a portion of the steel, which is evident
 from the sphericity of the particles.
    Experiment 2.  If air be  suddenly condensed  in  a
 ?ube by means  ol a. syringe, with a  piece of spunk attach-
 ed to the end of the piston, on drawing it out, the
 spunk will be inflamed.
    Rationale. Mr. Dalton  sometime since demonstrated,
 that when air is suddenly condensed,  the temperature 
55'
was increased.   In  this experiment, the air*  suffers a
considerable diminution of volume ;  in consequence of
which, caloric is given out  as sensible heat, and in so
large a quantity as to inflame the spunk.
  An instrument called the  condensing syringe, sold in
this city, for  the purpose of procuring fire instead of
the flint and steel, acts  on this principle.  The French
chemists have discovered, that if a proper mixture of
oxygen and hydrogen  gases, be  suddenly compressed
they quit their aeriform state, and produce water.
  A number  of interesting experiments on this subject,
have been  lately made by  the French National Insti-
tute.   Some  time ago  a soldier in the French army
found, that heat was produced  by the condensation of
the air in an air gun.
  Experiment 3.  If a  piece of phosphorus be put into
the end of the  piston of the condensing  syringe,  and
the tube filled  with oxygen gas and suddenly com-
pressed, it will be immediately inflamed.
   Rationale.  In this experiment the phosphorus unites
with the oxygen and forms phosphoric acid;  the tem-
perature of the oxygen gas, being increased  by  the
compression, causes the phosphorus to be immediately
inflamed.
   Experiment 4.  If two pieces of stick be rubbed very
smartly against each other,  they will smoke, and finally
take fire.
   Remark.  The production of heat by friction, is  not
owing to the density of the bodies being increased, as
is the case in the preceding experiments; for heat is
produced by rubbing  soft bodies against each  other;
the density of which, therefore, cannot be promulgated
by that means.  It is true, however, that heat is not pro-
duced by the friction of liquids; but then they are  too
yielding to be subjected to  strong friction.  It is not
owing to  the specific caloric of the rubbed bodies de-
creasing; for count Rumford found, that there  was no
sensible decrease, nor, if there were a decrease, would
it be sufficient to account  for the vast quantity of heat
which is sometimes produced by friction.  Neither is
the caloric evolved  during friction, owing to the com- 
56
bination of oxygen with the bodies themselves, or any
part of them.  Considering these circumstances, there-
fore, the phenomena is neither produced by an increase
of the  density, nor by an alteration in the specific calo-
ric of the substances exposed to friction, nor is it owint,.
to the  decomposition of oxygen gas of the atmosphere.
This question is at present inexplicable.   There is no
reason, however, to conclude with  count Rumford, that
there  is no such  substance as caloric, but that it is a
peculiar kind of motion.  There  is indeed an analogy be-
tween  caloric  and electricity ; and the phenomena has
been attempted to be explained on the principle, that elec-
tricity exists in those bodies; but such opinions require
the authority of facts to render  them admissible.
  There  are five sources, from which caloric may be
obtained in a state of sensible heat.  It radiates con-
stantly from the sun ; it is evolved during combustion ;
also in percussion, friction, and ntixture, which will be
noticed more fully in the course of the work. To which
we may add a sixth  source, viz.  electricity and galvan-
ism.  By  the  first, if applied in battery, metals may be
suddenly fused, and gases united,  which we are unable
to combine in any other mode.   The same  effects will
take place, if galvanism be substituted.
   Experiment 5.   Rub a particle of phosphorus on pa-
per, the friction produced will immediately inflame it.
   Rationale. In this case a sufficient quantity of caloric
is evolved,  to occasion the phosphorus  to burst into
flame.
   Experiment 6.  If a thermometer  be hung in the open
air, and then introduced into a hole bored in the trunk
of a tfee, the mercury will rise many degrees.
   Remark.  This  evidently  shews,  that  caloric is  aa
necessary for  the  support of vegetable, as it is for that
of animal life: whether this effect is owing to the de-
composition of some gas, the base  of which is absorbed,
and the caloric given out  in aiflfctMs'tate, or the conver-
sion of latent  into sensible heat, is a question yet to be
determined; or whether, with Mr. G. F.Lehman, the
heat of vegetables is the effect of certain necessary 
57
stimuli, acting on them, as is supposed, occurs in the
animal economy.*
  Experiment 7.  Take a piece of wrought iron,  and
hammer it briskly on an  anvil; it  will evolve sensible
heat, and finally become ignited.
  Rationale.   In this case,  the  wrought  iron, which
contains a large portion of latent caloric, suffers percus-
 ion, and gives out its latent, in the state of sensible
heat.
  Experiment 8.  Place a pan of snow over a fire, and
immerse a thermometer in it; notwithstanding the ac-
cession of heat, during the process of melting, the tem-
perature will be found to be the same.  When the whole
becomes fluid, the temperature will then be raised.
  Rationale.   This is a case, in which caloric chemi-
cally combines  with the snow: hence the thermometer
is not raised; but when the whole is melted, the acces-
sion of heat is then shewn by the rise of the mercury,
because the caloric  which  enters becomes sensible,
or free heat.
  Remark.  As ice has the property of absorbing all the
caloric with which it comes in contact, and, from the
preceding experiments, communicates  no  part of it to
the surrounding bodies till the whole is melted;  it has
therefore  been  employed as the means by which the
specific caloric of substances may be calculated.   The
instrument for this purpose is called  a calorimeter.
  Experiment 9. If a piece of ice cooled 20° below the
freezing point, be exposed to a hvtflre with a thermome-
ter stuck in it, the thermometer will rise very uniformly
till it comes to  32°, and then make a full stop until the
ice is all liquified : but,  as  in  the preceding  experi-
ment, the  instant all the ice is melted, the thermometer
will  begin to rise  again, and continue to rise until it
comes to 212°, the boiling point.
  Rationale.  As in the preceding experiment we  learn,
that the caloric, which is  received by the ice, is not ap-

  * Mr.  Lehman, in  a very able and ingenious  essay, has en-
deavoured to prove, thut the vegetable is governed bv  the same
laws as the animal kingdom. 
58
preciable by the thermometer until the ice is liquefied ;
in this case, however, the thermometer rises from 20°
to 32°, and at that degree remains stationary.
  Experiment 10.  When one part of sulphuric acid and
four parts of zcr, both at the temperature  of 32°, be
mixed ; the  mixture will indicate 4°.
  Rationale.   The fall of the thermometer  is owing to
the absorption of caloric from the sulphuric acid; the
ice, therefore, is  rendered fluid bv  the caloric  which
enters it.
  Experiment 11. If an amalgam of bismuth, and another
amalgam of lead and  mercury, be mixed in a mortar, they
will instantly become fluid.
  Rationale.   In this experiment  there appears to be a
mutual decomposition, or at least a new arrangement
of component parts ;  and the change,  which has thus
taken place, indicates the absorption, or combination of
caloric, causing the compound to assume a fluid state.
  Experiment 12.  Place in a glass vessel, containing
about an ounce  of a  solution of soda, a small thermome-
ter ; add a sufficient quantity of muriatic acid to saturate
the soda, and the mercury in  the thermometer  will
rise.
  Rationale.   In this experiment, a compound'of mu-
riatic acid and soda  is formed; and, at the instant of its
formation, heat is given out as  sensible  heat,  which
proves that  an alteration  ensues in the  capacity for
caloric, during chemical  changes.  Other experiments
of a like nature, will be hereafter  noticed.
  Experiment 13.  If carbonate of soda be  used  in the
same manner, with  sulphuric acid, cold will be the re-
sult.
  Rationale.   In this case the carbonate is decomposed,
carbonic acid gas is disengaged, and sulphate of soda
formed; but the decrease of temperature is owing to
the disengagement  of carbonic acid.
  Experiment  14.   Dip the bulb of a thermometer in
melted rosin so as to  coat the glass with it, and suffer
it to cool completely.  If the flame of a taper be now
applied to the bulb  so as  to melt the rosin, the mercury
in the thermometer will not rise at the approach of the 
o9
taper, but will actually be seen to contract as the  rosin
becomes liquid.
   Rationale.  It is evident, that when solid bodies pass
to the liquid state, their capacity for caloric  is propor-
tionably increased.    In this experiment,   therefore,
when the heat is  applied to melt the rosin,  the  rosin
not only  absorbs the heat which is  presented to it, and
which renders it  soft, but also combines with the ca-
loric of the mercury.  It therefore  falls.
   Experiment 15. If 1 lb. of  water  at 100°  bet mixed
with I lb. of water heated to 200°, the mixture will be
found to  give the exact mean temperature of 150° ;
but 1 lb.  ofmercury  at 100°,  and 1 lb. of water at  200°,
will produce a heat much higher than the mean  tem-
perature.
   Rationale.  From  this fact we learn, that mercury
has not so great a capacity for caloric as water : hence
it is, that the difference in the capacity arises from cer-
tain causes, which are influenced by chemical affinity—
that of one body  having a  superior affinity for  caloric
to another.
   Experiment 16. If alcohol coloured red with cochineal,
be introduced into a glass globe, having a  long slender
neck, up to a certain  mark, and placed  over a lamp ;
an expansion will ensue which will increase until the
 fluid begins to boil.
   Rationale.  As caloric expands all bodies with one or
two exceptions, in this  case  it dilates the alcohol, and
the degree  of expansion is shewn by the use of the flu-
id in the neck of the  vessel :  if it be taken to a cool
situation, or the  glass immersed in cool water, the  flu-
id  will descend, shewing that the expansion was  occa-
sioned by the caloric.  Fluids with the least density,
i. e. specific gravity, expand  most with the  same tem-
perature.  The expansion of mercury in  a  glass  tube,
forms the mercurial thermometer.
   Experiment 17. Place  the  beak of a retort under
water, and apply  the heat of a lamp, bubbles of air will
arise from the  mouth of th retort. 
60
  Rationale.  This experiment proves, that air as wen
as liquid bodies, is susceptible of expansion; for  on
applying the heat of a  lamp, its volume is increased,
which is shewn by the  extrication of bubbles.   Ablad-   i
der, three fourths filled with air, when exposed  to the
fire, is dilated, and when removed to a lower tempera-
ture, returns to its former state.
  It is on this property which air possesses, that the
trade winds are accounted for; for the sun near the equa-
tor expands the atmosphere, which is then counteracted
by the cold, and causes a current of air in  a  peculiar
direction, to be formed.  It is also this property that   I
gave rise to  the air  thermometer ;  of which Ave have  j
several kinds.  The most important of these is Les-  J
lie's Differential thermometer.  It is this also which con-  1
stitutes the pulse glass.
  Experiment 18. If an iron bar six inches long be ig-  j
nited  in a furnace, it will be found ^ of an inch longer  f|
than it was before.                                     fl
  Rationale.   The iron bar in this case  is expanded  by   I
the heat, notonly in length but  also in breadth ; which
on cooling however, returns to its former  dimensions.
To determine the minutest changes of expansion by
heat,  and the  relative  properties thereof,  instruments
have been used called pyrometers,  which are calculated
to shew the expansion from T7£77y to y^Wr °^an ^ncn-
   A number of inferences may be made on  this pro-
perty, of the expansion of metals by heat.   Suffice it to
say, that it renders time-pieces erroneous,  which how-
ever has been obviated by using a grid-iron pendulum^
composed of different metals, so that the expansion of
the one may counteract that of the other ;  that harpsi-
chords, 8cc. are out of tune by change of temperature ;
and that bodies which are brittle, or  which want  flexi-
bility, crack or break if suddenly heated or cooled.
  Remark.  Upon  the expansive  property of heat is
founded its artificial measurement.   The relative heat>
or temperature of bodies, is therefore measured by cer-
tain instruments, called thermometers and  pyrometers.
The former consists of a hollow tube of glass, hermeti* 
bl
cally sealed and blown at one end in the shape of a hol-
low  globe.  The bulb and  part of the  tube are filled
with mercury.  When the tube, thus prepared, is im-
mersed into a hot body, the mercury expands, and of
course rises in the tube ; but when it comes in contact
with a cold body, the mercury contracts, and  therefore
falls in the tube. To facilitate thermometrical observa-
tions, the tube is furnished with a  scale  of degrees,
which  vary in different  thermometers.   There  are
four thermometers used at present in Europe.  These
are Fahrenheit's, Reaumur's, Celsius', and  Delisle's,
differing only from each other  in the number of de-
grees into  which the space between the freezing and
boiling points  is divided.
  The pyrometer of Wedgwood is formed of pieces of
baked clay, and a rule or gauge.   The degree of heat
is shewn  by  the  contraction which they  undergo.
High temperatures only are ascertained by this instru-
ment.   Each  degyee of  this pyrometer  is  equal to
 130 degrees of Fahrenheit's.  Guyton has also con-
trived an instrument for the same purpose, which con-
sists of a lever of platina moved by the expansion of a
bar of the same metal, the whole being supported on a
mass of baked clay.   This property of alumina, of con-
tracting when  exposed to heat, has  rendered it an ex-
ception to the general principle, that caloric expands all
bodies.
   Experiment  19. If a pound of water at 172° be mix-
ed with apoundat 32°, the heat of the mixture will be
102°.
  Rationale. If a given quantity of caloric occasions the
ascent of the mercury through 20 degrees, it might be
asked whether a second addition, equal to the first, would
raise it through  precisely 20 more ? This  is the fact
from the foregoing experiment.  Here the hot water
will  be cooled 70°,  and  the  cold  will  receive 70°
of temperature;  consequently,  172—70,  or 32+70,
= 102, will be the heat of the mixture.   It  appears,
however, from the experiment of De Luc, that the ra-
tio of expansion does not, strictly, keep pace with the
                         p. 
o~
actual increments of  temperature ;  as,  ior  mstaii'V.
the expansion of mercury from 32 to 122, the first half
of the scale, is  to its  expansion from 122 to 212, the
higher half, as  14 to 15.
   Experiment 20. If in an atmosphere at 60°, we place
iron filings heated to redness, boiling water,  and vari-
ous other bodies of different temperatures,  they will
soon affect the thermometer in the same degree.
   Rationale.  This experiment shews, that uncombin-
cd caloric has a tendency to  an equilibrium ; for the
excess of caloric in the one  body  passes to the other,
until a uniform temperature is  the consequence.   The
same equalization of temperature is attained, though
less quickly, when  a  heated body is placed in the va-
cuum of an air pump.  The rate of cooling in air, is to
that in vacuo, (the temperatures being equal,) nearly as
five to two.  Caloric indeed  has the tendency to per-
vade all matter,  till an equilibrium of temperature  is
established.
   Experiment 21. Provide two tin reflectors, as describ-
ed in  Henry's Chemistry, 8vo. p. 28, twelve inches in
diameter, and segments of a sphere of nine inches radi-
us.   Place these on  a  table at some distance  apart,
with  their concave  surfaces  towards each  other.   In
the focus of one let the ball of an air  thermometer  be
situated ;  and in that of the other suspend aball of iron
about four ounces  in  weight,  and heated below igni-
tion.  The liquid in the  air thermometer immediately
descends.
  Rationale.  This is the celebrated experiment of pro-
fessor Pictet, to  shew the radiation of caloric.  In this
experiment the radiant caloric follows  the same law  as
the solar light ;  the angle of incidence being  equal to
the angle of  reflection.  The  caloric  flows first from
the heated ball to the nearest reflector, from this it  is
transmitted, in parallel rays, to the surface of the se-
cond reflector, by which  it is collected into  a focus on
the instrument. 
6.3
  Experiment 22. If the reflectors be placed in the
-.ime manner, and a flask  of boiling water put before-
one of them, the same effect will ensue.
  Experiment 23.  If the apparatus remain, and a  glass
vessel  filled with ice, or snow, be substituted for the
heated ball,  the  course of the  coloured liquor will be
precisely in  the opposite direction.
  Rationale.   At first view this experiment would ap-
pear to indicate the reflection of cold ;  but it is in fact,
only the reflection of heat, though in an opposite direc-
tion ; the ball of the thermometer being, in this instance,
the hotter body.
  Remark.  The nature of the  surface  ol bodies has an
important influence  over their power  of radiating ca-
loric.  These varieties in the radiating power of differ-
ent surfaces are  attended, as might be expected, with
corresponding variations in the rate of cooling.
  Experiment 24.  Take two thermometers of the  same
kind ; blacken the bulb  of one of them with Indian ink,
and expose them both to the sun.  That which is black-
ened will ascend 10 degrees higher than the other.
  Rationale.  Radiant caloric is absorbed with differ-
ent facility by different surfaces. Surfaces are endow-
ed with various powers of reflecting caloric.   In the
case before  us, the black ink acts in this  way ;  for it
cannot be supposed, that  the  black coating is gifted
with the power of retaining caloric, and  preventing its
escape ; because  from  experiments made, it appears
that a similar coating would accelerate  the cooling of a
body to which it is applied.  Colour, however, has con-
siderable influence over the absorption of caloric, as is
shewn by the experiments of Dr. Franklin.
  Experiment 25. Ifpieccs ol woolen cloth, of equal di-
mensions, but of different  colours,  viz.  black,  blue,
brown, and  white, be laid on the surface of snow, they
will sink in the  snow  in differentproportion.
  Rat;o?iale.  It is evident, in this experiment, that the
greater the  quantity of caloric absorbed,  and transmit-
ted to the  snow, the  farther  the cloth will descend. 
64
\r\ a few hours the black will have sunk considerablv
below the surface ; the blue almost as much ; the brown
evidently less ; and the white will remain  precisely in
its former  situation.  The -sun's rays,  therefore,  are
absorbed by the dark coloured cloth,  whilst they have
not the power of penetrating  the white.   Hence  the
preference generally  given  to  dark  coloured  clothes
during the  winter season, and to light  coloured ones
in the summer.
  Experiment 26. If six pieces of sheet copper, of the
same  dimensions,  be  painted on  one side,  white,
yellow, red, green, blue, and black, and the unpainted
surfaces be  placed  on  pieces  of cerate, composed
of  wax  and  olive  oil,  and  the whole  exposed to
the sun's rays, the same  effect as in the  preceding ex-
periment will ensue.
  Remark.   The motion of caloric through bodies, it
must be recollected, is  of two  kinds:  through some
bodies it moves with  great celerity.   In the one case it
is said to be transmitted through  the body, in the other
conducted through it.   See Thomson's Chemistry,  vol.
i. 310.   As caloric, like  light, is emitted from the sun
with considerable velocity, at the rate  of 200,000 miles
in a second, it could  never be  accumulated,  were it
not retained by its affinity for that body.  From  this
fact we may infer, that in every  case, the  rays of  the
sun only afford  heat  when they meet with an opaque
body, and not when  they  pass  through a transparent
one, as air and water  ; or when they are reflected by a
white or polished one.  On the principle before   no-
ticed, the Swiss peasants, when  they want to sow their
seed,  spread black cloths on the  surface of the snow, to
absorb the  sun's rays and facilitate its melting.
  Experiment 27.  Take a number of straight wires of
equal diameters and  lengths, but  of  different  metals,
for instance iron, copper,  gold, silver, he. cover each of
them  with  a thin coat of wax or tailow,  and  plunge
their extremities into water kept boiling, or into heat-
ed sand ; the wax or taiiow will  be melted oft' some
of the metals sooner than others. 
65
  Rationale.  Bodies which thus transmit caloric  are
called conductors of caloric.    Different metals, as is
seen in the last  experiment, possess very  different
powers of conducting caloric.  By the experiments of
Dr. Ingenhaus we learn, that metals conduct heat in the
following order: silver possesses the highest conduct-
ing power; next gold; then copper and tin, which are
nearly equal; and, below these, platina, iron, steel, and
lead, which are greatly inferior to the rest.   Accord-
ing to the relative power which bodies possess,  of con-
ducting heat, they are said to be good or bad conductors;
and those through which it does not seem to pass are
called non-conductors.  Thus it is, that some bodies are
warm, or capable of preserving warmth ; hence the dif-
ferent sensations excited by  different bodies, when ap-
plied at the same temperature to  our organs of feeling.
  Remark.  Next to metals, stones are the best conduct-
ors.  Glass conducts heat very slowly ;  wood and char-
coal still slower ;  and feathers, silk, wool,  and hair are
still worse  conductors.  As  clothing used in the win-
ter season  is a bad conductor of heat, the importance
of woollen  cloth to preserve the  warmth of the body, is
obvious.   Hare's  fur and  eider-down are the  warmest;
next to these, beaver's fur, raw  silk, sheeps wool, cotton
tvool, and the scrapings of linen.
  On the same  principle also, we learn, that those skins
are the warmest,  which have the  finest, longest, and
thickest fur; and that the feathers of the water-fowl, with.
many other animals, are capable  of. confining the heat
in winter, notwithstanding some   of them partly live in
the water.   The snow which falls in the  winter  season,
is doubtless designed  by Providence as a garment to
defend the  earth from the piercing winds, so that  na-
ture is never wanting in that economy, which serves to
shew the wisdom, power, and goodness of God,  not on-
ly in  forming, but in governing and supporting the
physical world.
  Experiment  28. Fill two large vials with hot water,
at the same temperature;  infold one in a piece of linen
cloth, and  cover  the  other  completely with, thick
                         F 2 
6u
fur.   it in half an hour's time the contents ot each be
examined, the water in the first vial will be found to
have lost several  degrees of heat more than that which
had been folded in fur.
  Rationale.  We learn by this experiment, the truth of
our remark, that fur is a bad conductor of caloric. It
is said, however,  that clothes, as well  as  light spongy
substances, such as furs and down, keep the body warm
in consequence of atmospheric air which they infold
•within them.
  Experiment 29.  Pour a little sulphuric ether upon the
surface of water,  and inflame it by a slip of lighted pa-
per.  After the inflammation  has  ceased, introduce a
thermometer, the temperature will be found to be the
same as at first.
  Rationale.   This experiment  is calculated  to shew,
that water is a bad conductor of caloric, and that when
it is to be heated, the heat should not  be applied at its
surface.   The heat,  therefore, which resulted from the
combustion, is carried off with the flame.
  Experiment 30.  Take  two rods, one  of glass, the
other of iron, both of the  same dimensions, and  hold
them towards the fire ; the iron  will become hot while
the glass will scarcely be affected.
  Rationale.  This is obvious from the foregoing ex-
periment: in  this instance  the  iron  rapidly conducts
the heat to the hand, while the glass, being a  bad  con-
ductor, scarcely transmits it.  If two rods, the one of
iron,  the other of glass, of the same size, be coated at
one end with wax, and the other extremity placed in a"
fire, the wax will be melted much sooner from the end
of the iron rod, than from the glass one.
  Exfierimcnt 31.  Take  a glass tube, eight inches in
length, and about an inch in  diameter.  Pour into the
bottom part, for about the depth  of an  inch, a  little
water tinged with litmus, and  then  fill up the tube  with
common water, pouring on the latter extremely gently,
so as to keep the two strata quite  distinct.  When the
tube is heated at the bottom, the  cold affusion will as-
cend, and will tinge the whole mass.  But if the upper 
67
part of the tube be heated, the coloured liquor will re-
main at the bottom.
  Rationale.   In all cases where liquid and aeriform bo-
dies arc concerned, they are found to convey heat on a
different principle from that observed in solids, namely,
by an actual  change in the  situation  of their  particles.
Hence in the above experiment, the caloric enters be-
low, lessens the density of the fluid in contact with the
under surface, which therefore rises and displaces the
fluid immediately  above, and causes a motion in the
particles, which is  continued until the liquor  becomes
of an uniform colour.  But if the heat be applied to the
surface, no effect of the kind takes place.
  That water is a slow, though imperfect conductor of
caloric, has been fully  established by the experiments
and inquiries of Dr. Thomson and Mr. Murray.  Con-
sequently, count Rumford's opinion, respecting the non-
conducting power of water,  is founded in  error.   The
experiments  and observations of Messrs. Thomson and
Murray, may  be found at large in their works on Che-
mistry.  There are several experiments, tending to
demonstrate the fact, that may be found by examining
these authors; which,  for  want of room, have  been
omitted.
   Experiment 32.   If a thermometer be immersed in
liquefying  ice or snow, it will indicate 32°.
   Rationale.   The temperature of melting snow, or of
thawing ice, is uniformly the same at all times, and in
all places.  During the thawing of ice or snow, the
thermometer shews only 32"?, the cause of which will
be presently explained.
   Experiment 33.   Place a thermometer in  pounded ice ;
the temperature will be 32°, and at the very same point
in water, which results from the liquefaction of ice.
   Rationale.   Dr. Black was the  first who proved, that
whenever caloric combines with a solid body, the body
becomes heated only until it is rendered fluid ; or that
whenever it has acquired the fluid state its temperature
remains stationary.   Whenever caloric becomes active,
it produces heat; whenever it passes into a liquid statQj
it produces cold. 
68
  Remark.  When certain bodies, as the metals, are
exposed to a sufficient heat,  the  attraction  of aggre-
gation is lessened, the caloric acting as a repulsive power,
and the body ceases to be solid : it appears,  therefore,
in a fluid  state.
  This phenomena is called fusion ; and  the body, thus
changed from the  solid to the fluid aggregate, is said
to be fused or melted.   Those bodies  which cannot be
rendered fluid by any  degree of  heat hitherto known,
are called fixed or infusible.   Fluidity is, therefore, by
no means essential to any species of matter, but always
depends upon the presence  of  a quantity  of caloric.
The caloric, necessary to accomplish this purpose, has
been called the caloric  of fluidity.
  Free caloric is  the  same as uncombined caloric, ther—
mometrical caloric, caloric of temperature, interposed calorie, ^
Uc By specific heat is understood the relative quantities
of caloric contained in  equal weights of different bodies
at the  same temperature.  Latent heat  is synonymous-
with caloric of fluidity.   Capacity for heat  is a term made
use of to express the property by which different bo-
dies contain certain quantities of caloric at any tempe-
rature. Absolute heat  implies the whole quantity con-
tained in any body.
  Experiment 34.   Expose a pound of water at 32°, and
a pound of ice at 32°, in a room, the temperature of
which is several degrees above the freezing  point, and
uniformly the same during the experiment.  Before
the ice is  melted, the water will arrive at the tempera-
ture of the room, several hours indeed  before it takes
place ; and the melted ice will give, as before its lique--
faction, the temperature of 32°.
  Rationale.   This experiment proves, that the ice du-
ring liquefaction  absorbs a considerable quantity of
caloric ; for the ice must, during the time of the expe-
riment, have been  receiving caloric,  because  a  hotter
body can never be in contact with a colder one, without
imparting heat to  the latter.  The caloric, therefore,
which has entered the ice, though not appreciable by the
thermometer, is in a latent state. 
69
   Experiment 35.  If to a pound of  water at 172? we
add a pound of ice at 32°, put into a wooden bowl, the
temperature will not be the arithmetical mean, but 32*.
   Rationale. This experiment is designed to shew, that
" the quantity of uncombined caloric that enters into a
pound of ice, and becomes united, during liquefaction,"
is not the arithmetical mean of the two temperatures,
but much below it, viz. 32°.  All the uncombined calo-
 ric of  the hot water, has therefore  disappeared.  By
subtracting 32° from 172? leaves 140°, the quantity of
 caloric that combines with a pound of ice during lique-
 faction.  It is, therefore, latent heat.   As much caloric
 is absorbed by the pound of ice, as would raise a pound
of water from 32«? to 172°.
   Other examples of the absorption of caloric, during
the liquefaction of bodies, will be given in the course
of the work ; for, on the sudden transition of solids into
fluids, is founded the well known production of cold by
frigoriflc mixtures, which will also claim our attention
 in due time.
   Remark.  Dr. Black drew, from a number of experi-
ments, the theory of latent heat; and has not only de-
monstrated the  fact in the experiments already men-
 tioned, but he has also shewn, that the fluidity of melted
wax, tallow, spermaceti, metals, &c. is owing to the same
 cause.  It is  said, that the same law is applicable to
 •sulphur, alum, nitre, &c.
   Experiment 56.  If water be cooled down below 32°,
 which may be effected if it be kept perfectly free from
 agitation, and then suddenly shook, it will immediately
 congeal, and the temperature will rise to 32°.
   Rationale.   In this experiment, the  water  is cooled
 down below  the freezing  point, without congealing;
 but on shaking it, it immediately freezes.
   It is said,  that this phenomena is governed by the
 same law, as is manifested in other cases, namely,  that
 liquids, in becoming solid, evolve or give out caloric, or,
 in common language, produce heat.
   Experiment 37.  Expose to the atmosphere, when at
a temperature below freezing, (for example,  at 25° of
Fahrenheit) two equal quantities of water, in one only 
70
of which  about a fourth of its weight cf -salt has beer
dissolved. The  saline solution will be gradually cooled,
without freezing to 25°. The pure water will gradually
descend to 32°, and will there remain stationary a con-
siderable time before it congeals.
  Rationale.  According to  the  general  law,  that a
warmer body in contact with a colder one  imparts  ca-
loric to the latter, it appears, that while  the water  re-
mains stationary, it is yielding caloric to the  atmosphere,
equally with the saline  solution.   Dr. Crawford  justly
observes, that water, during congelation  is acted upon
by two opposite powers.  It  is deprived of  caloric by
exposure to a  medium, whose temperature  is  below
32°, and it is supplied with caloric by the  evolution of
that principle  from itself, viz. of that  portion  which
constituted its  fluidity.   Consequently,  the powers
being equal, the temperature of the water must remain
unchanged until the caloric of fluidity is all evolved.
  Ex/ieriment 38.   Into a round tin vessel,  says  Dr.
Crawford,  put a pound of powdered ice ; surround  this
by a mixture of snow and salt in a large vessel; and stir
the ice in the inner one, till its temperature is reduced
to 4°  of  Fahrenheit.   To the ice  thus cooled, add a
pound of water at 32°. One fifth of this will be frozen;
and the  temperature  of  the ice  will  rise  from 4*.
to 32°.
  Rationale.  It is evident in this experiment, that the
temperature of a pound of ice is raised to 28°, which
is produced by the caloric evolved  by the congelation
of one fifth of a pound of water.
  Experiment 39.   Add to a saturated solution  of sul-
phate of potash, or any salt insoluble in alcohol, an equal
measure of alcohol ; a precipitation, and a considerable
degree of heat  will  be produced.
  Rationale. In this experiment, the water has a stronger
affinity for the  alcohol, than for the salt: therefore the
water  and  alcohol unite, the  salt is precipitated, a  con-
traction of bulk  ensues, and  the  latent becomes  sen-
sible heat.
  Experiment  40.   Water, when heated  until ebulition
ensues, will indicate 212° ; alcohol 176; and ether 98° cf
Fahrenheit- 
71
  Raiionuie.  Caloric, we have said, changes solid into
fluid, and fluid into aeriform bodies.  It is in fact this
property,  which ranks it among the most important
agents in nature.   It acts constantly  in  opposition to
the attraction of  aggregation,  and according  to  the
repulsive  power, bodies appear in  different  states.
Hence it is, that in this as well  as in other operations,
it places the particles of matter farther asunder, and
causes them to assume a new state.  When a heat of
212  degrees is  given to water, that fluid takes the
vapourized state ; when alcohol is subjected to a tempe-
rature of  176g  it boils; and  when ether is exposed to
98° it is dissipated in ebulition. Therefore, every body,
when of the same degree of chemical purity, and under
equal circumstances of atmospheric pressure, has one
peculiar point of  temperature, at which it immediately
boils.   Steam has the  same temperature  as  boiling
water.
   Experiment 41. If  water, which has ceased  to boil,
be placed under the receiver of an air pump, and the
 tii  exhausted, ebulition will  immediately commence.
   Experiment 42.  If ether  be  exposed in  a  similar
manner, in vacuo, the same phenomena will result.
   Rationale.  These and other  experiments of a  like
nature might be adduced to shew, tiiat the boiling point
of the same fluid varies, under different  degrees of at-
mospheric pressure.   In general liquids boil in vacuo,
with about 145° less of heat  than are required under  a
mean pressure of the atmosphere. These facts at once
prove, that the particles of  caloric are mutually repul-
sive, and  that this repulsive power is communicated to
other bodies.  It is  chiefly  the  pressure ot the atmos-
phere, which counteracts this repulsive tendency.
   Experiment 43. Place, over a lamp, a Florence flask,
about three fourths filled with water ,- let it boil  briskly,
during a few minutes; and,  immediately on  removing
it fiom the lamp, cork it tit htly up: the water will now
cease to boil; but, on cooling  the upper part of the
flask by a wet cloth, the  boiling will be renewed.
   Rationale.  An imperfect vacuum is produced bv the
application of cold, which condenses the steam, and, as 
<2
-water near the boiling points boils in vacuo, the ebuli-
tion is immediately renewed when the condensation of
the steam takes place.
   Experiment 44.   Fill a retort  one half or less with
water, and make it boil over a lamp; when it has boiled
briskly for a few minutes,  cork the mouth  as expedi-
tiously as possible, and remove it from the lamp.  When
the ebulition begins to slacken, it may be renewed by
dipping the retort in cold water.
   Rationale. The theory of this experiment is the same
as the preceding.
   Remark.  If the flask, or retort, be furnished with a
stop cock, cemented to its mouth, the phenomenon will
be more complete.  After it boils rapidly the cock must
be  shut.  Immediately the ebulition  ceases.  If  the
apparatus be removed, and the  cock now opened, the
accumulated vapour  which repressed the ebulition, will
then rush out with great violence, and the fluid will boil
very rapidly.  Considerable care, however,  should  be
observed in this experiment. It is intended to shew the
influence of pressure on ebulition.   In  the former  ex-
periments we stated, that if the upper part of the flask,
or retort, be suddenly cooled after ebulition, the phe-
nomenon of boiling would again be resumed;  but if
we immerse the flask,  or retort,  in  hot water, it will
be repressed or entirely destroyed.   If a flask be pro-
vided with a very long neck, and tightly corked while
it is boiling, and, after  it has become cold, be suddenly
reversed, the water in it will fall down with the apparent
weight of a  stone, because  the resistance of the atmos-
phere is removed.   On  this principle is founded the
water-hammer.  Other  experiments of this kind will be
introduced hereafter.
  It has been ascertained, that, notwithstanding the tem-
perature of  steam be no more  than boiling  water,  ac-
cording to the experiments of Mr. Watt, it still contains
near 1000« more caloric, and it is this that preserves it
in the form of steam.
  Experiment 45. Fill a jar withwater at the temperature
of 104°, and invert into it a vessel of the same.   Then
introduce a little ether, by means  of a small  glass tube 
7.j
closed at one end. The ether will rise to the top of the
jar, and, in its ascent, will be changed into an  aeriform
state:  or,
  Experiment 46.  Put a little ether into a small retort,
tic a bladder to  the  beak of it, and apply heat.   The
ether will take the gaseous  form and fill the bladder.
If the bladder be now held  in water,  the ether will as-
sume a liquid state, and the bladder will colapse.   The
bladder should  first be gently warmed to ensure the
success of the experiment: or,
  Experiment 47.  Attach a bladder to a vial,  in which
some ether had  been put,  and place the vial in water
heated to about  150° or 200°; the  conversion of the
Cther into the  aeriform state will  immediately  en-
sue :  or.
  Experiment 48. Introduce into a Florence flask water
coloured with cochineal, having previously put in a tea
spoonful of ether, and fill it with the coloured liquid.
Then invert  the flask in  a shallow vessel of the same
kind of coloured water, and  by degrees pour boiling
water  upon its bulb ;  the ether will  take the aeriform
state and  dispel  the  water.  By pouring cold  water on
the flask, the ether will resume its original state.
  Reitionale.  In  all these experiments the same  effect
ensues, which is owing to the  same cause, namely,
that uncombined caloric  changes liquids into  the  aeri-
form state, and that  aeriform bodies are converted into
the liquid, with  some exceptions, however, by the ab-
straction of caloric, as we have formerly observed.
  Experiirer.t 49.  Mix the filings  of zinc and tin; no
combination  will ensue until heat be applied: or,
  Experiment 50.  Mix soda and ice, no action will  en-
sue ; but if heat be  applied the ice will melt,  and then
dissolve the soda: or,
  J.xperimenl 5 1.  Potash and  silex, if mixed, have no
action whatever  on each  other ; but if submitted  to  a
great  heat, they melt and  form a  compound, called
glass.
  Rationale.  These experiments are designed to shew,
that  uncombined caloric promotes  the action of  che-
mical affinity.  Caloric serves not only to unite bodies
                        c 
74
but also to  separate them.   It is, therefore, the most
important instrument in the hands of the chemist: by
it compositions and  decompositions are effected.  In
some cases caloric acts as a  solvent; in others, it sepa-
rates bodies from each other, and, thus far, seems to be
explicable on the principle of elective affinity.
  Experiment 52.  Melt sulphur in a crucible, and add
the filings of iron; apply a heat sufficient to unite them,
and a sulphuret of iron will be produced.
  Experiment  53.  Take the compound  thus formed,
and expose it to an intense degree of heat, and, the sul-
phur will be dissipated.
  Rationale.  In  these two  experiments we find, that,
in the first case, uncombined caloric, at a certain tem-
perature, promotes  chemical  action, and  forms the
compound of sulphur and iron ;  and in the  second, by
subjecting the same compound to a higher temperature,
a decomposition  ensues; the sulphur is volatilized,
except what portion is converted  into acid, and the iron
remains in the crucible.   Hence  caloric  acts in a two
fold  capacity, that of composing and decomposing.
  Experiment 54.  Introduce two ounces of sulphate
of soda, in powder, into a teacup  of cold water, stirring
them together, and the water will only dissolve a por-
tion  of it.  Now apply heat, and the whole will be taken
up.    If the  solution be  suffered to stand undisturbed
until it  cools, the salt will  be observed to shoot  into
crystals.
  Rationale.  This experiment illustrates, that  caloric
promotes the solution  of  salts.  Supposing,  at the
common temperature of the air, that the water dissolves
only one half, but on applying heat the whole is taken
up:  when the temperature   is reduced, it is evident
that  the water  could not retain  the whole quantity in
solution, but that, from necessity, it must  separate a
part of the  salt, which is accoruingly separated  in a
crystalline form.
  Experiment 55.  Moisten  the bulb of a thermometer
with ether, which operation continue for a few minutes;
the mercury will  descend below the freezing point. 
75
   Experiment 56.  Put some water into a small tube,
 having one of its extremities closed, and pour over that
 part which contains the water some ether; continue the
 operation  for a few  minutes, and  the water  will be
 frozen.
   Rationale.   The conversion of liquid into aeriform
 bodies, depends on the presence of caloric.   On moist-
 ening  the  glass of the thermometer, a reduction of
 temperature  necessarily  ensues,  as  a  concurring cir-
 cumstance with the evaporation of the ether.  The
 heat is therefore taken from the mercury, which, con-
 sequently, contracts; the degree of which is shewn by
 the mercurial column.  The same theory precisely, is
 applicable to  the second experiment.
   Remark.   The cooling of rooms by sprinkling them
 with water, the action ol butter coolers, buxaros, or water
 coolers, the cooling of wine by  wrapping the bottle  i i a
 wet cloth, the use of tanned leather bags by the blacks in
 Senegambia, the wetting of the head and body with wet
 cloth,  in use on the borders of the  Persian Gulf, the
 method of making ice artificially in the  East Indies, are
 all on  the  principle of the production  of cold by eva-
 poration.
   Experiment 57.  Add eight pounds of iron filings at
 300° to one pound of water at 212°; the temperature
 of the  steam  will remain the same.
   Rationale.   It is evident as the temperature remains
 the same, that the steam must  contain, in a latent state,
 all the caloric which raised the temperature of eight
 pounds of iron filings from 212? to 300°.
   Experiment 58.  Place two  cylindrical flat bottomed
 vessels  of tin, five inches in diameter, and containing a
 small quantity of water at 50°, on a red hot iron plate,
 of the kind used in kitchens. In four minutes the water
 will begin to boil, and in twenty minutes the whole will
 be consumed.
   Rationale.  This is the celebrated experiment made
by Dr. Black, in order to determine the quantity of calo-
ric which  becomes latent during  the formation  of
steam. 
76
  In this experiment, the water  received  in  lour mi-
nutes 162? of temperature, or 40->- in each  minute.   If
the same proportion be  absorbed by the water during
the twenty minutes, we may  cohcludc, that 40 j -f 20»
= 810, have entered the water, and are contained in the
vapour.
  Experiment 59.  Mix 100  gallons  of water at 50°,
with one gallon of water at 212°.   The temperature  of
the water  will be  raised about  \\°.  Condense by a
common still  tub  1  gallon of water, from the state  ot
steam, by 100 gallons of water, at the temperature  of
30Q.  The water will be raised  11°.*
  Rationale.   From this experiment  it  appears, that
Slbs. of  water, condensed from steam, would raise the
temperature  of 100 gallons of cold water 9J- more than
8 pounds of boiling water;  and, by an  easy calculation,
it appears, that the caloric imparted to the 100 gallons  by
the steam, if it could be condensed in 1 gallon of water,
would  raise it to  950°.   A pound of  water, therefore,
from this data, in the state of  steam, contains more ca-
loric than a pound of boiling water, in  the proportion of
950 to 212.
  Remark. On account of the large  quantity of caloric
latent  in  steam,  it  renders its application useful  for
practical  purposes.   Thus water may be heated at a
considerable   distance, and  steam  conveyed through
pipes, either for warming manufactories, rooms, baths,
&c.  Steam may also be applied to the purpose of heat-
ing or evaporating water,  besides  other  operations,
which will be noticed in the course of the work. Dr
Black  remarks, that steam is  the most faithful carrier
of heat that can be conceived ; as it  will deposit it only
on such bodies as are  colder than 212°.  Its application
to the steam engine is the most important use of which
steam  may be made.
  Experiment 60.  Mix  by degrees,  in a Florence flask,
four parts of  sulphuric acid and one of  water, heat will
be evolved.
* ILn:-;-, 8vo. p. 424. 
11
   Rationale.  In this  experiment heat  is  produced,
which is owing to a condensation that takes place. Here
we are presented v ith the fact, that in some operations
heat is given  out  in  an uncombined state, becoming
sensible heat;  for the bulk of the acid  as well  as the
water, on mixture, becomes considerably less than be-
fore.  In all cases of mixture either heat or cold is pro-
duced ; if a contraction of bulk is the consequence heat
is  evolved; if an expansion,  cold is  the result; or, in
other words, the compound has a greater or less capacity
for caloric  than the separate ingredients.
   Experiment 61.   If to a portion of alcohol, sulphuric
acid be added by degrees, the same effect will ensue.
   Rationale.  This is  owing to the same circumstances
as stated in the rationale of experiment 60.
   Experiment 62.   Pour a small quantity of water upon
muriate of ammonia in a wineglass; shake the mixture,
and cold will be produced.
   1 ationale.  Dr. Black has clearly demonstrated that
all matter is  subject to  the  following law, viz. that
"  whenever a body changes its state, it either combines
with, or separates from, caloric."  Therefore, the cold
produced by the solution of this or other crystallized
salts, is owing to the water which was  combined with
them in  a state of solidity,  suddenly taking a liquid
form, and absorbing caloric to preserve it in a state of
fluidity;  consequently the sensation of cold is the con-
sequence.  The same bodies have at all times the same
capacity  for caloric, unless a change takes place in the:
state of these bodies.
   E'emark.   The number of freezing mixtures is con-1
siderable.  The substances, which may be employed-.
for experiments of  this kind, may be arranged in the
following order; for which we  are indebted to Pcpvs„
Walker and Lowi'tz.
c. 2 
7$
TABLE OF FREEZING MIXTURES.
Mixtures.	Thermometer sinks.
Muriate of ammonia - 5 parts Nitrate of potash - 5 Water - - 15	From 50° to 10°.
Muriate of ammonia - 5 parts Nitrate of potash - 5 Sulphate of soda - 8 Water - - - 16	From 50° to 4°.
Sulphate of soda - 3 parts Diluted nitric acid - 2	From 50° to 3°.
Sulphate of soda - 8 parts Muriatic acid - 5	From 50° to 0°.
Snow 1 part Muriate of soda - 1	From 32° to 0°.
Snow or pounded ice - 2 parts Muriate of soda - 1	From 0° to—5°.
Snow or pounded ice 1 part Muriate of soda - 5 Muriate of ammonia & Nitrate of potash - 5	From—5# to—18Q.
Snow or pounded ice 12 parts Muriate of soda - 5 Nitrate of ammonia - 5	From—18«to—25Q.
*Snow and Diluted nitric acid	From 0° to—46°.
Muriate of lime - 3 parts Snow - - - 2	From 32° to—50°.
 
79
TABLE OF FREEZING MIXTURES CONTINUED.
Mixtures.	Thermometer sinks.
Potash - - - 4 parts Snow 3	From 32Q to —51«.
Snow - - 2 parts Diluted sulphuric acid I Diluted nitric acid - 1	From—10° to—56°.
Snow - - 1 part Diluted sulphuric acid 1	From 20° to —60°.
Muriate of lime 2 parts Snow - 1	From 0° to — 66°.
Muriate of lime 3 parts Snow - - 1	From—40° to—73 o.
Diluted sulphuric acid 10 parts Snow 8	■ From— 68° to—91 °.
Nitrate of ammonia - 1 part Water - 1	From 50° to 4°.
Nitrate of ammonia - I part Carbonate of soda - 1 Water 1	From 50° to 3°.
Sulphate of soda - 6 parts Muriate of ammonia - 4 Nitrate of potash - 2 Diluted nitric acid - 4	From 50° to 10*.
Sulphate of soda - 6.parts Nitrate of ammonia 5 Diluted nitric acid 4	From 50° to 14°.
Phosphate of soda - 9 parts Diluted nitric acid 4	From 50° to 12°.
Phosphate of soda - 9 parts Nitrate of ammonia 6 Diluted nitric acid - 4	From 50° to 21°.
Sulphate of soda - 5 parts Diluted sulphuric acid 4	From 50° to 3°. J
 
80
  In using the saline substances, in order to p.odu.~
the effects  before  stated, they should be reduced to
powder, and contain their full quantity of water of crys-
tallization.   Some  other circumstances should be at-
tended  to, which will naturally recur to the operator.
  Experiment 63. Into a cup placed  upon a hearth put
three or four ounces of spirits of turpentine, and pour in-
to it (from a bottle fastened to a stick of some  length
to prevent  accident) a mixture of nitric and sulphuric
acids, in the proportion of an ounce of the former and a
quarter of an ounce of the latter ; instant flame  will be
produced.
  Rationale. In  this experiment we are presented with*
an  additional proof of our former position, namely, that
the compound of these articles has less capacity for calo-
ric than they possess in a separate state ; consequent-
ly,  a part of their  combined caloric  is  liberated,  and
produces  the inflammation.  The sulphuric acid appears
to promote the action very considerably. If the tempera-
ture of the turpentine be raised, the effect is more instan-
taneous.  The nitric acid, as well as the sulphuric acid, is
decomposed; a  part of its oxygen combines with a part
of the carbon of the turpentine, forming carbonic acid ;
another part unites with the hydrogen forming  water;
whilst the other portion is disengaged in  union  with
the azote  of the  nitric acid in the state  of nitric oxyd,
or nitrous gas.   The sulphuric acid also surfers decom-
position ;  sulphurous acid gas is evolved ; and oxyd of
carbon remains  behind.
   Remark.   It  has been asserted, that the  sulphuric
acid  acts  only  in this experiment by  depriving the
spirit of turpentine of any water it might contain.
  Experiment 64. Pulverise  a portion of charcoal, dry
it, and place it in a cup ; pour on it some concentrated
nitric acid, and flame will be produced.
  Rationale.  In this experiment the nitric acid is de-
composed ; a part of its oxygen unites with the carbon
forming carbonic acid, whilst the other portion is evolved
in union with the azote in the form of nitric oxyd gas. 
81
  Experiment  65. Into a tube containing about twelve
cubic inches, throw up, over water, about half its capa-
city  of nitric oxyd gas, and then the  same quantity  of
oxygen gas; a  considerable diminution will take place,
and sknsi-ble heat be given out.
  Rationale. Some gases when presented to each other
have no  action, but  only exist in  the state of me-
chanical mixture ; others  again when  brought  into
contact  exert  a chemical change ; their individuality
is destroyed ;  and  a new  compound is  formed.    If
they suffer no change, no alteration takes place in their\
specific gravity.  In this experiment the affinity is al-
tered ; for as soon as the oxygen gas is presented, both
gases quit the aeriform state, and unite into a  com-
pound called  nitric acid,  which immediately  unites
with the water ; at the same time caloric is given out.
In consequence of this property which nitrous gas
possesses, of absorbing oxygen,  Dr.  Priestley has re-
commended it in eudiometry to determine the  purity
of the atmosphere.   See Atmospheric Air, 
PART IV.
           OF GASES IN GENERAL.

  Gas is  a generic name given by Van Helmont ig
elastic aeriform fluids, and is now generally adopted,
The term air, which was used by Dr. Priestley, seems
rather to imply, that clastic  fluids  are only modifica-
tions of common or  atmospheric air,  the contrary to
which is known to be  true.  It  is not  necessary to re-
mark, that pneumatic chemistry  is considerably indebt-
ed to  Dr. Priestley, for its present flourishing state.
  Elastic fluids have been divided into two genera,
gases, atidvapours ; the former signify such elastic fluids
as retain  their elasticity in all  known temperatures;
the latter those elastic fluids  which lose  their elas-
ticity by  cold, and become  liquid,  &c.   This dis-
tinction may have its use ;  but there is no great reason
to believe the difference is not  in kind, but in  degree
only ; and that all the  gases would lose their elasticity
provided  the temperature  could be sufficiently re-
duced.  The gases may be considered simple  or com-
pound j  an  enumeration of which may be seen in the
general contents of the book; to which some add aque-
ous, alcoholic, and etherial vapour.
  A few remarks on the nature of simple gases, gase-
ous mixtures, &c. may, with propriety, be here noticed.
  Newton, in the 23d prop, of the second book of the
Principia, says that an  elastic fluid consists of particles
that repel one another by a force  which varies in the
simple inverse ratio of the central distances.  A  fluid,
however,  so constituted  would  exhibit the same  me-
chanical properties  as atmospheric air.  A gas con-
sists of a ponderable base united with caloric,  and some-
times with light (as  oxygen  gas) with an  affinity too
powerful  to  be  overcome, or destroyed,   except by 
83
 chemical action,  or  a  relative  change  in  affinities.
 The repulsive power, which always tends to  separate
 the particles of bodies, consequently acts in opposition
 to the attraction of aggregation, in the  case  with gases
 preserves them in an aeriform state.  On this power
 there have been  several  speculations ;   at this era of
 science, it is considered to be a peculiar matter called
 caloric, or the  matter of heat.    Some  imagined it to
 be  magnetical; others electrical, but these opinions
 have been exploded.
   The mode in which caloric exists in this  class  of
 bodies may be  shewn by experiment.   Introduce into
 a tubulated retort some dry muriate of soda, attach to it
 a globular vessel having two openings, from one end of
 which let a tube come and pass into water; then place
 a thermometer in the globe, and add to the salt half its
 weight of concentrated sulphuric acid.   Apply  heat,
 and gas will  come over.   It  will  be  found, that
  he mercury in the thermometer will rise only  a few
 -degrees ;  but the water in the tube, into which the pipe
 ■enters, will acquire  a considerable  accession  of heat.
 In this case, therefore, caloric first combines with mu-
 riatic acid, as it is disengaged from the salt, and exists
 chemically united,  as it is not appreciable by the ther-
 mometer ; but in coming to the water, the gas is ab-
 sorbed, partly decomposed, and caloric is given out in
' a free state, as  sensible  heat.   By compound gases  we
 understand an elastic fluid, which arises from a chemi-
 cal union of the elements of two or more elastic fluids,
 or of one  elastic fluid and another  inelastic body,  as
 carburetted hydrogen, in which carbon  and hydrogen
 are united, or as in nitric oxyd, in which azote and oxy-
 gen are combined.
   By  gaseous  mixtures we mean the union of two or
 more  gases.   Some  gases when  mixed, chemically
 combine with each other ;  others are merely diffused
 through the whole space.*
   With  respect  to the  classification  of gases,  some
 writers have applied the terms respirable and nonrespi-
* See page 13. 
81
ruble, supporters uvid non supporters of  combustion, Sec.
and in this  manner have divided them.   Some gases
effect no positive change in the blood,  while  others, ac-
cording to Dr. Beddoes and  professor Davy, produce
some positive change. As to the weights, specific gravi-
ties, constituent principles, See. of the gases, they will
be found under their proper heads.
  The pneumatic apparatus is a reservoir or  cistern too
well known to require description ; it is for the pur-
pose of collecting, transfering, and experimenting on the
gases.  It may be  made of wood, tin (painted or japanned)
or sheet iron painted with a thick coat.   Wood, how-
ever, is preferable.   See a plate in Lavoisier's and Hen-
ry's  Chemistry.  It is obvious, that  as some gases are
absorbed by water, that that fluidwould not answer for
all gases.*  For  collecting and experimenting on these
a mercurial apparatus is indispensably necessary.  A
trough about  12  inches long,  three inches  wide,  and
four deep,  is  sufficient  for all private  experiments
As to the method of collecting and transfering  gases
from one vessel to another, the operation is too simpie to
need description ; nor need we notice the  bell glasses
or air holders necessary in pneumatic  chemistry.  For
a particular account of these and other apparatus for
conducting  experiments  on the gases,  I would refer
the student to that excellent manuel, Henry's Epitome
of Chemistry, a  work designedly  calculated to instil
the  first principles into the  mind of the new beginner.
   Agreeably  to our plan, the firef-.aration of the gases
separately will be considered under  distinct sections,
and  in the subsequent part their characteristic propertie*
will  claim our attention.
* -See page 15. 
SECTION I.
 OF THE PREPARATION OF OXYGEN GAS.

  Experiment  1. Put into a retort a  small quantity of
oxygenized muriate of potash, and apply  the  heat  of a
lamp.  When the  salt begins to melt,  oxygen  gas
will be obtained in abundance.
  Rationale.  In this process a  decomposition of the
oxygenized muriate of potash takes place ; its  oxygen
is extricated in combination with caloric, forming  oxy-
gen gas, while the simple muriatic acid united to the
potash, in the state of muriate of potash, remains in the
retort.
   Experiment 2. Introduce into an earthen,  or coated
glass retort, or iron mattrass, a portion olnitrate of potash,
and expose the apparatus to the action of a strong  heat,
 until the retort becomes red hot.   A gas will be obtain-
 ed, which is oxygen gas.
   Rationale.   In this experiment the nitric acid of the
 nitrate of potash is partially decomposed.  The great-
 est part of the oxygen of the  nitric  acid  unites to
 caloric, and forms oxygen  gas.   The other part remains
 with the potash in the state of nitrous acid.   The  resi-
 due in the distilling vessel is therefore nitrite of potash.
 Care  should  be taken to lessen the heat towards the
 end of the process, otherwise azotic gas will also  come
 over.
   Remark.  This method of obtaining oxygen  gas, I
 would recommend for extensive experiments in prefer-
 ence to any other.   In my class, wherea number of ex-
 periments are made, I found  it more expeditious  in the
 end.
   Experiment 3. If black oxyd of manganese be  exposed
 in the same manner, and with the same apparatus, to a
 strong heat, oxygen gas will be given out.
   Rationale.  Black oxyd of manganese is an ore  of
 manganese, in which a quantity  of oxygen  exists in a
 combined state.  On exposing it, therefore,  to  a red
 heat, the affinity of the two is partially destroyed ; its
                          II 
86
©xygen unites with  caloric in the state of oxygen gas,
while the metal re-approaches the  metallic state.  A
gray oxyd of manganese, however, remains in the vessel.
  One pound of oxyd of manganese,  will afford  about
1400 cubic inches of oxygen  gas.
  Remark.  If  sulphuric acid be  -previously added to
the manganese, the gas is produced by a less heat and in
a larger quantity ;  a glass retort and an Argand's lamp
may then be used.
  Experiment 4. If red  oxyd of  mercury  (mercurius
precipiteitus per se) be treated in the same manner as
in  the  preceding  experiment,  oxygen gas will be
the result.
  Rationale.   This oxyd of mercury is  formed by ex-
posing mercury to a  heat of about 610° Fidir.
  If the temperature be raised to  about  1000° the at-
traction of oxygen is changed ;  oxygen  gas  is  given
out, and the mercury is revived.
  Experiment 5. If red oxyd of lead be heated, with or
without sulphuric acid, oxygen gas will  be produced.
  Rationale.   In this experiment also, the heat destroys
the former affinities ;  consequently, oxygen gas is giv-
en out, and, if sulphuric acid be used, a  sulphate of lead
remains in the retort.
  Experiment 6. Fill a glass bell with water, introduce
the leaves of vegetables under it, and place the bell in-
verted in a flat  dish  of water.   Expose the apparatus
to the rays  of the sun, and very pure oxygen gas will
be disengaged.
  Rationale.   In this experiment  the  water is said to
be decomposed ; the hydrogen combines with the plant,
to the nourishment and support of which it contributes,
while the oxygen is  set at  liberty.  Dr.  Manners in-
formed  me that he  exposed a plant to the action of the
sun's rays under water, which  contained carbonic acid,
and that he obtained a  large quantity of oxygen gas.
In this case, the carbonic acid, as well as the water, un-
derwent a decomposition; the carbon and hyd.ogen
were absorbed, and the  oxygen, not only of the water,
but also of the carbonic acid, was liberated. 
37
  Experiment 7.  Expose under  water, in the same
manner as in the former experiment, a portion of the
green matter which collects on stagnant waters, to the
rays of the sun ;  oxygen gas will be  disengaged in
abundance.
  Rationale.   The conferva, or green matter, of stag-
nant pools, Dr. Priestley discovered would afford, when
exposed to the  sun's rays, a large quantity ol empyreal
or oxygen gas.   It has been supposed by  some philoso-
phers, that this matter  is the product of spontaneous
generation.
  In this as in the preceding experiment, the water is
decomposed; its hydrogen is absorbed, and the oxygen
is given out in the state  of gas.
  Experiment  8. Expose the leaves of vegetables to the
sun's rays under water; oxygen gas  will be emitted:
expose the  same  leaves under lime water, and no gas
will be disengaged; now remove the leaves, wash them,
and expose them again  in pump water, and gas will be
given out as at  first.
   Rationale.  This experiment  I give on the authority
of my friend Dr. Manners, which experiment he insti-
tuted to prove that water isnot decomposed as is generally
supposed, but the carbonic acid, with which it is impreg-
nated ; for, when the leaves were exposed in water, either
distilled or boiled, he obtained not a  particle of gas.
When lime water was used, the effect was the  same.
Sec an Essay in the Memoirs  of the Columbian Che-
mical Society, by Dr. Manners.
   Dr. Woodhouse made a number of  experiments,  I
think in 1806, on this subject, an account of which was
published in Nicholson's Journal, and also in Wood-
house's edition of Chaptal's Chemistry ; wherein  he
endeavoured to prove, that water was not decomposed
by  vegetables, but that in every case in which oxygen
gas was  formed,  carbonic acid  was present.  Conse-
quently he inferred, that the emission  of oxygen was
from the decompositionof carbonic acid, and not from the
water.  The professor instituted these experiments  af-
ter Mr. Sennebier  had  made his on  the same subject. 
88
Mr. Sennebier proved, that if wa'rr be previously  boil-
ed, of course deprived of its air, the leaves do not emit
a particle of oxygen gas ; that those kinds  of water
which yield most air, contain in them the greatest quan-
tity of carbonic acid gas ; and that leaves do not  emit
any oxygen when pluv.ged in water totally destitute of
caibonic acid gas.*  If these conclusions be correct,
which we have no  reason to doubt, the theory  of the
decomposition of water by plants, is fallacious.  Berthol-
let  infers, th^t oxygen  is  given out  partly from the
water, and partly from the carbonic acid.
  Remark.  All plants  do  not emit oxygen gas with
the same facility.   There are some  which yield it the
moment the sun's rays come upon them, as the leaves
of the jacoboea or rag wort, of lavender, pepperment, and
some other aromatic plants.  Green healthy plants af-
ford more air than white or yellow ones.  Green fruits
also furnish  oxygen  gas.   The  nastutium indicum, in
the space of a few hours, gives  out more air  than is
equal to the bulk of all its leaves.   Several essays have
appeared on this subject.   See an interesting  one by
Mr. G. F. Lehman, " On the emissionof Oxygen gas by
plants," in the  Memoirs of  the  Columbian Chemical
Society, vol.i.
  Experiment 9.  Put concentrated oxygenized muriatic
acid into a bottle, and fit to it a bent glass tube, one end
of which pierces the cork of the bottle,  and the other
end reaches  under  a  bell  or   receiver, filled with
and inverted in a  basin of water, care being taken
that the  tube does  not touch the  acid ; expose the
whole to the  rays of the sun, and oxygen gas will pass
over into the receiver.
   Rationale.  This experiment is  founded on  the pro-
perty, of the decomposition of oxymuriatic acid by light,
for the production of oxygen gas  is  the  effect of that
decomposition.   The oxygenized  muriatic  acid is
therefore, changed into the common muriatic acid.
• See Thomson, v. j55, 
m
                SECTION II.

 PREPARATION OF CARBONIC ACID GAS.

  Experiment 1. Into a glass in which marble, or  chalk
has been put, pour  sulphuric, nitric or muriatic acid, a
decomposition will ensue, and carbonic acid  gas be
disengaged.
  Rationale.  In this experiment the marble, or chalk,
(carbonate of lime) is decomposed; the sulphuric, ni-
tric, or muriatic acid  unites with  the  lime, forming
the sulphate, nitrate, or muriate of lime, and the  car*
bonic acid is disengaged in a gaseous state.
  Experiment 2. Into a jar containing oxygen gas,  in-
troduce a piece of ignited charcoal; when the combus-
tion has  ceased, the remaining air  will be found to be
carbonic  acid; and if the charcoal be sufficient, the
whole of the oxygen gas will  be  converted  into  car-
bonic acid gas.
   Rationale.  The charcoal by  combustion in  oxygen
gas unites  with the oxygen; the result is carbonic acid,-
a compound of carbon and oxygen.  This experiment
should be made over mercury.
   Experiment 3. If the vapour of water be passed over
charcoal, heated to  redness in a gun barrel ; and  the
gas collected, it will be found to be carbonic  acid,
With HYDROGEN and C ARBURETTED HYDBOGEN-GASES.
   Rationale.  In this experiment the water is decom-
posed ;  its oxygen  combines with a part of the carbon
forming carbonic acid, whilst its  hydrogen is liberated
partly  in a  free state, and partly  in combination with
carbon, forming the carburetted hydrogen gas.
   Experiment 4.  Put into an iron mattrass some marble
or chalk, apply a considerable degree of heat, and car-
 bonic acid gas will be  obtained.
   Rationale.  In this case  the decomposition of the car-
bonate of lime takes place, on account of the action of'
 caloric,  which at a  high temperature breaks the affinity
of the carbonic acid and lime; it unites with-the first audi
                          h2 
DO
leaves the lime in that state which  is generally called
quicklime.
  Experiment 5.   If a tube be attached to the bung of
a barrel, in which the vinous fermentation has  com-
menced ; or if the air of a brewer's vat,  in which fer-
mentation is going on, be  collected and examined, it
will be found to be carbonic acid.
  Rationale.   During the vinous fermentation, the car-
bon of the vegetable matter  is partly carried off in
union with oxygen forming carbonic acid,  whilst the
other portion of carbon remains behind in combination
with hydrogen, and forms spirit, which exists in beer,
cyder, and liquors of this kind, in union with water and
mucilaginous matter.
  Experiment 6.  Mix together equal parts  of red lead
and charcoal, and expose  the mixture  to  the action of
a strong heat, in an earthern  retort;  carbonic  acid
gas will come over.
  Rationale.   In this case the red lead or oxyd of lead,
is decomposed by the charcoal ;  the oxygen is abstract-
ed, the lead revived, and carbonic acid formed.
  Experiment 7. Melt in a crucible a portion of nitrate
of potash;  when melted  throw in by degrees  some
charcoal powder; an immediate deflagration will ensue;
und if the gas be collected, it will be found  to be prin-
cipally carbonic acid.
  Rationale.  In this case the nitric acid of the nitrate
of potash is decomposed : the carbon unites with the
oxygen forming carbonic acid, whilst the azote is set at
liberty.  A portion of the carbonic acid  is disengaged,
and another portion remains with the potash of the de-
composed nitre, in the form of subcarbonate of potash.
  Remark.   The sources of carbonic acid are immense,
and widely diffused.  The chief are the  following :
   1. The atmosphere always contains a  small  portion,
 which varies in  the immediate vicinity of places where
 the processes of respiration and combustion are going
 on, though somewhat less than might be  expected.
 The general average is estimated at  about one hun-
 dredth part. 
91
  2. Almost every natural spring, as it rises from the
earth, contains a small portion of this  air; and some
waters hold  so large a portion as to give them, when
exposed to the air, a very brisk, frothy appearance, and
a very sensible  taste, and decidedly acid properties.
The celebrated springs of Spa, Pyrmont, and Seltzer,
and the Balltown in the United States, are of this kind.
  3. Every process in which coal,  wood, or any other
carbonaceous substance is burnt, is one which generates
this acid gas.  The same may be said of the processes
of respiration.
  4. The vegetation  of  plants  under  some circum-
stances generates carbonic acid.
  5. The spontaneous decomposition of vegetable and
animal matter, produces this gas in abundance.
  6. But the largest store of carbonic acid that exists*
is that enormous quantity which is solidified in all the
immense beds of  lime-stone, chalk, and calcareous
stones with which every part of the globe abounds.
Many of these contain 40 per cent, or even more of
their weight of this acid.
                SECTION III.

OF THE PREPARATION OF GASEOUS OXYD
                  OF CARBON.

  Experiment 1.  To one part of chalk, previously ex-
posed to  a low red heat for ten minutes, add an equal
quantity of perfectly dry filings  of zinc ;  let the mix-
ture be introduced into an earthen, or iron retort, and
exposed to a heat gradually increased.   As soon as the
retort becomes of a dull red colour, gas will be  disen-
gaged  in great abundance.  This gas is the carbonic
OXYD, Or GASEOUS OXYD of CARBON.
  Rationale.   This combination of carbon and oxygen
contains  a less  proportion of oxygen than is found in
carbonic  acid.  In this process, therefore, a decompo-
sition of  the carbonic acid of 'h« chalk takes place, in 
92
its nascent state.  The zinc  robs the carbonic acid, a?
it is liberated by the aetion of heat, of a part of its oxy-
gen at a high temperature,  and becomes  to a certain
degree oxydized.  The carbonic  acid, by being thus
deprived of a part of its oxygen, is converted into a
new inflammable gas.
  Remark.   In the commencement of the process car-
bonic  acid  gas is obtained ;  but when the  heat is in-
creased, the decomposition of the remaining acid en-
sues.   This gas is  said to hold the  same relation to
pure hydro-carburets and carbonic acid gas which ni-
trous  gas, or nitrous oxyd, does to pure azote and ni-
trous acid.
  Carbonic oxyd gas  may also be obtained  by several
other  processes.  If tin filings be mixed with charcoal,
and treated in the same manner,  the like result  will
ensue ; or, if equal quantities of scales of iron separated
in forging (black oxyd of iron) and  charcoal powder
previously heated to redness be mixed, and exposed to
the action of heat, the same effect will take place.  The
gas procured in  this way, is a mixture of about one
part of carbonic acid gas, and four of gaseous oxyd of
carbon ;  the former may be  separated by suffering the
gas to stand over lime water, which will absorb it, and
form  a carbonate  of lime.   By  employing  oxyd of
zinc, red oxyd  of copper, semi-vitreous oxyd of  lead,
black oxyd of manganese, and the rest of the metallic
oxyds  capable of enduring a red heat,  with  charcoal,
carbonic acid gas,  and carbonic oxyd gas  will be ob-
tained.   Carbonic  acid gas transmitted over  ignited
charcoal, also forms it.
             SECTION IV.

OF THE PREPARATION OF HYDROGEN GAS.

  Experiment 1.  Introduce into a flask about an ounce of
iron or zinc filings, and pour over them a few ounces of 
93
uut'rr ; then add sulphuric acid, and hydrogen gas Will
be evolved.
  Rationale.  Acceding to the  Lavoiserian theory of
chemistry, the water in this case is decomposed,  and
the acid promotes  the chemical  action.   All  metals
before  solution  are  oxydized, which must take place
either  before,  or in the  act of solution ; therefore,
when iron or zinc  filings, is presented to diluted sul-
phuric acid, the water is decomposed ; its oxygen goes
to oxydize the metal, which is  then dissolved by the
acid ; whilst the hydrogen is evolved in the state of gas
The oxygen is  therefore the bond  of union between
the metal and the acid.
  Experiment 2.  Let a gun barrel, having its touch-hole
screwed up, pass through a furnace ; adjust to its upper
extremity a retort charged with water, and let the other
extremity terminate in a tube introduced  under a re-
ceiver in the pneumatic trough.   When the apparatus
is thus disposed and well luted, bring the gun-barrel
to a red heat; and, when thoroughly red hot, make the
water  in the retort boil; the  vapour, when  passing
through the red hot tube, will afford hydrogen  gas
abundantly.
   Rationale.   Tn this experiment the oxygen of the
water combines with the iron at  a red heat, forming
an  oxyd ; and the  caloric applied combines with the
hydrogen of the water, and forms  hydrogen gas.
                SECTION V.

OF THE PREPARATION OF  SULPHURETTED
               HYDROGEN GAS.

  Experiment 1.  Put some sul/ihuret of iron (made by
melting three parts of iron filings and one of sulphur)
into a flask j pour a little diluted sulphuric acid upon it. 
94
and  SULPHURETTED  HYDROGEN  GAS will he  dlSCll-
gaged.
  Rationale.  In this experiment the water is decom-
posed; a part of the oxygen oxydizes  the  iron,  which
is  dissolved by  the acid;  the hydrogen then,  acting
upon the sulphur,  dissolves a portion of it, and forms
sulphuretted hydrogen  or  hepatic gas.  A portion of
sulphuric acid is also formed.
  Experiment 2.  Into a flask  introduce some sulphuret
of potash, and pour on  it diluted  muriatic  acid; apply
heat, and sulphuretted hydrogen gas  will  be dis-
engaged.
  Rationale.  Sulphur in a separate state, has no action
on water, yet if it be united to an  alkali, this combina-
tion  decomposes water  whenever  it comes in contact
with it, though the  alkali itself has no attraction either
for oxygen or hydrogen.  A part of the sulphur unites
with the oxygen forming sulphuric acid,  which then
combines with a part of the alkali and produces sulphate
of potash, whilst the hydrogen of the water, thus set at
liberty, unites with a portion of the sulphur, and forms
sulphuretted hydrogen  which is disengaged in union
with caloric  in  the state  of gas.  The  muriatic acid
unites with the other portion of alkali, forming muriate
of potash.  If sulphuret of potash be thrown into water
of the  common  temperature, it will be decomposed;
sulphate  of potash, undeeomposed sulphuret, and hy-
droguretted sulphuret will exist.  If an acid be  added,
or the  temperature raised, the latter would be decom-
posed, and sulphuretted hydrogen gas be  disengaged.
  Experiment 3.  If a  mixture of sulphur  with vegeta-
ble matter, as sugar, oil, or powdered charcoal,  be ex-
posed to  a strong heat, sulphuretted hydrogen gas
will  be obtained.*
  Rationale.  The hydrogen,  which exists  in vegetable
substances, or probably from water in its decomposition
by heat, unites with the sulphur, and produces sulphu-
retted hydrogen.   Gas  obtained by  this means, would
be impure, containing more or less of carburetted  hy-
drogen.
* Reese's Cyclopaedia. 
95
   Experiment 4.   If sulphur be exposed  to hydrogen
 ((as, in a gas holder, a portion will be  dissolved by the
 gas, and.the whole converted into sulphuretted hy-
 drogen gas.
   Rationale.  This  experiment proves, that hydrogen
 is susceptible of holding sulphur in  solution; which
 forms hepatic air.
   Experiment 5.  If sulphur  be melted in  a tube, and
 hydrogen gas passed through it, sulphuretted hydro-
 •■vkn gas will be formed.
   Rationale.  This is also a case of the simple solution
 of sulphur in hydrogen gas.




                 SECTION VI.

 OF  THE  PREPARATION OF LIGHT CARBU-
           RETTED  HYDROGEN  GAS.

   Experiment 1.  Fill a wide mouth bottle with water,
 and keep it inverted in some  stagnant water, with a fun-
 nel in its neck ; then with a  stick  stir  the  mud at the
 bottom just under the  funnel so as to  let the bubbles
 of air which  rise from the mud enter  into the bottle;
 when, by thus stirring the mud in various places, and
 catching the  air in the bottle, it is filled : the gas thus
 obtained is the light  carburetted  hydrogen.
   Rationale.  Hydrogen is capable of containing carbon
 in solution: in  this case we have a compound of the
 two.  Nature produces it ready formed in marshes and
 ditches, on the surface of putrid water, in burying-pla-
 ccs, common  sewers, and in those situations where pu-
 trid  animal and vegetable matters are  accumulated.
 It is also generated in the intestinal canal of living ani-
mals.
   Experiment 2.   If shavings of wood, or saw dust, be
put into a retort, and distilled with a heat gradually in- 
S(i
creased until the retort becomes red hot;  a great quail-
tity of gas will be liberated,  which, when caught over
lime water and washed, will be found to be the light
carburetted  hydrogen.
  Rationale.  When wood is subjected to destructive
distillation, it is resolved into its elementary principles,
and the product obtained shews that  it  contains hydro-
gen, carbon, and oxygen.  When the heat arrives at a
certain temperature, a part of the charcoal unites with
part of the oxygen, which forms carbonic acid, whilst
the hydrogen combines with another part of the char-
coal,  and forms the light carburetted  hydrogen  gas.
The  flame of burning wood is supposed to be this gas
in the state of combustion.
  Experiment 3.  If charcoal be moistened with water,
and  exposed in an  earthen  retort to a heat gradually
raised, a gas will come over consisting partly of carbo-
nic acid gas, and partly of light  carburetted hy-
drogen gas.
   Rationale.  In this case  the water  is decomposed,
and carbonic acid and carburetted  hydrogen gases are
produced.   The former may be  separated by lime wa-
ter.
   Experiment 4.  If charcoal be exposed to the solar
rays, concentrated by a lens, in hydrogen  gas, the same
combination will take place.
   Experiment 5. Expose some pit coal in a small earth-
en, or iron retort,  to the action of  a  strong heat; a
gas will come over, which when passed  through  lime
water, will be pure light carburetted  hydrogen
gas.
   Rationale.   As the coal  receives the heat, a vast
quantity of gas is liberated, not however perfectly pure.
This gas is formed, it is supposed, by the  decomposi-
tion of water in the  coal; for at the  same  time, some
carbonic acid passes over, which is produced from the
oxygen of the water and carbon of the coal.   The gas
obtained from pit coal has  been substituted for oil in
lamps, and has  been used successfully to  light up
rooms, for an account of which  see Thomson's Che- 
97
mistry, vol. i. p. 51. and  Parke's Chemical Catechism,
8vo.
  During the operation much bituminous matter is dis-
tilled.
  Experiment 6.   If acetite of potash be distilled, a gas
will be obtained which possesses the properties of the
light carburetted  hydrogen  gas.
  Rationale.   In  this experiment, the  acetous acid is
decomposed; its oxygen unites with a part of the car-
bon, forming carbonic acid, which attaches itself to the
alkali, whilst the hydrogen and  part of the -carbon are
dissipated in a gaseous state.
                SECTION VII.

OF THE PREPARATION OF  HEAVY CARBU-
          RETTED HYDROGEN GAS.

  Experiment 1.   If four parts of concentrated sulphuric
acid  and one of alcohol be  mixed together in a retort,
and a moderate heat applied, a large quantity  of gas
will pass over, which is the heavy carburetted hy-
drogen  gas, or the olefiant  gas of the Germans.
  Rationale.   By the action of sulphuric acid  on the
alcohol, a decomposition ensues.  A part of the acid it-
self is decomposed: the oxygen of the acid appears to
combine  with a portion of hydrogen  forming  water,
whilst the carbon of the alcohol is separated; the other
portion of hydrogen, being now disengaged, combines
with a part of the carbon, and forms the heavy  carbu-
retted hydrogen gas, at the same time some sulphure-
ous acid  passes over, from  which it is to be separated.
From the property which the gas possesses of forming an
oil with oxymuriatic acid gas, the Dutch chemists have
given it the appellation of olefiant gas,  and Dr. Thom-
son calls  it heavy hydrocarburet, or hydrocarbonate.
                         £ 
98
  Experiment 2.  Pass through a red hot earthen tube
in the state of vapour, alcohol or sulphuric ether, and a
gas will be obtained similar to the preceding.
  Rationale.   During this operation, the heat acts as a
divellent power; the hydrogen of the alcohol, or ether,
takes the gaseous form, which unites with  carbon ob-
tained from the same source, and produces the heavy
CARBURETTED HYDROGEN GAS.
  Remark.  There are  several species of the gas call-
ed carburetted  hydrogen, a full account of which may
be seen in Thomson's Chemistry.  What is called the
light carburetted hydrogen contains 28£ per cent, hy-
drogen, and 7\\ carbon, and the  heavy carburetted hy-
drogen, called also  the super carburetted  hydrogen,
and olefiant gas, is composed of 83 per cent, of carbon,
and 17 of hydrogen."
               SECTION  VIII.

OF  THE  PREPARATION  OF  ARSENIURET-
            TED HYDROGEN GAS.

  Experiment 1.   Mix a small quantity ol metallic arse-
nic with a few zinc or iron filings, and add to the  mix-
ture some diluted sulphuric  acid, arseniuretted hy-
drogen  gas will be obtained.
  Rationale.  In this experiment, the water is decom-
posed ; the oxygen unites with  the zinc or iron, which
is afterwards dissolved, and  the  hydrogen  combines
with a portion of the arsenic, forming the arseniuretted
hydrogen gas.
  Experiment 2.  If an alloy  composed of 15 parts of
tin and one of arsenic, be digested in muriatic acid ar-
seniuretted hydrogen  gas will  be evolved.
  Rationale.  In this process, recommended by  Stro-
meyer, the water in the muriatic acid  is decomposed;
hydrogen is evolved, which dissolves a portion of arse- 
99
nic, forming the gas in question, whilst the muriatic
acid unites with the tin into a muriate of tin.
  Experiment 3.  If liquid arsenic acid be digested with
zinc, an effervescence will ensue, and arseniuretted
hydrogen gas will be evolved.*
  Rationale. In this experiment the water of the liquid
arsenic acid is decomposed ; its oxygen as well us a. part
from the arsenic acid goes to the zinc and oxydizes it,
which is then taken up by the arsenic acid, forming arse-
niatdtei' zinc, whilst the hydrogen of the water, thus dis-
engaged, unites with a portion of the arsenic, and forms
arseniuretted hydrogen.
                SECTION  IX.

OF THE  PREPARATION OF  PHOSPHURET-
            TED  HYDROGEN GAS.

  Experiment 1.   Put four ounces of water into  an
eight ounce retort, and add a little solution ol pure pot-
ask, and give it a boiling heat with a lamp.   When it
boils, drop a small  piece of phosphorus into it, and im-
merse the beak of the retort into a vessel of water. Bub-
bles of phosphuretted  hydrogen gas will pass over,
and on coming  in contact  with the atmosphere, will
take fire.
  Rationale.  In this case the phosphorus unites  with
the potash, forming a phosphuret, which decomposes
the water:  the oxygen of which unites  with a part of
the phosphorus and converts it  into phosphoric acid;
whilst  the  hydrogen of the water, thus  set at  liberty,
dissolves the  other portion of phosphorus, and produces
the phosphuretted  hydrogen gas.  Phosphate of potash
remains in the retort.
                                          ♦
           * Ilccse's Cyclopedic, article Arsenic. 
100
  Experiment  2.  If a small quantity of phosphuret of
lime be thrown*into water, bubbles of phosphuretted
hydrogen gas will be evolved.
  Rationale.  In this ease  the water is decomposed by
the  phosphuret of lime : a part of the  phosphorus is
converted into the phosphoric acid by the oxygen of the
water,  which unites  with  the lime into a phosphate of
lime; the other part  of the phosphorus combines with
the hydrogen of the decomposed .water, and forms the
phosphuretted hydrogen gas.
  Experiment 3.  If  20 grains of phosphorus, cut very
small, and mixed with 40 grains of fine granulated zinc,
and 2 drachms of concentrated sulphuric acid be added
ttiereto, phosphuretted  hydrogen gas  will  rise to
lue surface, and take  fire.
  Rationale.  In this case  the zinc seizes the oxygen;
and the hydrogen, the other constituent of the water,
unites with a portion of  the phosphorus, forming the
phosphuretted hydrogen gas, whilst the oxyd of zinc is
t.iken up by the sulphuric  acid, and forms sulphate of
v.inc.
  Experiment 4.  If to a piece ol phosphuret of lime, put
 is water, a few drops of concentrated muriatic acid be
added, a disengagement of phosphuretted  hydro-
g..n  gas will immediately ensue.
  Rationale. In this experiment, like in the preceding,
t!ie water undergoes a decomposition ; the muriatic
acid promotes the action, probably by  separating the
hydro-phosphuret, like in  the case with hydro-sulphu-
ret of potash.
  Experiment 5. IIphosphorus be exposed to an atmos-
phere ol hydrogen gas, a portion will be dissolved in that
air, and form the phosphuretted hydrogen gas.
  P.ationale.  In this case a direct combination of phos-
phorus  with hydrogen takes place; if the phosphorus
be melted, while in the hydrogen gas, the combination
will  be  facilitated.   The  gas formed in this way con-
tains less phosphorus than  that produced by the phos-
phuret of lime ; it has therefore been called Itiiosphori-
zed hydrogen gas.  It is this gas which is otlen seen  ho- 
101
vering on the surface of burial-grounds, marshes, &c.
known by the name of will-o-the-wisp.
                SECTION X.

OF THE  PREPARATION OF AMMONIACAL
                      GAS.

  Experiment 1.  Introduce a mixture of two parts of
muriate of ammonia and one part of lime (quick-lime) both
in powder, into a retort, and apply  the heat of a lamp ;
a gas will be produced", which is the ammoniacal gas.
  Rationale.  In this experiment the muriate of ammo-
nia, being a compound of muriatic acid and ammonia, is
decomposed by the lime ; the muriatic acid unites with
this earth, forming muriate of lime, which remains in
the retort, and the ammonia combines with caloric, and
forms ammoniacal gas.
  Experiment 2. Introduce into a retort, or flask adapt-
ed to a syphon, a portion of liquid ammonia, and apply
the heat of a lamp; ammoniacal gas  will  be pro-
duced.
  Rationale.  As  the liquid ammonia is nothing more
than a solution of ammoniacal gas in water, it is obvious,
that on the  application of heat, the ammonia is disen-
gaged in the form of gas.
                SECTION XI.

OF THE  PREPARATION OF SULPHUROUS
                  ACID GAS.

  Experiment 1. Pour on to a small quantity of mercury,
put into a  retort, a portion of sulphuric acid;  apply
heat, and sulphurous acid gas will be formed.
i 2 
102
   Rationale.  In  this  experiment  the mercury  ab-
 stracts a part of the oxygen of the sulphuric  acid, as
 the latter is a compound  of sulphur and oxygen,  and
 becomes converted into an oxyd ;  the  sulphuric acid
 having thus lost a  portion of its oxygen, is transformed
 into the sulphurous acid.
   Experiment 2. Place in  an earthen dish  some  sul-
 phur ; set fire to  it, and when it is completely inflam-
 ed, cover it  with a large  bell  glass perfectly dry ; re-
 move the whole on a dish and surround it with mercu-
 ry.  The sulphur will burn for  some time.  When
 the vapour  has  subsided, the air in the glass will  be
 found to contain sulphurous acid gas.
   Rationale. This is a case of the slow combustion of
 sulphur.  During the  process, the sulphur absorbs the
 oxygen contained in the atmospheric air; the oxvgen
 not being  sufficient to oxygenate the sulphur com-
 pletely, the result is an imperfect  aeriform acid.
   Experiment 3. If sulphite of potash be exposed in a
 retort to the action of heat,  sulphurous acid gas will
 be disengaged.
   Rationale. In this case the heat  decomposes the salt,
 which is a compound of  sulphurous acid and potash,
 and unites with the acid forming  sulphurous  acid gas.
   Experiment 4. If concentrated  sulphuric acid be added
 to the sulphite of potash, and heat  applied, sulphurous
 acid gas will be produced.
   Rationale. In this   experiment, the sulphuric acid
 decomposes the sulphite; it unites with the alkali form-
 ing sulphate of potash,  whilst the  sulphurous acid is
 liberated.
   Experiment 5. Moisten charcoal  with sulphuric acid,
 and expose it to distillation ; sulphurous acid gas and
 carbonic acid gas will be obtained.
   Rationale.  In this case the charcoal  decomposes the
 sulphuric acid;  it unites with a part of the oxygen  and
 forms carbonic acid; at the same  time the  remaining
 compound of sulphur and oxygen is disengaged in the
^tMe of sulphurous acid gas, the sulphuric acid  being
 partiydeoiiydated. 
103
  Experiment 6. If a mixture ol sulphur and the oxyds
of lead, mercury, tin, or manganese, be subjected to heat)
sulphurous acid gas will be produced.
  Rationale.  In this experiment the  sulphur attracts
the oxygen of the metallic  oxyds, and becomes convert-
ed into sulphurous acid gas, while the oxyds are partially
restored to the metallic state.
               SECTION XII.

OF THE  PREPARATION OF NITRIC  OXYD
                       GAS.

  Experiment  1. If to a portion  of copper filings, put
into a retort, nitric acid be added, and heat applied, ni-
trous gas, or nitric oxyd gas, will be obtained.
  Ratioiuile.   In order the better to obtain this gas,
the acid should be diluted, and the first portions of the
gas suffered to escape.  In  this experiment the  water
undergoes no change, but the acid suffers a partial de-
composition : nitric acid, being a compound of oxygen
and azote, when presented to the metal, is decomposed ;
a part of the oxygen unites with the metal, thereby ox-
ydizing it, which is then dissolved by another portion
of the  acid, forming nitrate of copper,  at the same
time  another part being thus deprived  of some of its
oxygen, assumes a gaseous form, constituting the nitric
oxyd, or nitrous gas, which exists as a  permanently
elastic fluid  at the common temperature  of the atmos-
phere.
  Remark.   Other metals beside copper may  be used
for procuring nitrous gas, such as lead, mercury,  silver,
iron, zinc, &c.
  Experiment  2. Pour nitric  acid on  powdered tin, a
violent action will immediately ensue, and  a  copious
disengagement of nitrous gas take place.
  Rationale.  It is evident, that as the metals possess
different degrees  of affinity for oxygen,  the phc- 
104
nomena is more or less rapid.   In  this experiment
considerable heat is produced, during the oxydizement
of the metal, and the extrication of the nitrous  gas.
The rationale of this is similar to the preceding.
  Experiment 3. If copper wire, or strips of this metal,
be introduced into a retort, and the same quantity  of
nitrate of potash added, and  to this half its weight of
sulphuric acid;  on applying heat,  nitrous  gas will
be obtained.
  Rationale.  In  this  process nitrate of potash is de-
composed :  the sulphuric  acid unites with the alkali,
forming  sulphate of potash,  whilst the nitric acid is
disengaged, which acts immediately  on  the copper,
and causes, by its decomposition as in a former experi-
ment, an evolution of nitrous gas.
  Experiment  4. If coarsely powdered  manganese be
put  into an  earthen  tube, open  at both  ends,  then
placed in a furnace, and heat be applied  until the man-
ganese is red hot, and ammoniacal   gas passed over it
from a retort attached to one end,  nitrous gas  will
be given out at the other end of the tube.
  Rationale. Ammonia consists of hydrogen and azote : in
this case, when it comes in contact with the heated oxyd of
manganese, its hydrogen combines with a portion of the
oxygen given out, and forms water,  whilst another part
unites with the azote, and constitutes nitrous gas.
  Care  should be taken,  in making the  experiment,
not to suffer the ammoniacal gas to pass  through unde-
composed.



               SECTION XIII.

  OF THE  PREPARATION OF  AZOTIC GAS.

  Experiment 1. If a paste made ol sulphuret of potash^
or sulphuret of iron, be exposed to atmospheric air  in a
bell glass  over water, the  air will gradually diminish, 
105
as will appear from the ascent of the water, until only
about three fourths of its original  bulk remain.  The
remaining air is azotic gas, or nitrogkn gas.
  Rationale.   Atmospheric air is composed of oxygen
gas and azotic gc.s.   On presenting the sulphuret, the
former is absorbed, and the sulphuret is converted in-
to a sulphate.  The remaining air is the azotic gas.   If
carbonic acid gas existed in the air, its separation from
the azote may be accomplished by  means  of lime wa-
ter.   It is this property which some of  the sulphurets
possess, that has recommended them  in eudiometry to
ascertain the quantity of oxygen gas in the  atmosphere.
The water, with which  the  sulphuret is  moistened,
likewise  undergoes a  decomposition;  some  sulphu-
retted hydrogen gas is therefore formed.
  Experiment 2. If to lean muscular flesh cut in pieces
and put into  a  retort, nitric acid diluted with  double
its weight of water be added, and the  heat of  a  lamp
applied;  a gas will pass over, which will  be found to
be azote or nitrogen.
  Rationale.  Animal substances are quarternary com-
pounds, consisting of azote, carbon, hydrogen, and oxy-
gen.   On adding nitric  acid and applying heat,  the
equilibrium  of  the  respective  affinities is destroyed,
and azotic gas is evolved.   That the  nitric acid,  al-
though composed of azote as a necessary constituent,
does not afford  the nitrogen is obvious, from its  satu-
rating the same quantity of alkali  after as  well as  be-
fore the experiment.
  Experiment 3. If oxygenated muriatic acid gas be  re-
ceived in a  vessel containing liquid  ammonia,  nitro-
gkn g\s will be formed.
  Rationale.   The oxymuriatic  acid gas as well as  the
ammonia, are reciprocally decomposed  ; the oxygen of
the former unites with the hydrogen  of the latter and
forms water, whilst  the azote, the other constituent of
the ammonia, is set at liberty ; the  oxymuriatic being
reduced to the common muriatic acid. 
                        106

  Experiment 4.   If phosphorus be inflamed In a jar of
atmospheric air, until the combustion ceases, the air re-
maining will be found to be nitrogen gas.
  Rationale.  In this experiment the phosphorus robs the
air of its oxygen and forms with it phosphoric acid, which
appears in white fumes.  When these subside, the re-
maining air Avill  be tolerably pure azote.   It is said
that the azote holds a portion of phosphorus in solution
forming phosphuretted azotic gas.
  Remark.  Fourcroy asserts, that  azotic gas left in
contact with charcoal has the property of dissolving a
portion of it.  The gas has been called carburetted
azotic gas.
  In the same manner,  azote unites with phosphorus
and sulphur, forming the phosphuretted and sulphu-
retted azotic gases.
               SECTION  XIV.

OF THE PREPARATION OF NITROUS OXYD
                      GAS.

  Experiment 1.  Introduce  into a retort a portion of
nitrate of ammonia, and apply the heat of a lamp; the
salt will soon liquefy, and nitrous oxyd gas or gaseous
oxyd o? azote will be disengaged.
  Rationale. When the temperature has arrived between
340 and 480 degrees, the salt melts and a rapid de-
composition ensues. In this  experiment, therefore, the
nitric acid, as well as  the ammonia is decomposed; for
at a temperature  of 480*» the  attractions of hydrogen
and nitrogen, and that of  nitrous gas for oxygen  in ni-
tric acid are diminished,  while on the contrary, the at-
traction of the hydrogen  and ammonia for the oxygen
of the nitric acid, and  that of the remaining nitrogen of
the ammonia for the  nitrous  gas  of the  nitric  acid,
are increased; consequently,  a  change  of affinities
ensues.   The  hydrogen of the ammonia  unites  with 
107
the oxygen of the nitrous acid and forms water :  the
nitrogen of the ammonia then combines with the libe-
rated nitrous gas, and forms nitrous oxyd.
  After  the gas  is prepared  it is suffered to remain
over water before it is used.  The peculiar stimulating
effects of this gas when taken  into the lungs, which has
excited great attention in the literary world, will be
noticed hereafter.
   Experiment 2.  If nitrous gas be exposedto  alkaline
sulphites, a part of its oxygen is absorbed, and the gas is
converted into the nitrous oxyd.
   Rationale. In this experiment the sulphite is convert-
ed into the sulphate of potash by the  absorption of oxy-
gen from the  nitrous gas, which is thus changed into
Lhe nitrous oxyd.
   Experiment 3.  If nitrous gas be presented to sulphu-
retted hydrogen gas nitrous oxyd will be formed.
   Rationale.  In  this experiment the hydrogen unites
with a  portion of oxygen  and forms water, and with
azote it produces ammonia. Sulphur is deposited.  The
remaining oxygen and azote form the nitrous oxyd.
   Experiment 4.   Expose sulphuret of fiolash to nitrous
gas, and the latter will be changed into nitrous oxyd.
   Rationale.  In this case a part of the oxygen is ab-
stracted by  the  sulphur, which is acidified, whilst the
remaining gas  is converted into the nitrous  oxyd.  If
the sulphuret be a hydro-sulphuret,  the  sulphuretted
hydrogen will undergo decomposition.
   Experiment 5.  If the nitrous gas be collected, which
has been obtained by the action of nitric acid upon cop-
per, and exposed to  a solution of sulphate of iron, the
nitrous gas will  be absorbed, awd  the  remaining  gas
will be found to be nitrous oxyd.
   Rationale.   In the decomposition of nitric acid by cop-
 per, or any of the metals, it  appears, that besides ni-
 trous  gas, a portion of nitrous oxyd is generated.   Dr.
 Priestley first announced the fact.  As the nitrous dif-
fers from  the nitric oxyd,  or nitrous gas, only in the
 proportion of azote and oxygen, it would appear, that
 in preparing  nitrous gas, these elementary  principles
 arrange themselves  in two different orders; the first 
108
constitutes the nitric and the latter the nitrous oxyd.
The proportion of the latter, however, is inconsiderable
to the former.  When impure nitrous gas is exposed
to a solution of sulphate  of iron, Mr.  Davy  found that
the nitrous gas was wholly absorbed, leaving the nitrous
oxyd behind.  This solution forms Mr. Davy's test for
oxygen, in  eudiometry,  and is far preferable to Dr
Priestley's mode of using the nitrous gas.
                 SECTION XV.

 OF THE PREPARATION OF MURIATIC ACID
                        GAS.

   Experiment 1.   Into a tubulated retort introduce two
 parts of very dry muriate of soda, and pour on  it very
 gradually  one part  of  concentrated  sulphuric acid.  A
 violent action will ensue, and muriatic  acid gas be-
 comes  disengaged.
   Rationale.   Muriate of soda is a  compound of muri-
 atic acid and soda.
   On adding  sulphuric acid, it  is  decomposed.  The
 muriatic acid is given  out in the state  of gas, and a
 compound remains in the retort of sulphuric  acid and
 soda.
   Experiment 2.   If muriatic acid be exposed  to a mo-
 derate temperature  in a retort, a gas will come over,
 which is the muriatic  acid gas.
   Rationale. In this  process the application of heat dis-
 engages the muriatic acid gas from its  combination
 with water, in which it exists in the state  of acid, with-
 out distilling the water.
   Experiment  3.  If muriatic acid be put into a  cylindri-
 cal glass, and about one third or one fourth by  measure
 ol sulphuric add be added, a violent effervescence will
 ensue, and muriatic acid gas be evolved
 ^li0uate-'   TH8 exPeri™ent proves that the affinitv
 of sulphuric acid  for water, is greater than that of mu-
riatic acid ; consequently, the one  displaces the other. 
109
                SECTION  XVI.

OF  THE  PREPARATION  OF  OXYGENIZED
             MURIATIC  ACID GAS.

  Experiment 1.  Introduce into a retort one part of
b'ack oxyd of manganese and three or four of concen-
trated  muriatic acid; apply heat and gas will be ob-
tained. This is the oxygenized muriatic acid gas.
  Rationale.  In this experiment oxyd of manganese is
partly  deoxydated ;  a portion of its oxygen unites with
the muriatic acid, which  is changed into oxygenized
muriatic acid, and which takes the gaseous form.  The
oxyd of manganese, being thus partly deoxydized, is
dissolved by another portion of the muriatic acid, into
a muriate of manganese.
  Experiment 2.  To eight parts, by weight, of muriate
of soda, and three of powdered oxyd of manganese, put
into a tubulated retort, add  gradually  four parts of
sulphuric acid, diluted previously with three  of water.
On applying a gentle heat  oxygenized muriatic  acid
>as will be produced.
  Rationale. In this  case the muriate  of soda is decom-
posed  by the sulphuric acid,  which unites  with the
soda, for which it has a greater affinity, forming sul-
phate of soda, whilst the muriatic acid seizes the  oxy-
gen ot the oxyd, in the same manner  as  in the preced-
ing  experiment, and  forms with it oxygenized muri-
atic acid gas.
  Remark.  The disinfecting apparatus of Morveau is
formed of the above  materials placed  in a suitable  glass
vessel.   Most of the metallic oxyds will answer as well
as the manganese, but the latter is much cheaper, and
generally yields more oxygen.*
  *  As the disinfecting  apparatus of Morveau  lias been used in
hospitals, for the purpose of destroying contagion, or at least for
purifying die atmosphere, the reader may find a description of the
apparatus, and the mode of using it, in a work entitled, " Obser-
vations on the Means of preserving the Health of Soldiers and
Sailors, and on the Duties of the Medical Department of the Ar-
my and Navy ; with remarks on Hospitals and their Arrangement,"
by F.dward Cutbush, M D. Surgeon in the Navy of the United
States. 
no
   Experiment 3.  To an ounce measure of liquid muriatic
 acid, contained in a  gas  bottle, add three  or  four
 drachms of hyper oxymuriate of potash,  and oxymuri-
 atic acid gas will be evolved.  If the heat of a lamp
 furnace be applied, the action of the acid is promoted.
 By immersing the gas bottle in  a vessel of warm wa-
 ter, the same effect will ensue.
   Rationale.  The production of oxymuriatic  acid gas
 by the decomposition of hyper oxymuriate of potash by
 muriatic acid, depend  upon the superior affinity of the
 muriatic acid for  the alkali, in consequence of which
 the oxymuriatic acid is expelled, and muriate of potash
 is formed.
   Remark.  This process was first pointed out by Mr.
 Cruikshank.  This philosopher infers, that the gas ob-
 tained by this means contains one part of oxygen and 1.3
 of muriatic acid,  or 56.5 of muriatic acid, and 43. ;> of
 oxygen in  the hundred.   According to Mr. Chenevix
 the gas procured by this process is a mixture  of hyper
 oxymuriatic acid and oxymuriatic acid gas.
   Experiment 4. If nitric acid be added  to muriate of so-
 da and heat applied, the salt will be  decomposed, arftl
 an acid gas consisting partly of oxymuriatic  acid
 gas will be obtained.
   Rationale.   In the first place a part of the nitric acid
 goes to  decompose the muriate of soda,  with the base of
 which it forms nitrate  of soda,  whilst the muriatic acid
 unites with a part of the oxygen of the remaining  por-
 tion of nitric acid and forms oxymuriatic  acid.   The
 azote of the nitric acid still in union with oxygen, con-
 stitutes nitric oxyd, or nitrous gas, with which the oxy-
 muriatic is contaminated.
   Experiment 5. If oxygenized muriate of potash be put
 into a cup,  and sulphuric acid added, an action will en-
 sue, and oxymuriatic acid gas will  be disengaged.
 If heat is applied, the decomposition is more rapid.
   Rationale.  In  this experiment the  oxymuriate of
potash is  decomposed ;  the  sulphuric acid takes the
place of the oxymuriatic acid, and the latter assumes a
gaseous form. 
Ill
              SECTION XVII.

OF THE PREPARATION  OF FLUORIC ACID
                       GAS.

  Experiment 1.  Put one part ol oowdexed fluate of lime
(Derbyshire spar) into a leaden or tin retort, and pour
over it two or three parts of concentrated sulphuric acid.
When heat is applied, a violent action will  ensue, and
fluoric acid gas will pass over.
  Rationale.   The fluate of lime is decomposed by the
sulphuric acid ;  the  fluoric  acid is  separated in the
state of gas, whilst the sulphuric acid unites with the
lime, forming sulphate of lime.   It is this acid which
has the property of corroding glass ; hence the use of
a leaden or tin retort,  as  it  does not act upon either of
the  metals,  and  hence  also  its utility  in  etching on
glass.
  Exfieriment 2. If water, impregnated with fluoric acid
gas, be exposed to a moderate heat, fluoric acid gas
will pass over.
  Rationale.   In  this  case the heat destroys  the union
of the gas with the water j hence the former is disen-
gaged. 
                PART  V.

OF THE PROPERTIES OF  THE  GAS-F.s.
                  SECTION  I.

               OF  OXYGEN GAS.

   Experiment 1.  If oxygen gas be  introduced  into a
bell glass over water, or mercury, and ignited charcoal
brought in contact, combustion will  immediately com-
mence and scintillating sparks will be thrown out in all
directions.
   In showing  this  experiment the  red  hot charcoal
should be attached to a copper wire.
   Rationale.   In this experiment  the oxygen  gas is
decomposed, as it consists of oxygen, caloric, and light;
the carbon,  at the temperature  of  ignition, having a
greater affinity for oxygen than caloric, combines with
the oxygen, and forms carbonic acid, which  takes the
gaseous state, whilst heat and  light  are  set  at liberty.
If a certain quantity of charcoal be burnt,  or enough to
decompose all the oxygen gas, the remaining air will
be found to be unfit for combustion, or respiration, and
susceptible of separation by lime water : if this be intro-
duced, or the jar removed to a dish containing lime wa-
ter, the gas will be absorbed, the lime water will put on
a milky appearance, and carbonate of lime will be pro-
duced.
  Remark.   Oxygen gas, according  to Dr. Thomson,
is a simple supporter of combustio::.  The term support-
er is used to  denote the property  which some airs pos-
sess, particularly oxygen gas, of aiding and promoting 
113
combustion.  For the theories on  combustion see La-
voisier's and Thomson's Chemistry.
  Respecting the combustion of charcoal, it may not be
improper to add, that in all cases, whether it be burnt
in oxygen gas or in atmospheric air, carbonic acid gas
is generated ; and as this gas is deleterious to animal
life, it is important that proper ventilators  should be
used in  every situation in which it is burnt.
  Experiment 2.  Introduce into a bell  glass of oxygen
gas a piece of roll sulphur, previously inflamed, attached
to a copper  wire;  the sulphur will burn with a beauti-
ful blue flame.   Fumes will arise, which will gradually
subside.
  Rationale.  In this experiment the oxygen gas is de-
composed ;  the sulphur unites, in combustion, with the
oxygen, and forms both the sulphurous and  sulphuric
acids ; these acids being composed of sulphur and oxy-
gen.  The water under the air holder will be found to
have an acid taste, and to exhibit the properties of acids
in general.  Oxygen is the principle of acidity.
  Remark.  When sulphur is  burnt in contact with.
nitrate of potash, as in the sulphuric acid manufacto-
ries, it  is compdetely oxygenated; for  there the oxygen
is furnished by the  nitric  acid of the nitrate, which is.
decomposed..
  Experiment 3.  Fill a bell with oxygen gas,snd  intro-
duce a piece of phosphorus placed in a little cup;  set
it on fire by means of a crooked iron wire previously ig-
nited, and a brilliant flame will  be produced.
  Rationale. In this experiment the phosphorus unites
with the oxygen, forming  phosphoric  acid, which ap-
pears in a white smoke, and the light heat of-the gasv
us well  as of the phosphorus (for these bodies exist in
phosphorus) are set at liberty.
  Remark.   On account of this property, phosphorus.
has been used in eudiometry, to measure  the quantity
of oxygen gas in the atmosphere..  Forty  grains- of
phosphorus absorb generally sixty-five of oxygen- On
the mode of using it, see Thomson's  Chemistry.  Mr. 
il <
Henry has proposed the following method to shew the
combustion of phosphorus in oxygen gas.
  Experiment 4.  Fill a bell shaped rccevier, having an
opening in the  top, to which a compressed bladder is
firmly tied, with oxygen gas ;  and, as it stands inverted
in water,  press a circular piece  of pasteboard, rather
exceeding the jar in diameter, over its mouth.   When
an assistant has set fire to the phosphorus cover it instant-
ly with the jar of oxygen gas, retaining the pasteboard
in its place, till  the  jar is immediately over the  cup.
When this  has been skilfully managed, a  very small
portion only  of the gas will escape; and the inflamma-
tion of the phosphorus will he extremely brilliant.  The
expanded gas rises into the flaccid bladder, and is thus
prevented from  escaping into the room, and proving
disagreeable by its suffocating smell.
   Experiment 5.  If fine /r&?i wire, or thin harpsicord
wire, be twisted  in a spiral form, to the end of which
a little flax or tow dipped in sulphur has been put, and
to the other end a cork fixed, which fits the mouth of a
bottle, then  set on  fire, and introduced into the bottle,
previously filled with oxygen gas, the wire will  burn
with a most brilliant light and  throw out a great num-
ber of sparks.
   Rationale.  This experiment proves that the metals are
combustible, and that in the present instance, the iron
decomposes  oxygen gas.  During the combustion, oxy-
gen is absorbed by the metal, which is therefore chang-
ed into an oxyd, and heat and light are set at  liberty.
The iron, by thus uniting with oxygen, increases in
weight, and loses the properties of metallic iron.  It is
always necessary, in order to effect the  decomposition
of the gas, that the iron should be ignited, or that com-
bustion some  where should  commence the process,
Otherwise the affinity of oxygen and caloric would still
remain in equiiibrio.
   Remark.   Watch springs, and  steel  made sharp
pointed, will, if properly managed, shew the same ex-
periment.  Before my class, I have exhibited the phe-
nomena with perfect satisfaction by using the watch 
115
spring, and also by exposing it, in an ignited state, to a
stream of the gas, issuing from the hydro-pneumatic blow
pipe.
   All  the  metallic substances, with the  exception of
gold, silver, and platina, have the property of decompos-
ing oxygen gas.
   Experiment 6.   If metallic arsenic be put  into a copper
ladle, having previously affixed to it a piece of wood or
charcoal, then set on fire by means  of the blow  pipe,
and quickly introduced into oxygen gas, a beautiful white
flame will be produced, and  the arsenic be  consumed.
   Rationale.  In this  case the arsenic, a simple  com-
bustible body, decomposes the gas, and is converted, by
its combining with oxygen,  into an acid, the  arsenious
acid, which is found floating on the water (if the expe-
riment be made over water)  in the form of a white pow-
der : heat  and light are,  therefore, disengaged.
   Expteriment 7.  Make a small ball  of the turnings of
zinc and put in it a small piece ol phosphorus, put it into
a copper ladle, or attach  it to a copper wire, set it on fire
and introduce it into oxygen gas ; the zinc will be in-
flamed and produce a beautiful green flame surrounded
by a white one.
   Rationale.  The oxygen in this case converts the zinc
into an oxyd of zinc.
   Experiment 8.  If the filings, or turnings, of zinc,
copper, antimony,  iron, or steel, be  exposed to a cur-
rent of oxygen  gas from  a gasometer, they will burn
 with great rapidity.
   Experiment 9.  Take the metal obtained from potash,
or potassium, heat it and introduce it under a bell glass of
 oxygen gas, a rapid combustion will ensue, and potash
 be reproduced.
   Rationale.  As  potash is found  to be a compound
 body, consisting of a  peculiar metal united with  oxy-
 gen, in the state of an oxyd, agreeably to Mr.  Davy,
 it follows, that  potash is reproduced  in  this  experi-
ment. The potassium unites with the oxygen, and heat
 and light are, of course,  set at liberty. 
116
  Experiment 10. If a little Homburg's pyrophorus  be
introduced into oxygen gas,  immediate  flashes like
inflamed gun powder  will ensue.
  Rationale.   This effect is also owing to the decom-
position of oxygen gas.
  Experiment 11. A lighted wax taper let down into a
vessel of oxygen gas burns with great splendour ; if it
be blown out and again let down, the snuff  io instantly
rekindled.
  Rationale.   The first part of the experiment proves,
that oxygen gas is a  better supporter  of combustion
than common air> which is a compound  of oxygen and
azotic gases, and the second, that ignited  carbon (of the
wick) is immediately  inflamed in oxygen gas.
  Experiment  12.  If a piece of dry  coal be fastened
to a copper wire ignited, and immersed into oxygen gas,
it will burn  and throw out brilliant sparks.
  Experiment  13. Nitrate of lime and cliarcoal  mixed,
set on fire and introduced into the gas, will burn with an
orange  red colour.
  Experiment  14. Boracic acid and charcoal, \n the pro-
portion of one part of the  former and three of the lat-
ter, treated  in the same manner, affords a green.
   Experiment 15. Nitrate of strontian and charcoal pro-
duces a rose coloured flame.
   Rationale.   In these cases, the colours are produced
by  the  different substances, which  constitutes their
habits when exposed, under certain  circumstances, to
oxygen gas.
   Experiment  16. If two lighted tapers  be  placed in
two jars of the same  dimensions,  the one  containing
atmospheric air, and the other oxygen ; it will be found
that the taper will burn considerably longer  in the oxy-
gen gas than in the atmospheric air.
   Rationale.   As oxygen gas is a supporter of combus.
tion, and atmospheric air only a supporter of combus-
tion as it contains oxygen, it  follows that  the  taper
would burn for a longer time in ib.e one than in the
other. 
117
   Experiment 17.  If a bi d, mouse,  or other smJl ani-
mal be put into a vessel of oxygen gas, it will  be found
to live six times longer than in  the  same bulk  of at-
mospheric air.
   Rationale.   This is a proof that oxygen gas supports,
eminently, animal life.  Condorcet, accordingly, nam-
ed  it  vital  air.  The reason why oxygen gas thus
maintains animal life  is readily explained,  when we
 onsider, that animal heat is attributable to the decom-
position of oxygen gas by  the blood in the lungs; or
that the process of respiration which is a compound ac-
tion of inspiration and expiration, causes the  air to
come in contact with the disoxygenatedblood, that oxy-
gen gas is decomposed analagous to  combustion, and
that oxygen  is  absorbed, forming  the red blood, and
heat is thus  set at liberty from it.
  Remark.   Dr. Priestley and many other philosophers
have shewn, that animals live much longer in the same
quantity of oxygen gas  than of common air.  Count
Morozzo placed a number of sparrows, one after ano-
ther, in a glass bell tilled wit,h common air and inverted
over water.
                                        H.    M.
The first sparrow lived    -     -      -    3   -  0
  The second    -     -          -        0-3
  The third......0-1
  He  filled  the  same glass with oxygen gas and re-
peated the experiment.
                                        H.    M.
  The first sparrow lived     -   -   .-5-23
  The second               ...    2
  The third......1
  The fourth.....
  The fifth        .....0
  The sixth     -                    -    0
  The seventh.....0
  The eighth       .....0
  The ninth      -     -     .    .     .,     q
  The ten-.h        .....0
      10
      30
1   -  10
30
47
27
30
22
21 
118
  He then put in two together ; the one  died in 10
minutes, but the other lived an hour longer.  These
experiments, therefore, shew, that  a considerable dif-
ference exists between atmospheric air and oxygen gas
as it respects the vitality or the support of animal life.
  Dr. Higgins having caused  a young man to breathe
pure oxygen gas for several minutes, his pulse, which
was at 64, soon rose to 120 beats in  a minute.*  Pure
oxygen gas has been used also with success in cases of
suspended animation.  Water impregnated with it has
been found a valuable remedy in several diseases.
  Experiment 18. If a little dark coloured blood be pass-
ed up into a jar partly filled with oxygen gas, and stand-
ing over mercury ; or if a vial be filled with oxygen
gas, and a  portion of blood added and well  shook, the
gas  will  be  in part  absorbed, and the colour of the
blood will be  changed to a bright and florid red.
  Rationale. Blood, being found to contain subphosphate
of iron united with eight other ingredients,  when ex-
posed  to oxygen gas  changes its colour, (if it be dark)
to a red, which is owing to the absorption of oxygen.
For particulars, see Thomson's Chemistry.
  Remark. All the operations of nature, whether of the
animal, the vegetable, or the mineral kingdoms, are so
governed   by  invariable  laws, as  to co-operate with
each other.  It  is thus  by reciprocal  changes, which
are governed  by uniform laws, that revolutions are
brought about;  and  it is thus also, that the economy
of nature is produced from those operations, which con-
sist in regular and harmonious changes, and altogether
bespeaks  the handy  work of an artist acquainted with
his  materials.
  Oxygen gas is a component part of atmospheric air
in the  proportion of twenty-two parts in  a hundred.
It has never been procured in a separate state. Oxygen
gas, or the combination of oxygen with caloric and light,
is its most simple form.  The gas is permanently elastic,
compressible, transparent, inodorous and insipid.  The
specific gravity is 0.00135.  We have seen that it sup-
• Thornton's Philosophy of Medicine. 
119
ports inflammation and is necessary for respiration, in
which processes it is decomposed.  Oxygen is also a
principal constituent in water, in all acids, and metallic
oxyds,  and in almost all  animal  and vegetable  sub-
stances.  Oxygenizement  is a  process in  which  the
oxygen  unites with certain bases, forming either oxyds
or acids, in the formation of which  certain affinities
ensue.
         PRIMARY compounds of oxygen.
A. Binary.
2. a. With nitrogen.
  1. Atmospheric air.
  2. Nitrous oxyd.
  3. Nitric oxyd.
  4. Nitric acid.
?. b. With hydrogen, wa-
    ter.
-. c. With carbon.
   I.  Incombustible coal,
plumbago.
  2. Charcoal, (carbonous
oxyd.)
  3.   Gaseous  oxyd of
carbon, (carbonic oxyd.)
  4.  Carbonic acid.
•/. d. With sulphur.
   1.  Oxyd of sulphur.
  2.  Sulphurous acid.
  3.  Sulphuric acid.
e. e.  With phosphorus ;
  1.  Oxyd of phosphorus.
  2.  Phosphorous acid.
  3.  Phosphoric acid.
B. Ternary, with carbon and
        hydrogen.
a. a.  Oxyds.  Hydrocarbon-
     ates, alcohol, ether, oil,
     vegetable substances.
b. b.  Acids. Vegetable acid.
C. Quaternary. With hydro-
 gen, carbon, and nitrogen.
a. a.  Oxyds.   Animal sub-
stances.
b. b. Acids.  Animal acids.
  It has been supposed that oxygen gas is a principal
agent in putrefaction.  Dr. Manners placed a quantity
of fresh meat,  dried as much as possible, in order to
free it from moisture, under mercury, so as to exclude
it entirely from atmospheric air; in three days he dis-
covered that the putrefactive process had taken place.
Dr. Thomas D. Mitchell has since  repeated the expe-
riment, with precisely the same result, from which they
drew the following conclusion.  That external oxygen,
or oxygen gas of the  atmosphere, has no  influence
whatever in  the putrefactive process; and that  putre- 
120
faction ensues, in  consequence  of the equilibrium 01
the component parts of animal  substances being des-
troyed by the loss of vi'alit:,, in which also some new
products are formed. Dr. Manners observes, that con-
trary to the common opinion, no ammonia, sulphuretted
hydrogen, nor oxygen gas was formed, in  the process of
putrefaction, excluded from external air ; but that carbo-
nic acid  gas was given out.
  This subject, however, will be noticed  under its pro-
per head.
                  SECTION II.

            OF CARBONIC ACID GAS.

   Experiment  1.  Carbonic acid gas extinguishes fiame.
 for if a lighted taper be let down  into a vessel of this
 air, it will be immediately extinguished.   The smoke,
 if the vessel be shaken, wiil have  an undulating mo-
 tion.
   Experiment 2. Into three tubes of the same dimen-
 sions, introduce atmospheric air, carbonic acid gas, and
 oxygen gas, in each tube; plunge successively, and with
 swiftness, a lighted taper into each of them. In the tube
 containing atmospheric air, the taper will burn as usual;
 in that which contains carbonic acid gas, it will be ex-
 tinguished, and in the oxygen gas it will burn  with in-
 creased splendour.
   Experiment 3. If a candle be placed in a jar of com-
 mon air, and a jar ol carbonic acid gas be  poured, as you
 would water, into it, the flame* will be immediately ex-
 tinguished.
   Rationale. These experiments are designed to prove,
 that carbonic acid  gas  is not a supporter of combus-
 tion ; that although it contains oxygen, yet it is already
 combined with  carbon, with an affinity too great to
be overcome in this  manner.  Hence it extinguishes
flame. 
1^1
  Remark.  As the extinguishing of  flame is a promi-
nent character of carbonic acid gas,  commonly called
fixed air,  and as this gas  is often  found in vault1-;, cel-
lars, wells and the like, it may be always ascertained
by letting down a lighted taper.
 ' Experiment 4. Into a jar of the gas put a mouse, it
will  die in a few minutes.
  Remark.  This gas is, therefore, fatal to animal-life.
Many accidents  have  t>een produced by this gas.   In
the burning of coal, in the fermentation of wine, cyder,
beer, 8cc. it is generated.  The celebrated lake of Aver no,
where Virgil placed the entrance of  hell,  affords so
large a quantity of carbonic acid gas, that birds cannot
fly close over it with impunity.
  If butterflies and other insects be  destroyed in  this
gas, for cabinet specimens,  the colour  will be better
preserved than if they  were suffocated by the burning
of sulphur.  It is this gas in combination with soda, &c.
that constitutes the aerated waters, known by the name
of artificial mineral  waters.   It  is  found  in mineral
springs, and it is often  the solvent of iron, forming the
natural aerated  or  carbonated  chalybeate  waters, of
which the United States abound.
  Experiment 5.  Let the gas, issuing from a mixture of
carbonate  of lime,  and sulphuric acid, or carbonic acid gas,
be conveyed into a bottle, by means  of a syphon, with
its mouth uppermost.  Place a lighted taper into ano-
ther jar, or  bottle, containing atmospheric air, and pour
in the contents of the first mentioned jar, and the  can-
dle  will be instantly extinguished.
   Rationale. This experiment proves that carbonic acid
gas  is heavier than common air;  for, in the first place,
when the carbonic acid gas  comes in contact with  the
air of the bottle, it displaces it;  and in the second, on
pouring the gas  into the bottle, in  which the lighted
candle had  been placed, the gas will descend and ex-
tinguish the flame, shewing  that by its  superior gravity
it displaces atmospheric air.
   Remark.   It is on this account that carbonic acid gas
occupies  the  lowest situations ; hence it is found at the
bottom of wells, mines, cellars, and the like. The spe-
                         L 
\ll
cific gravity of this air, according to the experiments of
Kirwan,  is 1.500,  that of air being  1.000; or  it is to
air as 3 to 2.
  Experiment 6.   Let a  jar containing carbonic acid gat
stand a few hours  over  water.   It will be  found,  that
the bulk of the gas is considerably diminished.
  Rationale.  In this  experiment carbonic  acid gas is
absorbed by  the water,  which  thus acquires  a very
brisk and pleasant taste.
  Remark.   If pressure  be  employed, water  may be
impregnated with  upwards of three times its own bulk
of carbonic acid gas.  The specific gravity of  this sa-
turated water is   1.0015.  Various  kinds of apparatus
are employed to effect a combination of carbonic acid
gas  with water, but the most common of these is the
Nooth's apparatus, which has lately been improved by
Parker and  Magellan.   By  using this machine, how.
ever, water cannot be made to absorb  more than  half
its own  bulk of the  gas.   The apparatus  consists of
three pieces, all of glass, furnished with a valve and stop
cocks.  Different  machines have been invented  for the
same purpose. Some of the aerated alkaline waters pre-
pared in this city, I have found to contain between two
and  three times their bulk of gas. This can only be ef-
fected by using powerful pressure by means of apparatus.
   It is owing  to  the  presence  of carbonic acid, that
cyder, perry, ale, champaign and other wines owe their
briskness.
  Experiment  7.  Into  water  saturated  with  carbonic
acid gas, pour a little of the tincture of litmus, or immerse
into it a slip of litmus paper, or mix it with the infusion of
cabbage ; the blue  colour of the paper, or infusion, will
be changed to red.
  Remark.   This  experiment fully  proves, that  this
gas, in combination with water, exhibits the  characteris-
tic properties of acids.
  Experiment 8.   Expose water  saturated with carbonic
acid gas  to the atmosphere; it will be  found,  in the
course of a short time, that the water will have  lost its
carbonic acid. 
123
  Remark.   It is on this account that beer, cyder, per-
ry, 8cc. when exposed to  the air become vapid:  hence
also the reason why natural and artificial aerated wa-
ters on exposure to the air lose their properties.
  Experiment 9.   Expose aerated water under the  re-
ceiver of an air pump, and  exhaust the air.  When a
vacuum is produced, the gas will escape from the water
so rapidly as to present the appearance of ebullition.
  Rationale.  The affinity which subsists between wa-
ter and carbonic acid gas is, by removing the pressure
of the  atmosphere, destroyed; hence the gas is  disen-
gaged with considerable rapidity.
  Exp riment 10.   If water containing carbonic acid gas
be mixed with time, barytes, or strontian wafer,  or if a
stream ol carbonic  arid gas be made to pass into  either
of these solutions, the fluid, though perfectly transparent
before, will become turbid.
  Rationale. If either of  these waters come in contact
with carbonic acid, they immediately unite with  it, and
form a new combination, which will be either a carbonate
of lime, carbonate of barytes, or a carbonate of stroiitii-.ii.
  Experiment 11.   Pass  the air given out during respi-
ration,  through lime water,, which may be effected by
means of a glass tube or quill. The lime water will grow
turbid, and a precipitation of carbonate of lime take place.
  Rationale.  This experiment is designed to shew, that
the respiration of animals is another source of carbonic
acid.   If an animal be confined in oxygen gas over lime
water,  the water will also become turbid. This effect
is ex plained on the principle, that in respiration, a por-
tion of the  carbon of the  blood in contact with  atmos-
pheric  air in the lungs, combines with a part of the oxy-
gen, and is thrown out in the form of carbonic acid gas,
which is absorbed by the lime water, in the same man-
ner as in the preceding experiment.
  Experiment 12.  Suspend two pieces ol fresh meat in
common air, and in carbonic acid  gas; it will be  found,
that the meat hung in the carbonic acid gas will be pre-
served untainted sometime after the other has begun to
putrefy. 
124
  Rationule  In tins experiment, which is  intended to
prove that carbonic acid gas retards the putrefaction of
animal substances, several circumstances are to be taken
into consideration.
  1. The antiseptic quality of carbonic acid.
  2. The reason why it is so.
  It is a fact stated by some writers on this subject, that
those substances which contain most oxygen are good
to prevent putrefaction ; and as carbonic acid contains a
large quantity of it, it is considered abetter presc rvalue.*
  Experiment  13.   If water saturated with car bonk acid
gas  be  applied to the roots  of plants, it will  promote
their growth.
  Rationale.  In this case the  carbonic acid is decom-
posed.   The carbon unites w ith the vegetable, which
becomes a component part  of it,  while  the oxygen,
the other constituent of carbonic acid, is disengaged in
a free state:  hence it  is, that carbonic acid gas  exerts
powerful effects on living vegetables.   It is said  that
■ arbonic acid  gas, applied as an atmosphere to  plants,
proves injurious to their health.
   Experiment 14. Fill a tube with  a solution  of caustic
potash,  and introduce a portion of carbonic acid gas, the
gas will be diminished,  and, if the quantity be  suffici-
ent, will form carbonate ol potash.
  Rationale. In this experiment the gas is decomposed;
the carbonic acid itself unites with  the alkali, and forms
a compound consisting of carbonic acid and potash.
   Remark.  The combination of carbonic acid with al-
kalies,  earths, and metals, constitutes  a class of salts,
called carbonates : if the base of the salt be in excess, it is a
sub-carbonate, if both  unite into a  neutral compound, it
forms a carbonate, but if  the carbonic acid is in a super-
abundance, the salt is a super-carbonate.
  Carbonic  acid, formerly called  fixed air, aerial acid,
mephitic acid, cedceireous  acid, &c. contains 28  per cent.
of carbon, and 72 of oxygen.
  Experiment  15. Into a tube of glass introduce a bit of
phosphorus  and some  carbonate of  lime ; seal  the  tube

  • See an ingenious essay on this subject by Dr. Mitchell, in the
Memoirs of the Coluinhion  Cbcfinical Society. 
125
hermetically and apply heat,and charcoal will be de-
posited.
  Rationale.   This process was used by  Mr. Tennant
to effect the decomposition  of carbonic acid, which
takes place in the following manner: The substances
introduced into the tube are phosphorus, and carbonate
of lime, or lime and carbonic acid.  And the substan-
ces found in it, are phosphorus, lime, oxygen, and car-
bon.  Hence, therefore, the carbonic acid of the carbon-
ate is decomposed; its oxygen unites with the  phos-
phorus, for which it has a greater affinity, forming phos-
phoric acid, and with lime phosphate of lime, whilst the
carbon, the basis of carbonic acid, is  separated in the
form of charcoal.
  These experiments, which were first  instituted by
Mr. Tennant, were afterwards repeated and confirmed
by Dr. Pearson, and Messrs. Fourcroy, Vauquelin, Syl-
vestre, and Brogniart
  Remark.   Count Mussin-Puschkin effected the de-
composition of  carbonic acid, by  boiling a solution of
carbonate of potash and phosphorus together.
                SECTION  III.

      OF GASEOUS  OXYD OF CARBON.

  Experiment  I.   If gaseous oxyd of carbon, properly
prepared, be introduced into a bladder furnished with
a stop cock and  pipe, with a small aperture, and  set
fire to, as it is compressed out it will burn with a blue
flame.
  Rationale.  This gas is therefore  inflammable, and
during its combustion, it forms, with the oxygen, of the
air, carbonic acid ;  hence  it unites with another dose of
oxygen, and has its properties changed.
  Remark. This gas does  not explode  like other h>
fiammable gases with common air, but burns silently
                        l.  2 
126
with a lambent blue flame.   It detonates, however, in
the following manner:
  Experiment 2. To 100 measures of the gaseous oxyd,
add 45 of oxygen gas, and fire them over mercury in
a detonating tube ; and the gas, after the detonation, will
be found to have decreased from 145 to 90 measures.
  Rationale.  In this experiment  carbonic acid is pro-
duced, which constitutes the 90 measures left in the tube.
  Experiment 3.  When a stream of this gas is burnt,
in the same manner as hydrogen is (to shew the forma-
tion of water) no water will be formed.
   Remark.  This experiment shows that the  gaseous
oxyd contains no  hydrogen, which is always essential
in the constitution of water.
  Experiment 4.  If a mouse, or other small animal, be
immersed in a jar of thisgvw, it will destroy it in a short
time.
   Remark.  This  gas is, therefore, deleterious to ani-
mal life. When respired for a few minutes it produces
giddiness and fainting.
   Experiment 5.   Let a mixture  of gaseous oxyd  and
hydrogen gas, in equal quantity, be made to pass through
an ignited tube, the tube will become lined with charcoal.
   Rationale.  At a high temperature, hydrogen decom-
poses the gaseous oxyd of carbon-; it combines with the
oxygen and forms water, at the same  time charcoal is
deposited.
   Experiment 6. If a vial be filled  with a mixture of
two measures of carbonic oxyd gas, and two and two-
third measures  of oxymuriatic acid gas, then closed
with  a ground  stopper,  and allowed  to remain for 24
hours with its mouth inverted under mercury,  on
drawing the stopper under water, two-thirds of the gas
are immediately absorbed, and all  the rest by agitation
in lime water (except -|th ef a measure of azote.*)
   Rationale.  In  this experiment the  gases act upon
each  other at the  common  temperature of the atmos-
phere ;  that oxymuriatic acid gas gradually  parts with
• Nicholson's Journal, 1802, y. p. 205. 
127
a portion of its oxygen to the carbonic oxyd, which is
therefore converted into carbonic acid. And if proper
mixtures be employed,  the whole will  be converted
into carbonic acid and muriatic acid.
  Remark.  The substance known by the name of car-
bonic oxyd, or gaseous oxyd of carbon, was  confounded
with carburetted  hydrogen, till the  celebrated  Dr.
Priestley drew the attention of philosophers in a  dis-
sertation which he published in  defence  of the  doc-
trine  of phlogiston.   Our  countryman,  Dr. James
Woodhouse, professor of chemistry in the university of
Pennsylvania, repeated his experiments, and confirmed
his theories.  Other experiments were made on the.
American continent.  But the true nature of this  gas
was pointed out by  Mr. Cruikshank,  of  Woolwich,
Great Britain.  In  France also  a number of experi-
ments were made at the instance of the National Insti-
tute.  See Nicholson's Journal, vol. v. p. 201.  Ann. de
Chim. xxxix. 88, and xlii. 121.  See also the observa-
tions  of the Dutch Chemists, Ann. de Chim. xliii. 113.
   Carbonic acid is composed of about   \
               69 Carbonic oxyd
               31 oxygen.

               100
   But  100 carbonic acid are composed of 28  carbon
and 72 oxygen.  Consequently,

             Carb. ox. carb. ox. oxygen.
               28+72=69 -f  31.
               Carb. ox. carb. ox.
                 28 -f 41.=69 ;  or 69 parts of gaseous
oxyd  of carbon contains  28  parts of carbon, and 41 of
oxygen.  Hence it is composed of
                          41 carbon.
                          59 oxygen.

                         100.   Therefore  146  parts
of oxygen, are sufficient to form  100 parts of carbon in-
to 246 of carbonic oxyd gas. 
128
  Carbonic oxyd is lighter than common air, in the
proportion of 966 to 1000.  One hundred cubical inches
weigh 30 grains.
  Berthollet is of opinion, that there are  two different
species of inflammable gases containing carbon.  The
first species is composed of carbon and hydrogen ; the
second, of carbon, hydrogen, and  oxygen.    The first
he calls carburetted hydrogen, the  second oxycarbu-
retted hydrogen.  Under the latter term he includes the
gas obtained by exposing charcoal to a strong heat, the
gas obtained by distilling sugar,, carbonic oxyd gas, &c.
                 SECTION  IV.

              OF  HYDROGEN GAS.

   Experiment 1. If a bottle,  or jar, be filled with hy-
 drogen gas and exposed to the air with its  mouth up-
 wards, it will be found, that on letting down a lighted
 candle, the gas  will have escaped, for the candle will
 burn with its usual splendour.
   Experiment 2. If a tube twelve inches long and 1th
 of an inch diameter be filled with hydrogen gas, it will be
 five minutes in  losing one half of its gas.*
   Experiment 3. Fill  another bottle, or  jar, with the
gas, and  let it remain with its mouth  downwards, and
in  this   situation let  a lighted taper be immersed : it
will be immediately extinguished.
   Rationale.   As hydrogen gas is lighter than  com-
mon air, as its specific gravity, according to Kirwan,
is 0.0843, that of air being reckoned  1.000, it follows*
that on letting the jar remain with its mouth upwards,
the gas will be  displaced by atmospheric air.  In the
second place we are  furnished  with  a proof of this
fact,  for  on immersing a lighted taper it  is  extin-
guished.
            • Nicholson's Journal, vol. vui.  148. 
129
  Remark.  It is on  account of the levity of this gas
that it has been used in the construction of aeronautic
vesseis, or balloons, for  ascending in the atmosphere.
Although hydrogen gas, as  we shall see hereafter, is
inflammable, yet it is so only  in contact with a supporter
of combustion;  hence it extinguishes flame; it  being
of itself a non-supporter.
  Experiment 4. If a mouse be  introduced into a vessel
of gas, it will die in a few minutes.
  Remark.  Hence, hydrogen gas is deleterious to ani-
mal life.   A mouse put into a jar of this gas by Dr.
Gilby, of  Birmingham, lived 30 seconds without incon-
venience ; but in I minute and  33 seconds it was dead.
Seheele,  of  Sweden, Fontana,  Pilate  de Rozier, Mr.
Watt, and more  lately professor Davy, have inhaled it,
but with disagreeable consequences.
  Experiment 5. Fill a bladder with hydrogen gas, hav-
ing a stop cock attached to it, and  adapt the bowl of a
tobacco pipe to the end of it; prepare a  lather of soap,
and form bubbles with the gas ; these instead of de-
scending will ascend.  If a lighted taper be applied to
these bubbles, they will take fire and burn with noise.
  Experiment 6. If a mixture of atmospheric air and hy-
drogen gas  be used instead  of the  latter,  and  the
same experiment with the soap be  made,  itvviil, on
presenting the taper, take fire  and  explode.
  The theory of  these   phenomena  will  be  given
directly.
  Experiment 7. Into a jar of thej-as introduce a light-
ed taper, it will be extinguished.
  Rutiomde.   It is a  fact,  that  two  combustible  bodies
presented to each other without the presence of a sup-
porter of combustion, will, if the one be  on fire, extin-
guish the other : hence the lighted  taper is extinguish-
ed. Hydrogen gas is, therefore, unfit for a supporter of
combustion.   The  same effect may be shewn in the fol-
lowing manner :
  Exptriment 8. Pass up  into a tube  over mercury, a
portion of hydrogen gas, and then introduce a piece of
phosphorus  and tinder; if the phosphorus  be melted, 
130
which  may  be accomplished  by means of a  heated
wire, it will  not tuke fire.
  Experiment 9.  Let ajar containing a given  quantity
ol hydrogen gas stand over water ; no sensible diminu-
tion will take place.
  Remark.  This experiment shews, that no hydrogen
gas is  absorbed by the water.  If water, however, he
deprived of all its air by boiling, 100 cubic inches  of it
will imbibe  1.53 inches of the gas, at the temperature
of 60°.  By artificial  pressure water may be made to
absorb about  the  third part  of  its bulk of that  gas.
The taste of the water is not sensibly altered.
  Mr. Paul, who first formed  this compound, informs
us,  that it is useful in inflammatory fevers, and in ner-
vous complaints,  but it is  injurious in dropsy.
  Ex/ierimcnt 10. In a strong bottle capable of holding
about four ounces of water, mix equal parts of common
air, and hydrogen  gas.   On  applying a  lighted candle
the mixture will burn, not silently as in a former experi-
ment,  but with  a sudden  and  loud explosion.   If a
larger bottle be used, it should be wrapped round  with
a handkerchief,  to prevent the glass  from doing any
injury, in case the bottle should burst.
  Remark.  In this case the hydrogen  unites with the
oxygen of the air, and forms water.   If oxygen gas it-
self be used in the place of common air, the effect will
be  greater.
  Experiment 11. If a bell glass, furnished with a ca-
pillary tube, be filled with hydrogen gas  ; on immersing
the glass into  water, the gas  will be evolved out of the
tube, which, if inflamed, will  exhibit a beautiful  light,
forming the philosophical candle.
  Remark.  If the hydrogen be pure, the flame is of a
blue colour; but  if any substance is held in solution,
the  flame is tinged of different colours  according to
the substance. The temperature necessary for the in-
flammation  of hydrogen is about  1000°.   It is on this
principle  that artificial fire works are  constructed,
which consists of jets, tubes, &c. bent into different
directions, and formed into  various figures, which are 
131
pierced with holes of different sizes. The philosophical
lamp, invented by  Volta, formed of hydrogen gas and
the agency of electricity, which may be lighted an hun-
dred times without the least inconvenience, is a use-
ful  application of this principle.*
  Experiment  12.  Procure a tin apparatus, called an
air pistol, which is usually in the  form of two cones, at-
tached  at  the  base  with two apertures,  the touch-
hole and muzzle;  fill it with a mixture of hydrogen
and  oxygen gases, about in  equal parts, and inflame
the hydrogen by holding a taper to the  touch-hole, a
violent explosion will ensue.
  Remark.  This effect of  the combination of hydro-
gen with oxygen, may be shewn  in several ways, in all
of which water is formed. When 4 measures of hydro-
gen gas are mixed with ten measures  of common air,
the mixture detonates with equal violence ; and if the
experiment be made in glass tubes,  eight measures
only will remain after the combustion.
   Experiment 13. If an electric shock be passed through
a mixture of two parts in bulk of hydrogen gas and five
parts of atmospheric air,  in a detonating  tube, an explo-
sion will ensue, the  volume  of the gases be diminish-
ed, and the water  will rise in the tube.
   Remark.  In this case, the hydrogen unites  with the
oxygen of the  atmospheric air,  by the electric  spark,
and forms water; if the gas be pure and the proportions
correct, all the oxygen will be  dissolved or combined
with the hydrogen.  In order to  ascertain the purity of
hydrogen gas, Mr.  Berthollet has  recommended this
mode.  Thus, when  the bulk of  a mixture of four parts
of hydrogen gas and  ten parts of air is diminished after
explosion to eight parts, the hydrogen gas may be consi-
dered as pure; if only to nine, it contains some foreign
ingredients.  On this principle is also founded the eu-
diometer of Volta.
   If 300 parts of common  air, and 200 of pure hydro-
gen gas (which are measured by a scale on the tube,)
be introduced  into  the eudiometer, and the electric

   • For an account of this apparatus, see Adams's Lectures. 
132
spark made to pass through them ;  after explosion they
will be found oniy 30.5  measures.   There will, there-
fore, have been a diminution of 11>5 measures, of which
one third may be estimated to be oxygen.  Therefore,.
65 of oxgen have  been lost  by 3C0 of air, or 21 and a
fraction per cent.
  The following rule may be adopted, in order to as-
certain the purity of air.  Add to three  measures of
air under examination, two measures of pure hydrogen
gas,  and inflame them by electricity.   Observe the di-
minution when the vessel has cooled ;  and, by dividing
its amount by three, we obtain very nearly the quantity
of oxygen gas which has been condensed.  That water
is formed by the  detonation  of hydrogen,  is  evident
from the following experiment:
  Experiment 14.  Into a bell-glass  introduce  oxygen
gas,  and into a bladder furnished with a stop cock with
a pipe at the end bent like an S put  hydrogen; let the
bell-glass stand over mercury, and introduce the pipe
from the bladder,  turn the cock and press the gas; on
setting fire to it it will burn  in the oxygen until it is
consumed.  Water will be condensed on the sides of
the glass ; or,
  Experiment 15.  Let the inflamed gas, as it comes from
the bladder, come in contact with iron, or in a glass bottle;
water will be formed, and condense on the colder body.
  Remark.  Various  other modes have been adopted
to exhibit the some phenomena.   See Water.
  Remark.  From the experiments  of Mr. Biot it ap-
pears, that if a proper mixture of hydrogen and oxy-
gen  gases be suddenly compressed in a condensing
syringe, the gases will quit their aerifrom state and form
water. In an apparatus constructed for the purpose, an
extremely brilliant light was seen to be  emitted.*
  The combustion of hydrogen and oxygen gas, is suc-
cessfully applied for the purpose of exciting an intense
degree of heat by the blow pipe.  The construction of
this instrument may be seen in the  Annates de Chimic,
American Philosophical Transactions,  and  the Philadelphia
* Nicholson's Journal, xii. 219. 
l3o
edition of the Conversations on Ch mieslry, we therefore
It -g leave to refer the reader to these works.        >
  Experiment 16.  Into a  glass bottle put iron filings
•md sulphuric acid with five or  six parts  of water;
and fit a cork into the  neck, through  which a glass
tube is  passed, having  its  upper  extremity drawn
out to a cupillary bore.  By setting fire to the hydro-
gcn gas, which escapes from this extremity, a continued
current or jet of flame is produced,  which is  allowed
to pass into  a tube  either of glass, earthen-ware, or
metal.  If the tube be not too large,the  flame becomes
smaller as it is  depressed, when the tube covers the
flame to a considerable depth, very clear sounds are
produced.  But, on  the  contrary, if the  tube be too-
narrow, the flame will  be extinguished,  and  in  pro-
portion as the tube is enlarged, the sound diminishes,
so that there is a certain limit at which it totally ceases.
The same happens when the tube is too long.  The
sounds may be raised at pleasure by either using tubes
of various figures  or dimensions, or made of different *
substances.*
  Rationale.  In this  experiment a sound  like that of
the Aeolian harp is produced.  That the percussion of
glass, by a rapid stream  of gas, should produce a sound,
is not extraordinary ; but the sound here is so peculiar,
that no other gas has a  similar effect.   Perhaps  it is
owing to  a brisk  vibratory motion of the glass occa-
sioned by the successive formation and condensation of
small drops of water on  the  sides of the  glass tube, and
the air rushing in  to replace the vacuum formed.
  Experiment 17.   If flowers, or any other figures be
drawn on a ribbon or silk with a solution of nitrate of
silver, and the silk moistened with, water, be then ex-
posed to the action of hydrogen gas, the silver will be
revived, and the figures finally fixed upon the  silk will
become visible ana shine with metallic  brilliancy.
  Experiment 18.  By proceeding in the same  manner,
and using a solution  of gold mnitro muriatic acid,  silks
may be  permanently gilt at a most insignificant «x«

        *  Nicholson's Journal, 8vo. i. 129. and iv. 23.
                          M 
154
 pense, and will exhibit an appearance the mo^t beauti-
 ful that can be conceived.
   Experiment 19.  Immerse a slip of white  silk in a
 solution of nitro muriate of gold in distilled  water, arid
 dry it in the air.  Silk thus  prepared will not be alter-
 ed by  hydrogen  gas ; but if another piece  of silk be
 dipped in the  solution and exposed, while wet, to the
 same current of hydrogen gas, instant signs  of metallic
 reduction  will appear,  the  colour will change  from
 yellow to  green, and a  brilliant film of reduced gold
 will soon glitter on its  surface.
   Exficriment 20.   If a piece of silk be immersed in
 a solution  ol nitrate of silver, and dried in a dark place,
 and then submitted to hydrogen gas, the silver will not
 be reduced ; but, if exposed, while wet,  to a stream of
 the same gas,  the surface will quickly be coated with
 reduced silver;  various colours, such as blue, purple,
 red, orange, and yellow, will accompany the reduction,
 and the threads  of the silk  will look  like silver  wire.
   Experiment  21.  Dissolve  some muriate of tin in pure
 water,  then dip  a piece of white silk in the  solution
 and dry it  in the air; if this be now  immersed in hy-
 drogen gas, no change will be observed ;  but  if  it be
 exposed, while wet, to the same current of gas, the re-
 duction will soon  commence, attended with  a great
 variety of beautiful colours, as red, yellow,  orange,
 green, and blue, variously intermixed.
   Rationale.  In all these   experiments the  metallic
 oxyds,  which are united with the acids in the  form of
 salts, are decomposed by the hydrogen ; which unites
 with the oxygen of the oxyd  and forms water.  The
 revivification of metals, in the above, as well as  in other
 experiments, for which we are indebted to  Mrs. Ful-
 ham, affords a doctrine  on which both  the  phlogistic
 and antiphlogistic theories have been supported.
   Remark.  According  to a modern idea it has  been
 asserted, that hydrogen  in these cases unites with the
metal itself; that it was the phlogiston of  the older
chemists ; and  that in every instance where  a metal
was oxydized, it  was given  out; but  that in  the re-
duction of a metal, it was absorbed. But these opinions, 
I J J
however ingenious, are vague and hypothetical; whicl;;
therefore, require some direct experiments to establish
the existence of the principle of phlogiston.
  Exp riment 22. If a small tube, or cylinder, be filled
with hydrogen gas, and a piece of fresh made  charcoal
be brought in  contact with it, the volume of the  gas
will  be diminished.
  Jiemark.  Charcoal,  having the  properly of absorb-
ing hydrogen  gas,  is rendered useful for a variety of
purposes.   Its action as an antiseptic may  depend in a
great measure  on the absorption  of hydrogen.  Coal
thus containing hydrogen, when  brought in contact
with atmospheric air,  forms water by the  combination
of this gas with oxygen.
  This  gas, formerly  called inflammable  air,  and by
some chemists phlogiston, and known  also to miners
by the name ol fire-damp, was discovered about the be-
ginning of the  18th century.  The following are  the
primary compounds of hydrogen.

A. Binary.
    a. With oxygen ; water.
    b. With azote ; ammonia.
    c. With sulphur ;  sulphuretted hydrogen.
    d. With phosphorus ; phosphuretted hydrogen.
B. Ternary.
    a. With carbon and oxygen.
     1. Oxyds; hydrocarbonates, vegetable substances,
     2. Acids ; vegetable acids.
C. Quaternary.
    With carbon, azote, and oxygen.
     1. Animal  oxyds.
     2, -------acids. 
i3G
                 SECTION  \ .

    OF SULPHURETTED  HYDROGEN GAS.    '
                                                  i

   Experiment  1.  If a bottle filled with  sulphuretted.
 hydrogen gas, be inverted in  a basin of water ; an ab-
 sorption will take place, more especially if agitation he
 used.
   Rationale.  This  is a direct combination of sulphu-
 retted hydrogen  gas with water;  this solution has been
 called by some hydrothionic acid, as it exhibits some of
 the properties of acids.
   Remark.   According to the  experiments  of Dr.
 Henry, 100 cubical inches of water, at the temperature'
 of 50°, are capable of absorbing 108 inches of sulphu-'
 retted  hydrogen.  It  is the solutien  of sulphuretted
 hydrogen in water, that imparts to those waters called
 mineral, such as Harrowgate, the smell of fetid eggs.
   Experiment 2. To water, holding sulphuretted hydro.
 gen gas in solution, add infusion  of litmus, or the infu-
 sion of violets ; these reagents will become red.
   Remark.   Hence the solution, in this respect, pro-
 duces the effect of an  acid.
   Experiment 3.   If water impregnated with sulphuret-
 ted hydrogen, be exposed to the air, it will become co-
 vered with a pellicle of sulphur.
   Rationale.   In this experiment the sulphuretted hy-
 drogen  parts  with its sulphur,  which is deposited,
 whilst the hydrogen is disengaged partly in a free state.
 It would appear, however, that  oxygen is the  decom-
 posing cause;  in that  case water would be produced.
   Experiment 4.  If to  a similar solution ol gas in water,
 nitric acid be added; sulphur will instantly  be precipi-
 tated.
   Rationale.   The  oxygen of the acid unites with the
 hydrogen of the sulphuretted  hydrogen, and forms wa-
 ter, while the  sulpiuir is precipitated.  Hence  nitric
acid has been used  as a test for s>;!phur in. hepatic wa-
ters. 
137
   Experiment 5.  Set fire to a portion of the gas as it
 r.scapes from the gas holder, and nfiame of a bluish red
 colour will be produced.
   Rationale.  This gas is, therefore, like hydrogen, in-
 flammable, and  in this experiment is decomposed by
 the oxygen of the atmosphere; the products of combus-
 tion being water, from the union of oxygen with the
 hydrogen, and sulphuric and sulphurous acids from that
 of the oxygen and sulphur.
   Experiment 6.  Mix equal parts of sulphuretted hydro-
 gen gas and oxygen gas over water, and apply a lighted
 taper;  a smart  detonation  will take  place, and both
 gases will disappear.
   Rationale.  Part of the oxygen unites to the hydrogen
 of the sulphuretted  hydrogen  gas,  and forms water,
 whilst another part of the oxygen unites with the sul-
 phur, and generates sulphurous acid.
   Experiment 7.   When three parts ot sulphuretted hy-
 drogen gas  are mingled with two of nitric oxyd gas, or
 nitrous  gns,  the mixture  will burn with a yellowish
 green flame.
   Rationale.  In this experiment  the nitrous gas acts as
 a supporter of combustion; its oxygen converts the hy-
 drogen into  water, a part of the sulphur is  deposited^
 and azotic  gas remains in the vessel.
  Experiment 8.   II carburetted hydrogen gas be passed
 through melted sulphur; it will be decomposed, and*tt£~
phuretted hydrogen gas obtained.*
  Rationale.  In this  experiment the charcoal, held in
 solution, in the  carburetted  hydrogen, is  deposited,
 whilst the hydrogen dissolves the sulphur, forming the
 sulphuretted hydrogen gas.
  Experiment 9.  If equal parts of sulphuretted hydro-
 gen gas and  atmospheric air be introduced  into a bell
 glass,  that  of sulphuretted hydrogen  first,  a diminu-
 tion will ensue, sulphur will be precipitated, and azote
 left behind.

                •Ann. de Chim. xxi.SS.
                       H a 
158
  Rationale.  In this case the oxyg«.-n of the conmiou
air unites with the  hydrogen, for which the  hydrogen
has a greater  affinity than  for the  sulphur,  and form
water, whilst the  sulphur is precipitated and  the azote
of the atmospheric air  remains in the vessel.
  Remark.  On this principle we account for the depo-
sition of sulphur in certain situations ;  for as-soon as at-
mospheric air comes in contact, it decomposes the sul-
phuretted hydrogen (for the hydrogen is generally the
solvent of the sulphur) and causes the sulphur to be
deposited.  Hence also,  the reason  why sulphur is pre-
cipitated  in the neighbourhood of hepatic waters.
  Experiment 10.  Take a tube closed at one end; fill
it with sulpihurettcd hydrogen gas, and invert it over a con-
centrated solution, of potash ; the gas will be absorbed, and
the  alkali will.acquire the colour and odour of sulphu-
retted hydrogen.
   Rationale.  The  gas is absorbed by the  alkali, and a
peculiar compound is  formed.  If  the alkali is saturat-
ed with the gas, it will  be converted into a hydro-sul-
phuret of potash.  In this state, it forms with the potash,
a triple compound; on exposing it  to heat, the gas will
be evolved.
   Remark.  The alkalies and some of  the  earths will
 combine with sulphuretted  hydrogen.   These com-
pounds  are colourless if  kept in close  vessels, but on
exposure to  air, they become coloured, which is pro-
 duced  by the absorption of oxygen.   The  hydrogen
 unites with the oxygen and forms,water, whilst the sul-
 phur is deposited, which darkens the sulphuret.
   Experiment 11.   If sulphuretted hydrogen  and sulphu-
 rous acid gas, be mixed together  over mercury, they
 mutually decompose  each other, and sulphur is depo-
 sited :  or,
   Experiment 12.   If a- watery solution of sulphuretted
 hydrogen be mixed with  another of sulphurous acid gas,
 they decompose each other, and sulphur is precipitated.
   Rationale.  In these experiments the hydrogen pos-
 sesses a  stronger affinity for oxygen than sulphur; con-
 sequently, it takes it from the sulphurous acid, and forms 
139
water, wui'.st the sulphur of the sulphuretted hytiroge:,
as well  as of the sulphurous acid is deposited.
  Experiment  13.  If into  a jar containing  fresh pre-
pared sulphuretted hydrogen gas, standing over mercury,
we add by degrees ammoniacal gas, dense fumes will ap-
pear, the gases will  vanish,, and a new compound will
be formed.
  Rationale.  In this experiment, the  gases quit their
aeriform state; the  sulphuretted hydrogen combines
with the ammonia, and  forms a saline compound, called
hydroguretted sulphuret of ammonia.
  Experiment  14.  If  oxygenized muriatic acid gas be
mingled with  sulphuretted hydrogen gas, over water, at
the instant the gases come in contact with each other,
their bulk  will be diminished, and the vessel become
lined with sulphur.
  Rationale.   A part of the oxygen of the oxymuriatic
acid gas unites with  the hydrogen of the  sulphuretted
hydrogen gas, forming water, whilst  another portion of
oxygen combines with a part of the sulphur and produ-
ces sulphuric acid •*  at the same time the other portion
of the  sulphur is precipitated, and muriatic acid gas
cemains.
   Experiment L5. If the electric spark be passed through
sulphuretted hydrogen gas in a tube over water, the vo-
lume of the gas will be diminished and sulphur be pre-
cipitated.
   Remark.  It is evident that the electric fluid changes
the original compound,.so  that the hydrogen is dimin-
ished, and  the sulphur precipitated.
   Experiment 16.  Write  on  paper  with  a solution of
acetate of lead, or a solution of silver, bismuth, mercury,
or  tin, or moisten a  slip of paper with either of these
solutions, and expose it to the action of sulphuretted hy-
drogen gas, the paper will instantly become blackened.
   Remark.  Writings performed with these solutions
are invisible when dry, but become  visible  when im-
mersed in a bottle filled with this gas.  Whether this
gas. is applied in a state of gas, or in water impregnate 
140
ed, the effect is the same, as in the following  expert-
rrient.
  Experiment 17.  To a solution of acetate of lead, add
water  impregnated with sulphuretted hydrogen; the
lead will be precipitated of a deep brown colour.
  Remark.   Hepatic water precipitates all metallic
solutions, excepting those of iron, nickel, cobalt, man-
ganese, titanium, and molybdenum.  It  is therefore a
useful  chemical reagent.   Sulphuretted hydrogen gas
tarnishes  silver, mercury, and other  polished  metals,
and instantly blackens white paint.
  The putrid smell, arising from house drains, sewers,
&c. which has the property  of tarnishing silver  spoons,
is a mixture of this gas with putrid  effluvia.
  Rationale.  In the experiments before given, the de-
composition of  metallic solutions by sulphuretted hy.
drogen is explained in the following manner : metallic
solutions  are formed in the first place by the union of
oxygen with the metal, forming an oxyd, which is then
taken up  by the particular   acid forming  the metallic
salt.  When any of the metallic solutions before named,
are brought under certain circumstances, in  contact
with sulphuretted hydrogen, the hydrogen abstracts the
oxygen from these bodies,  and  causes them to re-ap-
proach the metallic state, wfuUst  the sulphur in its turn
unites with the metal thus regenerated, and converts it
into a sulphuret.
  Remark.  On this  principle  some of the sympathetic
inks are formed, and also the effect on metallic cosmetic*
is accounted for.  Ladies, who  have  been in the habit
of using some of these preparations, have become dark
tawnies by bathing in waters holding sulphuretted hy-
drogen gas in solution.
  Experiment 18. IIsulphuretted hydrogen gas be pass-
ed  over ignited charcoal, it will be  decomposed,  and
converted into carburetted hydrogen gas.
  Rationale.   Here it is evident the  sulphur is disen-
gaged, and the charcoal takes its place.
  Remark.  Sulphuretted hydrogen gas, called also stink'
ing sulphurous air, and hepatic air was first investigated 
141
by Schecie.  Its specific gravity, according to Kirwan,
:s 1.106, that of air being 1.000.  It is composed of
                  20.8 sulphur,
                  17.6 hydrogen,

                  38.4
  Hence 100 parts of  hydrogen a-e combined in the
-as with 118  parts of sulphur.  See Ann.  de Chim.
xxxii. 267.  According to Thenard 100  parts  contain
29 of hydrogen, and 71  of sulphur.
   Sulphuretted hydrogen forms the link by which co-
lorific acids are joined to the acids strictly so called. The
Germans have,  therefore, given it the name of hydro-
thionic acid.  As an instrument of chemical analysis it
is usually employed in two states.   1. Dissolved in wa-
ter, in which state it  is called liquid sulphuretted hy-
drogen.  2. Combined with alkalies, by causing a cur-
rent of sulphuretted hydrogen to pass through an alka-
line solution, till the liquid is saturated.  The liquid
is then heated to expel .the excess of gas.  In that state
it is called an alkaline hydro-sulphuret.
                SECTION VI.

OF LIGHT CARBURETTED HYDROGEN GAS.

  Experiment 1.   If a bladder be filled with light car-
buretted hydrogen gas, and inflamed in the same man-
ner as directed in the experiments on hydrogen gas,.it
will burn with a deep blue colour.
  Rationale.  As this gas is a solution of carbon in hy<-
drogcn, it follows,that in combustion, the carbon unites
with oxygen and forms carbonic acid, and the hydrogen
hy combining with the same principle, generates Avater.
  Experiment 2.   If soap  bubbles be made with this
gas, they will not ascend as those of hydrogen, but will
fall to the ground. 
142
  Remark. A jar filled with carburetted hydrogen g\,s,
held inverted for a few  minutes, exchanges its contents
for common air.  The specific gravity of light carbu-
retted hydrogen gas, is said to be greater  than that of
hydrogen gas, or that of common air: 100 cubic inches
weigh from 16 to 21 grains.
  Experiment 3.  If six measures of light carburetted
hydrogen gas, be exploded over mercury by the electric
spark with four measures of oxygen gas, the volume
will be augmented to 12'- measures.   On throwing up
lime water, the  bulk will  be diminished ;  the residue
will  probably amount to 10^ on which nitrous ganr will
have no effect.  If two measures of the remaining gas
be fired with one ol oxygen, and the volume  should be
reduced to one; we  may conclude, that the whole resi-
duary gas would  require about S\ measures of oxygen
to saturate it, and produce  5 measures of carbonic acid
gas.
  Rationale.   This is an experiment, stated originally
by Mr. Cruikshank, in which the decomposition of light
carburetted hydrogen gas is effected by means of oxy-
gen  gas.   A part of the oxygen converts the carbon
into carbonic  acid, whilst the other  part converts the
hydrogen into water.
  Experiment 4.  If one measure of light carburetted hy-
drogen gas, be mixed, over water, with two measures of
oxymuriatic acid gas, and  the vessel  be suffered to re-
main  inverted for twenty-four  hours  with  its mouth
corked; and the cork be  afterwards  removed under
water, the water will rise and occupy about .43 parts of
a measure, the diminution being 2.57  measures.  On
mixing the residuary gas with lime water .09 parts more
become absorbed.
  Rationale.   In this experiment a mutual decomposi-
tion ensues.   In consequence of the  oxygen given out
by the oxymuriatic acid gas,  we have no less than four
new compounds.  1. Part  of the oxygen  unites  with
the hydrogen and  forms  water.    2. Part combines
with the charcoal and forms carbonic acid.   3. A still
less quantity unites  with  another portion of charcoatj 
l4o
.«.nd produces gaseous oxyd of carbon.  The oxymuria-
tic acid is reduced to the state of common muriatic acid
gas.^
  Experiment 5.  When a stream of carburetted hydro-
gen gas is burnt under a long funnel-shaped tube open
at both ends, water will be formed which will condense
on the glass.
  Rationale. This experiment is to shew the formation
of water in the combustion of this gas, which arises from
 he union of the hydrogen with  oxygen.
  Experiment 6.  If  a stream of the gas be burnt in a
vessel of oxygen gas, carbonic acid, as well  as water, will
dc produced.
  Rationale.  In this case  the carbon of the gas unites
with the oxygen, and forms carbonic acid.
  Experiment 7.   Let  the oxygen gas, after the  combus-
tion, be removed to  a  vessel of lime water ; a consider-
able absorption will ensue.
  Rationale.  In  this experiment the carbonic acid,
which was formed  in the combustion, unites with the
lime of the lime water, and forms carbonate of lime.
  Remark.   Carburetted  hydrogen,  formerly called
heavy  inflammable air, was occasionally collected and ex-
perimented on hy Dr. Priestley ; but it was not known
until lately, that there were several varieties of this gas.
One hundred cubic inches of  the gas, obtained from
wetted charcoal according to Mr. Cruikshank, weighed
14.5 grains, and required 66 cubic inches (22.4) grains
of oxygen  to saturate them.  The compound  yielded
40 cubic  inches, or 19 grains of carbonic  acid, and 9
grains of water.  Hence this gas consists  of nearly 4 of
carbon, and 1.3 of hydrogen.
  In order to ascertain the quantity of the ingredients
in the carburetted hydrogen gases obtained from differ-
ent sources; they  may be known  by firing them in a
detonating tube  over mercury, with a known  quanti-
ty of oxygen gas, and observing the nature and quantity
of the products, which are carbonic acid and water. 
144
                    Measures of oxygon  Measures ft car-
    Kind of gas.       gas required to satu-  home  acid pro
                    rate 100 measures.  duced.
Pure hydrogen gas      50 to 54
Gas from charcoal,           60              35
.--------coal              170             100
-------_ stagnant water     200             100
Olefiant gas                284             179
Now since, for the formation of each measure  of carbo-
nic acid  gas, in  the  foregoing  experiments, an equal
volume of oxygen gas is required, we may  learn, by
deducting the number in the third column from the cor-
responding one in the second, what proportion of oxy-
gen has been allotted to the  saturation of the hydrogen
of each hydro-carburet-  Thus, for example, in burn-
ing the gas  from coal, 100  measures of oxygen have
been employee! in forming carbonic  acid; and the re-
maining  70 in saturating  hydrogen.  But 70 measures
of oxygen are sufficient to saturate  140 of hydrogen gas
arid a quantity of hydrogen must therefore be contain-
ed in 100 measures of gas from coal; which expanded
to its usual elasticity would occupy 140 measures.
                SECTION  VII.

   OF HEAVY CARBURETTED HYDROGEN.

   Experiment  1.  Introduce  into a  glass  tube  three
parts ol fresh prepared heavy carburetted hydrogen gas, and
add  to it gradually four parts of fresh prepured oxy-
genized muriatic acid gas.  After each addition of the
gas shake the mixture : an absorption  will take  place,
caloric will be liberated, and the  tube will become
filled with white vapours.  When the gases have to-
tally disappeared, an oil of a  pearl gray colour will be
deposited.
   Rationale.  In this experiment the gases are decom-
posed; the oxygen of the oxymuriatic acid gas unites 
115
with the hydrogen and carbon and forms an oil, of  an
agreeable and penetrating  odour,  and of a % sweetish
taste; which, on-exposure to the air, becomes yellow.
The oxymuriatic is, of course, converted into common
muriatic acid.
  Experiment 2. If equal parts of oxygen gas and heavy
carburetted hydrogen gas, are  introduced into a deto-
nating tube, and the electric spark passed through them,
a momentary expansion will ensue ;  the tube will be-
come lined with a fine black soot of charcoal, and  light
carburetted hydrogen gas will remain.
  Rationale.  This experiment proves that the  heavy
carburetted may be converted into the light carburetted
hydrogen gas, by the agency of oxygen gas and the elec-
tric spark; for the oxygen unites with a part of the hy-
drogen and forms water, whilst a portion of carbon is
deposited, and the remaining hydrogen and carbon, be-
ing in proper quantities, constitutes the light carburet-
ted hydrogen gas.
   Remark.  We  have already observed, that there are
two species of carburetted hydrogen  gas, and that these
differ in the proportion of their component parts.  Dr.
Henry calls  the  carburetted  hydrogen gas, a  hydro-
carburet, and Mr. Watt named it hydro-carbonate ; but
the  gas we  have just  noticed  differs  from  that to
which Dr. Henry  has given the  name of hydro-carbu-
ret, in containing different proportions of the hydrogen
and carbon.
   The olefiant  gas,*  or more  properly super-carburet-
ted hydrogen, called also, oily carburetted hydrogen, which
was first examined by a society  of Dutch chemists, is
composed of
                    83  carbon
                     17  hydrogen.

                   100.
 Besides possessing the  mechanical  properties of com-
mon air, this gas  has  a disagreeable odour.   It does  not
• From " oil making *'
         N 
14G
support combustion, nor animal life.  Its specific gravi-
ty is 0.905, that of air being  1,000.   It burns  with a
dense white flame, and with very  great splendour.  If
it is fully decomposed with oxygen gas, by  employing
one hundred cubic  inches with three hundred inches
of oxygen, according to Mr. Dalton, there is formed a
quantity of carbonic  acid equal to 200  inches.  The
remaining 100 of oxygen, united with the  hydrogen
and formed water.   As the olefiant gas contains more
carbon than the other species of carburetted hydr6gen,
the propriety of the new term will appear obvious. A
brief view of the ingenious experiments and obser-
vations on this  gas, as well as the gas obtained from
moist charcoal, wood, peat, pitcoal,  from oil and spirits
(which  are  carburetted hydrogen gases) by Dr. Wm.
Henry, may be seen in Thomson's Chemistry, vol. i.
page 48 to 65.
  The gas obtained by distilling pitcoal he remarks, is a
mixture  of the light carburetted hydrogen with some
carbonic oxyd and olefiant gas ; and the gases obtained
from oil and wax by distillation contain more  or less
of the latter.  The passing of ether, camphor, or alkohol,
through  red hot tubes, instead of furnishing the light
carburetted  hydrogen gas alone,  affords  a portion of
olefiant gas.
  When applied to  the purpose  of  illumination,  the
hydrocarburet from coal, from lamp oil, or from wax,
produces as much light  in an Argand  lamp as oil in
substance does; this is attributed to the  olefiant  gas
which it contains.
               SECTION VIII.

   OF ARSENIURETTED HYDROGEN GAS.

   Experiment 1.  If a jar of arseniuretted hydrogen gas
be  exposed with  its mouth upwards, the gas  will be
displaced by the atmospheric air. 
M7
   Remark.  The specific gravity of this gas, the ba-
 rometer at 30 inches, is 0.5293, that of air being 1.000 :
 'lence 100 cubic inches of it weigh  16.4.
   Experiment 2. If an animal be immersed in a vessel
 ot this gas, it will die in a few minutes.
   Remark.  This  gas is, therefore, deleterious to ani-
 mal life;.
   Experiment 3. Immerse a lighted taper into the gas,
 perfectly free of atmospheric air, it will instantly be ex-
 tinguished.
   R mark.  This gas is a non supporter of combus-
 tion,  consequently  it  extinguishes  flame ;  that  al-
 though combustible, yet, like other inflammable gases,
 it requires a supporter of combustion.
   Experiment 4.  If a lighted taper be applied to the
 p,as, as it comes from the syphon, it burns with a  blue
 lhunc ;  and, if the combustion be effected in a narrow
 glass vessel, the arsenic is deposited.
   Rationale.   In this experiment, whilst the  hydrogen
 unites with oxygen and forms water, the arsenic  com-*
 bines with another portion of oxygen, and forms arseni-
 ous acid, which is deposited.
   Experiment 5. If two parts  of this gas and three of
 oxygen gas, are brought in contact with a lighted taper,
 an expansion takes place, and water and arsenious acid
 are formed.
   Rationale.   In  this, as in the  former  experiment,
 the oxygen goes to convert  the  hydrogen into water,
 and the arsenic into arsenious acid,  commonly called
 the white oxyd of arsenic.
   Remark.  Equal parts of these gases do not explode
 so loudly, but give a more vivid flame.  Two parts of
 this gas and one of oxygen  leave a small residue.   Ac-
 cording to the experiments  of Stromeyer, it requires
 for combustion 0.72 parts of its bulk of oxygen gas.
   Experiment 6.  Mix equal  parts of this gas with sul-
phuretted hydrogen gas, no action will ensue, but if oxy-
 muriatic acid  gas be now added, the  bulk diminishes,
 and yellow flakes are deposited. 
148
  Rationale.  In this experiment a part of  the  oxygen
of the oxymuriatic aeid gas, unites with the hydrogen
and forms  water, whilst another part unites with  the
arsenic, whi  h then combines  with a part of the sul-
phur, forming a sulphuretted oxyd of arsenic, of a yellow
colour.
  Remark.  Hence these two gases furnish  us with i
delicate test for detecting  the presence  of arscnicd
hydrogen.
  Experiment 8. If concentrated nitric acid be  sudden-
ly agitated with theg-as, an evolution  of red fumes,  and
an explosion accompanied with flame ensue.
  Rationale.  In this experiment the arsenic quits the
hydrogen and decomposes the nitric acid,  in  conse-
quence of which nitric oxyd is evolved, and the arsenic
is partly  converted into  arsenic acid.  If the  nitric
acid, previously to its being used, be diluted with water,
the arsenic, according to Trommsdorf, will be oxydized,
and the hydrogen will remain pure.
  Remark.  This gas, called also arsenical hydrogen gas,
i-'„s  discovered by  Scheele, and afterwards noticed bv
Proust, and lately experimented upon by Trommsdorf.
According to Stromeyer, it is  composed of 106 parts
arsenic and 2.19 hydrogen.  These  proportions, how-
ever, do not accord with its specific  gravity, as stated
by Trommsdorf.
  Mr.  Davy has lately announced  the existence of
t hree other gases, which are metallic compounds, or hy-
drogurets, viz.  telluretted, potassuretted, and borutted hy-
drogen gas.  These  are nothing more than hydrogen
gas holding in solution the metals called tellurium,potas-
sitim, and boracium.   All these gases, which are but lit-
tle known, are  said to contain their own bulk of hydro-
gen gas. 
149
                SECTION  IX.

   OF PHOSPHURETTED HYDROGEN GAS.

   Experiment 1. If a jar of phosphuretted hydrogen gas
be placed over water, at the  temperature between 50°
and 60°, according to Raymond,  about one  fourth  of
its bulk will be absorbed.
   Rationale.  The water absorbs the gas, and assumes,
if the solution  be complete, an orange colour.  If the
temperature of 212° is applied, the  whole of the gas
will be  disengaged, and the water remains behind in a
state of purity.
   Remark.   Water  impregnated  with this  gas has a
bitter and  disagreeable taste, and a strong  unpleasant
odour.
   Experiment 2. Expose  a solution  of phosphuretted
hydrogen gas, in water,  to the atmosphere ; oxyd  of
phosphorus  will  be deposited, and the hydrogen will
escape.
   Rationale.  In this case the decomposition  is effected
in consequence of the disengagement of hydrogen, and
the absorption of oxygen by the phosphorus, which  is
deposited in the form of an oxyd.
   Experiment 3. Pass electric  shocks through  phos-
phuretted hydrogen gas ; its  volume will  be  increased
and a decomposition take place.
   Rationale*  In  this experiment the  water, which  is
contained in the gas is decomposed ; its oxygen unites
with the phosphorus and forms phosphoric acid, and the
hydrogen is evolved.
   Experiment 4.  If the gas, as it  passes  from the rc-
< ort, through  water, be suffered to come in contact wTith
the atmosphere, the bubbles will burst with a slight ex-
plosion, and produce flashes of fire in the circumambi-
ent air.   A circular dense white smoke will rise like a
ring, enlarging as it ascends,and forming a sort of coro-
na extremely beautiful.
   Experiment 5. If a wide mouth phial be filled with
                       K 2 
150
theses over mercury, it will take fire when  suffered to
escape into the air  by  inclining the phial.   This ex-
periment, however, must be made with caution.
  Rationale.   In the combustion of phosphuretted hy-
drogen gas, a decomposition of this, as well as the oxy-
gen gas  of the atmosphere takes place.   The  phos-
phorus unites with  the oxygen and  forms phosphoric
acid, which is disengaged in Avhite  fumes, and the hy-
drogen, by combining with another portion of oxygen,
produces water.  It is to the  water which is carried
off with  the phosphoric acid, in which it is enveloped,
that the white appearance of the corona is attributed.
   Experiment 6.  If phosphuretted hydrogen gas be con-
veyed into a receiver of oxygen gat ;  at the instant they
come  in contact, a brilliant flash of fire takes place, ac-
companied with a report.
   Rationale.   The  same thing is applicable to this, as
in the former experiment.
   Remark.  Great caution should be taken in making
this experiment; for, if more  than a bubble  or two
come  in contact with the oxygen at once, a consider-
able explosion may follow.  It  may not be improper
to  add,  that it is in consequence of the  rapid decom-
 position of the gases,  when brought into contact, that
 flame ensues ; for the  caloric of the phosphuretted hy-
 drogen  gas,  as well as of the oxygen gas, is immedi-
 ately  set at liberty.
   Experiment 7.  To fresh prepared phosphuretted hy-
 drogen gas, add oxymuriatic acid gas over mercury; a
 detonation will take place accompanied with flame and
 vapour.
    Rationale.   The  oxygen of  the oxymuriatic  acid
 unites with  the  phosphorus and the hydrogen, and
 forms phosphoric acid and  water; the  oxymuriatic
 acid being changed into common muriatic acid gas.
    Experiment 8.  If phosphuret of lime be dropped into
 water,  and half its weight of  oxygenized muriate of pot-
 ash added ;  and if the vessel be now filled with water,
 and three or four parts of concentrate dsulphuric acid
 poured through a tube to the bottom, flashes of flame
 will be produced. 
151
  Rationale.   In this  experiment the  phosphurel of
lime as  well as the  oxymuriate of potash, ate decom-
posed, together with  the water.   The phosphuret
combines with  the oxygen, whilst the hydrogen, the
other constituent part of the water, dissolves a portion
of the phosphorus, and forms phosphuretted hydrogen
gas, which is  inflamed under the water by  the action
of oxymuriatic acid gas disengaged  from the oxymu-
riate of  potash by the  sulphuric acid.   Phosphuretted
hydrogen gas, therefore, burns in nascent oxygenized
muriatic acid gas under the surface of water.
  Experiment 9.  If sulphurous  acid and phosphuretted
hydrogen gases, be mingled together, they mutually de-
compose each other.
  Rationale.  In this  process the hydrogen unites  with
the oxygen of the sulphurous acid gas, and the sulphur
and phosphorus are deposited in flakes of ayellowcolour.
  Experiment   10.  If phosphuretted hydrogen gas  be
exposed to the light of the sun in a white glass jar it
will be decomposed;  but  if kept in the dark,  or the
jar painted black, it will undergo no decomposition.
   Rationale.  In this case the  light  has the tendency
of separating the hydrogen from the phosphorus; the
latter will be  deposited on the  glass ; but when the
light is  shut out no effect of this kind follows.
  Experiment 11.  Make a solution  ol muriate of gold,
consisting of one part of the  muriate and  eighteen
parts of water, and wet  a silk ribbon  with  the  solu-
tion ; then expose it over mercury to an atmosphere of
phosphuretted hydrogen  gas for a few days, and the
ribbon will  become coloured with gold.
   Rationale.  The hydrogen as well as the phosphorus
unites with  the oxygen of the oxyd of gold, forming
water and phosphoric acid.  The oxyd of gold, there-
fore, which  was dissolved in the muriatic acid, being
thus deprived of its oxygen, becomes  reduced to the
metallic state,  and attaches itself to the ribbon.
   R emark.  A number of amusing experiments of this
nature maybe made by using other metallic solutions.
   The  gas, to which Fourcroy and  Vauquelin have
 given the name of phosphorized hydrogen, they obtain- 
152
ed by letting  bits of phosphorus remain in conta:!
with hydrogen gas for  some  hours ; but it appears
that hydrogen  will combine with different proportions
of phosphorus.  The compound procured by melting
phosphorus in  hydrogen gas, by means of a burning
glass, was discovered in 1783, by Mr. Gengembre, to
which the name of phosphuretted hydrogen was given.
Mr. Kirwan appears to have discovered it in 1784 with-
out the knowledge of Mr. Gengembre's experiments.
But various experiments have been made since that
period.  It may not be improper to remark, that in the
preparation of phosphorus itself, as  we shall  see here-
after,  in which phosphoric acid and charcoal are em-
ployed, phosphuretted hydrogen gas is extricated; this
takes place by the union of  hydrogen, probably from
the water  which the materials might contain, with a
portion of the phosphorus.
                SECTION  X.

            OF  AMMONIACAL GAS.

  Experianent 1.   If a mouse be introduced into a jar
ol ammoniacal gas standing over mercury, it will be in-
stantly -destroyed.
  Remark.  This gas is therefore fatal to animal life.
  Experiment 2.   If a lighted candle be let down into
a jar of this gas  it goes out three or four times  suc-
cessively ;  but at each time the flame is  considerably
enlarged by the  addition of another  flame  of a  pale
yellow colour, and at last this flame descends from the
top of the vessel to the bottom.*
  Remark.   This gas is, therefore, a non-supporter of
combustion.
  Experiment 3.   If a jar filled with this gas be placed
with its mouth upwards,  it  is soon found to exchange
its contents for common air.
* Priestley, hi. 391. 
153
  Remark.   It is lighter  than atmospheric air.  But
its specific gravity haa been stated differently by dif-
ferent chemists.  Mr. Kirwan found it 0.600 that of
air being 1.00.
  Experiment 4.   If hydrogen gas be  introduced into a
long tube,  and half its quantity of ammoniacal gas  be
added, and to this a like quantity of  muriatic arid gas;
the  cloud which  is formed will not rise beyond  the
confines of the h.-drogen gas.
  Rationale.  After adding the.ammoniacal to the hy-
drogen gas, it is  evident that  the  latter displaces the
former; for on adding the muriatic acid gas it falls,
and unites  with  the  ammonia (which now is at  the
bottom) and forms the white fumes, or muriate of am-
monia.  The cloud thus generated will not rise  with-
in the space occupied by  the  hydrogen gas ; conse-
quently, the "latter had kept its place below the  other
without mixing with  it.
  Experiment 5.   If a jar of the gas standing over mer-
cury,  be transferred to a tub of water, or if a little wa-
ter be introduced into it;  or if ardent spirit be used
instead of  water, applied  in this way, or in a sponge,
paper, &c.  the gas will be immediately, absorbed.  If
the  gas be pure, the  whole  will combine with  the
water, or spirit.
  Rationale.  This absorption  of ammoniacal  gas  by
water takes place so rapidly, that a mercurial  trough
is absolutely necessary in  collecting it; the water and
gas unite and  form a fluid, called  liquid ammonia.
  Remark.   From Mr. Davy's experiments, it appears
that 100 grains of water absorb 34 grains of ammonia-
cal gas, or  190 cubic inches.   Therefore a cubic inch
takes  up 475 cubic inches of the gas.  When a piece of
ice is brought into contact with this gas, it melts and
absorbs the ammonia, while at the same time its tempe-
rature is diminished.   Cold water absorbs this gas  al-
most instantaneously, and at the same time heat is evolv-
ed, and the specific gravity of the  water is diminished.
If a temperature  of  130°  be applied, the gas quits the
water.  The combination  of ammoniacal gas with wa-
ter, in the  formation of liquid ammonia, is effected in 
154
the large way by distilling a mixture of muriate of am-
monia and quicklime with water.   Here the ammonia-
cal gas is given out  by the muriate, which is decom-
posed by the lime, which then unites with the water in
distillation, and forms liquid  ammonia.   If sub-carbo-
nate of potash is employed in the place of the lime, we
have a product of  ammonia, partly combined with car-
bonic acid.  But this subject will be considered under
the head of alkalies.
   Experiment  6.   If a piece of paper coloured yellow
with turmeric, or blue with cabbage juice, be exposed to
ammoniacal gas, the former will become brown, and the
latter of a green colour.
   Remark. Ammoniacal gas, like its solution in water,
will change some vegetable  colours of a brown, some
of a green, and  reproduce the blue colour of reddened'
litmus paper.   This is a characteristic property of the
alkalies.
   Experiment 7.   If ammoniacal gas and  muriatic acid
gas be mixed together, they will quit their gaseous
form, and produce a concrete substance.
   Rationale.   As soon as these gases meet, they unite,
that is, the muriatic acid  combines with the ammonia,
and forms muriate of ammonia, whilst the caloric is set
at liberty.
   Experiment 8.  If  carbonic acid be mingled  in the
same manner with this gas, a mutual decomposition
will ensue, and a solid be produced.
   Rationale.   Here the gases quit their aeriform state,
and heat is  liberated;  carbonate  of  ammonia being
formed.
   Experiment 9.  If two parts  of  oxymuriatic acid gas
be added to one part by measure, of ammoniacal gas, a
brisk detonation is produeed,  accompanied  with yel-
lowish light.
   Rationale.  Ammoniacal  gas consists of azote, hydro-
gen, and caloric ; and oxymuriatic acid gas of oxygen,
muriatic acid, and  caloric.  A reciprocal decomposition
ensues.  The hydrogen of the ammonia unites with the
oxygen ©f the oxymuriatic acid gas and forms water, while 
155
 1 lie azote, the other component part of the ammonia, be-
 comes disengaged.  The oxymuriatic acid, being thus
 deprived  of its oxygen, is converted into the common
 muriatic  acid gas, which, by uniting with the unde-
 composed ammonia, forms  muriate of ammonia; but
 if a smaller  proportion of ammonia be mixed, no mu-
 riate of ammonia will be generated, for the decomposi-
 tion of all the ammonia will then be complete.
  Remark.  If the solution of ammoniacal  gas in wa-
 ter, be brought in  contact with oxymuriatic acid gas, a
 decomposition will also ensue analogous to the last ex-
 periment.
  Experiment 10.  If a mixture ol ammoniacal gas and
 oxygen gas be passed through a red hot porcelain tube,
 a detonation takes place, water is formed, and azotic
 gas emitted.
  Rationale.  Here it is evident that  the oxygen ab-
 stracts the hydrogen from the azote, and forms water,
 which, together with azotic gas, is given out.
  Remark.  If the proportion of oxygen gas be consi-
 derable, nitric acid is also  formed,  in consequence  of
 the combination of azote with the superabundant oxy-
 gen.
  Experiment 11.   If oxyd of manganese be ignited  in
 an earthen tube, and ammoniacal gas be made to pass over
 it, the latter will be decomposed.
  Rationale.   When  a red heat is applied to oxyd  of
 manganese,  oxygen  gas  is  given out in abundance.
 Therefore, on presenting ammoniacal gas to it in  this
 state,  the  hydrogen of the ammonia will  unite with a
 part of the oxygen given out, and form water;  whilst
 the azote combines with another portion of oxygen and
 produces nitric acid; and, as a portion of ammonia passes
 undecomposition, the  ammonia unites with the nitric
 acid, and forms nitrate of ammonia.
  Experiment 12.  If about 200 electric shocks  be pass-
 ed through ammoniacal gas in a detonating lube, it will
increase  three times its original bulk, and be decom-
 posed. 
loti
  Remark.   If a small  quantity of water be admitted,
the gas will not, as heretofore, be completely absorbed
by this fluid, but a part will  remain.   On  examining
the gas, it will be found that the original compound is
destroyed, and that the  hydrogen and azote  are only in
mechanical mixture.
  Experiment 13.  The decomposition ol ammonia may
also be.easily shown by the galvanic apparatus; for a
solution of the  gas in water,  exposed to the action of
the galvanic fluid, will  have its component  parts sepa-
rated in the same manner as in the former experiment
  Experiment 14.  If ammoniacal gas be made to pass
through a red hot  iron tube  containing phosphorus, it
will be decomposed.
  Rationale.  The products in this experiment, accord-
ing to Fourcroy, are  phosphuretted  hydrogen gas, and
phosphuretted azotic gas.  The ammonia is, therefore,
decomposed ; its hydrogen unites with a part of the
phosphorus, forming the phosphuretted  hydrogen gas,
whilst its azote combines with another  portion of the
phosphorus, and produces phosphuretted azotic gas.
  Experiment 15.  Pass ammoniacal gas through ignited
charcoal in a gun barrel  heated to redness, and a new
product, called prussic acid, will come over.
  Rationale.  In this experiment part  of the charcoal
unites with the ammonia, and produces a compound
containing hydrogen, carbon, azote,  Sec.
  Experiment 16. If tin is moistened with nitric acid, and
after a minute or two, aJittle  potash or lime  added, am-
moniacal gas will be  ey<jf|fed.
  Rationale.  The nitr$recid and  the  water which it
contains are decomposed in this experiment; the oxy-
gen of each unites with the tin, and reduces it to the
state of an oxyd ; while at the same  time the hydrogen
of the water combines with the azote of the acid, and
forms ammonia, which  is driven off by the stronger affi-
nity of the potash or lime.
  Remark.  Ammonia as a gas, or in a state of purity,
called also alkaline gas, has been known but a few years:
in combination it has been long known by the name of 
.157
volatile alkali, spirit of sal ammoniac, spirit of urine, spirit of
hartshorn, isfc.
  One hundred parts of ammoniacal gas are said to con-
tain about 80 parts of azote and 20 of hydrogen.  From
some late experiments of Mr. Davy, he concluded that
ammonia contained a small portion of oxygen in its com-
position.  Since Mr. D. has announced the fact, no less
than four new analyses of ammoniacal gas have been
made, and these by chemists of the first eminence. Mr.
Davy and Dr. Henry both agree in the result of their
experiments :  they  make the composition of ammonia
to be 74 measures, by bulk, of hydrogen gas, and 26 of
azotic gas, but they  do not point out the  oxygen.  For
an account of the experiments on ammoniacal gas with
potassium, see a modern publication of Mr. Davy.
                 SECTION IX.

         OF SULPHUROUS ACID GAS.

   Experiment 1.   If a jar of sulpihurous acid gas be ex-
posed with its mouth upwards to the atmosphere, and
a lighted taper let down, the taper will be extinguished.
If the jar  is inverted, it will exchange its contents for
common air.
   Remark. In this case we are furnished with two facts:
first, that sulphurous acid gas is heavier than common
air; secondly, that it extinguishes flame, and, of course,
is  a non-supporter of combustion.
   Experiment 2.  Into a jar of gas, introduce a mouse ;
it  will die in a few minutes.
   Remark.  This gas is, therefore, fatal to animal life.
   Experiment 3.  Introduce some of the gas into a jar,
or tube, over mercury, and throw up a portion of water.
The gas will be diminished, and the mercury will rise
in  the vessel; or,
                        o 
158
   Experiment 4.  If the gas, as it arises from the retort,
be allowed to come in contact with cold water, by im-
mersing the beak of the retort in that fluid, a rapid ab-
sorption will ensue.
   Remark.  In  either  case the gas combines rapidly
with water.  If even ice be present  it melts instanta-
neously.   Water saturated, acquires  the odour of the
gas.  When it is exposed to a temperature of about 65
or 70°, the sulphurous acid is evolved in bubbles of
air.
   Experiment 5.  To water impregnated with sulphu-
rous acid gas put into a retort, apply a gentle heat, and
immerse the beak into mercury, in  a mercurial trough;
sulphurous acid gas will come over.
   Rationale.   In this experiment the  application of
heat decomposes the compound of sulphurous acid and
water, and disengages the  former  in the state of sul-
phurous acid gas.
   Remark.  Water  saturated with this gas carried to
the maximum is 1.0513 sp.  gr. and forms liquid sulphu-
rous acid.
   Experiment  6.   If  into water impregnated with sul-
phurous acid gas, infusion of litmus be  added, the colour
will not be reddened, as acids in general do, but, on the
contrary, it totally destroys  its colour.
   Rationale.  The character of the acids, generally, is
to redden  litmus, but this acid is an exception to this
property:  the destruction  of  the  colour, however, is
owing to a change of affinities  in the rays of light,
agreeably to the observations on colours given under the
head of light.
   Experiment 7.  If a red  rose be confined in a jar of
this gas, or if it be exposed to the fumes of burning sul-
phur, its colour  will be destroyed, and at  length  the
flower will become quite white.
   Remark.  It is on this account that sulphurous acid
gas has been employed in the  bleaching of a number of
substances, as straw, for the purpose of bonnets, &c.
It is usually obtained for this purpose by burning the
common roll sulphur in confined situations, to the air 
159
of which the articles are exposed in a wet state.  By
the combustion of sulphur, however, we obtain not only
sulphurous  acid, but also a portion of sulphuric acid;
the latter is  inconsiderable to the former.
  Experiment 8.  If sulphurous acid gas be made to pass
into sulphuric acid, cooled by a frigorific mixture, the
gas will be absorbed, and the sulphuric acid  assume a
solid form.   If a part of the  concrete acid be laid upon
a glass plate, it exhibits an effervescence.
  Remark.  This concrete  acid (a kind  of glacial sul-
fihuric acid)  is produced  by the combination of sulphu-
rous acid gas with sulphuric acid.
  Experiment 9.  To a portion of water saturated with
this  gas, add a  little oxyd of manganese; the  pungent
smell of the water and other characteristics of sulphu-
rous acid will soon disappear.
  Rationale.  In this experiment part of the oxygen of
the oxyd unites with the sulphurous acid, and converts
it into sulphuric acid.
  Experiment 10.  If to two parts of sulphurous acid
gas, standing over mercury,  one part of  oxygen gas be
added, no union will ensue, if even the mixture be suf-
fered to stand for some months; but if a small quantity
of water be added to the mixture,  an absorption gradu-
ally takes place, the volume of the gases  become dimi-
nished, and sulphuric acid is formed.
  Remark.  The water here promotes the union; the
sulphurous acid gas first unites with it, for which it has
a strong affinity, and the  oxygen then converts the sul-
phurous into the sulphuric acid.
  Experiment 11.   Convey oxygen gas and sulphurous
acid gas into an earthen  tube heated  to redness ; they
will form sulphuric acid.
  Rationale.  In this experiment  the  oxygen at a high
temperature combines  with the sulphurous  acid, and
sulphuric acid is produced.
  Experiment 12.  Add to  sulphurous acid gas  some
hydrogen gas, and no change will take  place ; but,
  Experiment 13.  If we transmit a mixture  of three
parts of hydrogen gas and one of sulphurous, acid gas 
ICO
through an earthen tube, sulphuretted hydrogen gas will
be evolved, and sulphur deposited at the other extremi-
ty of the tube.
   Rationale.  A part of the hydrogen unites with  the
oxygen of the sulphurous acid  and forms  water, and
sulphur is separated ;  another part of the hydrogen, by
combining with a portion of the sulphur, forms sulphu-
retted  hydrogen,  whilst the remaining  sulphur is left
undisturbed.
   Remark.  In a  former experiment, the oxygen con-
verts  the whole  of the  sulphur into  sulphuric acid,
whereas in the latter hydrogen gas decomposes the sul-
phurous acid, and forms water, &c.
   Experiment 14.  When sulphurous acid gas and ammo-
niacal gas are mingled together, a mutual decomposi-
tion will ensue.
   Rationale.  In this experiment a sulphate  of ammo-
nia is  generated,  which is owing to the conversion of
the sulphurous into the sulphuric acid by afurther union
with oxygen, given out somewhere, which  combines
with the ammonia, and forms sulphate of ammonia.
   Experiment 15. Ignite a quantity of charcoal in a tube,
and pass through it sulphurous acid gas ;  a decomposi-
tion of the gas will ensue.
   Rationale.   The products in this experiment are car-
bonic acid, sulphuretted hydrogen, and  sulphur.   At
the temperature of ignition, the  charcoal unites with
the oxygen of the sulphurous  acid, and forms carbonic
acid, whilst the sulphur is disengaged.   A portion of
water  in the  coal being also decomposed, affords hy-
drogen, which dissolves a part of the sulphur, and con-
stitutes sulphuretted  hydrogen.
   Experiment 16.   If fresh prepared muriate of tin be
exposed to sulphurous acid gas, it will be decomposed.
   Rationale.  The oxygen of the acid unites with the
muriate forming oxymuriate of tin, for which it has a su-
perior affinity, whilst  the sulpur is deposited.
   Experiment 17.  If sulphurous acid gas be surrounded
with a mixture of snow  and muriate of lime, it is chang-
ed into a liquid state. 
161
  Remark.   This takes place in consequence of a re-
duction of temperature; for by using the snow and mu-
riate of lime, caloric is absorbed from the gas, which,
therefore, takes the liquid state. The reduction of tem-
perature  should always be—18°.
  Experiment 18.   Expose  unbleached wool,  or linen*
wet with water, to the action  ol sulphurous acid gas,it
will gradually become white.
  Remark.   Hence also we  learn the utility of this  gas,
(which is usually prepared for the purpose, by the slow
combustion of sulphur) in its  application to the bleach-
ing of a number of substances, conformably to Experi-
ment 7.
  Experiment 19.   If a piece  of linen stained by means
of fruits,  be wetted and exposed to this gas, the colour
will be discharged.
  Remark.   Hence its application to the purpose ofre-
moving fruit stains.
  Sulphurous acid gas, formely cMedphlogisticated sul-
phuric  acid, was examined by  Stahl, and afterwards by
Scheel, Priestley and other philosophers.  It is com-
posed, according to Thomson, of 53 sulphur and 4T oxy-
gen in the  hundred, or  100 sulphur and  88,6 oxygen.,
                SECTION XII.

            OF NITRIC OXYD GAS.

  Experiment 1.  If an animal be confined in a jar of
nitric oxyd, or nitrous gas it will be immediately suffo-
cated.
  Remark.   Hence this gas is deleterious  to  animal
life.
  Experiment 2.  If water  be boiled,, and. after it has
become cold, exposed to nitrous gas, a portion of. the
gas will be absorbed.
                         02. 
162
  Remark.   It appears, from  the  experiment of Mr,
Davy, that  100 cubic  inches of water at  the common
temperature, and previously freed from air, absorb 11.8
cubic inches of nitrous gas, or nearly one-tenth, as Dr.
Priestley had ascertained.  Dr. Henry says,  that water
will absorb only live per cent.   The solution has no par-
ticular taste, and does not redden blue vegetable co-
lours.  The gas is expelled again by boiling  the water;
it separates also when  the water is frozen.  The solu-
tion of nitrous gas in water according to La Grange, is
converted by long keeping, into nitrate of ammonia, in
consequence of the decomposition of the water.
  Experiment 3.  Nitrous gas,  if washed, does not red-
den litmus paper, when introduced into it  through wa-
ter.
  Remark.  Nitrous gas, as we shall see hereafter, when
it comes in contact with the least portion of oxygen gas,
or atmospheric air, is partially  converted  into nitrous
acid.   If the gas be washed, in order to  free it from
any portion of  acid, the effect on litmus will  not ensue.
  Experiment  4.  If 16 measures ol atmospheric  air be
passed up into a tube containing 7\ measures of nitrous
gas, or about two measures of atmospheric air and one
of nitrous gas, the two fluids will unite, red  fumes will
appear, and the volume of the gases will be diminished,
at the same time heat will  be evolved.
  Rationale.  The oxygen of the atmospheric air unites
with the nitrous gas, and forms nitrous acid, whilst the
azote, the constituent of atmospheric air, remains un-
touched.
  Experiment  5.   If one ounce measure of oxygen gas
be mingled with two ounce measures of nitrous gas,the
volume of the gases will almost entirely disappear.
  Rationale.   The same thing happens in this experi-
ment as,in the former.
  Remark.   Mr. Dalton* informs  us, that nitrous gas
will combine with two different proportions of oxygen
gas.  Twenty-one measures of oxygen gas uniting with
36 measures of nitrous gas, or with 72 measures.
• Pliil. Mag. xxiii. 
163
  When 85 measures of nitrous gas, containing 13 per
cent, of azotic gas, are added to a mixture of one hun-
dred measures of oxygen and azotic gases, they will be
reduced to 39 ;  consequently, if 11 measures of azotic
gas contained in 85 measures of nitrous gas, be deduct-
ed,  we find that the air, under examination, contained
28 per cent, of oxygen gas.  Upon this property which
nitrous gas possesses of  absorbing the oxygen of the
atmosphere, Priestley and Fontana founded their eudi-
ometers.   There are several sources of error, to which
the nitrous test is liable, notwithstanding the improve-
ment lately made in its application by M. Humboldt.*
Mr. Dalton has given some useful  observations on the
use of this test, which may be seen in Henry's Chemis-
try, 8vo. p.  153.   And Mr. Davy has applied the gas, for
the  same purpose, in solution, as we shall presently de-
scribe.
  Experiment 6.  If a piece of litmus paper be passed
up  into a jar containing a mixture ol oxygen gas and ni-
trous gas, it will be reddened ; or,
  Experiment 7.  If a piece of litmus paper be  pasted
in a jar near the bottom, and washed nitrous gas thrown
up, the colour will not be changed ; but if oxygen gas
be now added, the colour will immediately be convert-
ed to a red.
  Remark.  This, as well as the preceding experiment,
is designed to shew, that nitrous acid is formed in the
admixture of oxygen and nitrous gas, for the  original
colour of  the litmus is changed to red.
  Experiment 8.   Into a jar, over mercury, introduce
proper measures of nitrous gas and oxygen gas, having
previously thrown up a solution of caustic potash. After
standing for some time, remove the solution,  and ex-
pose  it to the atmosphere ;. afterwards evaporate ;
crystals of nitrate of potash will  be  formed, or a salt
which contains nitric acid.
  Experiment 9.  To a portion of the  salt  of the last
experiment, add  sulphuric acid and apply heat j nitric
acid will be disengaged.
* Ann. de Chim. xxviii. p. 123. 
164
  Rationale.  The union  of nitrous gas with oxyget.
takes place in Experiment 8, which is absorbed by the
alkali, forming  nitrate of potash; this is decomposed
in Experiment 9, in which  the  sulphuric acid unites
with the alkali, and the nitric acid is disengaged.
  Experiment 10. Let nitrous gas pass as it is liberated
from the materials which afford it, into a  bottle con-
taining colourless nitric acid.  The acid will undergo
successive changes of colour, first yellow, then green,
next orange  coloured, and  at last dark olive-coloured
and fuming.
  Rationale.  In this experiment the nitrous gas is ab-
sorbed, and converts the nitric into nitrous acid.  The
successive changes in colour depends on the absorp-
tion of different quantities of nitrous gas.   Dr. Priest-
ley found, that 100  parts  of nitric acid of the specific
gravity 1.400 absorbed, in two days, 90 parts of nitrous
gas.   When  seven parts of gas have been absorbed,
the acid acquires an  orange  colour; when  18  have
been absorbed,  it becomes green ; and the whole quan-
tity which it  is  capable of condensing, changes it into a
liquor, which emits an immense quantity of red fumes.
  Experiment 11.   If  to nitric acid, thus impregnated
with nitrous gas, heat be applied ; the colour of the
acid will be resumed.
  Rationale.  In this  case the heat disengages nitrous
gas, and the fuming acid is changed  into the colourless.
  Experiment 12.  Inflame  a  mixture of one part of
nitrous gas and  four of hydrogen  gas, the flame will ap-
pear of a green colour.
  Remark.   Nitrous gas, therefore, imparts a green
colour to the flame of hydrogen gas.
  Experiment 13.  If a jar of nitrous gas be prepared,
and a burning taper immersed into it; the  taper will
be extinguished.
  Remark.  Nitrous gas, though  considered a  sup-
porter of combustion, only however, under certain
circumstances,  in  this instance extinguishes flame.
The  same thing will happen to  ardent spirit, oils, kc.
But if it were  possible that these substances should
have the power of decomposing nitrous gas, conse- 
165
quently the  disengagement of its oxygen, combustion
would of course take place.  This occurs however in
certain cases, as in the following :
  Experiment  14.    Introduce  some fresh prepared
pyrophorus,  placed in a copper spoon, into a jar of the
gas; the pyrophorus will instantly take fire,  and the
volume of the gas be diminished.
  Rationale.  In this experiment the  pyrophorus takes
the oxygen from the nitrous gas, consequently a dimi-
nution ensues, and the azote, the other constituent of
nitrous gas,  is left behind ; it will be found at the same
time, that the union of a portion of the carbon of the
pyrophorus, with some of the oxygen forms carbonic
acid, for on throwing up lime water a turbidness takes
place.
  Experiment 15. Phosphorus, if inflamed, and convey-
ed into a jar  ol nitrous gas, will burn with considerable
splendour ;  but if it be  introduced  into the gas and
even melted, no combustion will follow.
  Rationale.  The phosphorus in this experiment de-
stroys the former affinities  existing between the oxy-
gen, azote and caloric,  but in order to effect this de-
composition the  temperature must be  considerably
raised.  Hence the phosphorus unites with the oxygen
and forms phosphoric acid, heat and light are evolved,
and the azote remains in the form of gas.
  Experiment  16.  Ignite a piece of charcoal, and in
that state introduce it into a jar of the gas,  and  vivid
inflammation will ensue.
  Rationale.   In this case, as in the one with phospho-
rus, the charcoal at a high temperature changes the
equilibrium  of affinities, consequently decomposes the
nitrous gas,  carbonic acid  being formed, whilst  the
azote remains.
  Experiment 17.  Pass the  electric spark through a
mixture ol hydrogen and nitrous gas ; no decomposition
will take place.
  Experiment 18.  But if these gases be made to pass
through a red hot porcelain tube, a detonation will en-
sue, water will be formed, and azotic gas evolved.*
* Fourcroy, ii. 91, 
166
  Rationale.  In this experiment,  the hydrogen unites
to the oxygen of the nitrous gas,and forms water, and
azotic gas is  disengaged.
  Experiment 19.  Pass electric sparks through nitrous
gas, and decomposition will ensue.
  Rationale.  In this experiment,  according to Dr.
Priestley nitric acid and azotic gas are produced, which
can only take place by the  abstraction of a part of the
azote, whilst  the remaining azote unites with the oxy-
gen forming  nitric acid.
  Experiment 20.  Expose  a solution of the green mu-
riate, sulphate or nitrate of iron to nitrous gas, an ab-
sorption will immediately take place, the solution will
assume a brown colour, and  any uncombined azotic
gas will remain unabsorbed.
  Remark.  This is an experiment to prove that ni-
trous gas is  absorbed by the muriate, sulphate, and
nitrate of iron.
  Rationale.  In this experiment the nitric oxyd is ab-
sorbed by the solution of iron ; which takes place, ac-
cording to Davy, in the following manner :
  1. That it  depends merely on an equilibrium of affi-
nities produced by simple  attractions.
  2. The affinity of the green oxyd of iron for the oxy-
gen of nitrous gas  and water.
  3. The affinity of the hydrogen of the water for the
azote of the nitrous gas; and,
  4. The affinity of the principles of sulphuric acid
for nitrogen and hydrogen.
  It would appear, however, that this explanation is not
altogether consistent with the laws of chemical affinity;
for  instead of the  gas being  decomposed, which  we
consider to be nothing more  than a mere solution, it
is combined  with the water,  in  consequence only  of
their respective affinities for each other.
  The solution, thus combined with the gas, has the
property of absorbing oxygen from the atmosphere,
as we  shall presently see.
  If the green oxyd  of iron decomposes nitrous gas
and water according to Mr.  Davy,  the  solution will
certainly not have the property of absorbing oxygen, 
167
because  the  green oxyd  of iron, according to him,
would  take  the  oxygen from the  nitrous gas, and  of
course would decompose it, producing either nitrous
oxyd or azote, neither of which can unite with oxygen
from the air.
  If the  hydrogen were  to  unite  with the  azote ac-
cording to his second  position, ammonia would be pro-
duced ; and as to the principles of the sulphuric acid,
viz. sulphur  and oxygen  having an affinity  for  azote
and hydrogen, the  supposition would not appear che-
mical.
  Remark.   Seventy-five cubic inches of a concentra-
ted solution  of the muriate of iron  absorb  about   18
of nitrous gas ;  sulphate of  iron absorbs only one half
this quantity.  The  gas  absorbed may  be expelled
again by heat.
  Mr.  Davy  has proved that  all  salts containing the
black  oxyd of iron, possess the  same property, and
that they  all absorb nitrous  gas unaltered.   This
gas is also absorbed by the white prussiate of iron,  in
contact with water, according to the experiments of Mr.
Davy,  and  also  by  several other  metallic salts,  if the
metals which form them are at the minimum of oxy-
dizement;  the  solution of nitrous  gas in the green
sulphate of iron  has been extensively used in eudiome-
try to  determine the quantity of oxygen gas in the at-
mosphere.   The most commodious method of apply-
ing this  solution is by means of Dr. Hope's eudiome-
ter.  This solution, in which nitrous gas has the same
property as  in an unmixed state, removes  every ob-
jection to the gas as  a test for oxygen.
  Exheriment 21. Nitrous gas left in contact with iron,
is gradually decomposed, and changed into nitrous
oxyd.   See Experiment 23.
   Rationale.  Here the iron unites with a part of the
oxygen, and consequently reduces it to a state  of ni-
trous oxyd, or gaseous oxyd of azote.
.   Remark.   Dr. Priestley announced this fact, and in
this manner  he discovered nitrous oxyd.
  Experiment 22.  If alkaline  sulphites, hydroguretted
sulphurets,  muriate  of tin,  sulphuretted hydrogen gas,  or 
168
iron or zinc filings be put into a jar of nitrous gas, and
suffered to remain for a week or more the gas will be
decomposed.
   Rationale.  In this  experiment a portion of oxygen
is abstracted by these substances, which are convert-
ed into oxyds or salts, and the  gas  is consequently
changed, forming nitrous oxyd.  In some cases  water,
ammonia, as well as nitrous oxyd, are  generated. The
water is formed by the union of oxygen and hydrogen;
and the ammonia by the combination of azote and hy-
drogen.
   Experiment 23.   When  nitrous gas is  exposed to
wetted iron  filings, a diminution of its volume  takes
place; the  iron becomes  oxydized,  and  ammonia is
formed, together with nitrous oxyd.
   Rationale.  This is an experiment, in which nitrous
gas is decomposed by nascent hydrogen gas.   The
water is decomposed ; its oxygen unites with the me-
tal, while its hydrogen combines with a part  of the
azote of the nitrous gas, and forms ammonia, the ni-
tric oxyd being  reduced to the nitrous oxyd.  Another
portion of the hydrogen unites with the excess of oxy-
gen of the  nitrous gas, and forms water.
   Experiment 24.  When powdered  tin is moistened
with strong nitric acid, and, when the  red fumes have
ceased to arise,  if some quicklime or solution of pure
potash be added, nitric acid is decomposed, and  ammo-
nia is generated.
   Rationale.  In this  experiment the tin  unites with
the oxygen of the nitric acid as  well as of the  water,
and the hydrogen and azote are set at  liberty.  Before
they have assumed  the gaseous state,  these  two bases
combine and form ammonia.  The ammonia thus ge-
nerated unites with a portion of  undecomposed nitric
acid, and is  disengaged from this  combination by lime
or potash.   See  Ammoniacal Gas.
  Experiment 25.  If oxyd  of manganese be  heated to
redness in an earthen tube, and ammoniacal gas passed
through it,  nitrous  gas will be formed.
  Rationale.   The  hydrogen of  the  ammonia  unites
with a part  of the oxygen  given  out  from the oxyd, 
WJ
and  forms water,  whilst the azote  from the  same
source combines with another portion of oxygen, and
constitutes nitrous gas.   See Ammoniacal Gas.
  Remark.  Nitrous gas, called also nitric oxyd, was
obtained accidentally by Hales, but its properties were
investigated by Dr. Priestley, at an early period of his
philosophical  researches.  Mr. Lavoisier,  the father
of antiphlogistic chemistry, and  afterwards professor
Davy, the  learned chemist  of the Royal  Institution,
have made a number of experiments on this  gas, in
order to determine the proportion of its  constituent
parts.  According to Davy's experiments  nitrous gas
is composed of 100 parts of azote and 136 parts of
oxygen ; or,

Azote  Oxygen  Nitrous oxyd.
1.00  -f-  0*58 = 1.58    " Oxygen  Nitrous gas.*
               1.58 -f   0.78  =  2.36
or, it is composed of 57 oxygen, and 43  azote.
  Gay-Lussac has  instituted some experiments on ni-
trous gas, in which it appears that it  is composed of
equal bulks of oxygen and azotic  gas united together,
and its specific gravity  is exactly  the mean.
               SECTION XIII.

               OF AZOTIC GAS.

  Experiment  I.  If into a  long  narrow tube, divided
into cubic inches, and these again in to hundredth parts,
we throw up, over water, one cubic inch of azotic gas,
no absorption will ensue.
  Remark.  Although water absorbs no sensible quan-
tity of azotic  gas, as is proved by  this  experiment,
yet  if it  be first boiled, in  order  to  free  it of all the
air which it might contain,  and then  employed, it will
* Thomson.
   P 
170
be found that 100 inches of it are capable  of absorb-
ing,  according to Dr. Henry, only 1.47 inches  of the
gas at the temperature of 60°.
  Experiment 2.   Pass a slip of htmus paper into a jar
of the gas, it will come out unaltered.
  Remark.   Hence this  gas shows no signs of acidity.
  Experiment 3.  A mouse put into  a vessel of the
gas, is instantly killed.
  Remark.   Hence it is fatal to animal life; hence also
the origin of its name, azote, which signifies, " destruc-
tive to life."
  Experiment 4  If a lighted taper be plunged into the
gas,  the flame will be extinguished.      v
  Remark.   It is on  account of this  gas that a  candle
is extinguished  in atmospherical  air,  as soon  as  the
oxygen is consumed. But,
  Experiment 5.  If a mixture of four parts  of azotic -*\
gas and one  part of  oxygen gas be made, and a taper
immersed in, it will  burn as in atmospheric air.
  Remark.   This mixture resembles atmospheric  air,
which is composed of the same  gases about  in this pro-
portion.
  Though  we are not capable of imitating exactly the
air of the atmosphere, yet we may approach very near
it, from our  knowledge of the  nature and quantity of
the gases which compose it, in our imitation, we have
only  mechanical mixture.
  Experiment 6.   Into  a jar  of azotic  gas introduce
phosphorus in  the  state  of  inflammation ; it  will
immediately be extinguished.
  Remark.  This  also proves, that azote is  a non-sup-
porter of combustion.
  Experiment 7.  If  13  parts of azotic gas and 87 of
oxygen gas, be passed up into a  tube over mercury, and
electric sparks transmitted through them by means of
conductors, the  volume gradually diminishes,  and ni-
tric acid is  generated.
  Experiment 8.   Proceed  in the  same  manner as in
Experiment 7, but throw up some tincture of  litmus;
the litmus will be changed to red.
  Rationale.  Azote,  therefore, is  capable of combus- 
::i
•Jon with oxygen at high  temperatures ; the bases  of
these gases unite and form nitric acid.
  Remark.  Dr. Priestley originally made this experi-
ment ; from which Mr. Cavendish made the important
conclusion, that nitric  acid  was composed of oxygen
and  azote.   This discovery was  announced to the
Royal Society on the 2d of June, I 78 5.  It is supposed,
that at certain periods, the electric fluid of the atmos-
phere combines azote  with oxygen,forming nitric acid,
which  has been detected in rain  water, and also  in
snow.
  Azote, called also n'trogen, from  its being a compo-
nent of nitric acid, and sfiton by professor Mitchell  of
New York, was discovered in 1772, by Rutherford  of
Edinburgh ; and bcheele procured it from the atmos-
phere as early as 1776.
  Azote is a simple substance. Dr. Priestley supposed
it to be composed  of  dejiplogisticated air (oxygen gas-)
and phlogiston ; hence  he  gave it the  name of phlogis-
licated air.  The specific  gravity of azote  is to  com-
mon air as .985 to 1.000  It has  been found in the
mineral waters of Bath and Buxton, Great Britain.
  Dr. Austin succeeded  in combining azote with hy-
drogen, and formed ammonia; for an account of the
experiment, see Thomson, i.  111.
  According to Trousset, the gas emitted by the skin
is pure azote.
  The following are the primary compounds of azote
A. Binary.
    a. a. With oxygen.
       1. Atmospheric air.
      .2. Nitrous oxyd.
      3. Nitric oxyd.
      4. Nitric acid.
    b. b. With hydrogen.
       1. Ammonia (nitroguret of hydrogen.)
    c. c. With sulphur.
       1. Sulphuretted azotic gas.
    d. d. With phosphorus.
       1. Phosphuretted az.otic gas. 
172
B. Quaternary,  with hydrogen, carbon, and oxygen.
    a. a. Oxyds.   Animal substances.
    b. b. Acids. Animal acids.
             SECTION  XIV.

           OF  NITROUS  OXYD GAS.

  Experiment 1. If a glass cylinder or tube be filled with
nitrous oxyd inverted in a basin of water, that has been
previously boiled ; on agitating it a considerable dimi-
nution of volume will ensue.
  Remark. This diminution, of course, is an absorption
of the gas.  Water absorbs 0.86  parts of its bulk of
this gas, or according to Dalton nearly its own bulk.
It acquires  a  sweetish taste ; but its  other proper-
ties  do not differ perceptibly from common water.
According to Mr. Davy* when this gas combines with
water, it expels the common air which was  dissolved
in the water.  Hence when  this  gaseous oxyd is ex-
posed to a sufficient quantity of water, a residuum al-
ways  appears ;  this is atmospheric air.   The quantity
of common air thus produced, generally amounts to^th
part of the volume of water.f
  The absorption of nitrous  oxyd and the evolution of
common air by water, is in consequence  of the supe-
rior affinity of water for nitrous oxyd.
  Experiment 2.  If  water impregnated with the gas
be introduced into a retort, and exposed to the  tem-
perature of 212°, the whole of  the gas  will be  libe-
lated.
  Rationale.  In this case it is apparent, that caloric
destroys the affinity subsisting between water and ni-
trous  oxyd ; the latter is therefore expelled.

         * Da vy's He searches, p. 89.    t Accura, 
173
   Experiment 3.  Introduce a lighted taper into a jar
of nitrous oxyd;  the  flame will become larger, and
throw out sparks.  The lustre,  however, as the com-
bustion goes  on, will diminish, the flame  gradually
lengthen, and become  surrounded with a pale blue cone
of light until the  process ceases.
   Rationale.  In this experiment the gas is  gradually
decomposed ; its oxygen goes to  maintain the combus-
tion, and heat and light are set  at liberty.   In  order
that bodies should burn in nitrous oxyd, it  is neces-
sary that they should  be in the  state of inflammation,
as appears from the following experiment:
   Experiment 4.  Fill a jar over  mercury with the gas
and keep it over that  fluid ; introduce into it a small
piece of sulphur, camphor, or phosphorus, and touch these
substances with a bent wire  heated to a dull redness.
The sulphur, camphor, or phosphorus, will melt, and
by continuing the  heat it may even be made to sublime
in the gas, but no accension will  take place.
   Experiment  5.  When phosphorus is exposed in a jar
of the gas, and in this situation  touched with a wire
heated to whiteness, it will detonate with prodigious
violence.
  Rationale..   In order to overcome the affinity of oxy-
gen for azote, to effect the combustion of a substance*
it  is necessary that a high  temperature should be ap-
plied ; hence  in  this  experiment the  decomposition
takes place  with  considerable violence when a white
heat is used.   The  products  of the combustion are
azotic gas, phosphoric acid, and nitric acid;  a part of
the oxyd remains undecomposed.
  Experiment  6.  Introduce into  a jar of the gas some
phosphorus in  the state of inflammation.; combustion
will go on as rapidly as in oxygen gas;  or,
  Experiment  7.  Let the  jar containing the gas  be
placed over mercury ; introduce  the phosphorus in a
small tube containing oxygen gas, so ballanced as to
swim on the surface of the mercury without commu-
nicating  with the oxyd.  Then   fire the phosphorus
in the oxygen gas  by an ignited iron wire ; by which,
at the moment of combustion, the tube containing it
                      B 2 
174
must be raised in the gaseous oxyd, and thus the com-
bustion continues.*
  Rationale.  In this experiment, as well as in Experi-
ment 6, the phosphorus decomposes the nitrous oxyd ;
a part of its oxygen uniting  with it  forms phosphoric
acid.
  Experiment 8.  Sulphur put into a copper ladle and
inflamed,  and  then introduced  into the  gas, will be
extinguished;  but,
  Experiment 9.  If it be introduced in the state of
actual combustion, and not when the flame is of a feeble
blue colour, it will continue burning with a beautiful
flame very much enlarged and of a rose  colour.   Or,
this experiment  may be made  in the same  manner as
Experiment 7.
  Rationale.   When sulphur is introduced into nitrous
oxyd, when its flame exhibits a  blue colour, the  tem-
perature is not sufficient  to destroy  the union of oxy-
gen and azote ; consequently the flame is extinguished;
but if it be introduced when in an actual state of com-
bustion, or when it exhibits a white flame, it continues
to burn for some time in the manner stated in the ex-
periment.  When half the quantity of the  gas is de-
composed, the sulphur is extinguished.  The products
are sulphuric  acid and azote, arising from the decom-
position of the gas, and the union of phosphorus with
oxygen.
  Experiment 10. If red hot charcoal be introduced into
the gas it burns with more brilliancy than  in the at-
mosphere.
  Rationale.  In this experiment charcoal decomposes
the gas;  it  unites with its oxygen and  forms carbonic
acid, while its azote is set at liberty.  The same result
happens in the following  experiment.
  Experiment 11.  Introduce a piece  of charcoal  into
the gas, and set  it on fire by means of a burning lens
posed to the sun's rays;  combustion will ensue, as in
Experiment 10.
* Accum. 
175
  Experiment 12.  Introduce iron wire into the gas in
the same manner as in oxygen gas, (which see) it will
burn with the same brilliancy as in oxygen gas.
  Rationale.  Part of the nitrous oxyd is decomposed ;
its oxygen oxydises the iron, which is converted into
the black oxyd, while its azote is disengaged.
  Experiment 13.  Make a  ball  ol zinc shavings,  put
into it a piece of phosphorus, and attach it to a copper
wire; set fire to the phosphorus, and immediately intro-
duce it into a jar of the gas, and the zinc will burn with
a white  flame surrounded by a green one.
   Rationale.   During the combustion, which  is a de-
composition of the gas, the zinc is converted into an
oxyd, and appears in the form  of dense white vapours.
The zinc thus unites with the oxygen, and azote is set
free.
  Experiment 14.  If pyrophorus be introduced into the
gas, accension will immediately follow, provided  the
temperature be raised to about 500°, which may be ef-
fected by touching it with a  wire sufficiently heated.
   Remark.   During this combustion, the oxygen is
separated and azote disengaged;  only a part of the gas,
however, is decomposed.
  Experiment 15.  When nitrous oxyd is made to pass
through a red-hot porcelain tube, it is decomposed, and,
according to  Priestley, is converted  into nitric acid and
common air ; or,
   Experiment 16.  If electric  sparks are made to tra-
verse this gas, the same result ensues.
   Remark. The proportions  of azote and oxygen are,
therefore,  differently arranged ; for the original  gas,
though  composed of the same principles, is changed.
   Experiment 17. If 35 parts of nitrous oxyd and 15 of
carburetted hydrogen be passed up into a detonating tube,
and elective shocks transmitted, an  explosion will  en-
sue, and the space occupied by the  gases will be about
60.
   Rationale.  The gases are mutually decomposed; car-
bonic acid, some water, &c.  are formed. The products
differ according to the proportions of the gases mixed, 
176
   Experiment 18.   If ten grain measures ol phosphu-
retted hydrogen gas, and 52 ol nitrous oxyd are  detonated
by the  electric spark, the volume of  the gas. left be-
hind will fill a space nearly equal to 60.   On agitating
this fluid with water, no absorption will take place. On
admitting nitrous gas a diminution ensues.*
   Rationale.   In using a small quantity of phosphuret-
ted hydrogen, both the phosphorus and hydrogen arc
consumed; whilst  the superabundant  gaseous  oxyd is
converted into nitrous acid and atmospheric  air by the
ignition; or  a certain quantity  is partially  converted
into atmospheric air by the combination of a  portion of
its oxygen with the combustible gas.   The  following
experiment given by Accum, in  relation to the preced-
ing, will further illucidate the point.
   Experiment 19.   Twenty-five  parts of nitrous oxyd
mingled with 10 ol phosphuretted hydrogen, after inflam-
mation  by the electric  spark, occupy a space equal
to 25.
   Rationale.   We conclude, therefore,  that when phos-
phuretted hydrogen and  gaseous oxyd are to each other
as 25 to  10, they both disappear :  in this case the phos-
phorus unites with a part of the oxygen and forms phos-
phoric acid;  the hydrogen with the other part, forming
water, whilst the azote is set at liberty.
   Experiment 20. Make a mixture of about equal parts
of nitrous oxyd and  hydrogen gas, and detonate the mix-
ture in a tube by the electric spark; water and azote
will be  formed; or,
   Experiment 21.   Make a similar mixture  and apply
a lighted taper; an explosion will  ensue, and the same
products be formed.
   Rationale.   In this  experiment the  hydrogen unites
with all of  the oxygen of the  nitrous  oxyd, and forms
water, whilst the azote is disengaged.
   Experiment 22. Prepare another mixture of hydrogen
gas and  nitrous oxyd, in which the proportion  of hydro-
gen is smaller, and detonate them by the electric spark.
The product contains also nitric acid.
• Accum. 
177
   Remark.  The formation of nitric acid is the conse-
quence of a smaller quantity of hydrogen being pre-
sent ; therefore, oxygen and azote unite in proper pro-
portions, and constitute it.  If a larger quantity of hy-
drogen is used, the products would be in that case only
water and azote.
   Experiment 23.  Introduce  nitrous oxyd  properly
prepared, into an oiled silk bag or bladder, furnished with
a stop cock, and receive it into the lungs ; a singular
sensation will  be produced in the system.
   Remark. The apparent action of this gas on the body,
is one of  its most extraordinary properties.   Animals
when wholly  confined in this gas die speedily; but
when it is received into the  lungs it does not prove fa-
tal, because, when received into the lungs, it is mixed
and diluted with atmospherical air present in that organ.
The gas may be breathed  repeatedly from the bag and
back again, as long as it will last. " The sensations that
arc produced, vary greatly in persons of  different con-
stitutions ; but, in general, they are highly pleasurable,
and resemble those attendant on the pleasant period of
intoxication.   Great exhilaration,  an  irresistible pro-
pensity  to laughter, a rapid flow of vivid ideas, and an
unusual fitness for muscular exertion, are the ordinary
feelings it produces. These pleasant sensations it must
be added, are not succeeded, like those accompanying
the/ grosser  elevation from  fermented liquors, by any
subsequent  depression of nervous  energy."   For the
effect of this gas on Mr. Davy, see his  Researches.*
Nitrous  oxyd, formerly dephlogisticated  nitrous air,
was discovered by Dr. Priestley in 1776.  In 1793, the
associated Dutch chemists examined it and demonstrated
it to be a compound of azote and oxygen. It has also been
examined by Davy, who published an  excellent disser-
tation on it in the year  1800.  Nitrous oxyd is suscep-
tible of combination with alkalies, in certain processes,
and forms a class of salts, called azotites, which will be
considered hereafter.

  * See also Woodhouse's edition of Chaptal's Chemistry, and Dr.
Barton's  Inaugural Dissertation. 
178
  Nitrous oxyd, or gaseous oxyd of azote, is composed
of seven parts  by weight of oxygen, and 12 of iizote,
or nearly 63 of azote, and 37 of oxygen in the hundred.
Its specific gravity, accordinjv to lK\y,is 1.603, that of
air being 1.000.   It is to common uir nearly ;.s ."> to 3.
Dr. Thomson classes this  gas among  the  oxyd sup-
porters.
                SECTION XV.

           OF MURIATIC ACID GAS.

  Experiment  1.  If a jar, filled with muriatic acid gu»
over mercury, be raised from the mercurial trough, it
will discharge its contents for common air.
  Remark. The specific gravity of this gas, according to
the experiments of Mr. Kirwan, is 1.929, that of air being
1.000, at the temperature of 60° barometer 30 inches:
100 cubic inches of it weighs 59.8  grains.
  Experiment 2.  If a mouse be immersed in a jar of
the gas, convulsions will ensue, and  immediate death
will be the consequence.
  Experiment 3.  If a lighted taper be plunged  into
the gas, the flame will be extinguished.
  Remark.  Dr. Priestley, however, observes, that  mu-
riatic acid gas, has a considerable effect upon the flame
of burning bodies ; for a burning taper before it goes
out, assumes a green colour, and the same tinge appears
the next time the taper is lighted.  A white vapour
surrounds the extinguished wick, which is  attributed
to the combination of water, produced by the combustion
of the candle.
  Experiment 4.  Pass up into the jar  of the gas, the
infusion of litmus, or infusion of red cabbage ; on its com-
ing in contact, the colour will be changed to red.
  Rationale.  Muriatic acid  gas when in contact  with
water, of  which the  infusion is made, is absorbed.  It 
17U
acts therefore, ad an acid, and changes the colour of the
infusion to red.
  Experiment 5. Into a jar of the gas introduce a small
quantity of water ; an absorption will immediately en-
sue, and, if the saturation be complete, it will exhibit
all the properties of muriatic acid ; or,
  Experiment 6. Let the beak of the retort, from which
the gas is obtained, pass  into water, no bubbles of air
will arise, but on the contrary, the gas will be absorbed,
and the water will probably go over into the retort; or,
  Experiment 7. Let the gas pass into a receiver moist-
ened with water; an absorption will  ensue, which will
be known by the properties of the water being altered.
  Rationale.  The  union of muriatic acid-gas with wa-
ter takes  place in consequence of a strong affinity^ the
result of this combination is muriatic acid.  The pre-
paration of muriatic acid is effected by the decomposi-
tion of muriate of soda by  sulphuric  acid, in contact
with water.   In this case at the moment the gas is dis-
engaged, it unites with the water.   According to Mr.
Kirwan an ounce measure troy of water absorbs 800 cu-
bical  inches (or 420 times  its  bulk) of muriatic acid
gas ;  and the water by  this absorption, is increased
about one third its original volume.  Dr. Thomson says,
that a cubic inch of water at the temperature of 60 de-
grees, absorbs 515  inches of the gas, which is equiva-
lent to 308 grains nearly.  See Muriatic Acid.
  Experiment 8. If a tube coming  from the retort pass
into a three necked bottle, of a Woulfe's Apparatus, in
which water and a thermometer had been  put, and the
gas be disengaged from  the materials, a considerable
increase of temperature will  ensue, which will be shown
by the rise of the mercury.
  Rationale. This is owing to a condensation of the gas,
in consequence of its absorption; for a portion of caloric
necessary in the formation of the gas, is given out in a
free state, which is appreciable  by the thermometer.
  Experiment 9.  If watei' thus impregnated be expos-
ed to heat, the gas will be expelled. 
180
    Rationale.  In this experiment, the application of heat
 overcomes the affinity subsisting between the constitu-
 ent parts cf the liquid  acid; consequently, muriatic
 acid gas is expelled, and if the heat be not two power-
 ful, the water will remain behind.
    Experiment 10.  If a current of the gas be passed into
 a vessel filled with/cf, broken into small pieces, an im-
 mediate liquefaction will take place.
    Rationale.   This phenomena is attributable to the ra-
 pid absorption of the gas, in its reduction to the liquid
 state, and  the consequent disengagement of  caloric,
 which of course liquefies the ice.
    Experiment 11. Into a wide mouthed bottle introduce
 half its capacity of the gas; remove it from the  mercu-
 ry, so that atmospheric air may be admitted; dense white
 vapours,  accompanied  with a considerable degree  of
 heat, will  be produced.
    Rationale.  The muriatic  acid gas unites  with the
 moisture in the  air, and is  more or less  changed into
 muriatic acid ; hence the evolution of uncombined ca-
 loric.   According as the atmosphere is more  moist, or
 saturated with water, the phenomena is more  striking.
    Experiment 12.  Into a jar standing over  mercury
 and containing half its bulk of muriatic acid gas,  put an
 equal quantity ol ammoniacal gas; an absorption will ensue,
 heat be evolved, and white fumes will be formed, which
 in the  course of a short time, will condense on  the sides
 of the vessel;  or,
   Experiment 13.  Into a cup put a mixture  of muri-
 ate of ammonia and quicklime, and add a sufficient quan-
 tity of water to slack the  lime ; now introduce the cup
 with its contents  under a jar containing ammoniacal gas,
 and the same appearance will ensue; or,
  Experiment  14.   Into one of two cups put muri-
 ate of soda with half its weight of sulphuric acid ; in the
 other muriate of ammonia and quicklime as in the last ex-
 periment ;  heat the former, and introduce  it under a
 large glass vessel; and when the quicklime has slacked
 put it also  under  the jar, and a considerable cloud will
be formed. 
181
  Rationale.  lW all these experiments  the two  gase?
quit their aeriform  state, heat is evolved, and  muriate
of ammonia produced, which  at  first appears in  the
form of clouds.  If the experiment be made over mer-
cury, and the gases pure and in proper proportions, the
mercury will rise and fill the vessel.  In the last  expe-
riment, muriatic acid gas is disengaged from the  muri-
ate of soda by the sulphuric acid, and ammoniacal  gas
from the muriate of ammonia by quicklime; consequent-
ly, when the gases, thus disengaged, come in contact,
the same result takes place.
  Experiment 15.   If el ctric  sparks be  made to pass
'hrough this gas, its bulk is diminished, and hydrogen
gas is evolved.
  Remark.   This effect is attributed to the water con-
tained  in the gas.   It ceases when it is partly deprived
of moisture, as has been proved by Mr. Henry.
  Muriatic acid gas, formerly called marine acid air, was
first examined by Dr. Priestley. It is supposed that the
base of this  gas is hydrogen  and oxygen, as the con-
stitute  parts of  muriatic acid; but this conclusion is
unfounded.  Besides its absorption by water, which con-
stitutes the liquid  muriatic acid, it is absorbable  by ar-
dent spirit, ether,  fat, and  essential  oils, melted wax,
phosphorus, and many other bodies. According to some
recent experiments, it appears that water is an essen-
tial constituent of muriatic  acid gas ; that the  gas can-
not be formed unless water be present; and that it can-
not be deprived of its water without  losing its gaseous
form.   According  to Berthollet, 100 parts of muriatic
acid gas, after being exposed to the cold produced by a
mixture of snow and salt, still retain 56 7 parts by weight
of water.   From  Mr. Davy's experiments we  infer,
that the water contained in muriatic acid gas amounts
to id of the weight, while Thenard and Gay Lussac
make it only }th of the weight.  The attempts  made to
prepare muriatic acid gas free from water, have hitherto
failed  notwithstanding the sagacity  of  Davy  and the
French chemists.
S. 
182
                SECTION  XVI.

  OF  OXYGENIZED  MURIATIC ACID GAS.

  Experiment 1.  A mouse or other animal, if confined
in a jar of oxymuriatic acid gas,  is affected with convul-
sions, and death finally ensues.
  Remark.  It is obvious, therefore, that oxymuriatic
acid gas cannot be breathed without proving fatal. The
death of Pelletier, a chemist of considerable  eminence
in France, was occasioned by his  attempting to respire
it.  A consumption was the consequence of this attempt,
which in a short time proved fatal.  A mixture of this
gas with atmospheric air, when  breathed, occasions a
violent and almost consumptive  cough,  attended with
much  pain in the chest.  In preparing it, therefore, care
should be taken to avoid its escape  into the atmos-
phere.
  Experiment 2. If a vial filled  with the gas be brought
into contact with water, especially if it  be shaken, a  ra-
pid absorption takes place, and the water will ascend
in the vial.
  Rationale.   When water is brought into contact with
oxymuriatic acid gas,it loses its former properties, and
unites with the gas ; and, if the impregnation be com-
plete, it forms the oxymuriatic  acid.
   Remark.  Scheele found, that after standing 12 hours
over  water, |ths of  the  gas was absorbed.   The spe-
cific gravity of water, fully saturated, according to Ber-
thollet, is 1.003 at the temperature of 43° ; a cubic inch
of water is capable of absorbing about 1.6 grains (French)
of this gas.   The best method of effecting the impreg-
nation of  water, is by means of a Woulfe's apparatus,
the bottles of which should be  surrounded by ice-cold
water.  Water thus saturated has a pale greenish yel-
low colour, and a suffocating odour like the  gas;  its
taste, however, if perfectly free from muriatic acid, is
not acid, but astringent.   Its purity from the muriatic
acid may be known by the following experiment. 
183
  Experimen' 5.  To the watery solution ol oxymuria-
tic acid gas, add nitrate of mercury ,- if a white precipitate
is formed, the common muriatic acid is detected.
  Rationale.  The  common and not the oxygenized
muriatic acid, occasions a precipitation with  nitrate of
mercury, which is owing  to the acid combining with
the  oxyd of mercury, and forming sub-muriate of mer-
cury.  If the water used for the purpose contains  com-
mon salt in solution, which is generally the case, a pre-
cipitation will also arise from this cause.
  Experiment 4.  Into water saturated with the gas im-
merse patterns of unbleached calico ; the colour of which
will be  discharged.
  Rationale.  This  gas, even in combination with wa-
ter, as we shall  hereafter see, has the property of dis-
charging vegetable  colours, or of bleaching  certain
stuffs.
  In this experiment the acid is decomposed, its oxy-
gen goes to discharge the colour, and is reduced to the
state of common muriatic  acid, as is evident from the
following experiment.
  Experiment 5.  To a-portion of the remaining liquor
in Experiment  4, add nitrate of mercury, and a copious
precipitation will ensue.
  Experiment 6.   Expose water saturated with the gas,
to a temperature little above that of freezing water;
the gas will separate in the form of a liquid heavier than
water.
  Remark.  According to the experiments of Berthol-
let, it appears that water saturated with the gas, if put
into bottles, and surrounded with ice, is decomposed ;
that is, the gi„» separates, and takes the concrete form,
which immediately descends to the bottom of the ves-
sel.  The smallest heat makes it rise in bubbles, and
endeavour  to escape in the form of  gas.  Westrumb
remarks, that it becomes solid when exposed in large
vessels to the temperature of 40° ; and that then it ex-
hibits a kind of crystallization.. 
184
   Experiment 7. Expose the solution of the gas in wa-
ter to the direct rays of the sun, a decomposition  will
ensue, and oxygen gas will be evolved.
   Rationale.   In this experiment the rays of light de-
composes  the gas ;  its  oxygen is disengaged  in  the
form of gas, while its base remains in union with the
water in the form of muriatic acid.
   Remark.  The oxygen gas may be collected, by ex-
posing the solution in a gas bottle furnished with a bent
tube, which terminates in the pneumato-chemical ap-
paratus.
   Experiment 8. Introduce into a jar of the gas, a sprig
of mint, a rose,  Sec. their colour will soon be destroyed,
 and the gas diminished; or,
   Experiment 9.  Put flowers, of variegated colours,
or green leaves, into the gas ; keep them in it for sonic
time, and their colours will be discharged; or,
   Experiment 10.  Suspend a piece of yellow wax in
the gas; its colour will gradually disappear, and white
v> ax will be formed ; or,
   Experiment 11. Introduce into a jar of the gas some
• mbleachcd linen, or calico, previously moistened with
water, their colour will  soon  disappear, except those
which are yellow.
   Rationale.   The  action  of oxymuriatic acid gas in
the operation of bleaching, depends  upon the facility
with which it parts with its oxygen ; the vegetable sub-
stances  seize it with avidity ; and  by this  absorption
lose their  colour;  the  oxymuriatic being reduced to
the state of common  muriatic acid.
   Remark. Oxymuriatic acid, therefore, renders vege-
table colours white and not  red (as it  discharges the co-
lour of  litmus) as other acids do; and the colour thus
destroyed, can neither be restored by alkalies nor acids.
If the vegetable substances are sufficient, the whole of
the oxymuriatic  acid is decomposed.
  Experiment 12.  Introduce a burning taper, affixed
to a wire, into a tall jar of the gas, it will burn of a red
colour, and  more vividly  than in atmospheric air;  a
great quantity of smoke will be formed. 
185
   Rationale.  Oxymuriatic acid gas is, therefore, a sup-
porter of combustion.  In this experiment it is decom-
posed ; its oxygen unites with the carbon and hydrogen
of the( wax) taper, and forms carbonic acid and water;
the oxymuriatic returning to the state of common mu-
riatic acid.
   Experiment 13.   If  a piece of phosphorus, dried on
blotting-paper, and put into a copper ladle, be introduc-
ed into a jar of the gas,, it will instantly take  fire, and
burn with a greenish white light.
   Rationale.   The phosphorus, at the  common tempe-
rature of the atmosphere, decomposes oxymuriatic acid;
its oxygen unites with  the phosphorus,  forming phos-
phoric acid; and the oxymuriatic is changed into the
muriatic  acid.
   Experiment 14.  When sulphur is presented to oxy-
muriatic acid gas, no action ensues ; but if it be melted,
and then introduced into the gas, it will take fire and
burn rapidly.
   Rationale.  Sulphur at the common temperature does
not inflame spontaneously in this gas,  because it is ob-
vious that it cannot separate the oxygen from the acid
gas, but when its temperature is raised, by melting it,.
it will then decompose the acid; hence sulphuric  acid
is generated, and  the  oxymuriatic is reduced to the
state of muriatic acid.
   Remark.  Sulphur, however, when fastened to the-
end of a glass rod, and confined in the  gas, is slowly-
oxygenized, and drops down in a liquid form.  It was.
by passing streams of this gas through flowers of sul-
phur, that Dr. Thomson obtained a new combination of
oxyd of sulphur with muriatic acid, which he- termed.
sulphuretted muriatic acid.
   Experiment 15.   If charcoal of beech  wood be finely
pulverized, made  perfectly  dry,  and  heated  to about
90a, and then introduced into a jar of the  gas, it will
immediately inflame.
   Rationale.   In  this  experiment the  carbon unites
with the oxygen, in combustion, forming carbonic acid ;
                        0.2 
186
heat and light are set at liberty, and  the  oxymuriatic.
acid is changed into the common muriatic.
  Remark.  According to professor  Lampadius,  the
diamond also, when heated to redness, and plunged in-
to oxymuriatic  acid gas, burns in  it with  great splen-
dour;  but this  experiment has  failed in the hands of
other chemists.
  Experiment 16.   Let fall into a tall  jar containing
oxymuriatic acid gas, a few leaves of copper, usually
called  Dutch metal, before it reaches  the bottom of the
jar it will take fire and burn with a pale  green light;
or,
  Experiment 17.  Let fall in a similar manner gold
leaf, it will  take fire as in Experiment 16  ; or,
  Experiment 18.  Introduce silver leaf into the  gas,
and the same effect will ensue ; or,
   Experiment 19.  Heat a piece of fine copper wire to
redness, and immerse  it in the gas,- combustion will al-
 so  take place ; or,
   Experiment  20.   Pulverise  metallic antimony,  and
 throw it into a tall jar of the gas, a brilliant white light,
 accompanied with sparks, will be produced;  or,
   Experiment 21.  Introduce arsenic in the same man-
 ner ; a fine green or blue  flame, attended with sparks,
 and a  dense white smoke will be the  result;  or,
   Experiment 22.  Pulverise bismuth,  and throw the
 powder into the gas,  a bluish flame will be formed;
 or,
   Experiment 23.  Nickel used in the same manner, af-
 fords a yellowish white flame ; or,
   Experiment 24.  Cobalt thrown  into the gas, produ-
 ces a bluish white flame ;  or,
   Experiment 25.  If zinc, in powder, be introduced in-
 to the gas, it will burn with a white flame, and emit an
 abundance of sparks;  or,
   Experiment 26.  If tin is used, a bluish white  light
 will be formed;  or,
   Experiment 27.   If the filings of leadbe substituted.
 -a clear white flame will be produced; or, 
187
  Experiment 28.   If iron filings be thrown in, a bright
red flame will be'the result.
  Remark.  In all these experiments, in order to in-
sure success, the gas should be pure, and heated to the
temperature not short of 70°.   It is necessary that the
metal should be reduced to a fine powder, and employ-
ed in the proportion of one grain to two or three cubic
inches of the  gas.  Iron, lead, and zinc, are  more dif-
ficult to  inflame than  any of the former.  The very
malleable metals, such as gold, silver, Sec. which can
be reduced to extremely thin leaves, are best applied to
the gas in this state.  The  most readily oxydized me-
tals, as we shall presently see from the rationale, burn
with  the greatest brilliancy.   Into the bottom  of the
jar a'little sand may be  poured to prevent it from being
broken.
  Rationale.  Oxymuriatic acid gas is a compound of
oxygen, muriatic acid, and caloric.  On presenting to
it any of the before mentioned metals, it is decomposed,
and  so rapidly as to occasion spontaneous accension.
The  oxygen  is abstracted by the metal, which is  con-
verted into an oxyd, whilst the light and heat of the gas
are set at liberty in the form of fire.  The oxymuriatic
acid is, therefore, reduced to the common muriatic acid.
The metal, being of course oxydized, and in this state
susceptible of union with muriatic acid, combines with
the remaining acid into a muriate.  Gold leaf,  for in-
stance, though insoluble in this state in muriatic acid,
when thus oxydized, is readily soluble  in this acid, with
which it forms muriate of gold.  Copper leaf also, by
combining first  with oxygen  and then with muriatic
acid, constitutes muriate of copper, similar to the na-
tive muriate brought from Peru.  The  different colours
the metals assume in oxymuriatic acid gas, is owing to
the different refrangibility of the rays of light, which is
set at liberty in the act of combustion; and  which,
from  certain  habits or  affinities, is  decomposed, by
which certain rays  are  absorbed, and others reflect-
ed. 
188
   Experiment 29.  Into a jar of the gas introduce su
phuret of antimony, reduced  to a fine powder, in the
same manner as before, and combustion will ensue.
   Rationale.  In this experiment the acid gas is decom-
posed.  The sulphur as well as the antimony unite«
with  oxygen, and converts the oxymuriatic into  tho
common muriatic acid.
   Experiment 30.  Introduce in the same manner into.
the gas either cinnabar (sulphuret of mercury) iron py-
rites (sulphuret of iron) or realgar (sulphuret of arse-
nic) they  will take fire as in Experiment 28.
   Remark.   Other metallic sulphurets will exhibit the
same phenomena, the theory of which is analogous to
the former.
   Experiment 31.  Into a wine glass put one part of
hyperoxymuriate of potash, and pour  on it two or three
of sulphuric acid; now  add one part  of sulphuric ether,
alcohol, or oil of turpentine, an accension will take place,.
accompanied with a crackling noise.
   Rationale.   In this experiment the hyperoxymuriate
is decomposed by the  sulphuric acid, sulphate of pot-
ash  is  formed, and oxymuriatic acid gas is evolved.
This gas, therefore, acts on the ether, alcohol, or oil of
turpentine, which ever is used, and inflames it; the oxy-
gen in that case  changes the hydrogen and carbon of
which it is composed into carbonic acid and water.
   Remark.   The same phenomena  occurs with other
substances besides  inflammable fluids, as camphor, re-
zin, tallow, pitch, &c.
   Experiment 32.  Into a cylinder put one  part of hy-
peroxymuriate of potash, and three or four of water, with
half a part of oil of olives, or of linseed oil: now add four
parts of sulphuric acid, a violent action will take place,
much charcoal will be deposited, and ignited sparks
will pass through the black fluid.  On adding more of
the hyperoxymuriate and sulphuric acid the whole mass
takes fire, and burns with a dense yellow flame.
   Rationale.  In  this case the  hyperoxymuriate is de-
composed, a part of the sulphuric acid unites with the
potash, forming sulphate of potash, and disengages the 
189
 »\yinu;iatic acid ;  the other portion of the acid partial-
ly decomposes the oil by which its carbon is partly set
at liberty, which inflames.  A still further addition of the
salt and acid, sets the whole on fire, the result of which
is the formation  of carbonic acid and water, from  the
union of carbon and hydrogen of the oil,  with oxy-
gen.                                     # .
  Experiment 33.  Into a  wine glass, two thirds filled
with water, put one part of phosphorus, and two of oxy-
muriate of potash.  Pour through a tube  or funnel, to
the  bottom, three or four parts of concentrated sulphu-
ric acid; the phosphorus takes fire, and burns vividly
under the surface of the fluid.
  Rationale.  In this case the oxymuriate  is decompos-
ed as in the last experiment, and the oxymuriatic acid,
thus disengaged, is acted  upon by  the  phosphorus;
■ ombustion therefore ensues, phosphoric  acid is form-
ed, and the oxymuriate is reduced to the  common mu-
riatic acid.
  Experiment  34.  Into a vessel or jar of oxymuriatic
ncid gas introduce some nitrous gas; the mixture  be-
comes warm, reddish fumes appear, and nitro-muriatic
acid is produced.
  Rationale.  The nitrous gas takes part of the oxygen
from the oxymuriatic acid gas, and is converted  into
nitrous acid, which by uniting with the remaining acid,
constitutes nitro-muriatic  acid.
  Experiment  35.  Introduce into a jar of the oxymu-
riatic gas either sulphurous or phosphorus acids, a decom-
position will ensue.
  Rationale.  The sulphurous or phosphorous acids are
converted into sulphuric,  or phosphoric  acids, by the
union of oxygen from the oxymuriatic acid, which is
therefore changed into the muriatic.
  Experiment  36.  Introduce into a well  ground stop-
pered bottle a mixture of three parts of hydrogen gas and
four of oxymuriatic acid gas.   Put the stopper in its
plase, and keep the  bottle 24 hours inverted with its
mouth under water.  On withdrawing the stopper near- 
190
ly the whole of the gas will have disappeared; and the
remainder will be absorbed by the contact of water.
  Rationale.   In  this case the oxygen unites with the
hydrogen and forms water, and the oxymuriatic acid is
changed into muriatic;  hence on presenting the mixed
gases to water, the muriatic acid gas is absorbed.
  Experiment 37.  Pass a mixture of oxymuriatic acid
gas and hydrogen  gas through a red hot porcelain tube,
a violent detonation will take place.
  Rationale.   In  this experiment, the hydrogen unites
with the oxygen and forms water, and muriatic acid gas
is disengaged.
  Experiment 38.   Put  in  a detonating tube  three
measures of hydrogen gas with four of oxygenized muria-
tic gas, and pass  an  electric  spark through them.  A
detonation will ensue, and nearly the whole will be ab-
sorbed.
  Rationale.   The theory of this is analogous to the
last experiment.
  Remark.  According to  Mr. Cruikshank, the pro-
portion of hydrogen and pure oxymuriatic acid gases,
necessary for mutual saturation, is three of the former
*o three and a half of the latter.
  Experiment 39.  Introduce into the detonating tube
one measure of carburetted hydrogen gas from moistened
charcoal, from distilled coal, or  from stagnant water,
with three or four measures of  oxymuriatic acid gat,
and pass the electric spark through the mixture, a deto-
nation will ensue.
  Rationale.   A  part of the oxygen of the oxymuriatic
acid unites with the carbon, held in solution in the gas,
and forms carbonic acid, whilst another part combines
with the hydrogen and forms water.   Muriatic acid gas
will remain.
  Experiment 40.  Make a mixture similar to the pre-
ceding, but with about half the quantity mentioned, of
oxymuriatic acid gas;  pass the electric spark as before,
and  an abundant precipitation of  charcoal  will take
place. 
191
  Rationale.  In this case the oxygen, not being suffi-
cient to saturate both the carbon and hydrogen, unites
with the hydrogen and forms water, whilst  the carbon
held in  sc ution in the gas, is precipitated in the state
of charcoal.
  Experiment 41.  To two measures of carbonic oxyd
gas, add two thirds of the oxygenised gas, and allow them
to stand, [jr 24 hours, in a bottle which is entirely filled
by the mixture.  On withdrawing the stopper at this
period under water, the water will rush in, and will fill
two thirds of the bottle.
   Rationale.   The carbonic oxyd is converted into car-
bonic acid by the addition of oxygen from the oxymu-
riatic acid gas, by which  means the oxymuriatic gas is
changed into the  muriatic.   On presenting the mixed
gases to water, after they have stood for 24 hours, two
thirds of the gas will be absorbed,  which is muriatic
acid gas, and the remaining one third will be absorbable
by lime water; hence it is  carbonic  acid.
   Exjn riment 42.  To 21 measures of supercarburetted
 hydrog.  ^fias  (olefiant gas)  add 3 of the oxygenized gas;
a diminution  of bulk will ensue and a thin film of oil will
form on the surface of the water.
   Rationale.   Although this phenomenon is not per-
fectly understood,  yet  from circumstances we  may
conclude, that the hydrogen and carbon of the gas unites
with a portion of oxygen so as to constitute an oleagi-
nous fluid.
   Remark.   One measure of  carburetted hydrogen,
from ether or camphor, mixed with two measures of
oxymuriatic  gas, and allowed to remain 24 hours in a
vial closed with a  ground stopper, mutually decom-
 pose each other; water, muriatic acid,  carbonic acid,
 and  carbonic oxyd are formed, accordingly,  when
 water is admitted, the whole is absorbed except about
 0.43 of a measure:  0.09 of this residue is absorbed by
 lime water;  the rest is carbonic oxyd.   When there is
 an excess of oxymuriatic acid, the resulting substances
 are water, muriatic acid,  and carbonic oxyd.*
                     * Cruikshank. 
192
   Experiment 42.  Introduce sulphuretted  hydrogen gas
 into a jar partly filled  with the gas; a condensation,
 and a precipitation of sulphur will ensue.
   Rationale. The oxygen of the oxygenized gas unites
 with the hydrogen, whilst the sulphur is precipitated,
 being of course separated from the hydrogen.
   Experiment 43.   Mix oxymuriatic acid  gas with am-
 moniacal gas, a rapid combustion, attended with a white
 flame, instantly  takes place.*
   Rationale.  Both the gases are decomposed; the hy-
 drogen of the ammonia unites  with the oxygen  and
 forms water, whilst the azote, the other constituent of
 the ammonia is  disengaged, and muriatic acid is repro-
 duced.
   Remark.  Accum observes, that this experiment suc-
 ceeds remarkably  well, if about  eight cubic inches of
 ammonia  are  sent  up in a jar  holding at least fifty
 cubic inches of  oxygenized muriatic acid gas.
   Oxymuriatic acid gas, formerly dephlogisticated  ma-
 rine acid air, is  composed, according to Chevenix, of
 77.5  muriatic acid, and 22.5 of  oxygen  in the hun-
 dred.
   Oxymuriatic acid was discovered by Scheelein 1774,
 during his experiments on manganese ; since that pe-
 riod its nature and properties were investigated by the
 first chemists of Europe.  The oxymuriatic acid gas
 is not invisible, but  has a yellow-greenish colour.
   Oxymuriatic acid gas, as appears  from the  experi-
 ments both of Davy and the French chemists, contains
 water as an essential constituent.  For the experiments
 and observations upon this subject, see the Appendix
 to Thomson's Chemistry.  Thenard  and Gay Lussac
 have  shewn  that hydrogen gas, olefiant gas, and other
 similar gases decompose oxymuriatic acid gas, simply
 in consequence  of  the hydrogen  which they contain.
 They have shewn  that gases which contain no hydro-
 gen, as nitrous gas, produce no change upon oxymu-
 riatic acid gas, unless water be present.  As carbonic
oxyd is  not  decomposd by it,  this is  additional  proof
• Fourcroy, Ann. de Chim. iv. 255. 
I'Jo
that  hydrogen  is not  one of the constituents of that
gas.  Thus it appears that oxymuriatic acid is one of
the most  intimate  combinations  known,  and that the
presence of water,  or the formation of it,  is almost al-
wavs necessary for  its decomposition.*
                SECTION XII.

            OF FLUORIC ACID  GAS.

  Experiment 1. Into a jar ol fluoric acid gas  standing-
over mercury, immerse a lighted taper; it will become
green and be immediately extinguished.
  Remark.  Hence this gas does not support  combus-
tion.  In order to  prevent the action of the gas on the
glass, it should be coated inside with wax.
  Experiment 2.   An  animal plunged into the gas,  is
affected with oonvulsions, and instantly dies.
  Remark.  It is,  therefore, unfit for respiration.
  Experiment 3.  On immersing a piece of flesh into
the gas  it is soon  corroded.
  Remark.  Besides muscular flesh, it corrodes skin  as
instantaneously.
  Experiment 4.  Into a  jar of  the gas, standing over
mercury, introduce a little water, and agitate it; the
gas will be absorbed, accompanied with an evolution of
heat.
  Rationale.   On presenting water to fluoric  acid gas,
a partial condensation of  the latter ensues; hence the
extrication of heat; and the solution takes the name  of
fluoric acid.
  Remark.  Water, thus  impregnated, will be found  to
possess all the properties of the gas,  some of which
we have  already  stated; it  will  corrode glass, flint,
quartz, and other siliceous substances.  Fluoric acid is
specifically heavier than  water,  has an acid taste, red-

        * See the Appendix to Thomson's Chemistry.
                         R 
191
dens vegetable blues, and does not freeze twr.il cooled
down to 23°.
  Experiment 5.  Expose water  saturated  with  the
gas to the action of heat, the gas will be disengaged.
  Rationale.  Caloric tends to  separate not only the
particles of bodies,  but substances fiom each other:
hence the acid takes the gaseous form, forming fluoric
acid gas.   The last portions of the gas which remains
with the water, is disengaged with more obstinacy than
the first, owing probably to the  strong affinity subsist-
ing between determinate proportions of water and gas,
which can only be  overcome by  the application of a
greater heat.
  Remark.  Gas obtained by this means is purer than
*.hat procured in glass vessels;  for, if they were used,
a quantity of silex is dissoLved, which is deposited the
moment the gas is absorbed.   In obtaining it, however,
ieaden vessels should be employed.
  Experiment 6.  If the gas, as it isbues from a leaden
or tin retort, be received in a dry glass vessel, it will
corrode it, and render it opaque.
  Remark.  Hence  it is that  this gas dissolves silex,
which it takes from  the glass, as glass is  a compound
of silex and  alkali.   On this  property,  the idea was
conceived of etching on glass, either by means of the
gas or the liquid acid.
  Experiment 7.  Powder some fluate of lime, and strew
it on the surface of a pane of glass, and pour some sul-
phuric acid upon it; the glass will be acted upon; or,
  Experiment 8.   If a pane be  coated with a thin co-
vering  of  wax,  and  any  figure drew upon it; when
powdered fluor spar is put on, and sulphuric acid added,
the  glass will be corroded only  where the  wax has
been removed ;  or,
  Experiment 9.  Take a pane of glass,  cleanse it and
cover it over either with a thin coat of bees wax, isin-
glass dissolved in water, or engraver's varnish. When
it is dry trace upon it by means of a graver, or any sharp
pointed instrument, any subject whatever.   Then in-
troduce into a leaden basin or  cup  a sufficient quan-
tity ol fluate of lime,  with half its  weight of sulphuric 
195
acid ; place it in a sand bath and ap"ply heat; then hold
the pane of glass close over it, in order that  the gas
which is disengaged may act  upon  the  glass, which
will soon become corroded, and appear like  engraven
when the varnish or coating is removed.
  Rationale.  In this as well as in the two preceding
experiments, the fluate of lime  is decomposed; sul-
phate of lime is formed,  and the fluoric acid is disen-
gaged in the form of gas.  As this acid  does not act
on wax, and  some other substances of this kind, it at-
tacks the glass in every place where  the coating is re-
moved.  It destroys the  glass by  dissolving its silex,
and  consequently produces a corrosion.
  Remark.  This gas may be employed advantageous-
ly for  engraving labels on glass bottles, intended for
containing acids, for graduating glass tubes, as eudiome-
ters and thermometers ; for ornamenting glass vessels;
for  removing injured enamels, See.  The art of etching
on glass is not of very modern date.   Beckman in his
History of Inventions, observes, that it was employed
for   that purpose by  Henry Swankard as early as 1670.
He seems  to have kept his art for  some time  secret;
but  the receipt was  made public by  Pauli, in 1725.
  Experiment 10.  Let the gas, as it comes from a glass
retort, be  received  in  a  vessel filled with water and
resting upon mercury ; the bubbles as they come over,
will  become enveloped in  silex, and leave, as they as-
cend to the surface of the water, traces in the form of
tubes.
  Rationale.  The fluoric acid gas first  corrodes the
retort, and dissolves the  silex ; this  solution  when  it
comes in contact with water is  decomposed.   A con-
densation,  with an  extrication of heat ensues ; conse-
quently it  takes a liquid  form, and the silex is depo-
sited.
  Experiment 11.  Introduce  the gas into a receiver
lined with wax, as before mentioned, previously  pla-
cing it over any substance  capable of retaining- moisture,
such as lizards, frogs,  moist fruits,  bits of spor.gc, &c.
either of these substances so exposed will be encrust- 
196
ed with a coat of silex, and may thus be preserved for
years.
  Rationale.  It  is  evident that the moisture  absorbs
the gas,  which deposits the silex it acquired from the
retort, in the act of its condensation.
  Experiment 12. _  Let the gas as  it issues from  the
materials in a leaden retort, come in contact with lime
water, an immediate precipitation will ensue.
  Rationale.  The fluoric acid  quits its aeriform state,
and  unites  with the  lime, forming a precipitate  of
fluate of lime.  Hence the use of the acid as a test for
the detection of lime.
  Remark.  Margraff  so  early as  1768 wrote  on the
subject of fluor or Derbyshire spar, in which he proved
that it contained no sulphuric acid, but that he disen-
gaged a peculiar acid which corroded and  pierced holes
through  the  retort.  Schecle afterwards examined the
nature of this acid, which he found consisted of a pe-
culiar acid, to which the  name of fluoric has been ap-
plied, and the gas  has been called fluoric acid gas.
  The properties of this  gas have been investigated by
Dr. Priestley. Mr. Davy has lately decomposed its base,
by means of  potassium, and the decomposition is  at-
tended with combustion.*   A proof that oxygen is one
of its constituents.
  The base of the acid is  analogous to sulphur.t  From
some experiments  he concludes  that this acid is truly
an acid product.   But this subject, as well as its com-
binations, will be noticed under the head of fluoric acid.
Thenard and Gay Lussac have obtained a peculiar gas'
by exposing  a mixture of fluate of lime and vitreous
boracic acid  to  the action  of  a  strong heal, as in the
following manner :
  Experiment 13.   Expose in  an iron tube to a strong
ueat, a mixture ol fluate <fi lime and vitreous boracic acid,
and a gas will come over, to  which  fi.enard and Gay
Lussac have  given  the name of fluo-boitie ge:s.

  " {'nil. Mag. xxxiii.  89.      f Nicholson's Join-nal, xxii. 2o8. 
197
  Rationale.  In this experiment the boracic acid com-
bines with the fluoric and forms a compound gas which
is disengaged.
  Remark.   When  this gas is mixed with air or  any
other gas,  except the  oxymuriatic  acid, it produces
dense white fumes,  unless the gases  have been pre-
viously  artificially dried.   Water absorbs  this gas in
great quantities, and when saturated with it is limpid,
smoking, and very caustic.  By  heat about one fifth
part of the gas is expelled.   The liquid then assumes
the appearance of sulphuric acid  ; it is equally caustic,
does not boil till heated considerably above the boiling
point of water, and when distilled over, condenses  like
that acid.  It acts like sulphuric acid on vegetable sub-
stances,  in charring them, and forming a quantity of
water.  With alcohol it forms a  peculiar ether.*
  It may not be improper to  add, that according to
Thomson (vol. v. p.  811.)  when  fluate of lime  and
sulphuric acid are heated in leaden vessels, no gas is
obtained, but only an  acid liquid, consisting of water
and fluoric acid combined  together.
  When exposed to the air  it emits vapours.  When
mixed with water it heats, and even enters into ebul-
lition.   When brought  in contact with glass, it  acts
upon it, becomes hot, imd is  converted into siliciferous
fluoric acid gas.  When allowed to touch the skin a
white spot is formed, with the pain of a burn, which
terminates  in  a blister.    The best remedy is to
touch the place with a weak  solution of potash. When
brought in contact  with potassium, a violent combus-
tion takes place, hydrogen  is evolved, and  fluate of
potash and  water disengaged.
  Fluoric acid gas may likewise  be obtained from the
animal kingdom ; its base  has been discovered in the
enamel of the petrified teeth  of an elephant; also in the
enamel of the human teeth, and in ivory.  Besides oc-
curring in the fluor spar, it has been detected in other
 stones.

 • See Thomson's Appendix to vol. v. Also Murray's Supplement.
                        n  2 
PART VI.
              ATMOSPHERIC AIR.

  That fluid which surrounds the globe to a certain
height, in which the processes of respiration, combus-
tion, vegetation, 8cc. are carried on, is called the atmos-
phere.  It possesses  mechanical as well  as  chemical
properties;  those of the latter will only be described.
Atmospheric air  is a compound of about 22  per cent.
of oxygen and 77 of nitrogen.
  Experiment 1.  Take a bladder partly filled with air,
and hold it to the fire ; the air  within will gradually di-
late, and if the  heat be continued, will burst  the blad-
der; or,
  Experiment 2.  To the bottom of a hollow glass-ball
let an open bended tube be affixed.  Fill the lower part
of the bended tube with mercury; the external surface
will  be pressed by the weight of the atmosphere, and
the air inclosed in the ball of  the tube by means of the
mercury will be equally pressed by the spring of the air
within the vessel.  Immerse the ball in boiling water,
and  the mercury  will rise.
  Rationale.  The  expansion  or dilatibility of the at-
mosphere is daily exemplified to our senses in the pro-
duction of wind, as this effect presupposes a previous
expansion.  Heat has a tendency to overcome the at-
traction of cohesion, so far as  to place the particles of
bodies beyond a certain sphere of action ; hence  they
dilate or expand.  This effect is  counteracted by cold,
by pressure, &c. as is evident from the following expe-
riment.
  Experiment 3.  Immerse the bladder, or hollow glass
ball  into a vessel  of cold water; the air will  condense
or contract into its former state. 
199
  Remark. The theory of Mongolfier balloon depends
on the rarefaction of the air, thereby lessening its spe-
cific gravity, and causing the balloon to ascend in a me-
dium more dense, until an equilibrium is attained.  It
appears, that the air  which is disengaged  in firing of
gun  powder, is rarefied by the heat, so as to occupy a
thousand times the space of the whole of the gun pow-
der employed.
  Experiment  4.  If a lighted taper be placed  under a
jar of air over water, it will burn  for a certain length
of time; and on observing it, it will be found that the
pressure of the air becomes proportionably less on the
water immediately under the jar, while part of the wa-
ter in the  dish, in which the jar was placed, will rise or
be forced up.
  Remark. We therefore see  that atmospheric air is
necessary for combustion, that in that process a part of
it is consumed, and that an external pressure forces the
water up into the jar.   The pressure of the air may be
demonstrated  by  a  variety of  experiments; the baro-
meter, an instrument calculated to  shew the difference
in atmospheric pressure, which is about l5lbs. upon a
square inch ; the construction of pumps and  various
other hydraulic machinery; the variety of effects in the
economy of nature, all tend to prove this fact.
  The specific gravity  of common air is usually reckon-
ed 1.000 : it is 8.16 lighter than water.  One hundred
cubic inches of it weigh 31 grains troy.   As it respects
the  density of the air, we may remark, that as it is an
elastic fluid, and compressed at the surface of the earth
by the whole weight of the incumbent atmosphere, its
density diminishes according to its height above the sur-
face of the earth, about in the ratio of the compression;
or the density decreases in a geometrical progression,
while the heights increase in an arithmetical progres-
sion.   That it is this pressure of the air that preserves
many of the operations of nature in order, is evident;
thus it is, that water will boil in vacuo much  sooner
than in the open air, and also on the tops of high moun-
tains ;  that evaporation is consequently retarded, &c 
200
  Experiment 5.  Take an instrument called a  pulsr
glass, which consists of two bulbs exhausted of its air,
one of which is filled with  coloured alcohol, connected
together by means of a glass tube, and hold one of the
bulbs in the hand in a sloping position ;  the heat of the
hand will cause the fluid to boil.
  Remark.  This  instrument  shews, that a very  small
degree of heat would be sufficient to evaporate most of
our  fluids if we had no atmosphere.
  Experiment 6.  Fill a long  necked bottle with boil-
ing  water, and cork it close so as to exclude the air.
Put it now in a vessel of cold water, and the water will
sink in the neck of  the bottle as it cools, and recom-
mence its boiling with great violence ;  or,
  Experiment 7.  Fill a flask two-thirds with hot water,
and place it over a lamp that boiling maybe produced;
when  this has taken place remove the flask  from the
heat, cork it tight,  and wet the upper surface; and,
notwithstanding the boiling has ceased, it will be re-
newed.
   Rationale.  In both cases, as liquids boil with a less
 heat in vacuo, an  imperfect vacuum is formed :  in the
 latter  case a condensation of the vapour  ensues, con-
 sequently a vacuum is produced, the pressure of the
 air is  removed, and ebullition commences.
   Experiment 8. Fit a cork to a bottle sufficiently large,
 and adapt to it a small taper ;  light it and introduce it
 into the bottle,  holding of course atmospheric air, and
 it will burnfor a short time ; when it has ceased remove
 it,  placing the thumb on the aperture of the bottle, and
 introduce it, lighted a second time; it will be immedi-
 ately  extinguished.  Invert the bottle in a basin of wa-
 ter, withdraw the cork, and the water will ascend.
   Remark.  This  experiment proves, besides, that air
 is necessary to combustion, and that a diminution ensues
 in  that process.
   Experiment 9.   IIphosphorus be burnt in a given  vo-
 lume of atmospheric air, in the manner describedin that
 of oxygen gas,  a diminution of bulk will ensue. 
201
    Remark.  This effect, as we shall  hereafter see, de-
 vends on the formation of phosphoric acid by the union
 of phosphorus  with the oxygen of the atmosphere.
    Experiment  10.  Procure two'circular pieces of lead,
 three inches diameter, and half an inch  thick, from the
 centre of each of which proceeds a perpendicular iron
 w ire, six or eight inches high; to the end of both wires
 fasten apiece  of wax taper.   Provide  also two jars,
 each two inches diameter, and twelve long,  and having
 a neck at the top, with a compressed bladder tied upon
 it.   Fill one of  the  jars, leaving the bladder empty,
 with oxygen  gas; and, at the same instant, with the
 aid of an assistant, invert both jars over the burning
 candles, keeping  the oxygen  gas in its place till  the
 jar is inverted, by a piece of pasteboard.
   Rationale.  As in every combustion, according to the
 Lavoiserian theory, a diminution, consequently an  ab-
 sorption of oxygen ensues, it follows in this instance,
 as  will be found on experiment, that in oxygen gas the
 candle will burn for a longer time, and with more bril-
 liancy than in the atmospheric air.   On the  first im-
 pression of  the flame, a quantity of expanded gas  will
 rise into each bladder, which is to be pressed out at the
 close of  the experiment, in order that  the  absorption
 may be compared in both cases.  The diminution  will
 be  found to be  greater in the jar of oxygen  gas.  The
 products of combustion always depend upon the sub-
 stances  submitted to  that process.   In the present in-
 stance, as carbon and  hydrogen are the principal con-
 stituents of tallow, or wax, the products are carbonic
 acid and  water, resulting from the union of oxygen with
 the carbon and hydrogen, during which the heat  and
 light of the oxygen gas  are disengaged  in a free state.
 After combustion what remains is  therefore carbonic
 acid, aqueous vapour,  and azotic gas.
  Experiment 11.  If two tubes each containing oxygen
 gas and atmospheric air be inverted in two separate cups
 filled with a solution of sulphuret of potash,and exposed
in that situation for some time, it  will  be found, that in
the tube  containing atmospheric air, about  -£ths of  its 
^02
original volume will remain, but in that containing oxy-
gen, it will ascend much higher, and if the gas be pure,
will even absorb the whole.
   Rationale.  In this case the sulphuret absorbs oxygen,
and is changed into a sulphate, from the fornu.tioa of
sulphuric acid.  As  atmospheric air  contains  7 7  per
cent, of  azote, the greater diminution in the  oxygen
gas is not surprising when wc  consider, that  tho sul-
phuret absorbs oxygen only.  Hence the use of gradu-
ated tubes,  certain solutions, Sec. in ascertaining  the
purity of the atmosphere, or for determining the pro-
portion of its  constituent parts.  Hence  also the con-
struction of eudiometers.
   Remark..  Air was for many years considered a sim-
ple  substance.  The  celebrated  Dr.  Priestley  made
many experiments on  atmospheric air, which he began
in  1774,  in which he showed, that common  air was
composed ol air deprived of phlogiston or dephlogisticattd
air (oxygen  gas) and air  saturated with phlogiston, or
azotic gas.  After him Scheele proceeded  to the ana-
lysis of air by using liquid sulphurets, phosphorus,  8cc.
which when confined along with air, have the property
of diminishing its bulk.  After  subjecting air to these
and other substances, the  residue he named foul  air.
The composition of the atmosphere being known, phi-
losophers took it for granted  that the proportion of its
oxygen varies at different times and in different places;
and that upon this variation depended the purity or noxi-
ous qualities of air. Various methods were accordingly
invented, to determine the proportions of its constitu-
ent parts.  Eudiometers, or more properly oxyometers,
were constructed for this purpose.  It may not be im-
proper to notice them.

        1. Priestley's and Fonta/a's Eudiometer.

  The first  eudiometer was made in consequence of
Dr. Priestley's discovery, that when nitrous  gas is mix-
ed with  air over water, a  diminution of bulk ensues,
owing to the combination of the  gas with the oxygen of
the air, and the absorption of the nitric acid  thus form- 
203
ed by the water.  The nitric oxyd unites with the oxy-
gen, leaving the azote of the air behind, and by making
the experiment in graduated  tubes, the precise quan-
tity of oxygen absorbed, and azote  which  remains, may
be readily determined.
  Dr. Priestley's method  was to mix  together equal
bulks of air and nitrous gas in a low jar, and to transfer
the mixture into a narrow graduated glass tube about
three feet long, in order to measure the diminution of
bulk. Dr. Falconer invented a more convenient instru-
ment.   Fontana, however, improved  upon this  plan of
determining the purity of the air.  Mr. Cavendish de-
serves the credit  for  determining with  precision, by
this mode, the constituents of the air. It is unnecessary
to enter into  a  detail on his  improvement,  or the ob-
servations of chemists, as the nitrous test has been em-
ployed by Mr. Davy with more accuracy  in a different
manner.

               2. Davy's Eudiometer.

   In order to get rid of anamolies, Mr. Davy proposed
 he  following method  for using  nitrous gas.  Take a
small glass tube graduated into 100 equal parts; fill
this tube with the air to be  examined, and plunge it into
a bottle or  any other convenient  vessel, containing a
concentrated  solution of green muriate or sulphate of
iron, strongly impregnated with  nitrous gas.  If the
tube be agitated an  absorption will ensue, the degree
of which indicates the quantity of oxygen absorbed.
  Rationale.  Nitrous gas held in solution in this man-
ner, has the same avidity  for combining with oxygen
as it has in the  state of gas ; hence it is, that when oxy-
gen is presented to  it, as it is  in atmospheric air, it ab-
sorbs it, and is changed into nitric or nitrous acid.  The
degree  of absorption is shewn by the graduated scale.
  Remark.   One  cubic inch of moderately impreg-
nated solution  is  capable of absorbing  five  or six
inches  of oxygen in common processes, which takes
place in a few minutes. 
204
   Bymeansof this, Mr. Davy examined the air brought
 r.-om Bristol, England, and found it always to contain
 about 21 of oxygen, which is about the same that the
 honourable Al.m Seybert nnde it in the  city of Phi-
 ladelphia.*

              3.  Scheele's  Eludiometer.

   This is a graduated glass  vessel containing a given
 quantify of air exposed to newly prepared liquid  alka-
 line or earthy sulphurets,or to a mixture of iron filings
 and sulphur, formed into a paste with water.  As these
 substances have the property of absorbing oxygen, its
 modus operandi is readily perceived.
   It requires some time to make an experiment, and at
 best inaccuracies will arise, owing to the evolution of sul-
 phuretted hydrogen gas, and occasionally the absorp-
 tion of azote, notwithstanding they embrace the im-
 provements cf Dr. Marti.

               4. Volta's Eudiometer.

   This consists  in detonating  a mixture of hydrogen
 gas and atmospheric air, in a graduated glass tube, and
 measuring the diminution after combustion. Gay Lus-
 sac and Humboldt have highly recommended this plan.
 When .100 measures of hydrogen  are mixed with 200,
 or any greater bulk of oxygen, up to 900 measures, the
 diminution of bulk after detonation is always  146  mea-
 sures.   The  same diminution is retained, if the hydro-
 gen be increased up to a certain quantity.  It is, there-
 fore, ascertained, that 100 measures of oxygen gas re-
 quire 200 of hydrogen for complete combustion. Hence,
 if equal bulks of the air, to be examined, and of hydro-
 gen gas, be exploded, and the diminution of bulk be as-
 certained and divided by three,  the quotient represents
the number of measures of oxygen in the air.

  • See his Experiments in the Transactions of the American Phi
losophical Society. 
205
               5.  Berthollet's Eudiometer.

    This method of ascertaining the proportion of oxygen
 i* by the use of phosphorus; it has been used, in the
 state of rapid, as  well as spontaneous combustion. The
 latter has been recommended by Berthollet, which ab-
 sorbs the oxygen of the air completely.  It consists of
 a narrow graduated glass tube,  containing the air to be
 examined, into which is introduced a cylinder of phos-
 phorus supported upon a glass rod, while the tube stands
 inverted in water.  The phosphorus should be nearly
 as long as the tube.   Immediately white vapours rise
 from the phosphorus, and fill the tube.  These  contu
 nue until the whole of the oxygen combines with phos-
 phorus, when they cease, the process is at an end.
   Rationale.   The phosphorus unites with the  oxygen,
 and leaves the azote untouched.
   Remark.   Berthollet has remarked, that the volume
 of azotic gas  is increased to -^th  part; consequently, the
 bulk ofthe residuum, diminished by -'-gth, gives us the
 bulk of the azotic  gas of the air  examined ; which bulk
 subtracted from the original mass of  air, affords the
 pioportion of oxygen gas  contained in  it.  There are
 several circumstances to be attended to in experiments
 on air, as.the density, or barometrical pressure, tempeT
 rature, kc. which  may be found  in Thomson, iv. 21.


                6. Hope's  Eudiometer.

   In Nicholson's  Journal, iv. 210, we have a descrip-
 tion of an eudiometer invented  by professor Hope of
 Edinburgh. It consists of a small bottle, of the capacity
 of 20 or 24 drachms, destined to contain the eudiome-
 tric fluid, having a small stopper at the side.  Into the
 neck of the bottle a tube is accurately fitted, by grind-
 ing, which holds precisely a cubic inch, and is divided
 into 100 equal parts.  To use  the apparatus, the bot-
tle is first filled with the liquid employed, which is best
prepared  by  boiling a mixture of quicklime and sul-
s 
206
phur with water, filtering the solution, and agitating it
for some time in a bottle half filled with common air.
The tube, filled with  the air under examination, is next
put into its place ;  and on inverting the instrument, the
gas ascends into the bottle,  where it is brought exten-
sively into  contact with  the liquid, L\ brisk  agitation.
An absorption ensues; and, to supply  its place, the
stopper in the side is opened under water, a quantity
of which  rushes into the bottle.  The  stopper is  re-
placed under water;  the agitation renewed ;  and these
operations performed alternately,  till no further dimi-
nution takes place.   The tube is then withdrawn, the
neck of the bottle being under water, and  is held  in-
verted in water for a few minutes; at the close of which
the diminution will  be apparent.  Its amount may be
measured by the graduated scale engraved on the tube.
   It was a matter  of  some moment to discover means
by which the quantity of oxygen in the atmosphere might
be ascertained, as  atmospheric air ministers to the sup-
port of animal life, only  in consequence of the oxygen
gas which it contains. Air,  after having been received
into the lungs, and again  expired, is found to have lost
considerably of its  oxygenous part, viz. 10 or 12 per cent.
   Experiment 12.   Take caustic potash, and expose it
to the atmosphere ; it will deliquesce, and after it has
remained some short time, will effervesce on the addi-
tion of acids.
   Remark.   Atmospheric air contains  also  carbonic
acid, in the proportion of  about one or two per cent.
hence the caustic  alkali absorbs it, which is evident by
the effervescence, on  the addition of acids ; that it like-
wise contains water is shewn by the same experiment,
as the alkali deliquesces.
   Experiment 13.   Confine  a mouse  in  a small  glass
jar, and tie the jar over, quickly and firmly, with moist-
ened bladder.  When the life of the animal is extinct,
the bladder exhibits a hollow surface.
   Remark.  This  method was contrived by Mayow, to
shew that  atmospheric air is diminished in volume by
animal  respiration.   The heat of the animal will first 
207
expand the air, and consequently make the bladder con-
vex ;  but after the  animal is dead, the air within will
be considerably diminished.  The exact amount of the
diminution may be shewn,  by confining a mouse, over
water, in a graduated jar, furnished with a stop  cock,
and  containing common air.   We have seen  that air
is not a simple element, as was maintained by the an-
cient philosophers, but that it is7 composed of  oxygen
and azotic gases,  as its principal constituent part; that
it possesses fluidity, elasticity, expansibility  and gra-
vity ; that it  is necessary for  respiration, combustion,
and various other processes.
  Mr. Parke, in his Chemical  Catechism,  has  made a
just  remark on the use of the atmosphere.   Were it
not for atmospheric air, says he, we should be unable to
converse with each other;  we should know nothing of
sound, or of smell, or of the pleasures which arise from
the variegated prospects which  now surround  us.  A
French writer, of considerable note, adds, that  in the
use of atmospheric air, nian is the only being who gives
•o it all the modulations of 'which it i» susceptible.  With
his voice alone, he imitates the hissing, the cries, and
the melody of all animals; while he enjoys the gift of
speech denied to  every other.  To the air he also some-
times communicates  sensibility ; he makes it sigh in
the pipe, lament in the flute, threaten in the trumpet,
and animate to the tone of his  passions even the solid
brass, the box tree and the  reed.  Sometimes he makes
it his slave : he forces it to grind, to bruise, and to move
for his advantage an endless variety of machines.  In
a word,  he harnesses it to his car, and obliges it to waft
him  over the  stormy billows of the ocean.
   If there were no atmosphere surrounding the earth,
only that part of  the sky would appear light in which
the sun was  placed; and if a person should turn his
back to the sun,  he would directly perceive it as dark
as night; for in that case there would be no substance
to reflect the  rays of the sun to his eyes.  It is owing 
203
to refraction, that  the sun  cnlivV.rns the earth some-
time before it rises, and sometime after it sets.*
   The atmosphere, says Fourcroy, is avast laboratory,
in which nature operates immense analysis, solutions,
precipitations, and combinations: it is a grand receiver,
in which ail the attenuated and volatilized productions
of terrestrial bodies are  received,  mingled, agitated,
combined, and  separated.  Notwithstanding this mix-
ture, of which  it seems impossible  for us to ascertain
the nature, atmospheric  air is sensibly the same, with
regard to its  intimate qualities, wherever we examine
it.
   The constituent parts of the atmosphere  more pro-
perly speaking, are considered under four heads, viz.
1. Air.    2. Water.    3. Carbonic acid gas.  4.  Un-
known bodies.   We  have before observed, that com-
mon air  is composed of oxygen and azotic gases, that
the. atmosphere contains water, which varies at differ-
ent seasons as is shewn by an instrument called the hy-
grometer, which gives  rise to clouds, fogs, rain and
dews ; and that it also contains carbonic acid.   Besides
these there are other  bodies found, or contained in it,
such as hydrogen gas, carburetted hydrogen gas, con-
tagious  matter, electricity, Sec. to which  we may add
the stones which sometimes fall from the atmosphere,
during  the  appearance of luminous bodies or  meteors,
commonly called fire balls. When these meteors burst,
an explosion is the consequence, and a shower of stones
fall to the earth.   A table of these remarkable pheno-
mena may be seen in  Thomson's  Chemistry, iv.  122.
These stones have been carefully analysed,  an account
of which may  be seen in the  same work.   Professor
Silliman  of  Yale College, Connecticut, examined a
meteoric  stone which fell in that neighbourhood, and
found the result nearly the same as those found in Eu-
rope.

      * Gregory's Astronomical Lessons, page 78—82 
PART VII.
                   OF WATER.

   Experiment 1.   If water, contained in a small  glass
tube  be exposed to a freezing mixture (see the table
of freezing mixtures) it will lose its fluidity, and be
converted into ice.
   Rationale.  Water when cooled down to 32° assumes
the form called ice. This process is, therefore, nothing
more than the abstraction of caloric  from  the  water,
which is effected by the freezing mixture.
   Remark.  If this process  goes on very  slowly, the
ice assumes the form of crystalline needles, crossing
each other at angles either of 60° or 120°, as Mr. De
Mairan  has remarked.  Ice, while kept at  a tempera-
ture below 32°, is very hard, and maybe pounded into
the finest  dust.  It is elastic.  Its specific gravity is
less than that of water; the  latter is always supposed
to be 1.000, which is made the measure of the specific
gravity  of every other body.
   It is by this abstraction of  heat, or reduction of tem-
perature, that  the atmosphere, being the agent by which
this change is effected, deprives the water of a certain
portion  of its caloric.  As  water holds atmospheric air
in solution, it is owing, it is said, to this circumstance,
that ice contains vacuities filled  with  air,  and  that it
expands in the act of freezing.   Rocks and trees are
often split during intense frosts.   A spherule of water,
according to the calculations of the French Academi-
cians, only one inch in diameter  expands in freezing
with a force superior to the resistance of thirteen and
an half tons weight.  It may be remarked, that though
s 2 
210
fresh water freezes when reduced to the temperature
of 32°, sea water  does not freeze till cooled down to
28.5°.
  Underneath the poles  the water is always solid, to
which  the coldness at the poles is attributed.   At the
whimsical marriage of Prince  Gallitzin, in 1739, the
Russians applied  ice  to the same purpose as stone.
Blocks of ice were employed in building a house ;  can-
non were also made of it, which performed their office
several times,  in  honour of the  day, without burst-
ing.
  In cements and  mortar, in which water is employed,
it is said to become still more hard than in  ice.
  Experiment 2.   Put some w ater into a pot or kettle,
introduce a thermometer, and cause  the water to boil;
it will  be found, that the mercury indicates 212°, which
is the  boiling point.
  Rationale.  The conversion of water into steam or
vapour, takes place when the temperature is at 212°,
with a phenomena called boiling.   It is therefore by the
accession of temperature,  that water is changed into
vapour.
  Remark.   Steam is  an invisible fluid like air, but of
a less  specific  gravity.  It occupies about  1800 times
the  space that  water does.  Its  elasticity  is so great,
that it produces the most violent explosions when con-
fined.   It is said, that water, in being converted into
vapour, combines  with more than five times the quan-
tity  of caloric that is required to bring ice cold water
to  a boiling point, and occupies a space 800 times
greater than it  does when in the form of water.  Steam
has  therefore been employed as  a useful and powerful
agent, in the  construction of the  steam  engine, the
discovery  of  which is a great acquisition  to the
arts.*
   The phenomena of boiling  are owing  to the  rapid
formation of steam at the  bottom of the vessel.   The
boiling point of water varies according to the pressure

         • See Evans's Treatise on Steam Engines, 8ro. 
211
of the atmosphere, as  is shewn by the following ex-
periment.
  Experiment 3.   Heat water to 70°, and introduce it
in a cup under the receiver of an air pump; exhaust
the air, and ebullition will ensue.  Again, by confining
water in a  proper  apparatus, as in a Papin's digester,
it may be almost heated red hot without boiling.  The
mixture of various salts with water affect its boiling
point considerably.
  Experiment 4.   Let a thermometer bulb, and part of
its tube, having a wide bore, be filled with water, tinged
with  a  little  litmus, which may be  introduced  by the
same means as those used for filling with quicksilver.
Immerse the thermometer in  water at the temperature
of 40° ; and when the included water may be supposed
to have attained the same degree of heat, remove the in-
strument successively into water of the temperature of
36°  and 329.  At each immersion the water will rise
in the tube.   Bring its temperature again to 40°, and
it will descend to the same point as before.  Place it in
water of 50?, and  it will again be expanded.
   Remark.   This  experiment is designed to shew, that
the enlargement of the bulk of water begins long before
its temperature has descended to the freezing point,
viz.  at about  40° Fahrenheit.   We  find that precisely
similar effects appear to result from two opposite causes,
for the  bulk of water is alike increased by reducing or
raising its temperature.
   Mr. Dalton, however, is of  opinion, that in  the ap-
parent  expansion  by a lower temperature, there is a
deception, arising from the contraction of the glass,
which  must lessen the capacity of  the bulb, and force
the  water up the stem.  This opinion is contrary to
that of  count Rumford and of Dr. Hope.
   Experiment 5.   Place water under the receiver of
 an air pump, and exhaust it; bubbles of air will arise
 from the water; or,
   Experiment 6.   Put water into a retort, heat it,  and
 collect  the air which rises; it will be found to be  at-
 mospheric air.  Or, 
212
   Experiment 7.  Fill  a barometer  tube,  about  3*
inches long, sealed at one end with quicksilver, except
about four inches, and the remainder with water.   On
inverting the open end of the tube in  quicksilver, bub-
bles of air will  be seen, in a short time, to rise from
the water.
   Remark.  These experiments prove, that water con-
tains air in solution, and that it is separated when sub-
jected to certain processes.   The greatest part of this
air is driven off by boiling ;  but, from the experiments
of Dr. Priestley, it appears that the whole of it is  not
separated.  Water owes its  agreeable taste to the air
which it contains ; hence the insipidity of boiled water.
It absorbs oxygen gas in preference to  common air,
and nearly in the same proportion, as was first ascer-
tained by Scheele.   Mr. Driessen has shown, that in
order to free water from air, it must be boiled at least
for two hours, and kept in a flask with its mouth invert-
ed over mercury.   In order to ascertain whether water
be perfectly free from air, Mr. D. has  instituted the
following method.
   Experiment 8.  Tinge water blue  with litmus, fill a
flask with it, invert the flask under water,  and introduce
into it pure nitrous gas till about ^thof the vessel is fill-
ed : if the water contains air, a portion of the nitrous
gas will combine with its oxygen, and be converted in-
to nitric acid, and the litmus become red.
   Remark the proportion of air may be  estimated by
the quantity of ammonia necessary to restore the blue
colour to the litmus.
   Experiment 9.   Put carbonate of potash, or salt of
tartar of the shops, into a dish, and expose it to the at-
mosphere ; in a few days it will have  become moist or
deliquated.
   Rationale.   The alkali absorbs moisture, for which it
has a strong affinity, and becomes of a  fluid  consis-
tence.
   Remark.  Water is contained in the air of the  at-
mosphere, even during the dryest weather.   See  At-
mospheric Air. 
213
   Experiment  10.  Expose solid alkali in the  same
manner as in tie last experiment to an atmosphere of
oxygen, hudrogen, or any of the gases ; it will gradually
become fluid.
   Remark.  Gases, in their usual state, contain  com-
bined  with  them  a  quantity of. water,  which  often
amounts to a considerable proportion of their weight;
hence the  cause of the alkali becoming fluid.
   Exheriment 11.   Pass the vapour of  water  through
a gun barrel containing charcoal, previously heated to
redness ;  the water will be decomposed by the coal.
   Rationale.  This  effect takes place agreeably to the
rationale given under hydrogen and carburetted hydro-
gen gas, which see. ••
   Remark.  The simple combustibles have no action
on water while cold.  Hydrogen does not act upon it
even at a red heat.  Charcoal  forms with  it, when ig-
nited,  carbonic  acid and carburetted  hydrogen gas.
Phosphorus at a red heat has not been tried. Sulphur,
as far as is known  at present  does not decompose it.
Of the metals, iron, zinc, antimony, and  tin, decompose
it  when assisted by heat; silver, gold, copper, and pla-
tinum, have no effect upon it.   See subsequent expe-
riments.
  Experiment 12.   Pour water on pure  barytes, lime or
utrontia ; it will be found that it will  dissolve any of
these earths, until it is saturated.
  Remark. The alkaline earths  are soluble in water,
but the earths proper are insoluble in it.
  Experiment 13.   Glauber salt, nitre, and  a variety of
salts are soluble in water, wdiich may be seen by pour-
ing  that fluid upon them.
  Remark.  The substances on which   water  has this
effect, are  said to be soluble, and there are various de-
grees of solubility.  Water unites also with acids.
  In most  cases an absorption of caloric, in other words
a production of cold,  is  attendant on  solution.  See
Freezing mixtures.  In other cases caloric is evolved,
or heat is produced.  The common salt of tartar, dur-
ing solution  in water, raises  the temperature of the
solvent; and caustic potash in a state of dryness, does 
214
the same still mo< e remarkably.  As the difference, in
the crystallized and uncrystallized state, depends chief-
ly on their containing in the former, but not in the lat-
ter, water chemically combined, we may infer, that the
cold produced  during the solution of salts, is occasion-
ed by the conversion of the water, which exis s in these
bodies, from a solid to a liquid form.  See Caloric.
   Experiment 14.   Put an ounce  of sulphate of soda into
a vial, and fill  the bottle with water, and air will  be
evolved.
   Remark.  During the  solution of salts in water, a
quantity of air is  disengaged.   The  air contained in
the pores  of the salt  will be  thus  disengaged,  but a
very small portion of salt will be1 dissolved.  On shak-
ing the vial more salt will be dissolved,  and a fresh
portion of air will be liberated.  The air, that now ap-
pears, is  extricated from the water in consequence of
the affinity between the water and salt  being greater
than that between the water and the air.
   Experiment  15..  Into a flask, having a  long neck,
introduce an ounce or two of  sulphate of soda.   Then,
add as much water  as will  fill the globe, and about
three  fourths of the  neck.  This should be done with
as little agitation  as  possible, in order that  the  salt
may not dissolve till required.  Mark, by tying a thread,
the line where the waiter stands  ; and then agitate the
flask or matrass, and a considerable diminution will re-
 sult.
   Remark. The salt will dissolve ; the air will be set at
liberty ; and during the solution, the water will sink
considerably below its level.  That during  the solu-
tion of salts, the bulk of water changes is  therefore
evident.   This contraction of bulk is owing to the di-
minution of temperature ; and, when  the water has re-
 gained its former temperature, it will  also be  found,
that its bulk is increased by the addition of salt.
   Experiment  16.  Introduce into a flask  half a pound
of sulphate of soda;  pour on it  barely a pint of water,
and apply the heat so as to boil the water.  The whole
of the salt will be dissolved.   Boil the solution for a
 few minutes, so as to  drive out the air; and cork  the 
215
bottle tightly, immediately on its removal from the fire.
To prevent more completely the admission of air, tie
the cork over with a bladder.   As the  vessel cools an
imperfect vacuum will be formed over the solution;
for the steam, which arises during the ebullitio:., ex-
pels the  air, and takes its place.   The steam is con-
densed, again when the vessel cools.   The  solvtion,
when perfectly cold, may be shciken without any  effect
ensuing, so long as the vessel is kept closely stopped ;
but, on removing the cork and shaking the vessel, the
solution  will immediately congeal, and heat be pro-
duced.
   Remark.  This experiment shews, that water has its
solvent power increased by diminishing the  pressure
of the atmosphere. It also shews, that calo.-ic is evolved
during the transition of bodies from a fluid to a solid
state.  It is  the reverse of that, in which cold is pro-
duced, or caloric absorbed, during the solution of salts.
   Experiment 16.   If wat< r be  thrown on  ejuicklime, it
will lose its former state, and becomes slacked lime.
  Rationale. This combination of lime and water, during
which an evolution of heat takes place, in the language
of  Proust, is a hydrate of lime.
   Remark.  Water, therefore, combines in two forms;
in  the first it  acts as a solvent, by which a solution
is  effected ; in the second it loses its fluid form and
assumes that of  the  substance to which it has uni-
ted, as  in hydrates  and crystallized bodies. In the
latter way it  unites  to  lime, alumina, to many  saline
bodies, and to metallic oxyds.   The crystals of barytes
and strontia, are hydrates of these alkaline earths, and
 crystallized potash and soda and  hydrates of the fixed
alkalies.   The hydrates of potash and soda contain
about 30 per cent, of water.  Hydrate of alumina, is the
 spongy alumina of Saussure.
    Experiment 17.  If to a solution of nitrate of copper, a
 sufficient quantity of potash be added, a blue precipitate
 will be formed, which when washed and dried,  forms
 hydrate of copper.
    Rationale.  The potash unites  with the nitric acid,
 forming nitrate of potash, and the copper is precipitated 
216
 in union with oxygen and water in the state of hydrate
 of copper.
   Remark.  This precipitate is composed of 25 parts
 water, and 75 of black  oxyd of copper.
   Experiment 18.   If to a  solution ol sulphate of iron,
 potash be added in the  same manner,  a hydrate of iron
 will be obtained.
   Rationale.   Analogous to the preceding.
   Remark.  Tbis hydrate  is of a  green colour, and
 readily parts with its water.
   Experiment  19.  If to a  solution of tin in muriatic
 acid, the same alkali be added, a hydrate of tin will be
 precipitated.
   Rationale.  Analogous to  the preceding.
   Remark.  This preparation is of a white colour, and
 loses, when distilled about 5 per cent, of  water, and is
 converted into prot-oxyd of tin, or tin oxydized to the
 minimum.  There is reason to believe, that  most all
 the metals will form peculiar compounds with water.
   Experiment 20.   Put gypsum or sulphate of  lime into
 a crucible, and apply a  sufficient heat to  drive off the
 water, which  it contains; take the calcined  gypsum,
 powder it, and add to it a portion water;  it will again
 become  solid almost immediately.
   Rationale.  On exposure to heat, the gypsum loses
 its water, but the component parts  of the plaster (pro-
 vided the heat be not too considerable) remains unal-
 tered ; on adding water, the affinity of the plaster is so
 great  for  it*  that  the  whole  of  the pulverent mat-
 ter will  be converted to a  solid.
  Experiment 21. Procure a gun barrel, the breech of
 which has been removed, so as to form a tube at each
 end.  Fill this  with iron-wire coiled  up  in  a spiral
 form.  To one end of  the  barrel  adapt a small glass
 retort, partly filled with water, and to the other a bent
 glass tube, the  open end of which terminates under
the shelf of the pneumatic cistern.   Let the barrel be
placed horizontally (or  rather with that end,  to which
the retort is fixed, a little elevated in a furnace hav-
ing two openings in its body  opposite to  each other.
Light a fire in  the furnace ; and when the gun barrel 
217
has become red hot,  apply  a lamp under the retort
The steam of the water will  pass over  the  red hot
iron, and will be decomposed, and hydrogen gas will be
disengaged.
  Rationale.  In this experiment the water is decom-
posed, its  oxygen unites with the iron, forming the
oxyd of iron, and its  hydrogen is  disengaged in the
form of  gas.
  Remark.  From experiments of this kind, conducted
with the utmost  accuracy, as  well as from synthetic
investigations,  water  is found to be composed of 85
parts of oxygen  and  15 of hydrogen  by weight, very
nearly.  Hydrogen gas being about  eleven times lighter
than common air, the proportion of gases, by volume
required to form water, is about two of hydrogen to one
of oxygen.  It  is not necessary to remark, that water
was one  of the  four supposed  elements.   Mr. Caven-
dish must be considered as the discoverer of the com-
position  of water.  The experiments of Mr. Cavendish
were repeated  in England and France.  Mr. Lavoisier,
assisted  by several of the  French Academicians,  in-
stituted a  series of experiments on water, about the
same time, and proved that water is composed of hy-
drogen and oxygen;  it has, therefore, been called an
oxyd of  hydrogen.
   Experiment 22.  Introduce iron  wire into an earthen
tube, and  ignite it in a furnace ;  pass the vapour of
water through  it, and hydrogen gas will be obtained.
   Rationale.  The effect is the same as in the preced-
ing experiment: if the iron wire  be  first weighed, it
will be found, after the experiment, to have increased in
weight in proportion to the quantity of oxygen absorb-
ed.  If the additional weight  be added  to that of the
hydrogen  gas, it will make up  exactly the weight of
the water that  has disappeared.
   Experiment  23.  Pass the vapour of water through
an ignited gun barrel containg charcoal, the water will
be decomposed.
   Rationale. The  oxygen  of the water unites with
the charcoal forming carbonic acid, and  the hydrogen
is disengaged  partly  in a free state, and partly united
                        T 
218
with the carbon in the state of carburetted hydrogen
gas.  See Hydrogen and Carburetted Hydrogen Gas.
  Experiment 24.  When two wires from  the opposite
extremity of a galvanic battery are placed  in  a tube
containing water, so  that they are distant from  each
other one quarter or half an inch, a stream of  gas is-
sues from each wire—from the positive wire  oxygen,
from the negative, hydrogen gas;  and these are in the
proportions which when exploded, either by galvanism
or electricity,  re-forms water.
  Remark. This experiment is designed to shew, that
water is susceptible of decomposition  by  the galvanic
influence.  The decomposition may also be effected in
the following manner :
  Experiment  25.  Take a narrow  glass tube, three or
four inches long ; fit each end with a cork, penetrated
by a piece of slender ir >n wire, and fill the tube  with
water.  Let the ends of the two wires be distant from
each other about three fourths of an inch; and let the
one be  made to communicate with .the bottom of the
galvanic pile, the other with the top.  On making this
communication, bubbles  of air will form,  and will as-
cend to the top of the tube.
  Rationale.  The wire is oxydized by  the  decompo-
sition of the water; its oxygen  unites with the  iron,
while its hydrogen appears in the  state of gas.
  Experiment 26.   By using a similar  apparatus, but
with the substitution  of gold wire, or some metal that
is not oxydized by water,  we obtain a mixture of hydro-
gen and oxygen gases.
  Rationale.  It is apparent that in the case with iron,
which readily  unites with oxygen, the oxygen is ab-
sorbed, and the hydrogen is set at liberty ; but in the
experiment with gold wire, the water  is  also decom-
posed, but, as the  metal is not readily oxydized, the
oxygen as well as the hydrogen is set  free.
  Remark. This experiment is similar  to that perform-
ed by the society of Dutch chemists.   Dr.  Wollaston
has adopted the following method for effecting  the de-
composition of water. 
219
  Experiment 27.  Let two fine gold wires be fixed in
separate small glass tubes by fusion; and let the end of
these tubes be ground till the  very section or extremi-
ty of each  is laid bare, let the other end of each tube
be furnished with a larger wire connected with a me-
tallic ball,  which wire  communicates with  the  gold
wire  within.   These two tubes are then fixed by fu-
sion in a larger  glass tube,  provided with a conical
drawn aperture,  through which  it can be filled  with
water, ail but a small vacuity or bubble, and then seal-
ed.  If a  small  stream  of electricity, or galvanism be
passed through it, the water is decomposed.
   Remark.  The decomposition of water by galvanism
was announced by Messrs. Nicholson and Carlisle, in
the year 1801.  A very  evident difference may be ob-
seived in the  quantity of gas  extricated from the two
wires of the galvanic machine.  That connected  with
the zinc end is much less in quantity than what issues
from the copper end.   By placing the two wires in
separate legs  of  a  syphon, as represented in Nichol-
son's Journal, 4to. vol. iv. plate 21, the two gases may
be separated.
   The phenomena which occurs in the decomposition
of water by galvanism,  Davy has explained in confor-
mity to  the general law  which he established as regu-
lating the  chemical  changes  produced by that  agent.
The law is, that  different substances  have such a rela-
tion to galvanism, that some are attracted forcibly to the
positiveothers to the negative side of the galvanic airange-
ment; oxygen and those compounds  in which it pre-
dominates being attracted to  the positive side ; hydro-
gen, inflammable and metallic substances, to the ne-
gative.  Hence  he concludes that when water is sub-
mitted to  the action of galvanism,  the oxygen  of a
portion of it  is attracted to  the positive side, and its
hydrogen  repelled ;  the opposite process takes place
at the negative side, the hydrogen being attracted, and
the oxygen repelled; and at  the wires connected with
 the two sides, these gases appear in  their insulated
 form.  In the separation of the gases, by the agency of
 galvanism, in the decomposition of water, it is assert
 ed that the water at one wire receives positive elec- 
220
tricity and appears as oxygen, and at the other receives
negative electricity, so as to assume the form of hydro-
gen.  This hypothesis appeared extravagant, and little
or no attention  paid  to it, until  sir Humphrey Davy
brought it forward,as connected with the general theory
of the dependence of the chemical forms of matter on
electrical powers.  Water positively electrified would
be  hydrogen ;  water negatively electrified, oxygen  ;
and, says Mr. Davy, as in  the  physical experiments of
temperature, ice, added, to a certain quantity of steam
by an equilibrium of heat, produces  water; so in the
chemical experiments of  the  generation of water, the
positive  and negative electricity of oxygen and  hydro-
gen in certain proportions would annihilate eacli other,
and water alone be the result. No certain conclusions,
however, can be drawn, from our imperfect knowledge
of this subject.
   Having  had the pleasure of witnessing the decom-
position  of water by galvanism, conducted in a very
simple and  ingenious manner by Mr. Franklin Bache,
by which the oxygen and  hydrogen were  separated in
distinct  vessels, it appeared  from the  phenomena, as
Well as from the products of the experiment, that hy-
drogen, as we have already  stated, is given out at the
negative wire, but oxygen was not given out at the po-
sitive wire, but from the positive end of the connecting
wire, i. e. the end which is under the same  glass with
the positive wire.  His apparatus was the  following.
Two bell glasses were inverted over water in separate
vessels,  under each of which was carried a wire, one
from the positive, the other from the negative end of
the battery.  These bell glasses were now connected
by a wire.   It was perceived the moment the connec-
tion was made, that hydrogen, gas was extricated from
the negative wire,  as  heretofore stated; but,  on the
the contrary, the oxygen was not given out at the posi-
tive wire, but  from the positive end of the connected
wire as before  noticed.  This experiment, therefore,
contradicts some conclusions heretofore made.   Mr. B.
supposes, that the water is decomposed at  the negative
end, at which ^he hydrogen is given out, and that the 
221
oxygen, from its attraction to the positive pole, is carried
along the  connecting wire, and a part at least is given
out at the positive end of this wire.  This rationale,
from the phenomena of the experiment, appears to be
correct, or at least extremely probable.
   We are told that the  portion evolved by the wire
from the zinc end will be  found to be oxygen, and that
from the other end hydrogen, in the proportion by
measure of one of the former to two of the latter. The
following method of effecting the decompositionof water,
was  employed by Messrs. Dieman and Van Troostwyk.
   Experiment 28. Take a glass tube, about one-eighth
of an inch diameter, and twelve inches long, one of the
ends of which is  sealed hermetically, and insert a gold
wire, projecting about an inch and a half within the
tube, at this end.   Fix another  wire about the distance
of five-eighths of an inch from the extremity of this,
which may extend to the open end of the tube.  The
tube is next to be filled with distilled water, and to be
placed inverted in a vessel of the same.  When thus
disposed, electrical shocks are to be passed between the
two ends of the wire through the water ; and, if these
shocks be sufficiently strong,  bubbles  of air will  be
formed at each explosion, and will ascend till the upper
part of the wire is uncovered by the  water.   As soon
as this is  effected, the next  shock that is passed will
3et fire to the air, and the water will  rise again in the
tube, a very small quantity of gas remaining.
   Rationale.  The decomposition of the water is effect-
ed, as in the  former experiments; the  hydrogen and
oxygen of which are first liberated, and then inflamed
by a subsequent shock, and water is reproduced.
  Remark. Mr. Cuthbertson has invented an apparatus,
of a similar kind, which exhibits the same experiments
with less trouble to the operator.   It may be seen des-
cribed and figured in Dr. Pearson's paper in the Phi-
losophical  Transactions  for 1797, or in Nicholson's
Journal, vol. i. and ii. 4to.   See Oxygen Gas.
  Experiment 29.  Fill, with hydrogen gas, a bladder
furnished with a stop cock and bent pipe.  Then pour
                          T.2. 
r)22
into a shallow  earthen  dish as much  mercury as will
half fill it, and invert over this a glass bell, full of com-
mon air and  perfectly dry.   Expel the hydrogen gas
through the pipe ;  light the stream, and bring it under
the glass bell, by raising this, and depressing it into
the mercury ; as soon as the inflamed gas is introduced,
a portion of air will escape, at first, in consequence of
the rarefaction*  As the combustion continues, water
will form, and will condense on the sides of the glass.
   Rationale.  The hydrogen unites with the oxygen of
the air, heat and light are disengaged, and water is form-
ed ; or,
   Experiment 30.   Procure a large glass globe, capa-
ble of holding three or four quarts, and having two
openings opposite to each other, which may be drawn out
for a short distance, like the neck of a retort. Inflame the
stream of hydrogen gas, and  introduce it into  the cen-
tre of the  globe.   The rarefied and vitiated  air will
ascend through the aperture of the globe, and a constant
supply of fresh air will be furnished from beneath.  A
quantity ol water will be generated, which will be con-
densed on the inner surface of the vessel; or,
   Experiment 31.  If hydrogen gas be burnt in the same
manner in a vessel of oxygen gas, water will be formed,
and if the hydrogen be sufficient, and the oxygen pure,
the whole of the oxygen will disappear;  or,
   Experiment 32.  By employing the hydro-pneumatic
blow pipe,  by which  oxygen and hydrogen are united,
the formation of water may be shewn ; or,
   Experiment 33.  If a proper mixture of oxygen and
hydrogen gas, according to Mr.  Biot, be suddenly com-
pressed, by an instrument similar to that of the condens-
ing syringe,   combustion  will  ensue, and  water  be
formed.
   Rationale.  By compression, the particles of gas are
brought into intimate  union, a sufficient heat is there-
 fore disengaged to inflame the hydrogen, and combus-
tion ensues.
   Remark.  Besides the analytical experiments  before
enumerated to prove the composition of water, we are
furnished with other proofs drawn from synthetical in- 
223
vestigations, so that both  analysis and  syntheses con-
firm the fact, that water is composed of the base of two
gases united, viz.  oxygen and hydrogen.  Water  is
formed in the combustion of different substances, which
contain hydrogen, as in the following experiment.
  Experiment 34.  Put a little alcohol in a tea-cup,  set
it on fire, and  invert a large bell glass over it.  In a
short time an aqueous vapour will be seen to condense
upon  the inside of the bell, which by means of a dry
sponge may be collected,  and will be found to be pure
water.
  Rationale.  Alcohol is a compound of hydrogen and
carbon ;  during combustion, its hydrogen unites with
the oxygen of the air, and produces water.
  Remark.   Nature also decomposes water in many of
her operations, particularly by means of any living ve-
getable.  See  Oxygen Gas.  From the decomposition
of water is attributed. the formation of oil, wax, gum,
rosin, sugar, &c.  Fish, and all cold-blooded amphibi-
ous animals, are, it is said, endowed with the power of
decomposing water :  a fish, we are told,was kept three
years in a vessel, and fed  only with water ; and at last
it became too  large to live any longer in the vessel.*
   Mr. Davy,  according to some recent speculations,
suspects that water is not a compound  body, but is the
ponderable  base both of  oxygen and hydrogen gases,
assuming these forms according to their electrical states.
An hypothesis of this nature  has  been suggested by
Ritter, and adopted by some of the German and British
chemists.  Water they regarded as  simple: when unit-
ed to negative electricity, it constitutes oxygen gas ;
when united to positive electricity, it forms  hydrogen
 ^as. and in both is the sole gravitating matter.

            * Rondelet de Piscibus, lib.i. cap. 12. 
PART  VIII.
         OF SIMPLE  COMBUSTIBLES.

  By combustibles we understand those substances which
are capable of combustion.  They are either simple or
compound. By simple combustibles we mean those bo-
dies which have not hitherto been decomposed.  The
metals, however, may be classed under this head; but
the greater number of their properties are so different
from those which we include in this class, that  it is
proper to consider them by themselves as a distinct set
of bodies.
                  SECTION I.

                  OF CARBON.

   Experiment 1.  If pieces of oak, willow, hazle, or other
woods deprived of their  bark, be buried  in sand in a
crucible, and exposed, covered, to the  strongest heat
of a wind furnace, the charcoal of wood will be formed.
   Rationale.  The conversion of vegetable  matter, or
ligneous fibre, into  charcoal,  by exposing wood,  or
other vegetable substance, to the action  of heat in a
close vessel, or in a crucible covered with  sand, to pre-
vent the admission of air, takes place in consequence
of the disengagement of its volatile parts,  and the con-
version of the fibre, by its decomposition, into a black
substance, which  from the process is called charcoal,
and is considered an oxyd of carbon. 
225
   Remark.  Charcoal is, therefore, the coaly residuum
of any vegetable that has been  burnt in close vessels.
For  common  purposes, charcoal is made by disposing
the wood in heaps  regularly arranged, and covered with
earth, so as', to prevent the access of any more air than
is absolutely necessary to support the  fire, which is
kept up tiil all the water and oil are  driven off;  after
which the hie is extinguished by shutting up all the air
holes.   Charcoal  is generally black, sonorous, brittle,
very light, and destitute of taste  or smell.  It is so po-
rous that it may be seen through with a microscope.
  Experiment 2.   Pulverise charcoal, and wash it with
diluted muriatic acid, and afterwards with a considerable
quantity of distilled water; it will  then be purified.
  Rationale.  As charcoal may  contain foreign matter,
principally earth, the addition of  muriatic acid will carry
it off, in combination, and  thus  leave  the coal, as it is
not acted  upon by  the acid in a pure state.
  Remark.  It  is of considerable  importance in some
delicate experiments, to have the charcoal  of the ut-
most purity.   By  this method we  are  furnished with a
means of  accomplishing  it.   As  charcoal enters into
the composition of gun powder,  it is also  of impor-
tance to have  it for this purpose in as fine a state as
possible.   This is  effected by charring the wood in iron
cylinders : light woods  are preferred, such  as willow,
alder, poplar, and  linden.   When iron  cylinders are
employed, it is the custom in England to collect the
pyroligneous aciel from the wood, by dry distillation.
  Experiment 3.   Put bone into  a crucible, in the same
manner as in Experiment l,or introduce it into an iron
cylinder; on exposing it to a red heat, it will be convert-
ed into coal.
  Rationale.  In this case, the  volatile  matter of the
hone is dissipated, and the  solid  or  fixed  parts are
changed, by the action of heat, into a carbonaceous sub-
stance, known by the name of ivory or bone black.
  Experiment 4.   Pour water upon charcoal, and let it
remain for some time ;  it will be found that  the water
has no action upon it: but, 
2i£6
  Ex/ieriment 5.  Make a little cheircoal perfectly dry,
pulverise it very  fine, and  put it into a warm tea cup.
If some strong nitric acid  be now poured  in,  so as to
trickle down the inner side of the vessel and mix with
the charcoal, it will burn rapidly, giving out a beautiful
flame, and throwing up the  powder so as to resemble a
beautiful fire work.
   Rationale.  The acid is decomposed, combustion en-
sues, and the oxygen of the acid unites with the coal,
forming carbonic acid, at the same time nitrous gas is
disengaged.
   Experiment 6.  Take charcoal, pulverise it, and mix it
with a weak  solution ol gum arubic ; it will form the
writing ink of the ancients.
   Remark.  The ancients  wrote with  levigated char-
coal.   The writings found in  Herculaneum, which
were formed with  this ink, are still a perfect black.
Hence its indestructible nature.  The incorruptibility
of charcoal was known in ancient times.   The temple
of Ephesus was built upon wooden piles, which  had
been charred on the outside to preserve them.   Bishop
Watson in his  Chemical Essays,  vol. iii. 48, says, that
the beams of the theatre at Herculaneum were convert-
ed into charcoal by the lava which overflowed that city ;
and  during the lapse of seventeen hundred years the
charcoal has remained entire as if it had been  formed
but yesterday.
   It is said that there still exists charcoal made of corn
in the days of  Caesar, which is in so complete a state,
that the wheat may be distinguished from the rye.  We
are told also, that about forty years ago a quantity of oak
stakes were found in the bed of the Thames, in the very
spot where Tacitus says that the Britons fixed a vast
number of such stakes, to prevent the passage of Julius
Caesar and his army.   They were charred to a consider-
able depth, retained their form completely, and were
firm at the heart.  It  was a custom among the ancients
to char the outside of those stakes  which were to be
driven into the  ground or placed  in water,  in order tr
preserve the wood from decay. 
227
  Experiment 7.  Mix together 2 J or 3 grains ol lamp-
Hack, or finely pulverised charcoal, with a solution of 25
grains olgum copal in 200 grains of oil oflavendar, so that
they may be  intimately combined, and the writing ink
of Mr, Close  will be formed.
  Remark.   As all  writing inks, into the composition
ef which iron enters, are liable to decay by time, and
to be destroyed by various agents, the above  composi-
tion was recommended to obviate these objections.
  Experiment 8.   If new-made charcoal be rolled up in
clothes which have contracted a disagreeable odour, it
will  effectually destroy it.
  Remark.  Hence  it is, that  charcoal  has been used
to destroy the feted or disagreeable odour, which clothes
contract when kept in close situations.
  Experiment 9.   If a piece olfiesh-meat, which has be-
gun  to be tainted, be rubbed daily with powdered char-
coal  ; its sweetness will be  restored :  or, if meat  be
buried in  charcoal, which is  to be  renewed  daily, it
may be preserved sweet for some time ; or,
  Experiment 10.   If charcoal be added topulrid water;
the  putrid quality  will be discharged, and the water
return to its original state.  Hence the  use of charring
the inner surface of the  casks, which are used to con-
tain  water at sea.
   Rationale.   The  antiseptic  power of charcoal is ac-
counted  for  either by its preventing the action of air,
or a change in the body itself,by which putrefaction is
retarded; or, if the change has already  commenced,by
decomposing* the products of putrefaction.
   Remark.   Besides the application of  charcoal to the
purposes before stated, it may be used  for correcting
the empyreumatic  flavour of spiritous  liquors, which
it effects by absorbing the empyreumatic oil; and may
also be used  as a dentifirce.  Mr. Lowitz of Petersburg
has shewn that it may be used with advantage to purify
a great variety of substances.*
  Dr.  Black  remarks, that casks charred in the inside
to hold water in sea voyages, preserves the water uncor-
• See Crell's Annals, ii. 156. 
228
ruptcd.   Charcoal has a remarkable  effect in destroy.
ing the taste, odour,.and colour of many vegetable and
animal substances.  Common vinegar, by being boiled
in it, is rendered  perfectly limpid.   The colour  of lit-
mus, indigo, and other pigments, dissolved or suspend-
ed  in water, is destroyed.
  Experiment 11.   If a piece of new made charcoal, of
a known weight, be exposed to the  atmosphere for a
day, it will be found to have  increased  about 12$ per
cent, in weight.
   Remark  This effect, being owing principally to the
absorption of moisture, accounts for the rapid increase
of  weight, which  coal undergoes on exposure  to the
air. According to Allen and Pepys,when coal thus charg-
ed  with moisture, is exposed under mercury to the heat
of 214° its water is dissipated.
  Experiment 12.   If a piece of charcoal be heated, and
then plunged into a jar of atmospheric air; it will be
found that the bulk of the latter is diminished.
   Remark.  A piece  of charcoal previously  ignited,
and then plunged into mercury, in order to extinguish
it, and afterwards introduced into a glass vessel  filled
with common air,  M. La Metherie found absorbed four
times its bulk of air.  One fifth of the air was disen-
gaged on  plunging the charcoal into  water.  This air,
on  being  examined, was  found to contain a smaller
quantity of oxygen than atmospherical air does.
  Experiment 1 3.   Plunge a piece of charcoal, in the
same manner, into a jar of oxygen gas, and the bulk of
the latter will be diminished.
   Remark.   The  quantity of oxygen  gas  absorbed
amounts to about eight times the bulk of the charcoal.
This property of charcoal, of absorbing air, was noticed
by Fontana, Priestley, Scheele and Morveau. Morozzo,
however, published the first set of accurate experiments
on this  subject.   According to Mr. Rouppe and Dr.
Van Noorden of Rotterdam, seventeen cubic inches of
charcoal will  absorb, in five  hours, 48 cubic inches ot
air, or 2.8 times its bulk. 
                        229

  Experiment 14.  If charcoal  be exposed i.11 the same
manner to an atmosphere of hydrogen gas, an absorption
will take place.
  Remark.   The absorption of hydrogen  gas amounts
ro about 0.17.   It is  said that charcoal, which has im-
bibed oxygen gas, if it be brought into contact with hy-
drogen  gas, produces water from the union of the bases
of the two gases.
  Count Morozzo has given the following table of the
quantities of different gases absorbed by charcoal.   In
each experiment he  employed a piece of that substance
1 inch long, and ^ths  of an inch diameter. The receiver
containing gas was 12 inches long, and one inch diame-
ter.
Gas absorbed.	inches.	Gas absorbed.	inches.
Atmospheric	H	Nitrous	H
Carbonic acid	n	Hydrogen	^ i ~ 12
Ammonia	n	Oxygen	91 "■6
Muriatic acid	n	Sulphurous acid	5*
Sulphuretted			
„ hydrogen	n		
  Experiment 15. If pulverised charcoal be thrown into
a crucible containing melted nitre, in the state of igni-
tion, a violent deflagration will ensue.
  Rationale.  As charcoal has a great affinity for oxy-
gen, it acts in this case by decomposing the  nitric acid
of the nitrate of potash :  it  is, therefore, in the act of
combustion, converted into carbonic acid, part of which
is disengaged, and another portion unites with the pot-
ash of the decomposed nitre, whilst the  azote of the
nitric acid is set at liberty, still however in  union with
a part of the oxygen forming nitrous gas.
  Experiment 16.   If three  grains of pulverised char-
coal be mixed with ten of nitre, and the  mixture thrown
on a red hot fire shovel, a very brilliant combustion, ac-
companied with a loud detonation, will be  the conse-
quence.
  Rationale.  Analogous to  the preceding.
  Remark.  If fossil or pit  coal be used by  subjecting
a given quantity into a crucible containing a certain 
230
 proportion of melted nitre, the latter willbc decomposed,
 in the ratio to the quantity of the carbonaceous princi-
 ple.   Every 100 grains of nitre that are decomposed in
 this way, denote ten grains of carbon.
   Experiment 17.  If one part of powdered charcoal, one
 ol sulphur, and five ol nitre, be mixed together, and in-
 timately combined, gun powder will be produced.   Sec
 Nitrate of Potash.
   Remark.  The combustion of gun  powder depends
 upon  the decomposition of the  nitric acid of the nitre,
 by the charcoal; some other changes also take place s
 to the production and  expansion of carbonic acid  and
 other gases, which  will be hereafter noticed, the force
 of gun powder is attributed.
   Experiment 18.   If a mixture of charcoal and  nitrate
 of strontian be thrown on a red  hot shovel, a beautiful
 crimson flame will be produced.
   Rationale.  The  nitric acid of the nitrate is decom-
 posed; and, during the combustion, the flame of the
 charcoal is tinged by the strontian.
   Elxperimcnt 19.   If a mixture ol hyper-oxymuriate of
 potash and charcoal be placed on a shovel heated to red-
 ness,  a deflagration  will ensue.
   Rationale.  The  charcoal unites with the  oxygen of
 the oxymuriatic acid of the oxymuriate, and forms car-
 bonic acid.
   Experiment 20.   Wet a piece of charcoal with a solu-
 tion of muriate of gold, or place a thin  slip of it in the
 solution, and heat the  whole by means of a sand bath,
-and the gold will be revived forming a singular and
 beautiful appearance;  or,
   Experiment 21.   Proceed as  in the  last experiment,
 and place the vessel with its contents to the direct rays
 of the sun, and  the  same effect  will take place.
   Rationale.  As metals become insoluble the moment
 they part with their oxygen, in  this case the  oxygen of
 the oxyd of gold, which is held in solution, is separat-
 ed by the coal;  hence  the gold is precipitated.   For
 particulars, see Gold. 
231
  Experiment 2 2.  Ilred o xyd of lead be pu t into a cm -
cible, and exposed to a violent heat,  it will remain un-
altered;  but,
  Experiment 23.  If a mixture of charcoal vend red oxud
rfleadbe exposed to heat, the latter will bt»decomposed,
and the lead revived.
  Rationale.  The charcoal, therefore, acts as a flux ; for
it unites with the oxygen of the oxyd, and flies off in
the state of carbonic acid, leaving the lead in its metallic
state.
  Experiment 24.  If charcoal be put into sulphuric arid,
and  subjected to distillation, the acid will  be decom-
posed.
  Rationale.  As carbon has a stronger affinity for oxy-
gen  than sulphur,  in  this experiment the sulphuric
acid, which is a compound of sulphur and oxygen, is
decomposed ; sulphurous acid  and carbonic  acid  gas
passes over, and, if the quantity be sufficient, sulphur
will  be separated.
  Experiment 25.  II sulphate of potash  and charcoal be
mixed,  and thrown  into a crucible and heat applied,
sulphuret of potash will be formed.
  Rationale.  The  carbon unites  with the oxygen of
the  sulphuric acid  of the sulphate, and forms carbonic
acid; the sulphur  then  combines with  the alkali, and
produces sulphuret of potash.
  Remark.   Besides the properties  and uses of char-
coal already enumerated, it may be proper to add, that
it is a very slow conductor of caloric.   It is said to be
conveyed through  charcoal more slowly than through
sand, in the proportion of three to two.   Hence pow-
dered charcoal may be  advantageously employed to
surround substances which are to be kept cool in  a
warm atmosphere; and also  to confine the  caloric of
heated bodies.  Mr. Lavoisier concluded, from an ex-
periment which he made, that charcoal was a compound
of at least two bodies, both of which during  the com-
bustion of charcoal, unite to oxygen, and form, the  one
water,  and the  other carbonic  acid.   Charcoal then
according to Lavoisier, is a compound of hydrogen ajul 
23:2
carbon.   Priestley, Cruikshank,and Ber holh-t, junior,
have confirmed this deduction.  Charcoal, therefore, is
not pure carbon : it has been considered an oxyd 01 car-
bon.  Messrs. Allen and Fepys have lately determined,
■ hat charcoalf when properly prepared, contains no sen-
sible quantity of hydrogen.   Many bituminous substan-
ces, pit-coal, petroleum, Sec. contain  more or less car-
bon.  The solid bases of all vegetables, from the most
delicate flower to the  huge oak of the forest, is princi-
pally composed of carbon.   It is  a component part of
wax, oils, gums, rosins, Sec.  Carbon  combined  with
different proportions of iron, forms cast iron, steel, and
plumbago.  Charcoal is sometimes used  by mathemati-
cal instrument makers and engravers to polish then-
brass and copper-plates. Plates of horn, and lanthorn
leaves are polished with it.
   In the combustion of oil, turpentine, &c. a  soot is ob-
tained, called lamp black, which is nothing more than a
finer kind of charcoal.  As charcoal is an oxyd of car-
bon, carbon properly  speaking is only known  to us in
the state of diamond.   The diamond  is a precious
stone,  which has been known from the earliest ages.
U is transparent like crystals.  Its figure is commonly
in the form of a six sided prism, terminated by a six
sided pyramid.  It is so hard, that the  best tempered
steel makes no impression on it.   The  powder of the
diamond can only be obtained by grinding one diamond
against  another.  It is a nonconductor of electricity.
Its specific gravity is about  3.5.   For many ages the
diamond was  considered as incombustible.  Sir Isaac
Newton suspected that as  combustibles refract light
more powerfully than other bodies, and as the diamond
possesses this  property in great perfection, that the
diamond was capable  of combustion.  The Florentine
Academicians in the presence of Cosmo III, grand
duke of Tuscany,  in 1694  verified this conjecture.
Several  diamonds  were   consumed by  means of a
burning glass.   Several more were consumed, or des-
troyed,  in the  heat of  a furnace, in the presence  of
Francis 1,  emperor-of Germany.  Many chemists  in 
233
 Kuropc,among whom we may include Darcet, Rouelie,
 Macquer, Cadet, and Lavoisier, repeated these experi-
 ments.   They  proved, that the diamond was actually
 burnt.  The diamond is not soluble in water, nor is it
 acted upon by any chemical agent, except oxygen at
 very  high temperatures.  When exposed in oxygen
 gas to the rays of the sun, concentrated by a very pow-
 erful  lens, it becomes sensibly blackened; it is ignited,
 and at last consumed, carbonic acid gas being produced.
 Morveau, in 1800, found, by accurate experiments, that
 one part of diamond, during its combustion,  combines
 with  4.55 parts of oxygen, and the carbonic acid gas
 formed amounts to 5.55.  Carbonic acid gas, therefore*
 contains  one part of diamond or 4.55 of oxygen; or
 100 parts of carbonic acid gas are  composed of 17 88
 of diamond, and 82.12 of oxygen.  Charcoal requires
 2.57 times its weight of oxygen to convert it into car-
 bonic acid,  whilst the diamond requires 4.55 times its
 weight to undergo the same change.   This can only
 be explained by  supposing that charcoal already con-
 tains  a  considerable proportion of oxygen,  which is
 wanting  in  diamond.   This  conclusion,  however, has
 been doubted by  Messrs. Allen and Pcpys, from some
 experiments which they  made on the subject.  See
 Phil.  Trans. 1807.  For the gaseous compounds of
 carbon, see  Carbonic Acid, Carbonic Oxyd Gas, and Car-
 buretted Hyelrogcn Gas*.
  Mr. Davy has  submitted a variety  of carbonaceous
 substances to the agency of galvanism, and  from the
 results he has  given some new views with regard to
 their  mutual relations.  The nonconducting nature of
 the diamond, and its infusibility, rendered it impossible
 to act on it  by the galvanic discharge.  When  heated
 with potassium, no clastic fluid was given out, but the
 diamond  blackened, and scales seemed to detach them-
 selves from it, gray externally, and internally of the
 colour of plumbago.  For the conclusions on this sub-
ject by professor Davy, consult his paper in the Philo-
sophical  Transactions,  1809.  They appear,  however,
 ■ o be  generally speculative.
                        u 2 
234
  Mr. Pepys deflagrated charcoal with  the galvanic
power, after passing  through 16 persons with  wetted
hands joined.  Mr. Berthollet has lately exposed char-
coal to a violent heat in porcelain and glass retorts, and
shown that the gas wmch comes over, contains u mix-
ture of azote.  He inferred therefore, that azote is one
ef the constituents of charcoal.
  We shall conclude this subject, by giving the follow-
ing table of the
             Primary compounds of carbon.
a.  a.
   1.

   2.
  4,
b b,
a* a.

  .1.
   a.
   b.
   c.

   d.
   e.
   A. Binary.
With oxygen.
Incombusti-"
  ble coal.
Charcoal
 (carbonous ^>oxyds.
 oxyd.)
Carbonic
  oxyd gas.
Carbonic acid.
With metals; carbu-
•  rets.
  B.  Ternary.
With oxygen and hy-
  drogen.
Oxyds.
Alcohol. ■]
Ether.
Fixedoils
  and fats.
 Wax.
 Adipo-
   cire.
 Volatile
   oils.
 Resins.
 Camphor.
 Starch.
 Sugar.
 Fluid- or
  fusible
;> wiihout
  decom-
  position.
  /.  Jelly.
  n. Tannin.
2. Acids.
  a. Acetic.
  b. Oxalic.
  c. Tartaric.
  d. Citric.
  e. Malic.
  f. Lactic.
  g. Gallic.
  h. Mucous.
  k. Benzoic.
  I. Succinic.
   m. Camphoric.
   w. Suberic.
   o.^ Laccic.
   /*.*'Sebacic.
   q.- Kinic.
   r.  Saclactic.
   s.  Sebacic.
      C. Quaternary.
■* With azote, hydrogen, and
         oxygen.
    I.  Oxyds.
   a. Gum.
   b. Gum resin.
   c. Extracts.
    d. Lignin.
  •  e. Suber. 
235
/. Caoutchouc.            2. Acids.
g. Gelatin.                a. Prussic.
h. Albumen.               b. Zoonic.
i. Fibrin.                 c. Uric.
 k. Urea.                   d. Amnic.
  SECTION II.

OF PHOSPHORUS.
  Experiment 1.  Let a quantity of bones be burnt to
whiteness, and reduced to powder.   Put 100 parts of
this powder  into a basin of porcelain or stone ware, di-
lute it  with  four times its weight of water, and then
add gradually (stirring the mixture after every addi-
tion) 40 parts of sulphuric acid.   The mixtures become
hot, and a vast number  of air  bubbles are  extricated.
Leave  the mixture in this  state for 24 hours ;  taking
care to stir it well every now and then with a glass oc
porcelain rod to enable the acid to act upon the pow-
der.   Pour the whole now on  a filter of cloth ; the li-
quid which runs through the  filter is to be received
in a  porcelain basin; and the  white powder which re-
mains  on the filter, after pure water has been poured
on it repeatedly, and allowed to strain into  the  porce-
lain basin below, being of no use, may be thrown away.
Evaporate the strained liquor in earthen vessels, placed
in a  sand heat, and, when reduced to about half its bulk,
let it cool.  A white sediment will form in consider-
able quantity, which must be  allowed  to subside ; the
clear solution must be decanted, and boiled to dryness in
a glass or porcelain vessel.  A white mass  will  remain
which is the dry phosphoric acid.  Pulverise this and
mix it with its weight of charcoal;  or to the evapo-
rated  liquor, which when acquiring a thick  consistence
powdered charcoal may be addd, in sufficient quantity,
 to give it solidity.  In the latter mode, however, the
 materials are  apt to swell,  and boil over.   The mix- 
256
ture is then to be put into a stone ware retort, wl.it :,
may be coated in the usual manner, and the neck ot
which is lengthened out by a tin pipe.  The open end
of the pipe is to be immersed in a  vessel of water.
The heat is to be slowly raised,  and at length made
very intense.  An enormous quantity of gas escapes,
which takes fire on coming into contact with the at-
mosphere,  and  phosphorus  will distil over  in drops,
which congeal in the water.
  Rationale.  When bone,  and indeed most of  the
solid "parts of animals, are burnt in the open air,  their
volatile parts, gelatine, &c. are dissipated or consumed,
and there remains a white ash, called bone ash.   This
is principally composed of lime and phosphoric  acid
On adding sulphuric acid, the  phosphoric  acid is dis-
engaged, and a compound of lime and sulphuric acid
is formed.   The  phosphoric acid, therefore, remains
in solution. When the whole is  subjected to the  fil-
ter, the sulphate  of lime is separated, and the liquor
which runs through is phosphoric acid in solution, but
containing, however, an admixtuie of some  sulphate
of  lime.   Hence, on  evaporation,  this is deposited.
When the fluid is now evaporated to dryness, and the
dry mass,  which is solid phosphoric acid,  is mixed
with charcoal and distilled, the product of distillation
is phosphorus ;  for as the carbon unites with the oxygen
of the phosphoric acid, forming  carbonic acid, it fol-
lows, that the phosphorus  is deprived of its oxygen,
and is obtained in a free state.  The gas which takes
fire is phosphuretted hydrogen, arising either  from
the decomposition of moisture in the coal, or the com-
bination  of hydrogen, which coal generally contains,
with a portion of phosphorus.
  Remark.   As the phosphorus is apt to condense in,
or stop up  the neck of the retort and tin pipe, it  must
be occasionally melted  out of these, by a shovel full
of hot cinders, held under  them.  Three  pounds of
bones yield an ounce and a half and 30 grains of phos-
phorus, if the process be well conducted.
  Experiment 2.  Proceed as in the last experiment,
except the evaporation, and mixing of charcoal, and- 
237
add to the liquid a solution of nitrate of lead, by degrees
a white powder will fall to the bottom.  The addition of
the nitrate is to be continued until no more precipitate is
formed.  Collect this precipitate, by pouring the whole
upon a filter, wash it, dry it, and mix it with about Jth
of its weight of charcoal powder.  Expose the mixture
in a  retort to the  action of heat, as  in the last  experi-
ment, and phosphorus will be obtained.
   Rati<male.  In this experiment the  phosphoric acid
unites with the lead of nitrate, and forms phosphate of
lead, which is precipitated.  When this is mixed with
charcoal, and distilled, the charcoal  carries off the oxy-
gen  of the  phosphoric  acid,  forming carbonic  acid,
whilst the phosphorus is set at liberty, which is then
volatilized as before ; at the same time the lead is re-
vived.
  Experiment 3.  If nitrate of lead be  added to  urine,
a white powder will fall, which, when collected and
treated with charcoal as before, affords phosphorus.
  Rationale.  As urine  contains phosphoric  acid in
combination with soda and ammonia, in the form of a
triple  phosphate  or microcosmic salt, the addition of
nitrate of lead  separates the  phosphoric acid by com-
pound affinity.  The  nitric acid of the nitrate unites
with  the soda  and ammonia, whilst  the phosphoric
acid  combines with lead, and precipitates a phosphate
of lead.  This is then decomposed  by  charcoal, in the
same manner as before stated.
  Ex/ieriment 4.  If acetate of lead  be  added to  urine,
a powder is  also obtained,  which when treated in the
same manner with charcoal, produces phosphorus.
  Rationale.   The same as the preceding, except ace-
tate of soda and ammonia  are formed by the double
decomposition.
  Experiment 5.  If the phosphate of lead, produced as
in  the last experiment, be washed, and decomposed by
means of muriatic acid, the phosphoric acid is disengaged
in a  liquid state, which, when evaporated to dryness,
and mixed with charcoal, and treated as in the former
experiments, yields phosphorus. 
238
  Rationale.  In this case the phosphate of lead is pro •
duced from the urine, by the agency of acetate of lead,
and is decomposed by muriatic acid ; an insoluble mu-
riate of lead being  produced.  The phosphoric acid,
thus disengaged, being evaporated to dryness, and dis-
oxygenized by means of  charcoal, affords phosphorus.
  Experiment 6. According to Margraaf, if ten pounds
of urine be evaporated to the consistence of honey, and
mixed with muriate of lead (remaining after the distilla-
tion 4lbs. of minium and two of muriate of ammonia) and
half a pound of charcoal, and this  mixture dried in  an
iron pot until reduced to a black  powder, and distilled
in an earthen retort phosphorus will be obtained.
   Rationale.  The  muriate of  lead  here decomposes
the phosphoric salt, and  produces a phosphate of lead-,
which is decomposed by the charcoal  in the manner
before stated.
  Experiment 7.  Take a solution of phosphate of soda,
and mix it with one ol acetate of lead, in the proportion
of  one part of the former  salt, to one and a quarter of
the latter ; a precipitate  will be obtained, which when
collected, washed, dried, mixed with charcoal, and dis-
tilled, yields phosphorus.
   Rationale.  In this experiment a double affinity takes
place : the phosphoric acid unites with the lead form-
ing a phosphate of  lead, which is precipitated,  whilst
the acetic  acid of the acetate of  lead,  unites with the
soda, producing an acetate of soda, which remains in
solution.   The phosphate of lead is then collected, and
treated with charcoal as in the preceding  experiments ;
the theory of which has already been stated.
  Remark.   Brandt,  a  German  chemist,  discovered
phosphorus in the year 1669, when prosecuting some
experiments on urine.   Kunckel saw it, and communi-
cated the fact to one Kraft, a friend of his at  Dresden.
Kraft purchased the secret  from Brandt  for 200 dollars.
Soon after he exhibited it in France.  Kunkcl, however,
prepared it himself without any knowledge of the pro-
cess,  although he  saw the phosphorus which Brandt
prepared.   Kraft it is said taught Boyle, who commn- 
239
nicated  the process to Godfrey Hankwitz, a London
apothecary, who continued to supply all Europe with
phosphorus.   Hence it was known to chemists by the
name of English phosphorus.  It was afterwards made in
France.   But it was not until a subsequent period, that
it was found that bones would afford phosphorus.  This
fact was discovered  in 1769 by Gahn. Scheele, a Swe-
dish chemist, very  soon  after, invented a process for
obtaining it from bones.  Since this period, the process
was improved, principally by Fourcroy and Vauquelin.
Several dissertations have appeared on the properties of
phosphorus.
  Phosphorus, when pure, is semi-transparent, and of
a yellowish colour; but when kept some time in water,
it contracts the  appearance of white wax.  It may be
cut with a knife.  It is insoluble in water.  Its mean
specific  gravity 1.770.   Phosphorus, when used inter-
nally, is  poisonous.  It has been employed, however, as
a medicine. It is related in the Annales de Chimie,thata
great number of domestic fowls were poisoned merely
by drinking the water in which phosphorus had  been
put.  Mr. Davy suspects, that phosphorus, though con-
sidered a simple, is a compound body, and that it con-
tains hydrogen as one of its component parts.
  Experiment 8.  If figures be marked on a wall, with
phosphorus, and  the  room darkened, they  will appear
luminous.
  Rationale.   The emission of light is owing to the
gradual  absorption of oxygen, by the decomposition of
oxygen  gas; heat and light are set at liberty from the
gas, and the phosphorus  is converted into phosphorous
ccid.  The phosphorus emits a white smoke.
  Experiment 9.  If water be heated to  about 100°,
according to Pelletier, and phosphorus introduced into
it, it will melt.
   Remark.   Phosphorus  when exposed to the open air
and heat applied, will inflame ; but if the same heat be
used through the medium of water, it will only melt.
As phosphorus when first prepared is mixed  with im- 
2Vj
purities, it may be freed from them by mclt.ng it in ho«
water, and straining it through a piece of clean shamois
leather.   It may be formed into sticks, by putting it in
a glass funnel with a long tube, stopped at  the bottom
with a cork, and plunging the whole  under warm wa-
ter.
   Experiment 10. If a retort be filled with hydrogen, or
azotic gas, and  phosphorus introduced ; it will evapo-
rate when a temperature of 554° is applied.
   Remark.  The retort should be supplied with the gas,
to prevent  an  absorption, which may be effected by
filling a bladder with the gas; through the stop cocK
into the  retort, it may  be forced by compressing the
bladder.  The use of azotic or hydrogen gas is obvious,
as they are non-supporters of combustion.
   Experiment  11.  IIphosphorus be immersed in ajar
of oxygi n gas, heated to  60°, according to Fourcroy and
Vauquelin, a part of it is dissolved ; but, if the tempe-
rature of  the  gas be raised to 80°, the phosphorus be-
comes luminous.
   Remark.  We learn, therefore, that phosphorus burns
at a lower temperature in common air than in oxygen
gas.
   Experiment 12.  If a piece ol phosphorus be rubbed
between two pieces of brown paper, it will inflame.
   Rationale.  The heat produced by  friction inflames
the phosphorus, which of course, decomposes the oxy-
gen gas of the  atmosphere.
   Experiment .13.   If a piece of phosphorus, according
to Dr. Higgins, be exposed to a temperature of 60°, it
will inflame.
   Remark.  It is said, however, on the authority of Dr.
Thomson, that at a  temperature of  148°, phosphorus
takes fire, and gives out a great quantity of white smoke,
which when collected will be found to possess acid pro-
perties.   This  acid is the phosphoric, and is composed
of phosphorus and  oxygen.   From   Mr. Lavoisier's
experiments it follows, that  100 parts of phosphorus
during  this combustion, unite with 154 parts oxygen.
One grain of phosphorus condenses no less than 4\ cu- 
241
bic inches of oxygen gas, and five grains are capable
of depriving 102£ cubic inches of air of all its oxygen
gas.   It is conjectured, that the  reason  Avhy phospho-
rus sometimes inflames at a low temperature, is be-
cause it contains a portion  of oxygen.   It is also said
that phosphorus in this  state is au oxyd,  which has
been  called an oxyd of phosphorus.  Phosphorus in
this state is distinguished by its appearance—that of
white flakes.   It  is  this kind  which usually  forms
the phosphoric matches, and phosphoric bottles.  The
phosphorus, for this purpose, is  generally mixed with
sulphur.   Phosphorus, long acted upon by water, is
changed into an oxyd, which may be separated by plung-
ing it into water heated to about  100°.  The phospho-
rus melts, while the oxyd remains unchanged.
   Experiment 14.   If any light  substance  capable of
conducting heat be placed upon the surface of boiling
water, and a bit of phosphorus be  laid upon it, the phos-
phorus will immediately inflame.
   Remark.  The  heat of the water is here sufficient to
set the phosphorus on fire.
   Experiment 15.  II nitric acid  be  poured  on a mix-
ture ol phosphorus and oxygenized muriate of potash, flash-
es of fire will be emitted at intervals for some time.
   Rationale.  The oxymuriate is decomposed by the
acid; the oxymuriatic acid gas thus disengaged, inflames
the phosphorus, phosphoric acid and common muriatic
acid gas being the result.
   Experiment 16.   Introduce into a flask 30 grains of
phosphorus, and three or four ounces of water.  Apply
the heat of a lamp ;  so that ebullition may take place.
Balls of fire will issue from the water, after the manner
of artificial  fire works,  attended with most beautiful
coruscations.
   Rationale.  The ebullition of  the water  causes the
melted particles of the  phosphorus to be thrown up,
which are then inflamed by the  oxygen gas of the at-
mosphere.
   Experiment 17.   Put phosphorus into a tumbler of
boiling water, and from a bladder furnished with a atop
                      X 
242
  cock, force a stream of oxygen gas directly upon it, and
  combustion under water will  take place.
    Rationale.  The oxygen combines with the phospho-
  rus and forms phosphoric acid, as in a former  experi-
  ment, heat and light being set at liberty.
    Experiment  18.  Ifphosphorus, surrounded hy cotton
  rubbed in powdered rosin, be placed under the receiver
  of an air pump, it will take fire when a part of the pres-
  sure of the atmosphere is removed, and on the gradual
  admission of air, will exhibit a beautiful  phenomena.
    Remark. This experiment is rather singular. On re-
  moving the pressure of  external air, it appears that
  when a part of the air is exhausted,  consequently a di-
  litation of the remaining air  ensues, the phosphorus
  inflames, though a less  portion of oxygen gas is pre-
  sented to it.  On admitting fresh air, the combustion
  w hich  has thus begun, is continued.
    Experiment  19.  Put  a small thin bottle into  sand
  contained  in a ladle,  heat it, and introduce into it a
  few grains of phosphorus.  Stop the mouth of the bot-
  tle loosely, then add by degrees more phosphorus. The
  phosphorus will thus be melted, and form the phosphoric
  fire-bottle.
    Remark.  The phosphorus is partly oxydized.  On
  immersing a sulphur match, it  will inflame when it
  comes to the air; or,
    Experiment  20,  Proceed as in the last experiment,
  and add to the phosphorus one  sixteenth part of sulphur,
  melt them together, and a phosphoric fire-bottle will also
  be formed; or,
    Experiment 21. IIphosphorus and sulphur, in the same
  proportions, be added to  boiling water,  a compound
  will be formed having the same properties as the last.
  It must be taken out,  and put into a bottle.
    Experiment  22.  Take a glass  tube, about four m-
  4hes  long, and one line wide, closed at one  end.   A
  small quantity ol phosphorus is to be introduced into the
*  tube, and pushed to its extremity  by an iron wire, after
  which a taper covered at one end with wax is put into
  it; the open end of the tube is to be hermetically seal- 
243
ed, and the  other  plunged into hot water.  The phos-
phorus melts, and fixes as it cools  upon the taper.  A
line is then drawn by means of a diamond or file, at one
third  of the  tube.   To use these phosphoric tapers, the
tube is broken at the marked line ; and when it is quick-
ly drawn out, it takes fire, and burns rapidly.*
  Experiment 23.  IIphosphorus be dissolved in sul/ihu-
ric ether, forming the phosphorized ether, and poured into
a decanter containing a little water, a brilliant light will
appear, which passes with a serpentine motion along
the surface  of the fluid.   The air also becomes lumi-
nous.
  Experiment 24.   If air be now blown into the decan-
ter, the luminous  vapour disappears ; if the mixture
be  again agitated, several luminous  points appear at
the surface of the water.
  Experiment 25.   Dip a feather wetted with water
into phosphorized ether ; when the  fluids come in  con-
tact flashes of light appear (in a dark place) to issue out
of the mouth of the vial.
  Experiment 26.  Wet a lump of sugar with phospho-
rized  ether,  and drop it into a  glass of water a  little
warm.  The surface of the water will soon become lu-
minous ; and if it be moved by blowing gently with the
mouth, beautiful and brilliant undulations of its surface
will be produced, exhibiting the appearance of liquid
combustion.
  Experiment 27.   If phosphorized ether be rubbed on
the face or hands,  and the room be darkened, the face
or hands will appear as though they were on fire with-
out producing any dangerous effect, or  sensation of
heat.
  Rationale.    Water, in  some  of these  experiments,
has the property of separating phosphorus from its sol-
vent,  so that it emits, when exposed to the air, a lumi-
nous  appearance, which is nothing  more than a  slow
combustion of the phosphorus.
* Accvun, i. 198. 
244
  Experiment 28.  Put into a vial one part of /.hospho-
rus and six of  olive oil;  place it in warm ashes, and a
solution will be formed, which is the phosphoric oil, or
liquid Jihosphorus of some authors; or,
  Experiment 29.  Add to one part of phosphorus in a
mortar one sixteenth part of sulphur, and a small quan-
tity ol olive oil;  triturate them together, and phosphoric
oil will be obtained.
   Remark.   Phosphorus  dissolved in oil has the  pro-
perty of becoming luminous in the dark, as soon as the
vial  containing it is unstopped, and opaque again when
the vial is corked.  Liquid phosphorus, as it is called,
may serve for showing the hour of the night, by hold-
ing a watch against the bottle when unstopped.  Lumi-
nous writings or drawings, by means of a brush,  may
be formed with it.   It may be rubbed on the face or
hands without injury.
   Experiment 30.   Put a table spoonful of water into
a cup, put it over the  fire and add a small  quantity of
phosphorus : when the water boils pour into it about one
dl'zir. ol,  sulphuric acid, and  a considerable ebullition
will take  place, accompanied with combustion, which
will be followed by a loud explosion.
   Rationale.  The accension of phosphorus by sulphu-
ric acid, is owing to the evolution of heat by the mix-
ture ofthe acid and water.
   Experiment 31. With a needle pass a thread through a
small piece of phosphorus, previously freed from mois-
ture by immersing it in alcohol.   If this be suspended
in an aqueous  solution of muriate of gold, in a few mi-
nutes the phosphorus will become covered with pure
gold.
   Rationale.  The phosphorus has a  stronger affinity
for oxygen than gold has; hence the solution of the
latter is decomposed,  and the oxygen  taken from the.
gold.
   Remark.   Not only the solution of gold, but also the
solutions  of  silver, mercury, tin, lead, and  manganese
are all de-oxydizt-'d by phosphorus, and in some instan- 
-24.5
oes the phosphorus unites with a portion of the metal
forming a phosphuret.
   Experiment 32.  When phosphorus is exposed to the
air, it is changed first into oxyd of phosphorus, and then
into phosphorous acid, which appears in a liquid state.
   Remark.  According to the  quantity of oxygen ab-
sorbed, or the degree of  oxygenizement of the phos-
phorus, the acid produced will  be either the phospho-
rous or the phosphoric.
   Experiment 33.  If nitric acid be poured on phospho-
rous ; or nitric acid heated in  a flask  and phosphorous
gently added, phosphoric acid will be formed.
   Rationale.  The nitric  acid  is decomposed;  nitric
oxyd gas is evolved, and the phosphorous unites with a
portion of oxygen, and forms phosphoric acid.
   Experiment 34.   If oxymuriatic  acid  be added  to
phosphorus, the latter  will be changed  into phosphoric.
acid.
   Rationale.  Here the oxygen  of the oxymuriatic acid
unites with the phosphorus, and the oxymuriatic is ac-
cordingly changed into the common muriatic acid.
   Experiment 35.  If a glass tube be provided, about
thirty  or forty  inches in length, with one of its ends
closed, and filled with mercury; and then immersed in
a mercurial trough, the mercury will descend several
inches, or until  an equilibrium is established with the
pressure of the air.  A vacuum will therefore be form-
ed.  If a piece ol phosphorus be  thrown  up, no combus-
tion will ensue ;  but if oxygen gas be passed up, as soon
as it comes in contact, and the temperature gently rais-
ed, inflammation will ensue, exhibiting a beautiful phe-
nomena.  See Experiment 17.
   Rationale.   In vacuo, phosphorus does not bum, but
in oxygen gas,  as in  other experiments, combustion
takes place, and phosphoric acid is produced.
   Remark.   Phosphorus, besides the combinations al-
ready stated,  is susceptible of union with a number of
bodies.  The solid white  sublimate obtained by  intro-
ducing phosphorus into oxymuriatic acid  gas, Mr. Da-
vy considers as a compound of muriatic  and phosphoric
                       X 2 
246
acids, to which the name of murio-phosphoric acid has
been given.  Phosphorus unites with carbon, and forms
phosphuret of carbon, and with many of the alkalies,
earths,  and metals,  which will  be hereafter noticed,
These combinations arc given in the following tabic
of the
          Primary Cornjiounds of Phosphorus.
a. With oxygen.
     1.  Oxyd of phosphorus.
     2.  Phosphorous acid.
     3.  Phosphoric acid.
b. With azote.  Phosphuretted azotic gas.
c. With hydrogen.  Phosphuretted hydrogen gas.
' d. With sulphur.   Phosphuret of sulphur.
e. With metals.   Metallic phosphurets.
/. With salifiable buses.  Alkaline and earthly phos-
     phurets.
                 SECTION  III.

                  OF SULPHUR.

   Experiment 1.   If iron pyrites or sulphuret of iron be
broken into small pieces and put  into large  earthen
tubes, connected with a square vessel of cast iron, con-
taining water, as a receiver, and exposed to the action
•f heat; sulphur will be obtained.
   Rationale.   Pyrites used in this  experiment are a
compound of  sulphur and iron, and are known by the
name of martial pyrites.  When they are exposed to
heat, they are decomposed, sulphur  is disengaged, and
the metal remains in the distilling vessel.
   Remark.  The sulphur procured  in this manner ac-
cumulates on the water in the receiver, from which it is
taken and melted in large iron ladles, the earthy  mat-
ter is  thus partly separated.   It is again melted,  and
poured into cylindrical  wooden moulds, hence it takes 
247
that form, and is called in commerce roll sulphur.   This,
for the purpose of medicine, is purified by sublimation,
as we shall presently notice.
  Sulphur  is found abundantly in the earth, but princi-
pally in combination with metals.   With lead, copper,
tin, zinc, arsenic, 8cc. it forms native sulphurets.   With
alumina and lime, it forms the different schist, known by
the name of alum ores.  It exists in the neighbourhood
of volcanos, also in masses, in gypsum, marie,  some-
times in primitive rocks, and Van Humboldt has dis-
covered it along with quartz in a mountain of micaceous
schistus.  It has also been  detected in the albumen of
eggs, in mineral  waters, and  in  vegetable  substan-
ces.
  Experiment  2.   II roll sulphur be put into a vessel, to
which a subliming head is attached, and heat applied,
the sulphur will rise,  or sublime, in a  fine  powder,
forming the fiowers of sulphur.
  Rationale.  The heat causes the sulphur to be  va-
pourized, the  vapour of which condenses,  whilst  the
foreign matter remains behind.
  Remark.   In the large way flowers of sulphur  are
formed by conducting the process with a gentle heat in
a close room, where the sublimed sulphur is collected.
At a temperature of  170° sulphur begins to evaporate,
which may be  shown by placing it on  a heated shovel;
at 190° it begins to melt, and at 218,° it becomes as li-
quid as water.
  Experiment  3.   Boil one part ol fiowers of sulphur in
twenty parts of distilled water in a  glass vessel  for
about a quarter of an hour,  and then decant the water;
or,
  Experiment  4.   Pour boiling water on the sulphur,
decant the  fluid, and  dry the residue ; it will form  the
washed sulphur of the shops.
  Rationale.  Sulphur itself is insoluble in water,  but
that fluid has the property of dissolving any saline mat-
ter, or sulphurous acid which flowers of sulphur  ge-
nerally contain. 
248
  Experiment 5.   If three parts  of  nitro-muriatic  acid,
be  poured and digested on one  ot flowers of sulphur,
previously diluted with one part  of distilled water, the
fluid afterwards decanted, and the  residue washed in
distilled water, pure sulphur will be  obtained.
  Remark.  The nitro-muriatic has the property of dis-
solving  any  foreign  matter,  which was insoluble  in
water, when the sulphur passed the  operation of wash-
ing.  Hence the sulphur is purified.
  Experiment 6.   If sulphur be  melted  in a deep
earthen  vessel, and the  part  which remains  fluid be-
low the  surface  be allowed  to escape,  by piercing a
hole near the edge  of  the  vessel, the  sulphur  will
crystallize in.a needle-shaped octahedral figure.
  Remark.  The method of crystallizing sulphur was
contrived by Rouelle.   If the experiment be made in
a glass vessel, or upon a  flat plate of iron, the crystals
will be perceived, beginning to shoot when the tempe-
rature sinks to 220?.
  Experiment 7.   Put purified sulphur into alcohol; it
will remain unaltered, nor will the alcohol be changed;
but,
  Experiment 8.   Put flowers of sul/ihur into a mattrass
furnished with an alembic ;  suspend within it a cup
or  wide-mouthed bottle  containing alcohol, then put
on  the alembic,  and adjust a vial to the  beak ;  lute
the  joinings,  and apply  the  heat of a lamp, sulphur
will thus be dissolved, and distil over with the alcohol.
  Rationale.   The union of sulphur with alcohol takes
place in  consequence of the two meeting in a vapor-
ized state forming phosphorized alcohol.
  Experiment 9.   If to the  product of Experiment 8,
water be added,  the sulphur  will be precipitated.
  Rationale.   This is a proof that sulphur is dissolved.
The water unites to the alcohol, and  the sulphur be-
ing insoluble in diluted spirit, is precipitated.
  Experiment 10.  One part of sulphur added to eight
of sulphuric ether will be  dissolved.
  Experiment 11.  Threads dipped  in melted sulphur,
and afterwards inflamed,  previously placed in a cup,
and then covered  with a  jar,  will burn, and evolve a 
249
white smoke.   This will be absorbed, and a diminution
of volume  in the jar  will ensue.   The  water, if pow
examined,  will have a suffocating odour and taste, and
turn the blue colour of litmus paper red.
  Rationale.  This  experiment being an  instance of
the slow combustion of-sulphur, exhibits  the produc-
tion of an  acid, the sulphurous,  by the  union of the
sulphur with the oxygen of the atmosphere.  The sul-
phurous acid gas, the  product of  combustion, is ab-
sorbed by the water.  See Sulphurous Acid Gas.
  Experiment  12.  Introduce a mixture  of one part
of nitrate of potarii and six ol sulphur,  placed in a cop-
per spoon, and lighted, into  a  vessel of atmospheric
air placed over water, and a rapid combustion will en-
sue.
  Rationale. The sulphur, in  this case, is further oxy-
genized ; for the nitric acid  of the nitrate  of potash
is decomposed, and furnishes oxygen gas, into which
the sulphur is plunged the instant of its inflammation.
The product is, therefore, sulphuric acid ; or,
  Experiment 13.   If sulphur be burnt in oxygen gas,
the same product will be formed.
  Remark.   The combustion of sulphur was attributed
by Stahl to a principle, or substance,  which he called
phlogiston ; and that all bodies  which  contained it, he
affirmed were inflammable.  This theory was unsatis-
factory, and it was not until the time of Lavoisier that
it was properly explained. His experiments were con-
clusive.  He proved that the air was  diminished, and
that the body absorbed or combined with  the sulphur
was oxygen.  Hence it is, that  sulphur  is acidified in
the process of  combustion.
  Experiment 14.   If sulphur be  boiled in nitric acid,
sulphuric acid will be formed.
  Rationale.  The nitric acid is decomposed, a part of
its oxygen unites  with the  sulphur,  forming with  it
sulphuric acid, whilst another portion is dissipated in
union  with azote  constituting  nitric  oxyd or nitrous
gas.
  Remark.  From well attested  experiments, it seems
that sulphuric  acid is composed of 42.3 sulphur, and 
250
57.7 oxygen, and that sulphurous acid contains 53 sul-
phur and  47 oxygen in  the hundred.   See  Sulphuric
and Sulphurous Acids.
  Experiment  15.  If sulphur be melted in an  iron la-
dle,  and in this state poured into water, it  will be
found,  when  cold, of a red colour, and as soft as wax.
  Remark.  In this state, sulphur is employed to take
off impressions from seals and medals.  These casts
are  known by  the name of  sulphurs.   Sulphur, thus
treated, is said to be combined  w ith a portion of oxy-
gen forming an oxyd of sulphur.   This  is more par-
ticularly the case when sulphur is made viscid and red
by long boiling.
  Experiment 16.  If common sulphur be sublimed in-
to a vessel filled with the vapour of water, the sulphur
will  form into  flowers of a white  colour.
  Rationale.  In this experiment  the   colour of the
sulphur  is changed by its combination  with water,
forming the lac sulphuris or milk of sulphur.
  Experiment 17.  Into a solution of sulphuret of pot-
ash pour  diluted nitric or muriatic acid, and the sulphur
will be precipitated  of  a white colour.
  Rationale.  The acid  unites with the  alkali, and  the
sulphur is precipitated in union with a portion of wa-
ter,  which, when collected, washed, and dried,  forms
the milk of sulphur as in the last experiment.
  Remark.  When  lac sulphuris is exposed to a low
red heat in a  retort, or evaporating dish, it  soon ac-
quires the colour of common sulphur,  and, when the
retort is used, a quantity of water will be found in its
beak.   If also  a little  water is dropped into melted
sulphur, the portion in contact with  the water im-
mediately assumes the white colour of lac sulphuris.
Hence it is said that the orange, or greenish yellow is
the natural colour of sulphur.
  Experiment 18.  If charcoal,  according to  Messrs.
Clement  and  Desormes, be heated to redness in  a
porcelain tube; and, when it has been continued  in
this  state for  a short time, a portion of sulphur be
made to come in  contact  with it, excluding at the 
251
same time atmospheric air, a substance passes through
in the form of a liquid.
   Remark.  Lampadius obtained this liquid  by  distil-
ling a mixture of pyrites and charcoal, which he call-
ed alcohol of sulphur.  Some suppose it to be a com-
pound of sulphur and hydrogen.   With Berthollet we
may conclude, that this conjecture is correct, for that
chemist made a  number  of experiments  on  the sub-
ject, and proved that it is  composed of  sulphur and
hydrogen without any perceptible  mixture of car-
bon, and that it contains a greater proportion of sul-
phur than  sulphuretted  hydrogen.  It has  therefore
been called super-sulphuretted hydrogen.   Clement and
Desormes considered it as a compound  of sulphur and
charcoal.   There is a certain state only in which this
preparation is formed ; for if the proportions  be not
correct, or either of the materials not sufficient, a com-
pound of sulphur and hydrogen will be  formed, which
will  take the  aeriform state.
   Experiment 19.  Into a vial or tube introduce some
sulphur, melt it, and add  phosphorus, stopping the vial
at the same time, and a compound of phosphorus and
sulphur will  be  formed.
   Remark.   This combination, which was first noticed
by Margraaf, is, if the proportions of sulphur be suffi-
cient, a  sulphuret of  phosphorus.   When  properly
prepared it has a yellowish white colour, and a crys-
tallized appearance.   The compound of the two is more
combustible than phosphorus.
   Experiment 20.  If sulphur and phosphorus be put in-
to a flask, and  filled with water, and heat applied,  a
combination of the two will be formed.
   Remark.  The heat should be gradual, otherwise an
explosion may follow, as the water sometimes is said
to be decomposed.
   Remark.  Sulphur, though considered  a simple, is
affirmed to be a compound substance, especially from
some experiment made by Mr. Clayfield, in which hy-
drogen is a component part.  Sulphur unites, as we
formerly remarked,  with a variety of substances; as
will  appear from the  following table of 
252
      The Primary Compounds of Sulphur.

  a. With oxygen.
    1.  Oxyd of sulphur.
    2.  Sulphurous acid.
    3.  Sulphuric acid.
  tr. With azote.   Sulphuretted azotic gas.
  c. With hydrogen.
    1.  Sulphuretted hydrogen.
    2.  Super-sulphuretted hydrogen.
  d.  With water.  Milk of sulphur.
  e. With phosphorus.  Sulphuret of phosphorus
  f.  With oil.  Sulphurized oil.
g. With alkalies.
     1. Sulphuret of potash.
    2. Sulphuret of soda.
    3. Sulphuret of ammonia.
A. With earths.
  a.  Sulphuret of barytes.
  b.  Sulphuret of strontian.
  c.  Sulphuret of lime.
  d.  Sulphuret of magnesia.
  e.  Sulphuret of alumina.
i. With metals.
  a.  Sulphuret of iron.
     1. Common sulphuret of iron.
    2. Super-sulphuret of iron.
  b.  Sulphuret of arsenic.
     1. Red arsenic.
     2. Yellow arsenic.
  c.  Sulphuret of lead.
     1. Sulphuret of lead.
     2. Super-sulphuret of lead.
  d.  Sulphuret of tin.
     1. Sulphuret of tin.
     2. Sulphuretted oxyd of tin.
  e.  Sulphuret of antimony.
     1. Sulphuret of antimony.
     2. Super-sulphuret of antimony.
  f.  Sulphuret of silver.
  g. Sulphuret of bismuth. 
253
    h.  Sulphuret of  copper.
       1. Common sulphuret of copper.
       2. Super-sulphuret of copper.
    /.  Sulphuret of mercury.
       1. Ethiops mineral.
      2. Vermillion.
    k.  Sulphuret of palladium.
    /. Sulphuret of rhodium.
    m. Sulphuret of nickel.
    n.  Sulphuret of tellurium.
    o.  Sulphuret of uranium.
    p.  Sulphuret of molybdenum.
    q.  Sulphuret of tungsten.

  As it respects the preparation, and chemical proper-
ties of  these substances, such as have not been given
will be noticed under their appropriate heads.
             /.
                SECTION IV.

                OF BORACIUM.

  Experiment 1.  Put equal weights of the metal called
potassium and dry boracic acid  into a copper tube, and
expose it for some minutes to a slight red heat.  When
cold, wash the mass  out with  water, saturate the pot-
ash, which is formed, with muriatic acid, and throw
the whole upon a filter.   The olive coloured matter is
to be washed and dried.  It is boracium.
  Rationale.   According  to the experiments of Davy,
Thenard and Gay Lussac, that boracic acid is a com-
pound  of boracium  and oxygen, it appears that  in
this process the  boracic acid is decomposed ;  its oxy-
gen unites with the potassium,  forming potash, whilst
the  boracium is disengaged.   On  adding  muriatic
acid, the alkali is dissolved, and then detached from
the boracium.
  Remark..  The olive coloured  matter, or boracium,
ia suspected by  Mr.  Davy to contain a little  oxygen,
                        Y 
254
and that, when deprived of this principle, it combines
with metals, and forms compounds capable of conduct-
ing electricity.  He infers, therefore, that  if it  were
pure it would be of a metallic  nature.   Boracium  is
opaque, brittle, does not scratch glass, is a ncn-con-
ducter of electricity,  and has some resemblance  to
charcoal.  When exposed to a strong heat in a metal-
lic vessel, it remains unaltered, if common air or oxy-
gen be excluded.   It has now the property  of sinking
in sulphuric  acid.
  Experiment 2.   If boracium be heated in common air
to a temperature of about 600°, it inflames, and produ-
ces boracic acid; or,
  Experiment 3.   If it be exposed to oxygen gas, under
the same  circumstances, the  same  result will take
place.
   Rationale.   The  boracium unites with oxygen at a
high temperature,'and forms boracic acid ;  whilst the
heat and light of the decomposed gas are set at liberty.
In the former experiment the  oxygen is presented by
the atmospheric air.
   Experiment 4.  If boracium slightly heated, be placed
in contact with oxymuriatic acid gas, inflammation will
ensue, and the products  will  be boracic acid and oxyd
of boracium.
   Rationale.   At a moderate temperature, boracium
decomposes  oxymuriatic acid  gas ; a part  of it unites
with a part of the oxygen of the gas and forms boracic
acid, whilst another portion combines with the remain-
ing part of the oxygen, and produces a black coloured
matter, or oxyd of boracium, the oxymuriatic being re-
duced to the common muriatic acid.
   Experiment 5. If boracium be added to nitric acid, and
heat applied, it is changed into boracic acid.
  Rationale.   The  nitric acid is partially decomposed;
nitric oxyd gas is disengaged, and the boracium is con-
verted into boracic acid.
  Experiment 6.   If boracium be treated in the  same
manner in sulphuric acid, the same result will ensue. 
255
  Rationale.   The  sulphuric acid parts with a portion
of its oxygen, which converts the boracium into boracic
acid, whilst a disengagement of sulphurous acid takes
place.
  Experiment 7.  If boracium be added to potash or soda
in solution, a compound is formed  of a, pale olive co-
lour;  or,
  Experiment  8.   If the same articles be put into a
crucible and melted, the  like combination will be form-
ed.
  Remark.   It appears, therefore, that boracium is sus-
reptible of combination with  some of the  alkalies  in
the same manner as sulphur, forming what I would call
b'jraciurets.
  The properties of this substance have not been suffi-
ciently investigated to afford  extensive experiments,
although we are  considerably indebted to Mr. Davy
and the French chemists for  some  interesting facts.
Mr. Davy has  lately given the name of caron to bora.
cium.
                 SECTION  V.

                OF HYDROGEN.

  Hydrogen, as the base of  hydrogen gas, is a simple
substance, and is therefore classed among the simple
combustibles.  But as we only know it in the state of
combination, as for  instance  in hydrogen  gas, its  pro-
perties can not here be  investigated.  In  the work it
lias accordingly been considered in the  character of a
compound body, that of  gas ; for an account of which,
see the Preparation and Properties of Hydrogen Gas.
Under the latter  we have noticed its properties, and
also some of its combinations, in the formation of oils,
fats, ardent  spirits, ether, and other inflammable sub
stances of which it constitutes, a part, 
PART IX.
                  OF ALKALIES.

   Alkali is a wcrd of Arabian origin, and was introduc-
 ed into chemistry after its application to a plant  which
 still retains the name of kali.  This plant, when  burnt,
 the ashes washed in water, and the water evaporated to
 dryness, furnishes a white substance, which  was  called
 alkali.  According to Albsrtus Magnus, the word  signi-
 fies the « dregs of bitterness."  Alkali, in chemical
 language implies all  those substances which possess
 the following properties : viz. a caustic taste, volatiliz-
 ed by heat, capable  of combining  with  acids, and of
 destroying their acidity, soluble in water even when com-
 bined with  carbonic acid, and capable of converting
 vegetable blues to  green.  The  alkalies properly so
 called are  three, namely, potash, soda and ammonia.
 The  two first are called fixed alkalies,  because they
 require a red heat to  volatilize them;  the last is  called
 volatile alkali, because it readily assumes the gaseous
 form.   The general properties of the  alkalies may be
 learnt from the  following experiments.
   Experiment 1.   Take an ounce of a solution ol/iotash,
 and add to it about half an ounce ofsulphuric acid, or until
 it is saturated ; evaporate it gently for a few minutes ;
 or lay the mixture aside, and when cold, crystals will
 be formed, possessing characters  distinct from either
 the alkali or the  acid.
   Rationale.   The acid and alkali  combine, destroy the
 individual properties  of each other, and a mild salt, viz.
 sulphate of potash, is formed from these two corrosive
substances.
   Ex/ieriment 2.   If soda be treated in the  same man-
ner, a union will ensue and form  a  mi!d  salt,  as  in
the last experiment. 
237
   Rationale.   The sulphuric acid combines'with the
soda, and forms sulphate of soda.
   Experiment 3. To soda add muriatic acid, and the alkali
and acid will lose their separate properties, as before.
   Rationale. The muriatic acid combines with the soda,
forming muriate of soda.
   Experiment 4.   Make an infusion of red cabbage  and
put it into three wine  glasses.  To one add a solution
of alum, and a  purple  colour will be produced, to the
second a little  solution of potash, a green  will follow,
and to the third a few drops of muriatic acid, which will
change it to a crimson.
   Rationale.   As the action of acids is contrary to alka-
lies, it is evident that  the alum, which is a super salt,
and muriatic  acid, changes the  infusion to purple and
crimson, whilst the alkali  converts it to green, owing
to the circumstances already noticed  under  the head
of light.
   Experiment 5.   If to the tincture of litmus, which is
of a blue  colour, a few drops of any acid, say muriatic,
be added, its colour will be changed to a vivid red, but
on adding a solution of potash, this will  be  destroyed,
and its original colour will  be produced.
   Rationale*  Litmus is changed to red by acids, but if
alkali be added, the acid is taken up, forming with it
neutral salt  (muriate of potash) and consequently the
litmus regains its former colour.
   Experiment 6.   If paper be stained with litmus, and;
if this paper be first immersed in a weak.acid it will
be changed to red, and then immersed in a solution of
alkali, the original colour will be resumed.
   Rationale.  The same as before.
   Experiment 7.   If paper stained with an infusion of-
turmeric, be  dipped into an alkaline solution, it will be
changed to brown.   If it now be immersed in an acid,
its original colour will  re-appear.
   Rationale.   The alkali changes the affinities with the
rays of light, hence brown is the consequence ;  but the
presence of an acid destroys the  new affinites> and pro-
duces the original  colour.
                      Y 2 
258
   Remark.  This paper will detect the presence of soda,
though it should amount to  no more than ,A*th part
of the water.                             22°°   '
   Experiment 8.  Alkali dropt into the tincture of tur-
meric will exhibit the same  appearance, and the addi-
tion of an acid will produce the original colour.
   Rationale.   The  same as the preceding.
   Experiment 9.  If into a solution of potash pieces of
animal flesh be put, the latter will be so much corrod-
ed as to be soon entirely dissolved.
   Rationale.   The  theory  of this phenomena will  be
given hereafter.
   Experiment  10.  If a solution of  alkali be added to
the  syrup or infusion  of violets, it will produce a crreen
colour.
   Rationale.  As the natural colour of vegetables is af-
fected by various agents, as the preceding experiments
exemplify, in this instance  the blue colour is discharg-
ed, and that of green is formed, which is owing to the
causes before mentioned.
   Remark.  The origini.1  colour may  be restored by
adding a few  drops of acid; in that  case the alkali is
saturated: but, if more acid than is necessary be add-
ed, the infusion or syrup will be  changed to  red.
   Experiment  11.  If oil and water be added, no union
Will ensue, but if caustic  potash, soda, or ammonia be
mixed with them, a combination will take place.
   Remark.  This property of alkali serving as a media
between oil and water, answers to one of its characteris-
tic properties.
   The three alkalies have been discovered native in
combination  with ackls, forming  salts, as in nitrate of
potash, carbonate of soda, sulphate of soda, glauberite,
(sulphate of soda and sulphate of lime) muriate of soda,
subborate of soda, and  muriate of ammonia. 
259
                 SECTION I.

                  OF POTASH.

  Experiment l.  If wood be  burnt, and the residue,
or ashes, be washed in water, or elixated, and the solu-
tion evaporated, a substance will remain which is known
by the  name of potash; or,
  Experiment 2.  If lye, or caustic alkali, obtained by
passing water through a mixture of wood ashes and lime,
be evaporated to dryness, potash will  be the result.
  Rationale.  When  vegetable substances are submit-
ted to the action of heat in distilling vessels, its com-
ponent elements, oxygen, hydrogen, and  carbon, which
formed a three-fold combination in a state of equilibri-
um, unite two and  two, in obedience to the affinities
which  act conformable to the degree of heat employed.
Thus,  at the first application of the fire, whenever the
heat produced exceeds the temperature of boiling water,
part of the oxygen and hydrogen unite and form water;
soon after, the rest of the hydrogen and part of the car-
bon combine  into oil; and, lastly, when the fire is push-
ed  to a red heat, the oil and  water, which  had been
formed in the early part  of the process, become again
decomposed, the oxygen  and part of the carbon, unite
to form  carbonic  acid, a large quantity of hydrogen
gas is  set free, and nothing but charcoal remains be-
hind.
   In the combustion of vegetables in the open air a
great  part of these phenomena occur; but in this  case
the presence of the  air introduces three new substan-
ces, the oxygen and azote of the air, and caloric ; and of
these, two at least produce considerable changes in the
results of the operation.
   In proportion as the hydrogen of the vegetable, or
that which arises from the decomposition of the water,
 is forced out in the  form of hydrogen gas by the pro-
 gress  of the fire, it is set on fire immediately upon get- 
260
ting into contact with the air, water is again formed,
and the greater part of the caloric of the two gases be-
coming free produces flame.  When all the hydrogen
gas is driven out, burnt, and again reduced to water, the
remaining carbon continues to burn, but without flame;
it is formed into carbonic acid, which carries off a por-
tion of  caloric sufficient to  give it the gaseous form;
the rest of the caloric, from the oxygen of the air being
set free, produces the heat and light observed during
the combustion of the carbon.
  The  whole vegetable is thus reduced to water and
carbonic acid, and nothing remains but a small portion
of gray matter called ashes, being only the really fixed
principles which enter into the constitution of vegeta-
bles.  The ashes seldom exceeds a twentienth part of
the weight of the vegetable, and contain  the substance
known by the name of potash, or fixed vegetable alkali.
On adding water to the ashes, this substance is extract-
ed, which appears  in a concrete  form by evaporation.
The residue,  after the  action of water, is insoluble,
and contains generally earthy matter, and  some metallic
oxyds.   That potash, obtained by this process, is al-
ways more or less saturated with carbonic acid, is evi-
dent from the  product.  It is accounted for thus:  as
the potash  does not form, or at least is not set free, but
in proportion as the carbon of the  vegetable is convert-
ed into  carbonic acid by  the addition of oxygen, either
from the air or water, it follows that each particle  of
potash,  at the  instance of its formation, or at least of its
liberation, is in contact with a particle of carbonic acid,
and as there is a considerable affinity between these
two substances, they naturally combine together.  Al-
though  the carbonic  acid has  less affinity with potash
than any other acid, yet it is difficult to separate the last
portions from  it.   This is usually accomplished, how-
ever, by using quicklime, which  has the property  of
taking it from the alkali, rendering the latter caustic,
and of forming with it an insoluble compound.
  Remark.   This alkali was formerly obtained by burn-
ing vegetables in pots;  hence it acquired the name  of 
261
potash.  Potash, as it occurs in commerce,  is always
impure, containing a number of foreign substances.
When heated to redness many of its impurities are
burnt off; it becomes whiter than  before, and is then
known in commerce by the name ol pearl-ash.
  It is still, however, impure, and it can only be  sepa-
rated from its impurities by another process, which will
le noticed  directly.
  All vegetables yield less or more of potash in conse-
quence of  combustion, but  it is furnished in  various
degrees of  purity by different vegetables.  In the An-
nates de Chimie, tome xix. 157, is a table of the quanti-
fies  of alkali obtained from different kinds of wood.
Directions  for burning vegetables, in a proper manner
for  this purpose, will be found in the same volume,
page 194.
  Potash is prepared in large quantities in wine coun-
tries, by the incineration of wine lees  and must.  This
article is known in France by the name of cendres gra-
veldes.
  Potash is formed in what are called nitre beds, which
are collections  of  the refuse matter of vegetable and
animal substances.  See  nitrate of potash.  It  is
asserted, and we believe the observation to be true, that
the ashes which is left by vegetables in combustion,
pre-existed in them before  they were burnt, forming
what may be called the skeleton, or osseous part of the
vegetable.   But it is quite otherwise with potash; this
substance has never yet been procured from vegetables
but  by means of processes or  intermedia capable  of
furnishing  oxygen and azote, such as  combustion. As
potash is a compound substance,  haying a peculiar
metal for its basis, it is more remarkable that combus-
tion should produce a metal in combination with ano-
ther elementary principle, forming potash.  This sub-
ject is extremely obscure.  Potash is said to exist  in
minerals:  it  has been discovered in aluminous schis-
tus, in combination with acids, in pumice, leucite, zeo-
lite, felspar, &c.
  Potash was known to the ancient  Gauls  and Ger- 
262
mans.   They were the inventors  of soap, and Pliny
says they made it of ashes and tallow.*  Aristophanes
and  Plato  mention a  liquor which  appears to have
been a lye made  of the ashes of the beech tree.  The
Alchemists were acquainted with it.   Potash has been
known  under several  names.  It was called vegetable
alkali because it  is obtained from vegetables, and be-
cause it was long thought to be peculiar to the vegeta-
ble kingdom.  It was called also salt of tartar, because
it may be obtained by burning the salt called  tartar.
It is also the tartarin of Kirwan, the veg-alkali of Pear-
son, the kali of Klaproth, and the lixivia of Black.  In
chemical language, potash signifies the  pure alkali, in
commerce  the impure alkali.  Some  chemists have
given the name of potass to the pure alkali, and potash
to the alkali of commerce.  The latter contains nearly
one  fifth by weight of  carbonic acid, besides other im-
purities.   Potash is not a  simple  substance, but is a
compound body,  having for its basis, as  we shall after-
wards state, a peculiar metal called potassium.
   The union of  acids  with potash forms a class of bo-
dies called salts,  which are either sub, neutral, or super
salts.   See salts of potash.
   Experiment 3.  Prepare caustic lye of potash, by using
quicklime, evaporate it in iron pots, and if any crystals
should  form, separarate them, and continue the evapo-
ration until it becomes solid: pour over this, placed in
a  jar, some very strong alcohol, and the potash alone
will be dissolved, leaving  any sulphate  of potash,
earthy  matter,  &c. undissolved.    Decant  the  pure
liquor,  "and distil it in a retort till it becomes co-
lourless.   Evaporate  it then in a silver basin,  and
very pure potash will be prepared.
   Rationale.  The  lime renders the alkali caustic by
robbing it of carbonic  acid; the caustic  alkali on eva-
poration throws off some saline bodies, as sulphate of
potash; the potash is  then dissolved by the alcohol,
leaving all the salts with which it might be  intermixed,
• Plinii lib. xviii, c. 51. 
263
such fir instance as are insoluble in alcohol, at the bot-
tom of  the vessel.   On evaporating the liquor, the al-
cohol is dissipated, leaving  the alkali in  a perfectly
pure state.
   Remark.  This process for preparing pure potash,
was recommended by Berthollet.   Mr.  Lowitz has
given the following as less expensive.*
   Experiment 4.   Prepare  a  lixivium  of potash, freed
from carbonic acid in the usual manner,  and evaporate it
to a thick pellicle.   After the cooling, the foreign salt
which has crystallized is to be separated, and the evapo-
ration of the lixivium is to be continued in an iron pot.
During this second evaporation the pellicle of foreign
salts must be  carefully taken off by an iron skimmer.
When no more pellicle is formed, and the matter ceas-
es to bcil, it  is  removed  from the fire  and  suffered
to cool, continually stirred with  an iron spatula.  It is
then to be dissolved in double the quantity of distilled
water, and the solution filtered, and evaporated in a glass
retort till it begins to deposit regular crystals. If the mass
should  consolidate ever so little by cooling, a small
quantity of water is to be added, and it must be heated
again to render it fluid.  After the formation of a suffi-
cient quantity of regular  crystals, the fluid, which  is
very brown, is to be decanted, and the  salt, after being
suffered to drain,  must be  redissolved in the  same
quantity of water.  After the fluid  has stood for  some
days, it is to  be decanted, and  subjected to another
evaporation and crystallization.   This process must be
repeated  as long as the crystals  afford, with the least
possible quantity of  water,  solutions perfectly  lim-
pid.
   Rationale.   The theory of the action of quicklime in
rendering potash caustic, has already been noticed.
The process,  therefore, is nothing more than the sepa-
ration of foreign salts, owing to their different solubility,
from the alkali by  repeated solution, evaporation, and
crystallization.
* Nicholson's Journal, i. 14. 
264
  Remark.  This process, however, is imperfect when
pure alkali is to be formed ; that of solution in alcohol,
as in the first  process, is to be preferred.  This also
causes the alkali to assume a brown colour. Klaproth,
to prepare pure alkali, boiled equal parts of salt of
tartar  and carrara marble, or oyster  shells, burnt to
lime, with a sufficient quantity of water, in a polished
iron kettle.   The ley was then strained throgh clean
linen,  and though still turbid, was reduced by boiling,
till itcontained aboutone half of its weight of potash. It
was then passed a second time through a linen cloth,
and set by in  a  glass bottle. After some days when the
ley had become clear of itself, it was decanted off from
the sediment  into another bottle.   The specific gravity
of  caustic ley is to that of distilled water as 1090 to
 1000.   The water of potash, and the water of pure kali
of  the Dispensatory, are the same as caustic ley.
   Dr. Black discovered, in 1756, the cause of the caus-
ticity of potaah, and that potash of commerce consist-
 ed of  pure  alkali and carbonic acid.
   The  crystals of potash, formed according to the
 process of Lowitz, are generally octahedral in groups,
 and contain 0.43 water of crystallization.   When pot-
 ash, thus crystallized, is exposed to a red heat in a
 silver crucible, it becomes fused,  and affords a white
 mass extremely caustic and deliquescent.  An expe-
ditious process for preparing pure potash, which I have
frequently employed, is the following :
   Exheriment 5.   Put into a Wedgwood mortar an
 ounce or two of caustic potash or common caustic of
 the shops,  pulverize it, and pour  on it a sufficient
 quantity of alcohol; niter it has stood an hour or two
 filter the solution, and evaporate it in a silver cup.
   Remark.  As a  re-agent, potash thus  prepared is
 sufficiently  pure.   The solid alkali may  be dissolved
in pure  water.
   Experiment 6. Take causticley,&nd evaporate it over a
fire in a very clean iron vessel till it begins to thicken.
Then pour it  out  upon an  iron plate, and  while It
is congealing cut it into proper pieces, or pour it into 
265
iion moulds, and common caustic  of the shops wijl he
formed.
  Ex/.eriment 7.   Evaporate caustic ley  to  one  third,
then add powdered lime till it becomes thick, and the
wilder common caustic will be prepared.
  Experiment 8.   If to a  transparent solution  of the
potash of commcrf e, lime water be added, the mixture
uill become turbid, and  a precipitate will gradually
subside.
  Rationale.  As  lime renders alkalies caustic, and as
this is owing to the absorption of carbonic  acid by the
lime, this experiment shews that the moment the pot-
ash, which contains carbonic acid, comes in contact with
lime, the latter robs it of carbonic acid,  with which it
forms a turbid precipitate or carbonate of lime.
  Exjierimcnt 9.   Collect the precipitate  of the  last
experiment, and add to it muriatic acid, an effervescence
 will ensue.
   Rationale.  The muriatic  acid unites with the lime,
and the  carbonic acid is dismgaged,  proving that it is
carbonic acid which was taken from the potash.
   Experiment 10.  If dry potash be exposed to  the air
 in  an open vessel, it becomes fluid, increases in weight,
 and gradually assumes the  state of liquid  carbonate of
potash.
   Rationale.  The affinity subsisting between  potash
 and water is  considerable; hence on exposure to air,
 the alkali  absorbs moisture  from the  air and becomes
 liquid, at the same time (as carbonic acid is always pre-
 sent in the atmosphere)  it imbibes the  carbonic acid,
 and is   gradually changed into  a liquid carbonate of
 potash.
    Remark.  By this process the old pharmaceutical
 writers  made a preparation described under the name
 of oleum tartari pier  deliquium.
    Experment  11.   Put potash into  a crucible, apply
 heat until it becomes red  hot, the  aikali will  melt,
 swell,  and evaporate slowly in a white acrid  smoke.
 If a stronger  heat  be used,vit will give it a greenish
 tinge.
                         z 
266
  Remark.  As potash evaporates only ►'. a red heal.
it has received the name  ol fixed alkali.
  Experiment  12.  II potash and silex be  melted toge-
ther, they unite, and form a compound  called glass.
  Remark.  Potash, therefore, acts   as a flux :  when
siliceous substances are melted in this way,  the pro-
duct is glass,  an  account of which  will  be  given in
its  proper place.   But the density  of  the compound
depends on  the proportion of the potash ; for,
  Experiment 13.   If three or four parts  of potash be
melted with one of silex, the result will be a  mass  so-
luable in water, forming,  when so dissolved, the liquid
siliceous potash  or  liquor of flints.  This is prepared in
the following manner :
   Experiment  14.  Take  one part of silex reduced to
a fine powder (or  pure sand) and four parts of potaxh;
introduce them into a crucible, and  expose them to a
violent heat. The sand and potash will  now melt, puff
up, and continue to swell till the alkali has dissolved
the silex.  As long as the effervescence lasts, the cru-
cible is to be left uncovered,  when   it  cease-, it is to
be covered, and the heat  augmented.  Pour  the con-
tents on  an  iron plate.   Pulverise the mass, and dis-
solve it in water.
  Remark.  The silex may be separated from the  al-
kali by the addition of an acid, by which means pure
silex is obtained.   See Silica.
  Experiment 15.  Tf a slip of woollen cloth, or a piece
of muscular flesh, be immersed into  a Solution of pot-
ash; the animal substance will soon become destroyed,
and form a homogeneous compound.
   Remark.  Hench potash  acts  powerfully upon ani-
mal substances.
   Experiment 16.   If  a solution  of potash be  added to
nitro  muriate of platina,  a yellow precipitate will  be
formed;  but,
  Experiment  17.  If soda be added,  no precipitate
will appear.
   Rationale.  The potash unites with the acid, and pre-
cipitates the metal of  a yellow colour. 
267
  Remark.  As the solution of platina is precipitated
by potash, and not by soda, the presence of that alkali
may be known on adding the solution of platina. Hence
;he nitro-muriate of platina may be employed as a  re-
agent to discover the presence of potash.
  Experiment 18.   If to a solution  of potash, tartaric
acid  be added, crystals will be  formed  and gradually
fall to  the bottom.
  Rationale.  The  tartaric acid  unites with the alkali,
and forms a salt of diffkuit solubility called supertar-
trate of potash, or  cream of tartar.
  Ri mark.  On  this  property is founded the use of
this  acid in discovering the  presence of potash.  The
latter,  to shew the  effect, should be considerably dilu-
ted,  and the acid  should be added in sufficient quantity,
otherwise a neutral tartrate will be  formed, which is
very soluble.
  Experiment 19.   If equal parts of arnotto und/^;«i;.
be boiled in  water  until the whole are  dissolved, a li-
quid will be formed, which is sold under the name of
nankin dye.
  Remark.  Hence it is that  potash is used in the  art
of dying, in  order to  extract the  colouring  matter,
and  to serve, in  some cases,  both as a  solvent and a
mordant.  It also acts as  a precipitant to separate me-
tallic oxyds from their  solution  in acids.
  The use of potash in  the  arts is extensive ; in  the
preparation of colours, such as Prussian blue, French
and  mineral  greens, Scheele's green, in the formation
of potters5 blue  from  cobalt, soap,  alum, in bleaching
linen, in scouring wool, &c. potash is used.
   Experiment 20.  When three  parts of  sulphur  and
one  of potash are triturated together in a glass mortar,
the  sulphur acquires a green colour, the mixture  be-
comes hot,  and  exhales  an alliaceous  odour.   This
compound gradually attracts moisture from the atmos-
phere, and is totally soluble in water, which answers to
some of the  characters ol sulphuret of potash; or,
   Experiment 21.  If two  parts of potash  and one of
sulphur be  heated  in  a crucible, they melt and com-
bm<-. and  form a  sulphuret of potash,. 
268
  Rationale.   If the potash  cf commerce be used, the
carbonic acid is dissipated by the he.it: the sulphur and
alkali melt, unite, and form  a sulphuret of a brown-co-
lour, not unlike the liver of i.nimals.   Hence  it was
fjrmeiy called h'par sulphuris or liver of sulphur; but
when exposed to the air h scon becomes  green, and
even white.
  Remark.  When the fusion is complete the sulphu-
r-jt is to be poured  upon a marble slab ;  and as soon as
it becomes hard, it must be put into a well  closed bot-
tle.  The  sulphuret is hard and brittle.  Its  tuste is
acrid,  caustic, and  bitter, and  it leaves a brown stain
upon the  skin.   It is decomposed  by heat in the fol-
lowing manner:
  Experiment 22.  Put sulphuret of potash into a cruci-
i-le,  invert  over  it another crucible, having  a small
opening in its bottom ; then apply heat and the  sulphur
v, ill sublime.
  Rationale.   In this case, the action of heat decompo-
ses the sulphuret, and the sulphur is dissipated leaving
the alkali behind.
   J xperiment 23.  If in a solution ol sulphuret of potash,
syrup or  infusion of violets be  poured, its  colour will
be changed to green.
   Remark,   \\cnce it has some of the characters of un-
combined alkali.
  Experiment 24.  Dip a piece cf  white  calico in an
aqueous solution of acetate of lead, and then drop a little
solution of sulphuret of potash upon  it.   If this be now
placed  in the palm of the hand, the lead will be observ-
ed gradually to revive, and  will soon be reduced to its
metallic state ; or,
  Experiment 25.  Immerse a  slip  of white  silk in a
solution of sulphuret of potash  prepared with alcohol.
if a drop of an aqueous solution of sulphate of' mangaw se
Ue now applied, films of metallic manganese, bright as
silver, will instantly appear.
  Rational-.   Though it  is  asserted that sulphuret of
potash has the property of decomposing metallic oxyds,
yet we are disposed to  think,  that this reduction is 
269
owing to- sulphuretted hydrogen, which it is well known
possesses  this property by  carrying off  the oxygen, as
we remarked in treating of the properties of this gas.
In contact with  moisture,  sulphuretted  hydrogen is
produced from alkaline sulphurets.
  Experiment 26.  Expose  sulphuret  of potash to  the
air, or  moisten it with water; its colour will become
changed, and a fetid gas will be evolved, called sulphu-
retted hydrogen.
  Rationale.  This  is owing to the decomposition of
water,  in the same manner as was stated in the article
on sulphuretted  hydrogen gas, which  see.
  Remark.  The sulphuretted  hydrogen thus formed,
partly unites with the remaining sulphuret, and converts
it  into hydroguretted  sulphuret  of potash,  which has a
brownish green colour.   This preparation may also be
formed in the following manner :
  Experiment 27.   Introduce into a flask  two parts of
potash  and  one of sulphur; add to these a  sufficient
quantity of water, and boil them together.
  Rationale.  The sulphur  unites with the alkali; the
compound decomposes water; sulphate of potash and
sulphuretted hydrogen are  formed, and the remaining
sulphuret unites with the sulphuretted  hydrogen, and.
produces hydroguretted sulphuret of  potash.
  Ex/ieriment 28.   Introduce a solution of potash  into
a retort, and put  in a piece of phosphorus, apply heat,
and phosphuretted hydrogen gas will come over and take-
Tire.
   Rationale.   Though potash cannot be  combined with
phosphorus in any manner at present known, so as to
exhibit a distinct compound, yet if it be boiled with
phosphorus, a combination  is first formed, which then
acts upon the water, decomposes it,  and  emits phos-
phuretted hydrogen gas, a phosphate of potash remain-
ing in the retort.
   Experiment 29.  If zinc,  molybdenum, or iron be put
into a  solution of potash and heat applied, it will gra-
dually be oxydized.
                        z2 
270
  Remark.  Potash does not combine with any of  the
metals.  Some metals, however, which possess a strong
affinity for oxygen, when put into a solution of potash,
are gradually  oxvdized, and these oxyds  partially so-
luble.
  Experiment 30.  To red oxyd of iron put  a solution of
potash ; in a short  time it will be  changed into the black
oxyd.
  Remark. It appears, therefore, though this phenomena
has not been explained, th-.it the solution has the property
of abstracting oxygen, or of reducing the per into the
prot oxyd of iron.   The metallic oxyds which arc solu-
ble in potash according to Bergman and others, are, of
lead, tin, nickel, arsenic, cobalt, manganese, zinc, anti-
mony, tellurium, tungsten, and molybdenum.
   Experiment SI.   If four parts of  crystallized potash
reduced to powder, and three of uncompressed snow,
be hastily mingled together, the mixture  becomes fluid,
and an intense degree of cold is produced ; but,
   Experiment 32.  If equal weights  of potash, freed of
water by exposing it to heat, and dense sulphuric acid
be mixed together, a great degree of heat will be instant-
ly  produced, and, if the  experiment be made  in  the
dark,  flashes of light will  be seen to pass through the
mixture.
   Rationale.  The cause of the production of heat and
cold  in  mixture,  has already been noticed in treating
of caloric : the same principles apply to these experi-
ments.   In the first, as the crystallized potash contains
a quantity of water, the mixture  with snow causes heat
to be absorbed, which consequently, reduces the  tempe-
rature, but in the  second,  in which dry potash and  sul-
phuric acid are employed, the latent becomes sensible
heat, and, of course,  the temperature is  raised.
   Experiment 35.  Procure a  piece of potash, made
perfectly pure,  breath on it, in order to moisten it, and
place  it  on an insulated plate connected  with the nega-
tive side of a powerful galvanic battery.   Then bring
a metallic wire from the positive side of the battery in
contact with the upper surface of the alkali, and a vivid 
271
action v> ill soon be observed.  Small  globules of the
appearance of mercury will be seen, some of which will
burn with an explosion and bright flame as soon as they
arc formed.  These arc potassium.
   Rationale.  The potash is decomposed ; oxygen gas
is separated at the extremity of the positive wire, and
potassium  is formed at the other.
   Like other combustible substances, the combustible
base is repelled by positively electrified surfaces, and
attracted  by  negatively  electrified surfaces;  and the
oxygen follows the contrary order.   Hence their sepa-
ration and evolution.
   Re mark.  Heretofore  various opinions have been en-
tertained  respecting the composition of potash, in which
the chemists of Europe  were  engaged in order to as-
certain the correctness of these conjectures.  But the
researches of Sir  Humphrey Davy have shown, that
potash is a compound body, having a peculiar metal for
its basis, to which he has given the name of potassium,
united with oxygen.
   It has  been supposed, ever since our  countryman,
Dr. Woodhouse, made an experiment with potash, that
this alkadi had an inflammable basis.   I am disposed to
believe that the Dr. was the first  who hazarded  this
conjecture as to the inflammable nature of potash when
treated in certain ways.  The Dr. found that a mixture
of pearl ash with soot, calcined by a very intense  heat
in  a covered crucible, wdien  cold, caught  fire on the
affusion of water; the experiment was repeated  with
charcoal with the same  result;  and the inflammation
probably  arose  from the  action of the base of the alkali
on the water.*  The pyrophori, which takes fire spon-
taneously ih the air,  Mr. Davy considers  as a triple
compound of potassium, sulphur and charcoal.
   Potash, when dry,  is a non-conductor of electricity,
but it becomes a conductor  when slightly  moistened
on the surface.   Hence  in this side it is acted upon by
the galvanic influence.
' Nicholson's Journal, xxi. p. 290, 
272
  Besides analysis, Mr. Davy proved by synthesis the
composition of potash.   He accordingly  found,  that
potash is composed of about six parts of potassium and
one of oxygen, or nearly 86 parts of potassium and 14
of oxygen in the hundred.   For a number  of facts res-
pecting potassium, we are indebted to this philosopher.
From its composition, potash has been called the per
oxyd of potassium.  Besides the agency of galvanism in
decomposing potash, two French chemists, Gay Lussac
and Thenard,  have succeeded in separating the potas-
sium by means of iron filings, in the following manner.
  Experiment 34.  Into the middle of an iron gun bar-
rel is to be put a quantity of clean and dry iron filings
or turnings.   An iron tube, containing potash as dry as
possible, should be ground to one end of the gun barrel,'
and having a small hole through which the potash may-
run slowly when  melted.  To the other  extremity a
tube of safety, containing mercury or naptha, oughtalso
to be luted, and  great care should be taken that all the
lutings be air tight.  The gun barrel being laid across
a furnace, the iron turnings within it  are brought to a
white  heat, while  the  potash  is  kept cold by means
of ice ; then  the potash is brought  into  fusion, and
made to flow  slowly through the iron turnings. When
the process is at an end, a portion  of potassium nearly
pure is found near the tube of  safety;  but  the greatest
part of it is alloyed with the iron turnings.*
   Rationale.   The potash is deprived of its  oxygen, and
potassium is disengaged, which appears partly in a free
state, and partly in combination with the iron in the
form of an alloy.
  Remark. During the  operation hydrogen gas is emit-
ted, which has led to some conjectures as to its origin,
it is said to be owing to the decomposition of water,
but it has not  been satisfactorilyascertained.   Thomas
Cooper, Esq.  professor of chemistry in the college at
Carlisle, Pennsylvania,  repeated this experiment,  and
succeeded, I think after several attempts, in procuring
* Phil. Mag. xxii. 89 and 276. 
273
the mctd.*   John Redman Coxe, m. d. professor of
themistry in the  university of- Pennsylvania, and my-
self also performed it, but in our attempt we failed. The
professor, however, persevered, and finally prepared it.
The cause of the failure in  the first  attempt, was ow-
ing to the arrangement of the apparatus, and some un-
foreseen  circumstances.   That potassium was formed
was evident, from  the appearance of the iron, as it was
coated with a white covering, which was the alloy be-
fore mentioned.  My brother, Dr. E. Cutbush, succeeded
in procuring it, by using the heat of a blacksmith's forge.
T have not heard of any other atu mpts in this country,
except by a gentleman  in  New York, who was also
successful.  Galvanism,. I believe, has not been tried.
The general properties of potassium are:  It is white
like  mercury.   At 50° it is-a soft malleable solid; at
60° it is imperfectly fluid ;  at 100° it melts and is per-
fectly fluid.   At 32° it is hard and brittle.  Its specific
gravity  does not  exceed 0.6, hence it  is lighter than
water.  In the  open air, it is covered  with a crust of
potash in a few minutes.   It decomposes  water.  It
may be converted  into prot oxyd, or per oxyd of potas-
sium according to the  uu.-.r.thy of oxygen presented to
it.   It inflames in  oxymuriatic  acid gas.  It combines
with phosphorus, sulphur, and the metals.
   Experiment 35.   Expose a piece of potassium in a
small quantity of oxygen gas, and heat it gently, it will
he changed  into  prot oxyd of potassium of a reddish
brown colour; but,
   Experiment 36.   Make a piece of potassium very hot,
and introduce it into a small glass vessel of oxygen gas,
it will burn  with a brilliant  wdiite flame, and form the
pur oxyd of potassium or potash.
   Rati male.  In the former experiment  the potassium
unites with a smaller dose of oxygen ;  in the latter it
combines with a larger, producing flame, and is con-
verted into potash.

  * See I'ort Fulio, nnd Henry's Chemistry, 2 vols. 1810, in which
a plate \* given of* the  apparatus. 
274
   Experiment 37.   Introduce a piece of potassium into
 alcohol, ether, or naptha, instead of sinking, it will keep
 on the surface.
   Remark.   Hence  its  specific  gravity is inferior to
 any of these liquids.
   Experiment 38.   Drop a piece of potassium into ajar
 of oxymuriatic acid gas, it will burn spontaneously and
 emit a bright red  light, forming, at the  same  time, a
 white salt.
   Rationale.  The oxygen of the oxymuriatic acid gas
 unites with the potassium,  and forms potash, which
 then combines  with  a portion of muriatic acid  arising
 from  the  decomposition of the oxymuriatic gas, and
 generates muriate of potash.
   Experiment 39.  Potassium thrown into water, decom-
 poses it, and  produces  flame.   The result is the for-
 mation of potash;  or,
   Experiment 40.  If a globule be placed upon ice, it
 will spontaneously burn with a bright flame and perfo-
 rate a deep hole in the ice, which will contain a solu-
 tion of potash.
   Rationale.  In both instances the water is decompos-
 ed;  its oxygen umcC» V/lth the metal, to the reproduc-
 tion of potash, while its hydrogen is liberated,  which
 inflames and reproduces water.
   Experiment 41.  Add muriate of lime to  water, and
 put into the solution a piece of potassium ; inflammation
 will ensue as before, and the water will become turbid,
   Rationale.   Potash  is formed  in the same manner as
 before noticed, which, having a greater affinity for mu-
 riatic acid than lime,  unites with it, forming muriate  of
 potash, and separates the lime in a precipitate.
   Experiment 42.  Drop a piece  of potassium  upon a
 slip of  reddened litmus  paper  previously moistened,
and, after it burns, the paper will be restored to its' ori-
ginal blue  colour.
   Rationale.   The potassium unites with oxygen; the
potash formed acts  upon the reddened litmus, removes
the acid which occasioned the redness, and restores it
to its former colour, that of blue. 
275
   Experiment 43.   If potasstiim Lc  thrown into nitric
acid, it takes fire, and potash is formed, which combines
with the remaining acid, and forms nitrate cf potash.
   Rationale.   In this experiment, the potassium  de-
composes a part of the  acid ;  the  oxygen of the latter
forms with it potash, which combines with the remain-
ing acid, and  produces  nitrate of  potash, at the same
time nitric oxyd gas is disengaged.
   Experiment 44.   Introduce into  an iron retort, a mix-
ture of carbonate of fiotash or soda with flour or charcoal
and linseed oil;  and raise the  fire until a blue light is
oerceived in the interior of the vessel:  to this a copious
vapour soon succeeds, which consists of the metallic base
of the alkali.  It may be collected, by introducing a
 !ear iron rod, on which it condenses, with drawing the
rod before it becomes too hot, and plunging it into oil
of turpentine, when the metallic crust may be detached.
By repeatedly introducing  rods of  iron, a quantity may
be collected.*
   Rationale.  The carbon of the flour, if it be used, as
well as of the oil, according to Curadau, decomposes
the alkali, which parts  with its carbonic acid  by the
action of heat, and is decomposed;  its oxygen is disen-
gaged, and potassium is formed.
                  SECTION II.

                    OF  SODA.

  Experiment 1.   Take  the  plant  called salsola soda,
burn it, and lixivate the ashes ; evaporate the lixivium
to dryness, and the impure soda will be formed.
  Remark.  Different species of salsola especially the
salsola soda  when burnt, afford this  alkali.   Soda  is
called fossil  or mineral alkali, because it was thought  to
# Nicholson's Journal, xxiii. Supplement. 
270
be peculiar to the mineral kingdom.   It w\.s known to
the ancients under the name of ni'.rum.  The  soda of
commerce is also called barilla, because the  plant from
which the alkali is obtained bears the name in Spain.
The ulgee, especially ihefuci contain also a considerable-
quantity of soda.  In England the ashes of this plant is
:alled kelp; in France they arc called varec' The sal-
sola soda, which grows among the cliffs on the sea coast,
appears to be endowed with the property of  decompos-
ing sea sait.  If this be true, the process of  vegetation
must separate the muriatic acid, and absorb the  soda.
Hence  it acquired the name of salt-wort.    Dr. Barton
informed me, that he discovered the  salsola kali in large
quantities not many miles distant from the city of Phi-
ladelphia.*
   The Spaniards cultivate a number of marine plants,
as the salsola soda, the salicornia hcrbacca, 8cc. in salt
marshes, for  the sake of the  soda.   After  being cut
down they are dried like hay.   A deep pit is then pre-
pared, and a bundle or two of the dried vegetables set
on fire are thrown into it.  When well kindled  other
bundles are thrown in until the pit is  filled.   'When the
incineration is completed,  the soda is found  in the bot-
tom, caked into a solid mass.   It is purified by solution,
filtration, and evaporation.
   It is surprising that the salsola kali should grow in
an inland situation, so far from salt water.   Dr. Barton
having discovered this plant in immense quantities in
New-Jersey,in the neighbourhood of Gloucester, where
it is known by the name of sea briar,  naturally inferred,
that as it  was so far  distant from salt water it would
yield no soda; and indeed in this conjecture he had the
testimony of fact,  for  Jacquin observes,  that  plants
yielding soda in salt marshes, when  removed to inland
situations  afford only potash by incineration, and that
those plants which  grow in inland places, when trans-

   * Jameson, in his Mineralogy of the Scottish Isles, has given  a
full account of the manufacture of kelp. See also  Repertory of
Arts. vol. xii. 
ierred to a saline soil, as on the sea coast, in the course
of time produce soda.
  The union of acids with soda forms salts, which are
either sub, neutral, or super salts, see salts of  soda.
  Soda exists  native  in  combination with  sulphuric,
inuriatic and boracic acids.   With the sulphuric acid
it forms Glauber's  salt,  with the muriatic, common
salt, and with boracic acid, borax.   It is also found in
minerals, as in the whinstone, volcanic lava,and crysolite.
It has also  been discovered in the bile of animals, and
in other secretions.  It is obtained from sulphate of
soda in the following manner.
  Experiment 2.  According to Accum, if 560 parts of
potash in solution, be ladled into a boiling solution of
500 parts of sulphate of soda, agitated together, and
quickly heated ; then drawn off  into cisterns,  lined
with thick sheet lead, and allowed  to  cool in a tempe-
rature which should not exceed 55°, carbonate of soda
will be formed.
  Rationale. The sulphate  of soda is decomposed by
the carbonate of potash; the sulphuric acid unites with
the potash,  forming sulphate of potash, and the carbo-
nic  acid,  which was contained in the potash, passes to
the soda, and forms carbonate of soda.
  Remark.  The separation  of the carbonate of soda is
effected in the following manner: the fluid, after it has
been suffered to cool, is drawn off, and the mass of salt
washed with cold water, to free it from impurities,
and again put  into the boiler with clean water.  This
second solution is also evaporated at a low heat, as long
as any pellicles of sulphate of potash form on its sur-
face, and  fall to the bottom of the fluid.   The fire is
then withdrawn, and the  fluid ladled out in the cistern
to crystallize.   Unless the fluid be allowed to cool pret-
ty low before it is removed to crystalline, the salt ob-
tained will contain sulphate of potash.
  Experiment 3.  If acetate of lime in solution be added
to sulphate of soda, a decomposition will ensue, and ace-
tate of sodc  be formed, which, if exposed ta heat, will
leave the  *oda behind.
A a 
278
   liationale.   Acetate of lime and sulphate of soda de-
 compose each other;  sulphate  of lime, which pre-
 cipitates as the liquor cools, and acetate  of soda, also
 formed, remains in solution.   On  filtering the fluid,
 the sulphate of lime is separated, and the acetate of soda
 remains in solution.  On evaporating this, and subject-
 ing it to heat, the acetic acid is partly disengaged in a
 pure  state, and partly decomposed.
   Remark.  Besides these modes of obtaining soda from
 the sulphate; litharge  and acetate of lead have been
 Used, as well as charcoal assisted by heat.   The muri-
 ate of soda is sometimes  decomposed by potash, and
 sometimes  by lime  for the same purpose.  Soda  ob-
 tained by any of these processes is not chemically pure ;
 containing,besides carbonic acid,several other ioreii';n
 ingredients.   It  may be rendered pure, however, by
 using the same means as described under the article of
 Potash.
   Experiment 4.   Expose soda to the atmosphere ;  in
 the course of a short time it will become fluid, not how-
 ever  so considerably as  potash.   In a few days, it will
 change from this state, and become dry again.
   Rationale.   Soda not only absorbs moisture, but also
 carbonic acid: when it has acquired a sufficient quan-
 tity, and probably when it  has absorbed enough  of car-
 bonic acid, the affinity for water appears to  change. In-
 stead of its  taking any more from  the atmosphere, it-
 appears to part with it;  hence it becomes  dry, and ef-
 fervesces on the  addition of acids.
   Experiment 5.   Dissolve soda in water, evaporate the
 solution, and, if properly  treated, crystals may  be ob-
 tained.
   Remark. The properties of soda, in many particulars,
 is the same as those of potash.  It unites with sulphur,
 forming sulphuret of soda, and also sulphuret with the
 sulphuretted hydrogen.  The sulphuret and  hydrogu-
 retted sulphuret of soda possess the properties  of the
 sulphuret and hydroguretted  sulphuret of potash.  In
 its action on  metals, metallic oxyds, &c. it also agrees
with potash. 
                        279

   Experiment 6.  Let fall into a solution ol soda a few
 drops of oxalic aeid ;  a salt will be obtained of difficult
 solubility.
   Rationale.  The oxalic acid and soda forms a salt, the
 oxalate of  soda, which is  of. very difficult solubility ;
 but, on the contrary,  with potash the same acid produ-
 ces a salt,  the oxalate  of potash, which is very soluble.
 Hence oxalic acid has been recommended as a test to
 discover the  presence of soda in a solution of fixed al-
 kali.   See  Potash.
   Experiment- 7.  To a solution of pure soda add olive
 oil and shake the mixture.; a compound will be formed,
 which, if allowed to stand, will become hard, being the
 soap of soda o>' hard soap.
   1\> mark.. The theory of this combination, as well as
 the preparation of soap, will be noticed hereafter.
   Experiment 8.   If .-oela be treated in the same man-
 ner as potash by the galvanic battery, a  metal  will be
 obtained, called sodium.
   Rationale.  Analogous  to that of  obtaining potas-
 sium.
   Remark.  Notwithstanding the opinion of chemists,
 especially  of Fourcroy,  Desormes and  Morveau, res-
 pecting the composition  of  soda, Mr. Davy has proved
 that their ideas were erroneous, and that it is composed
 like potash, of a peculiar metal united with oxygen.  It
 is considered a metallic per oxyd, to the metal of which
 Mr. Davy  has  given the  name of sodium.   From a
 number of experiments on  the combination of sodium
 with oxygen, made in the same manner as those on the
 combination of potassium w ith the same  principle, Mr.
 Davy has shown, that soda is composed of about seven
 parts sodium, and two of oxygen, or nearly of sodium
 ~ 8, and oxygen 22, in the hundred.
   The phenomena which sodium exhibits, are nearly
 similar to those of potassium.  It is a white metal like
silver, and  at the  common temperature  of the atmos-
phere is solid.   It is  malleable.   It  begins to melt at
 120°, and becomes fluid  at  180°.  It is not volatilized
in a red heat.   It conducts  electricity and heat in the 
280
same manner as potassium. Its specific gravity is0.93>3.
It combines with oxygen; for on  exposure to air it is
soon covered with a crest Of soda, but as the alkali docs
not thoroughly deliquesce, the nucleus is not so soon
destroyed as happens  to potassium.  No combustion
takes place when sodium is thrown upon water, although
it decomposes that  fluid, which is said to be owing to
its insolubility in hydrogen  gas, as that gas is formed in
the decomposition of water.  It burns, however, in con-
tact with a small quantity of water.   Melted with dried
soda, a prot oxyd of sodium of a brown colour is formed,
and a division of oxygen between the soda and  the base
takes place.  It burns  in oxymuriatic  acid gas, and
unites with the sulphur, phosphorus, and the metals,
like potassium.
   One part of it renders forty  parts of mercury solid,
and of the colour of silver.  The amalgam of sodium
combines with the other metals and with sulphur, form-
ing triple compounds.   Thrown into the mineral acids
it is converted into soda.   In  nitric acid it produces
flame ; but in sulphuric and muriatic acids it occasions
an  evoiuuon* 01 neat.
   The process of  Thenard and Gay Lussac, by which
 potash is decomposed, does not succeed so well with
soda.  Mr. Davy says, that this is owing to hydrogen
contributing materially to the  result by the  affinity it
exerts to the alkaline base, and to the base of soda being
scarcely soluble in this  gas.  Caraudau, however, as-
serts, that his process  with charcoal, noticed in the ar-
ticle on potash, succeeds as well with soda as with pot-
ash.  By exposing mixtures of soda and potash to ig-
nited iron, Mr. Davy has obtained alloys, which appear
to be ternary compounds of the two alkaline basis with
iron. 
2SI
                SECTION iir.

                 OF AMMONIA.

  Experiment 1. If sixteen parts of muriate of ammonia,
thirty-two of fresh prepared quicklime, and ninety-six of
water, or one pound of muriate of ammonia, two pounds
of quicklime, and six pounds of water, according to the
Edinburgh Pharmacopea, be distilled, a product will be
obtained called water of caustic ammonia.
  Rationale.  In the article on the properties of am-
moniacal gas we stated, that when ammoniacal  gas was
absorbed by water, a  liquor  is  formed of a pungent
odour, known under the name of spirit of sal  ammo-
niac,  In  this  case the ammonia is liberated from its
combination with muriatic acid, which then unites with
the  water, and forms liquid ammonia. The lime, there-
fore, decomposes the muriate of ammonia; it unites
with the muriatic acid, forming muriate of lime, which
remains in the distilling  vessel, and the ammonia is
disengaged in the state of gas.  The  heat, as it causes
this  decomposition, also  evaporates  the  water.  The
aqueous vapour  accordingly absorbs the gas, and con-
denses with it in the state of liquid  ammonia, common-
ly called caustic spirit of sal ammoniac;
  Remark.  The quicklime is first slacked, and when
it is obtained in the  form of  powder, it is then added
to the muriate of ammonia dissolved in the water. The
whole is then  introduced into a retort,  and distilled
into  a refrigerated  receiver  with  a very gentle heat,
till  twenty ounces of the liquor are drawn-off.   Some
other particulars must be observed,  which will recur
to the operator.  According to the  London college, one
pound of sal ammoniac, two of quicklime, and one gal-
lon  of water are treated in the same manner.. The
Dublin  college adopt the  following formulae :  sixteen
ounces of sal ammoniac, two pounds of quicklime, and
six  pounds of water.
                       A a  % 
282
  Experiment 2.  Receive the gas, as it comes from
a mixture  of muriate 'f ammonia and (quicklime, into a
vessel containing water, so as  to confine it ; when the
water is  saturated, it will be changed  into a pungent
caustic liquor similar to Experiment 1.
  Rationale.  This is a direct combination  of  ammo-
niacal gas with water, similar to an experiment given
under the Properties of Ammoniacal Gas, which see.
  Remark.  Gottling proposed a method of obtaining
liquid ammonia,  by  receiving ammoniacal  gas into a
vessel of water, which he accomplished with more fa-
cility by using pressure.   He  employed  an earthen
ware cucubit,  with a tubulated capital.  To the spout
of the capital, one end of a  bent glass tube  is accu-
rately luted, while the other  end is introduced to  the
bottom of a tall  narrow mouthed glass  phial, contain-
ing the  requisite quantity of  water.  Into the cucubit
he puts  two parts of finely powdered lime,  and one of
muriate of ammonia,  and then applies the heat.   He
 does not shut the tubulature until the smell of ammo-
 nia  becomes  manifest, and opens  it again  as soon  as
 the  process is finished, and  before the vessels begin
 to cool, as otherwise the solution  of ammonia would
 flow back into the cucubit,  and spoil the whole opera-
 tion.  The management of the tubulure requires much
 caution.   We think the apparatus might be improv-
 ed by substituting Welter's tubes of safety.
   Experiment 3. If four pounds ol alcohol, four ounces
 of muriate of ammonia, and six ounces of carbonate of
 potash, be  introduced into a  retort and distilled, a li-
 quor will come over, which is called spirit of ammonia
 or ammoniated alcohol.
   Rationale.  Muriate of ammonia, decomposed by car-
 bonate of potash affords a product known by the name
 of carbonate  of ammonia: this differs  in the propor-
 tions of the ingredients,  hence it generally contains a
 variable quantity of ammonia, in consequence of the
 carbonate of potash (of the kind generally used) being
 never saturated with carbonic acid. In the experiment
 therefore, the muriatic  acid of the muriate of ammo-
nia unites with the potash, forming muriate of potash) 
283
which remains in the retort, and the  carbonic  acid of
the carbonate of potash combines with the ammonia,
thus disengaged and forms carbonate of ammonia. This
is volatilized together with the alcohol.  The two then
unite in distillation, and produce the ammoniated alco-
hol.  As the  ammonia is  necessarily combined with
carbonic acid, in order to make the same preparation
free  from that acid, the following formulae has been
used :
  Experiment 4.  Mix sixteen ounces of quicklime and
eight ounces of muriate of ammonia, and introduce  the
mixture into a glass retort; then add thirty-two  ounces
of alcohol, and distil to dryness.
  In this process, therefore, the quicklime decomposes
the muriate of ammonia, and the ammoniacal gas, thus
disengaged, unites with the alcohol.   It has also been
prepared by simple mixture, as follows:
  Experiment 5.  To two parts ol alcohol add one part
of caustic liquid ammonia ; and shake the mixture.
  Experiment 6.  If one part of muriate of ammonia,
one  of carbonate of potash, and two of water be distilled,
a product will be sbtained, which is the common wa-
ter of ammonia, or spirit of sal ammoniac ol the Dispen-
satories.
  Rationale.   The carbonate of potash and muriate of
ammonia mutally decompose each other; the muriatic
acid unites with the potash, forming muriate of potash,
and  the  carbonic acid combines with  the  ammonia;
but  as the ammonia is in excess, or  the  carbonate of
potash is not saturated  with the acid,  the  result is a
liquor,   which,  properly speaking, holds in solution
subcarbonate of ammonia.                     «
   Experiment 7.  If bones, horns, hoofs, 8cc.  be dis-
tilled, a product will be  obtained consisting of ammo-
nia and animal oil.
   Remark.   When the  solid parts of animals  are ex-
 posed to distillation,  with a heat sufficient  to  decom-
pose them, we obtain ammonia, and an empyreumatic
 oil.   This arises, principally, from a new arrangement
of the elementary principles : azote unites with hydro-
 gen, forming ammonia;  hydrogen and  carbon  form 
284
animal oil; and  the  ammonia unites in part with car-
bonic acid, produced from  the  union of carbon and
oxygen.   The residue, if carbonized, affords ivory or
bone black.
  As the  liquor obtained by distilling bones is always
impure, containing an empyreumatic animal oil, it i6
purified by one or more distillations.  It is then known
in the shops by the name ol spirit  of ha-tshorn.  Am-
monia was not known to the ancients.  The alchemists
were acquainted  with it; though in an impure state.
Basil Valentine described the method of obtaining it.
The name of volatile a/kali was given to it; it was called
hartshorn, because it was  often obtained by distilling
the horn of the hart; spirit of urine, as it was procured
from urine, Sec.
  The union of acids with ammonia forms a class of
salts.  See salts of ammonia.
  Experiment  8.   If five  parts of muriate of ammonia,
five  of sulphur, and six of quicklime be distilled, sulphu-
ret of ammonia will be formed.
  Rationale.  The lime  decomposes the muriate of
ammonia; muriate of lime is formed, and the ammo-
nia unites with the sulphur in the distillation, forming
sulphuret of ammonia-
  Remark.  The sulphuret of ammonia decomposes
water, and constitutes hyelroguri tted sulphuret of ammo-
nia,  known formerly by the name ol fuming liquor of
Boyle.
  Experiment 9.   If liquid ammonia be poured on the
oxyds of  silver, copper, tin, nickel, zinc, bismuth or
cobalt, the metal will be dissolved.
  Rationale.  Ammonia has  the property of dissolving
some of the metallic oxyds, and forms with them pe-
culiar compounds, which have  been called ammonia-
rets.  The solution  of metallic oxyds, however, de-
pends on  the degree of the oxydizement of the metal.
Thus, the prot oxyd of iron is soluble, but the per
oxyd is insoluble. The per oxyd of cobalt, according
to Thenard, is insoluble.
  Remark.  If ammonia is  digested on the oxyds of
nercury,  lead, or manganese, it is decomposed; its 
285
hydrogen unites with a portion of oxygen of the oxyd
and forms water, and azotic gas is emitted.  If consi-
derable heat be applied nitric acid is also formed, from
the union of azote with oxygen.
  Experiment  10. II liquid ammonia be added in excess
to a  solution of sulphate of copper, ammoniarel of cop-
per is formed.
  Rationale.  The first portion of ammonia unites with
the sulphuric acid of the sulphate, forming sulphate of
ammonia; the other portion combines with the oxyd
of copper, thus separated, and forms a solution of am-
moniaret of copper.
  Remark.   If the products of the experiment be eva-
porated to dryness,  and the dry mass be exposed to a
gentle heat, the  sulphate  of ammonia  is volatilized,
leaving the  ammoniaret behind, forming the cuprum
ammonieicum of the shops.   There is danger, however,
that the heat would separate a portion of the ammonia,
and partly decompose the oxyd, forming water  as be-
fore observed.  Oxyd of copper prepared in the first
instance, and then united with ammonia, appears to be
the best process.
  Experiment 11.  Add liquid ammonia to a solution cf
gold  prepared with nitro-muriatic  acid  diluted with
three times its weight of water; collect the  precipi-
tate,  which  is of a yellow colour, wash  it and dry it
gently upon filtering paper.  It is the fulminating gold
known also  by the name of aurate of ammonia.   This
powder is to be kept in a vial.  A few grains explodes,
when healed or rubbed; with great violence.
  Rationale.   The ammonia first decomposes the solu-
tion of gold ; it unites with  the acid ; the oxyd of gold,
thus  separated, combines with  a portion of ammonia,
and forms the fulminating gold.   When heated to a
temperature between  248° and 54°, or when struck
violently with a  hammer, it explodes.   The rationale
of this phenomena is as follows : the hydrogen of the
ammonia unites with the oxygen of the  oxyd, and forms
water; the  gold  is reduced, and the azote is evolved
in the form  of gas.  The great expansibility of this gas
explains the violence of the explosion.   See gold. 
286
  Experiment 12.  To a solution ol nitrate of silver add
lime water; collect the precipitate; pour upon it pure
liquid ammonia, and allow it to remain  for 1~ hours;
it is then to be decanted off, and the  black powder, on
which it stood, is to be placed  cautiously, and in very
small portions upon "bits of filtering paper.  This pow-
der is the fulminating silver.  When dry the  slightest
touch causes it to fulminate.
  Rationale. The lime water decomposes the solution of
silver; the oxyd of silver is treated with ammonia, which
unites with it.' It is therefore a compound of ammonia
and oxyd  of silver.   On  exposing the compound to u
slight friction, the hydrogen of the ammonia unites with
the oxygen of the oxyd and forms water, azotic gas is
disengaged, and the silver is reduced, at the same time
explosion takes place. See Silver.
  Experiment  13.  According  to  Fourcroy,  if liquid
ammonia be suffered  to stand on red oxyd of mercury,
the oxyd will assume a white colour.  If it be collect-
ed, washed, and dried, and placed upon ignited coals
it will detonate with  considerable violence.  This is
the ammoniacal fulminating mercury.
  Rationale.   The  ammonia  unites with  the  oxyd,
forming a compound  of ammonia and oxyd  of mer-
cury.   When exposed to  heat, the  hydrogen of the
ammonia combines  with the oxygen  of  the oxyd, and
forms water, the mercury  is revived, azote is disen-
gaged, and explosion ensues.  See Mercury.
  Remark.  The decomposition of ammonia  by elec-
tricity and galvanism, was  noticed  when treating of
ammoniacal gas ; for information on this  subject  see
that article.   When  the Stahlian theory of Chemistry
was in vogue, in which the imaginary element of phlo-
giston was considered an important subject of chemi-
cal  investigation, it was supposed that ammonia con-
tained that principle.   Scheele and Bergman both con-
cluded, that  it  is composed of azote and phlogiston.
But the experiments of Priestley led to  the inference,
that ammonia consisted of azote and hydrogen ; which
was afterwards sanctioned by Berthollet  in a very able
and luminous memoir published in 1785.  Heannounced 
287
 •l;.it it consisted of 121 parts of azote and 32 of hydro-
 gen. According to Dr. Austin's calculation it is compo-
 sed of 120 parts of azote and 32 of hydrogen.  Or 100
 parts of  ammonia are composed of about 80 parts of
 azote, and 20 of hydrogen.   Mr. Davy has since  con-
 firmed the experiments of Berthollet, and, beside, has
 rendered it probable, that this alkali contains oxygen.
 \  new metal  has  been  obtained  from ammonia, to
 which the name of ammonium has been  given, in the
 following manner:
   Experiment 14.   Place a  globule  of  mercury  in  a
 hollow cut in a moistened piece of sal ammoniac ; ex-
 pose it to the energy of a powerful galvanic battery.  It
 increases in bulk and arrives to the consistence of but-
 ter.  Its  specific gravity is  reduced to 3,000.   The
 mercury has therefore been  amalgamated  with  some
 metallic body.  If the amalgam be thrown into water,
 ihe mercury resumes its original state,  hydrogen  gas
 is emitted, and the  water  is impregnated with a weak
 solution of ammoniac. The metal, thus united with the
 mercury, has  been called ammonium, or  the base of
 ammonia.
   Remark.  Berzelius and Ponten  placed quicksilver,
 negatively electrified in  the  galvanic circuit,  in  con-
 tact with a solution of ammonia   The  mercury  ex-
 panded, and became a  soft solid.   It was supposed,
 therefore,  that this was occasioned by the  addition of
 metallic matter; that the ammonia having been decom-
 posed by the galvanic influence,  its oxygen abstracted,
 and its metallic base left combined  with  the quicksil-
 ver.  From this substance,  quicksilver and ammonia
 are reproduced  by exposure to the atmosphere, oxy-
 gen being absorbed ; and the same products are  ob-
 tained by placing it in water, hydrogen being evolved.
 Mr. Davy* has confirmed this conclusion, and obtained
 the amalgam  readily,  by subjecting quicksilver, in
 contact with muriate or carbonate of ammonia,  to  the
action  of the negative galvanic wire.  A similar  re-
 sult was obtained by employing the deoxydizing power
• Phil. Trans. 1808. 
288
of the  base of potash or soda,  either of these  bases
being united with quicksilver, and this compound be-
ing made to act upon muriate of ammonia; the amal-
gam increased to six or  seven  times its original vo-
lume, and the compound seemed to  contain more of
the ammoniacal base than that  procured by electrical
powers.  This amalgam  thrown into water, as before
noticed,  produces  ammonia and evolves hydrogen,
which  pre-supposes the. absorption of oxygen.  For
particulars on this  subject  I would refer the reader
to Mr. Davy's paper in the Philosophical Trnsactions,
and also to a chemical work, which he has lately edit-
ed, the  supplement to Murray's  Chemistry,  and the
Appendix to Thomson's Chemistry.
   In the opinion of Mr. Hembel, the  metals obtained
from the alkalies are nothing more than the alkalies
in a purer state  than we have heretofore been able
to obtain them.   There is indeed some  truth in this
opinion. 
FART X.
                  OF EARTHS.

  Although earth  in  common  language signifies  the
solid parts  of the  globe,  and sometimes the  mould in
which vegetables grow, yet the term here is  meant to
express a  class of bodies,  which have a variety of
common properties.  Substances possessing the  fol-
lowing characters, are classed under this head.
  1. Fixed, incombustible,  and incapable while pure
of being altered by the fire.
  2. No taste or smell;  at least when combined with
carbonic acid.
  3. Insoluble  in water,  or  nearly so; or at  least be-
coming insoluble when united with carbonic acid.
  4. A  specific gravity not exceeding 4.9.
  5. Not altered when heated with combustibles.
  6. When pure, capable of assuming a white powder.
  They unite also with  acids,  with the alkaiies, with
sulphur, phosphorus, metallic oxyds,  and with each
other, either by fusion or solution in water. But these
properties  are not completely general.
  The earths  were heretofore considered as elemen-
tary substances; but, not to slate the opinions or con-
jectures of chemists  respecting them, Mr. Davy was
led by analogy  arising from his experiments on  the
alkalies, to institute a series on this class of bodies, in
which he proved that they  were compounds of pecu-
liar  metallic basis and  oxygen.  The proportion of
oxygen and metal has not yet been ascertained in any
of the  earths.   The  inflammable base appears uni-
formly at the negative surface  of the  Voltaic circuit,
and the oxygen at the positive surface.  Baron Born
was of  opinion  many years  ago, that the earths were
compound  bodies.
   Bergman includes  all  substances, except the metals,
with the earths, which  require more  than one thou-
                       Bb 
2ro
sand parts  of  water for their  solution.  The earths
have been divided into two classes, namely, of alkaline-
earths and earths proper.   The first possess the genci. 1
properties of alkalies, such as changing vegetable blued
to green, and of neutralizing acids.   Lime, magnesia,
barytes,  and strontian are of this class.  Tin- earths
proper, which do not change vegetable- blues, nor neu-
tralize acids, are five in  number, viz. alumina, yttria,
glucina,  zirconia, and silica.  The combination of the
earths give rise to stones, and to different kinds of pot-
tery, as bricks, tiles, crucibles, flint  ware,yellow ware,
queen's ware, Wedgcwood ware, porcelain, Sec.
   An  enumeration  of  the dift'erent  minerals, arising
from the  combination of two or more of the primitive
earths, may be  noticed in  this place.   We shall use:
the arrangement adopted by  professor Coopc.-.*
EARTHS AND STONES.
  1. OR DIAMOND GLNUS.
 Diamond.*
   2. OR ZIRCON GLSUS.
 Zircon.
 Hyacinth.
  3. OR SILICEOUS GENUS.
      Garnet Family.
 Chrysoberil,
 Chrysolite.
 Olivine.
 Augite.
"Vesuvian:
 Leucite.
 Melanite.
 Garnet.
     Precious.
     Common.
      Ruby Fundly.
Spinell.
Sapphire.
      Sc.'.orl E\:n .'->/.
Topaz.
Emerald.
lleryl.
    Precious.
    Schoiioid.
Schorl.
    Black.
    Electric.
Thumcrstone.
Eisenkicsel.
      Quartz Family.
Quartz.
    Amethystine.
* Introductory Lecture, 8vo. p. 215.
* See Carbon. 
291
    Rock c-vs-ah
    Milk.
    Common.
    Prase.
Hornstone.
    Splintery.
    Conchoida!.
Petrified wood.
dm flint.
Chalcedony.
    Common.
    Cornelian.
Heliotrope.
Plasma.
Chrysoprasc.
Siliceous schist.
    Common.
    Lydian ortouch stone.
      Zeolite Family.
Obsidian.
Cats eye.
Prehinite.
Zeolite.
    Farinaceous.
    Fibrous.
    Radiated.
    Lamellar.
    Cubic.
Cross stone.
Lapis lazuli.
L azulite.
  4. OR ARGILLACEOUS
         GENUS.
Pure  Alumine.
Porcelain earth.
Clay.
     Common.
     Potters.
     Indurated.
     Slate.
Cimolite.
Jasper.
    Egyptian.
    Ribband.
    Porcelain.
    Common.
Opal
    Precious.
    Common.
    Semi.
    Ligniform.
Pearl stone.
Pitch stone.
Adamantine spar.
Feldspar.
    Compact.
    Common.   ♦
    Undecomposed.
    Decomposed.
    Adularia.
    Labrador.
Polishing slate.
Tripoli.
Alum stone.
Alum earth.
    Clay slate Family*
Alum slate.
    Common.
    Glossy.
Bituminous shale.
Drawing  slate.
Whetstone slate.
Clay  slate.
      Mica Family.
Lepidolite.
Mica.
Lappis ollaris. ~)
     Potstone. 5
Chlorite.
     Earthy. 
    Common.
    Slaty.
    Foliated..
      Trap Family.
Hornblende.
    Common.
    Basaltic.
    Labrador.
    Slate.
Basalt.
Wacke.
Clinkstone.
Lava.
   Litltomarge Family.
Pumice stone.
Green earth.
Lithomarge.
    Friable.
    Indurated.
Sculpture stone.
Rock soap.
Yellow earth.
5. OR MAGNESIAN GENUS.
    Soap stone Family.
Bole.
Native talc earth.
Sea froth.
Fuller's earth.
       Talc Family.
Nephrit.
    Common.
    Indian hatchet.
Steatite.
Serpentine.
    Common.
    Precious.
Talc.
    Earthy.
    Common.
    Indurated.
 \shcstos.
    Rock coi■',<.
    Amianthi:^
    Common.
    Rock wood.
Cyanite.
Arrow stone.
    Radiated.
    Common.
    Cilassy.
Tremolite.
    Asbestiform.
    Common.
    Glassy.
6. OR CALCAREOUS GFTNl'
A. Carbonates  of lime.
Agaric mineral. }
Rock milk.     \
Chalk.
Limestone.
    Compact.
    Common.
    Globular or.
    Oviform,
    Lamellar.
    Granular.
    Spathose.
    Fibrous.
    Pisolite.
Earth froth.
Slate spar.
Bitter spar.
Brown spar.
Fetid  limestone.
Marie.
    Earthy.
    Lithomarge.
Bituminous marie slate
Arragonite.
B- Phosphate of lime. 
293
 ■\patitc.
Asparagus stone.
C. Boratcd lime.
Bor.icitc.
D. Fluate of lime.
     Fluor.
     Earthy.
     Compact.
     Sparry.
C. Sulphate of lime.
Gvpsum.
     Earthy.
     Compact.
     Lamellar.
     Pol kited.
     Fibrous.
     Crystallised.
     Lamellar gypsum.
     Selenite of somS.
  7. OR  BARYTIC GENUS,
Witherite.
Heavy spar.
     Earthy.
     Compact.
     Granular.
     Curved lamellar.
     Straight lamellar,
     Not decomposed.
     Decomposed.
     Columnar.
     Fibrous.
     Bolognian spar.
     Prismatic barytes.
8. OH STRONTIAN GENUS.
Stronti.mite.
Cce'cstine.
  In this arrangement of stones it. is evident, that the
particular genus takes its-rise from the particular earthj
which  does or is  supposed to constitute the  greater
part of the stone.  This again is divided into families-,
species, and some-tines into subspecies.  This varies,
however, in different systems of arrangement.  Rocks,
w hich ale generally aggregated stones, have been class-
ed in the following: order:
      TIRST CLASS.
     Primitive Eocks
Granite
Gneiss..
Mica slate.
Clay slate.
    Common.
    Flint.
    Whetstone.
    Chlorite.
    Talc.      J
Samite.
    Common
    Schistose.
o
\i
         po:'p:v,-ry.~ ■

             Gray stone.
             Ilornstone
             Pitch stone
             Obsidian.
             Feldspar.
yj       Porphyry state.
»T       Quartz.
i-.          .....
f*        Primitive limestone.
         Serpentine.-
         Topaz rock*
              SECOND C'.ASS.
             Trei'Hution Recks
     b b  2 
25 ;
Transition clay slate.
Grauwacke.
     Schistose.
Transition limestone.
Hornblende slate.
Greenstone.
Mandelstone. ~)
Amygdalaid. 5
    - THIRD  CLASS.
 Secondary Rocks. ^
 Stratiform Rocks. ^
 Trap formation.
     Basalt.
     Basaltic porphyritic.
     Gray stone.
     Basaltic amygdolaid.
     Wackee.
     Basalt tufa.
 Stratified clay slate.
      Common.
      Alum schist.
 Stratified lime stone.
      Compact.
       5 Oolite.
       (Zoogenstein.
      Fetid stone.
      Marie.
      Bituminous marie
        schist.
  Sandstone.
      Common.
      Siliceous.
      Argillaceous.
      Marly.
      Ferruginous.
      Breccious.
  Stone coal.
       Slate clay.
      Stone coal-
    Bituminous sthiK
Chalk.
Gypsum.
Rock salt.
Ferruginous clay.
Clay  (letten.)
     FOURTH CLASS.
      Alluvial Rock.
Sand.
     Gravel.
     Fine sand.
     Quick sand?
 Mud.
 Common clay.
 Bituminous wood.
 Fossil ivpod.
 Aluminous earth.
 Tufa (soft friable earth.).
       FIFTH CLASS.
 Volcanic rocks.
 Lava.
      Vitreous.
      Compact.
      Cellular.
      Scoriaceous.
      Spongiform.
 Pumice stone.
 Volcanic ashes.
      Puzzolana.
      Volcanic  tufa.
      Piperino.
      Terras.
  Pseudo-volcanic rocks.
      Laniform earthy sen
        ria.
      Porcelain jasper.
      Half burnt clay.
      Argillaceous iron
        (scapiforme.) 
295
                 DIVISION  I.

        OF THE  ALKALINE EARTII^

                 SECTION I.

                    OF LIME.

  Experiment 1.  IIlimestone, either amorphous or crysr
tallized, as calcareous  spars, marble, or oyster-shells
be pulverised, and introduced into a crucible, or  por-
celain or earthen retort, and exposed for some time to
a strong heat,  quicklime or more properly lime will be
prepared. If the air, which is disengaged, be collected,
by adapting to the  neck of the  retort a bent tube of
glass conveyed under a bell, it will be found to be car-
bonic acid gas.  See the Preparation of Carbonic Acid
Gas.
   Rationale.   As limestone, calcareous spars, marble,
Sec. are carbonates of lime, or composed of lime and
carbonic acid, on exposure to  an intense heat, the car-
bonic acid is disengaged, leaving  the lime in the cru-
cible or retort in the  state of quicklime.  If the air
which is disengaged be examined, it will prove to be
carbonic acid  gas or' fixed air.
   Remark.  The operation of burning  lime, as it is
called, in the  large way, depends on this principle.   It
is conducted in kilns.   If the native carbonate are pure,
no vitrification takes place.   Lime, which  has  been
 partially  vitrified, is known by the name of over-burnt
lime.
   Experiment 2.  Pulverise marble and dissolve it in
 acetous acid; to the solution, previously filtered,  add
 rarbonate of ammonia.   When the precipitate  subsides,
 collect it, wash it, and expose it to a white heat for some
 hours, and pure lime will be obtained. 
296
  Rationale.  The impure carbonate of lime is decom-
posed by the acetous acid, carbonic acid is discngj'^ed,
and acetite of lime remains in solution.  When carbo-
nate of ammonia  is added, carbonate of lime is preci-
pitated, and  acetite of ammonia remains in- solution.
When the  former is collected, and  exposed to heat,
the carbonic  acid is disengaged, and the  lime remaim
in the  crucible.  Or, pure lime may be obtained in the
following manner :
  Experiment 3.  Dissolve oyster-shells in muriatic acid.
filter the solution, and add to it ammonia as long as a
precipitate appears ;  filter it again.  The  liquor is now
to be mixed with a solution of carbonate of soda:  the
powder which falls being washed and dried, and heated
violently in a platinum crucible, is pure lime.*
  Rationale.   The lime of the shell is dissolved by the
acid, the muriate of lime which is thus formed, is de-
composed by carbonate of soda, muriate of  soda remains
in solution, and carbonate of lime is precipitated.  On
exposing this to heat, the carbonic acid is disengaged,
and the lime is left.
   Remark.  Pure lime is of a white colour, moderately
hard, but easily  reduced to a powder.  It is caustic.
Its specific  gravity is 2.5.  It is infusible.  As  lime
was  observed  to lo.^e in weight  in  calcination, Van
Helmont particularly  made  an experiment to  ascer-
tain  what the volatile product was.   He as well as
others supposed  it  to be pure water.   While,  this
subject engaged  the  attention of  philosophers,  Dr.
Black  published  a set of experiments in  1756.  lie
found that it  was the same air disengaged  from it dur-
ing calcination, as was produced by the action of acids,
an idea which he drew from  Dr. Hales.   This air Dr.
Black called fixed air.  The investigations of Priestley
and others afterwards demonstrated, that this gas was
the same as carbonic acid gas of the moderns.
  Experiment 4. When water is poured on fresh burnt
lime it swelisr falls to pieces, and is soon reduced to a
* Thomson. 
297
\evy fine powder ; al the same time mu'ch heat is pro-
duced, and a part of the water flies off in vapour.
  Rationale.   The evolution  of  heat in  the process
ef slacking lime, is owing to a condensation of the wa-
ter, which combines with it; for part of the water unites
with the lime, and  thus becomes  solid.   The water
parts with its caloric of fluidity, and is  appreciable by
the senses.   When  two parts of  lime and one  part of
ice, each .32°, are mixed,  they  combine  rapidly, and
their temperature is elevated to  212.  It is inferred,
therefore, that a considerable  quantity which exists in
water, even in the siate of ice, is given out at the same
time.
  Remark.   Slacked lime well dried, according to Dal-
ton, is composed of three parts of lime and one part of
water. Mr. Lavoisier found, that 1000 parts of lime, when
slacked, were converted into  1287 parts.   This com-
pound has been called hydrate of lime. When the quan-
tity of lime slacked is great, the heat produced is sufiV
cient to set fire to combustibles.  Vessels loaded with*
lime have been burnt by this  means.  If considerable
quantities of lime be slacked, light  as well as heat is
emitted.   When lime  is reduced to  the consistence of
cream, by water, it is called cream of lime.  The pecu-
liar odour emitted during the slacking of lime, is owing
to a portion of the lime being carried off with the aque-
ous vapour.
  Experiment 5.   Expose  fresh  burnt lime to  the  at-
mosphere, it will attract  moisture, fall to  powder, and
gradually resume the state of carbonate  of lime.
  Rationale.   The disintegration of lime is owing to
the absorption of water ; and its gradual conversion into
carbonate of lime, is attributed to the absorption of car-
bonic acid.
  Experiment 6.   If water be added to quicklime it
will, besides combining with a portion forming hydrate
of lime, unite with it in a liquid state.  This liquid is
lime water.
  Remark.   Water, at the common temperature of the
atmosphere, dissolves less than 0.002  parts of its weight 
■2J8
of lime.   One ounce of water contains about one gram
of lime.   The solution is limpid.
   Lime water is usually prepared by slacking the lime
to a thin paste, and a sufficient quan'.i'.y of boiling wa-
ter afterwards  added.  This mixture  is to be stirred
repeatedly, the  lime allowed to  settle, and the clear
liquor decanted  for use.   Lime  water has a pungent
alkaline  taste,  and changes the infusion of violets or
cabbage to green.
   Experiment 7.   If lime water be exposed to the at-
mosphere, a crust will form on the surface, and, when
it is sufficiently large, will fall to the bottom.
   Rationale.  This phenomena ensues  in consequence
of the absorption of carbonic acid from the atmosphere;
a carbonate is formed, and is gradually  precipitated.
   Remark.  It is owing to the separation of lime from
its solution by  carbonic acid, that gives rise to the nu-
merous calcareous concretions or incrustations, as are
found in caverns,and springs, constituting stalactites, &c.
In Tuscany, artists employ certain waters which hold
a large quantity  of lime in solution, to  form basso relie-
vos, which they do by filling their moulds with the wa-
ter.
   Experiment 8.  Expose lime water to an atmosphere
of carbonic acid, and the same phenomena will ensuo
as in Experiment 7.
   Remark.   This is owing to the same  cause.
   Experiment 9.   Take  the vial  made  use of in the
last experiment, with its contents, and convey an addi-
tional portion of carbonic acid into it.  The carbonate
of lime will be dissolved, and the liquor  rendered trans-
parent ; or,
   Experiment  10.  If a small quantity of water satu-
rated with carbonic acid be added to lime water; a car-
bonate of lime will be precipitated; but on adding more
of the aerated water, the turbidness vrili disappear.
   Rationale. A small quantity of carbonic acid, whether
as a gas, or in solution in water, precipitates lime from
lime water as a carbonate ;  a still farther addition dis-
solves the precipitate, forming a super carbonate  of 
299
lime.  Hence lime  sursaturated with carbonic acid is
soluble in water.
   Experiment 11.  Expose the limpid solution of the
last experiment, in a flask, to the action of the heat, and
it  will again become turbid.
   Rationale.  The action of heat carries off the excess
of carbonic acid, and the remaining compound of lime
and acid, not being soluble, is-precipitated.
   Experiment 12.  To the precipitate of the last expe-
riment, add muriatic acid, and  the whole will  become
transparent.
   Rationale.  The carbonate of lime is decomposed by
the muriatic  acid ; carbonic acid is disengaged in ef-
fervescence, and muriate of lime is formed.
   Experiment 13.  If a solution of carbonate of potash
be added to lime water;  the mixture will become tur-
bid, and the precipitate will gradually subside.
   Rationale.  The carbonic acid of the carbonate pas-
ses to the lime,  at the same time, in proportion to the
quantity of lime water used ; the alkali is rendered caus-
tic.  See potash.
  Experiment 13.  If a tumbler half full of lime water,
be breathed into by means of a pipe or tube, the lime
water will grow  turbid.
   Rationale.  In respiration a quantity of carbonic acid
is  formed, which in this case as it passes from the lungs
is  absorbed by the lime water.
  Experiment 15.  Into a glass of lime water put a few \
drops of oxalic acid, oxalate of ammonia, or oxalate of
potash, and the lime will be precipitated.
   Rationale.  The oxalic acid, whether  free  or in a
combined state, has  the  property  of separating lime ;
hence it combines with it, and  forms an insoluble pre-
cipitate of oxalate of lime.  Oxalic acid is therefore a
test for lime.
   Ex/ieriment 16.  Mix  in a wine glass equal quanti-
ties of a saturated solution of muriate of lime, and a sa-
turated solution  of carbonate of potash, both  transpa-
rent  fluids, stir  the mixture, and a solid  mass will be
the product. 
300
  Rationale.  This effect takes place  by compound af-
finity : the muriatic acid having an affinity for the pot-
ash, unites with it, forming muriate of potash, whilst
the  carbonic acid  combines with the  lime, and produ-
ces carbonate of lime.
   Experiment 17.  If sulphate of magnesia he added to
lime Avater, a precipitation will take place.
   Rationale.  The precipitate produced  is  a mixture
of sulphate of  lime  and a portion of  magnesia, wrhich
occurs in consequence of the lime taking the acid from
the  sulphate of lime, whilst  that  portion of magnesia
thus dislodged from the sulphuric acid is separated.
   Experiment  18.   If lime water be added to a solu-
tion of alum, a precipitation will ensue.
   Rationale.  The sulphuric acid of the super sulphate
of alumina and potash (alum) unites with the lime form-
ing  sulphate of lime, and if the lime water be added in
sufficient quantity, the  precipitate will consist of sul-
phate of lime and alumina.
   Experiment 19.   If four parts of liquid muriate of
lime, according to Tromsdorf, and one part of lime be
boiled together until a drop on cooling assumes the con-
sistence of syrup ; then filtered through a cloth into
an earthen vessel, kept covered;  as  the  liquid cools
needle shaped  crystals of pure lime will shoot in it.
   Remark.  This experiment is said to succeed only on
a large scale, and when several pounds of  muriate of
lime are employed.  The crystals, although considered
by Tromsdorf  as pure lime, have since been shewn
to be merely a  sub muriate of lime.
   Ex/ieriment 20.  Three parts of oyster-shell pulver-
ised, and mixed with one of sulphur ; and exposed in
a crucible to a  moderate heat forms Canton's phospho-
rus.   See light.
   Experiment 21.   If a mixture of one part of sulphur
and two of lime be heated for at least an hour in a cover-
ed crucible, a compound will be formed called sulphu-
ret of lime.
  Remark.  The mixture should not be rammed tight
in the crucible.  A reddish sulphuret is the product, 
.30 j
which in the old nomenclature, is r.Aied calcareous liver
cf sulphur. When it is exposed to the air, or moistened
with water, its colour is changed to a greenish yellow,
sulphuretted hydrogen  is formed, and hydroguretted
sulphuret of lime  is produced.  See the Preparation of
Sulphuretted Hydrogen Gas.
  Experiment 22.  If the same mixture as in Experi-
ment 19, be boiled in about ten times its weight of wa-
ter, or if quicklime be sprinkled  with sulphur and then
moistened, hydroguretted sulphuret of  lime  will be
formed.
  Rationale.  The sulphur unites with  the lime, water
is decomposed, and its hydrogen in part combines with
the sulphuret, forming the hydroguretted su phuret.
  Remark.  When hydroguretted sulphuret of lime is
exposed to the  air, oxygen is absorbed, which combines
at first with the  hydrogen, and afterwards with sulphur,
and, according to Berthollet, converts the compound
into sulphate of lime.   The  hydroguretted  sulphuret
has the  p/operty  of dissolving charcoal  by the assist-
ance of heat.
  Experiment 23   Put into the  bottom of a glass tube,
close atone end, one part of phosphorus ; and, holding
the tube  horizontally, introduce five parts of lime in
small lumps, so that  they shall be  about two inches
above the phosphorus. Then place the tube horizontal-
ly among burning coals, so that the part of it which
contains the lime  maybe made  red hot, while  the bot-
tom of  the  tube  containing  the phosphorus  remains
cold.  When the  lime becomes red hot, raise the tube,
and  draw it along the  coals till that part of it which
contains the phosphorus is exposed to a red heat.  By
this means a union will ensue,  and fihosphuret of lime
will be formed.   This process was invented  by Doctor
Pearson:  or,
  Experiment 24.   According to Van Mons, introduce
into a flask some  carbonate of lime in powder:  put it
in a sand bath,  and expose it to a heat sufficient to ex-
pel the carbonic  acid.  Towards the end of the pro-
cess  introduce  gradually a third part of phosphorus,
                        c c 
302
  raking care to keep the lime in a red heat.   When the
  whole of the phosphorus is introduced, shut up the mat-
  trass with a stopper, provided with a valve  to let the
  gas escape, but permitting none to enter, and let the
  fire be  immediately withdrawn.   The product is phos-
  phuret  of lime ; or,
     Experiment 25.  According to Dr. E. Cutbush,* put
  a portion of lime, divided into small pieces, into a Hes-
  sian crucible, and expose it in a common furnace until
  the lime becomes red hot.   The phosphorus intended
  to be used, being dried by  means of  a spongy paper, is
  then put into another crucible, sufficiently capacious to
  contain the quantity of  lime.  The ignited lime is re-
  moved from the furnace, and placed in the crucible con-
  taining  the phosphorus, which is to be expeditiously
  covered with an inverted  crucible sufficiently  large to
  receive that which now holds the lime and phosphorus,
  care being taken to prevent the access of  atmospheric
  air, by surrounding the edge of the inverted crucible,
  in contact with  the brick or tile on which it rests, with
  some soft  clay or  lute.  When the  contents have re-
  mained  a sufficient time to  become cold, a phosphuret of
  lime will be found in the crucible.
     Rationale.  In the process of Dr. Pearson, a direct
  combination of the phosphorus and  lime  takes place,
  but  the lime  must  be made extremely  hot  to en-
j sure  success:  in that  of  Van  Mons,  the  carbonate
  of lime is first decomposed" by the heat, leaving more
  or less of an atmosphere of carbonic  acid, which pre-
  vents the combustion  of the phosphorus, but this very
  frequently  fails : in the process of Dr. Cutbush, which
  is more expeditious and certain, although some waste
  of the phosphorus ensues,  the union of the two is ac-
  complished without being  subject to the difficulties of
  either of the others.
     Remark.   Phosphuret of lime is generally of a deep
  brown colour.  When thrown into water, it decompo-
• Ecletic Repertory, vol. ii. p. 367. 
303
scs that fluid, and evolves phosphuretted hydrogen gas.
See the Preparation of Phosphuretted  Hydrogen Gas.
  Dr. Cutbush observes, that the phosphuret prepared
according to the last process is of different hues, from
a dark  c'n^col^te colour to that of  pink :  a  portion
thrown  into water continued to act  three hours :  the
water into  which it  had been  thrown, wdien  filtered,
emitted an alliaceous odour, and converted vegetable
blues into green, in  consequence of the lime held in
solution.  He supposes,that the red powder which was
found in the inverted crucible, was a phosphuret of car-
bon ; for, he adds, " I have tested this powder by inflam-
ing a portion of its oxygen gas ; a small quantity of phos-
phoric acid was formed, the remaining gas being pass-
ed into lime water, on agitation, produced a turbid ap-
pearance, indicative of the  formation of carbonic acid
by the union of the carbon of the phosphuret with oxy-
gen."
  Experiment 26.  If red oxyd  of mercury be boiled
with lime water, and the fluid then evaporated, small
transparent yellow crystals will be formed.
  Remark.  The compound, resulting from the union
of the oxyd of mercury and lime, has been called  by
some merciiriate of lime.   Lime water has the property
of dissolving other  metallic  oxyds, as the red oxyd of
lead and litharge.  This compound blackens wool, the
nails, the hair, and the white of eggs : the colour of the
skin, silk, the yolk of eggs nor animal oil, are affected by
it.  It is a common practice with perruke-makers, to
blacken hair by boiling it with lime and litharge.
  Experiment 27.   If lime and silicia be exposed to a
strong heat they melt; or if lime and alumina be treat-
ed in the same manner, fusion will ensue.
   Remark.  Hence  we  learn the utility  of  calcareous
substances, such as oyster-shells, limestone, &c. in the
fusion of some iron ores,  especially  the argillaceous
ores: it acts as a flux by melting  the argil, and  thus
separating it from the iron.
  Experiment 28. If lime, previously slacked, be mix* 
304
ed with sifweous sand, the cement or mortar for build-
ing will be formed.
  Remark.  The use of lime in the preparation of mor-
tar, is  one of its  most important applications.  The
hardening of mortar is a species of crystallization, ow ing
to the slow absorption of carbonic acid and water. The
best proportions for forming mortar  are, it is said, one
part of  lime and two of sand  mixed in the u.m.d way.
Dr. Higgins, however, says that three parts of fine sand,
four parts of coarser sand,  one part of quicklime re-
cently slacked,and as little water as possible, will form
the best mortar.  The Doctor also recommends tho
addition of bone-ashes, which he adds in the same pro-
portion as lime.   A little  manganese added to mortar
gives it the property of hardening under water ; so that
it may be employed advantageously for a variety of pur-
poses.
  Morveau's water mortar consists of four parts of blue
clay, six parts of black oxyd  of manganese, and 90 parts
of limestone, first calcined to expel the carbonic acid,
and afterwards mixed with 60 parts of sand and a suffi-
cient quantity of water.  Puzzollano and basalt have
both been used  for  the same  purpose.  My brother
William, of the  corps of engineers, informed  me, that
in erecting the batteries at  New York,  the borings of
cannon, Sec. was successfully  used  in making  water
mortar.   It is a  common custom to  employ the scales
of iron in preparing mortar to stand the weather.
  Experiment 29.   Put an  ounce of calcareous marl
into a flask, and add a certain weight-of diluted  muri-
atic  acid.   When the effervescence  ceases, weigh the
whole to ascertain  what portion of its weight it has lost
by the escape of the fixed air.   If the ounce has lost
only 40  grains, it may be concluded  that the ounce of
marl contained only 100 grains  of calcareous earth.
  Rationale.   The action of the muriatic  acid decom-
poses the carbonate of lime  of the marl, and the quan-
tity  of carbonic acid is shewn by  the diminution of
weight, and, therefore, concluding from similar expe-
riments, the proportion «f lime  may  be determined. 
305
  Remark.   Calcareous earth is used as a manure ; and
maris, generally, are employed, in consequence only of
the  calcareous earth they contain.   It  is said, that un-
less they contain more than 30 per cent, of lime, they
are  of no value to the agriculturalist.
  Beccher and Stahl supposed, that the earths and me-
tallic  oxyds were of a similar  nature ; and indeed it
was the  favourite opinion  of Lavoisier,  that all th©
earths might be metallic  oxyds.   Besides other opini-
ons respecting the earths generally, it was imagined
that lime was composed of carbon, hydrogen, and azote.
Mr. Davy,  however, by instituting some experiments
on lime by means of the galvanic battery, has shewn
that it has  a  metallic base, which he  called calcium.
When calcium was heated in the open  air, it burnt
brilliantly, and quicklime was formed.   Mr. Davy in-
ferred, therefore, that lime is  composed of calcium and
oxygen.
                 SECTION II.

                OF  MAGNESIA.

  Experiment 1.  If sulphate of magnesia be dissolved
in water, and a solution of carbonate of potash added,
a precipitate will be formed, which is the magnesia of
the  shops.
  Rationale.   When  carbonate  of potash is added to
sulphate  of magnesia, a  double decomposition  en-
sues ; the sulphuric acid of the sulphate  unites with
the  potash, forming sulphate of potash, which remains
in solution, and the carbonic acid of the carbonate com-
bines  with the magnesia,  forming  sub-carbonate of
magnesia, which precipitates.
  Remark.   Equal weights of the  carbonate  and  sul-
phate are generally employed, but, according to  the
Pharmacopea, they are separately dissolved and fil-
                       cc2 
306
tered ;  then mixed, and eight parts  of water added.
The temperature is raised to complete the decompo-
sition.   The  fluid, when  strained through a linen,
leaves  the magnesia, which is washed and dried.  The
sulphate of potash, which passes the  filter,  may be
evaporated and crystallized.  Two circumstances  in
conducting the  process  should be attended to.   1st.
Heat should be  used in order  to expel  a  part  of the
carbonic acid, which retains  a portion of  the  magne-
sia in  solution.  2dly.  The large  quantity  of water is
necessary to  dissolve the sulphate of potash.   This
however contains some undecomposed carbonate  of
potash ; for 100 parts  of crystallized carbonate of pot-
ash are sufficient for  the decomposition of 125 parts
•f sulphate of magnesia; and as the carbonate of pot-
ash of commerce contains a larger proportion of alkali
than the crystallized carbonate, a still less proportion
should be used.  There are sources of impurity, one
of which arises from  the  silica, which the potash of
commerce generally contains.  This may be separated,
by suffering the alkali to deliquesce, before it is used.
The sub-carbonate is  composed of about 48 acid, 40
magnesia,  and 12 of water.   It is decomposed by all
the acids, potash, soda, barytes, lime and strontian, the
sulphate, phosphate, nitrate, and muriate of alumina,
and the super-phosphate of lime.
   A Roman canon about the  beginning of the seven-
teenth century exposed a white powder to sale at Rome
 which he called magnesia alba, for the  cure of all dis-
 eases. The preparation was kept secret; but in  1707
a process was published for obtaining  it by calcining
the lixivium,  which remains  after the preparation of
nitre.   A process  also appeared, a  few years after,
 which consisted in precipitating  the magnesia  from
the mother ley of nitre by means of potash.  This  pow-
der was supposed to  be lime, until the contrary was
demonstrated by Hoffman.  Dr. Black, in  1755, made
a number  of interesting  experiments on  magnesia.
Margraff, Bergman and others also wrote on the same
subject. 
307
  Experiment 2.  If a solution of crystallized carbonate
of potash be added to another of sulphate of magnesia,
carbonate  of magnesia will gradually  be deposited in
brilliant hexagonal crystals, terminated by an oblique
hexagonical plane.
  Rationale.  As the potash,' in the crystallized  carbo-
nate, is fully saturated with carbonic acid, when it  is
added to sulphate of magnesia, the carbonic acid passes
to the magnesia, which gradually precipitates or forms
in crystals, whilst the sulphuric acid attaches itself to
the alkali.
  Remark.  Crystallized carbonate of magnesia is com-
posed of 50 acid, 25  magnesia, and 25  water  in the
hundred, and is soluble in about 480 times its weight
of water.
  Experiment 3.  If carbonate of magnesia be put into
a crucible, and kept in a  red heat for two hours, the
calcined magnesia of the shops will be formed.
  Rationale.  When carbonate  of magnesia is exposed
to heat, it loses its carbonic acid which escapes in the
form of gas, together with the water it generally con-
tains.
  Remark.  According to Dr. Black, magnesia, in cal-
cination loses  -j^ths of its  weight.  It should  always
be  kept from the air.  Magnesia may be obtained free
 from carbonic acid in the following manner
  Experiment 4.  To a solution of sulphate of magne-
 sia add caustic or pure potash,  and collect, wash, and
 dry the precipitate.
  Rationale.   The alkali  unites  with the sulphuric
 acid of the sulphate, and the magnesia is precipitated
 in a pure state.
   Remark.   Magnesia is a soft white powder, of little
 taste, totally destitute of smell, and the  specific gra-
 vity, according to Kirwan, of 2.3.
  Experiment 5.  If tincture of cabbage be added  to
 a mixture of one part of magnesia and six of water,
 the mixture will instantly become green.  See  Earths
in  General.
  Experiment 6.  Magnesia and  water, when  mixed,
 do  not adhere  together,  but  it  has, nevertheless,  a 
308
strong affinity  for  that fluid.   See the Remark to ex
pcriment 1.  One  hundred parts of magnesia tin own
into water, and then dried, are increased in weight to
118 parts.
  Experiment  7.  If magnesia be formed into a cake
with water, according to Darcet, and then exposed to
a violent heat, the water is entirely driven oft', and the
magnesia contracts  in its  dimensions ;  at the  same
time, it acquires the property of shining in  the dark
when rubbed upon  a hot iron  plate.
  Experiment 8.   If water be added to magnesia  and
then filtered,,it will be found  that a minute portion is
dissolved.
  Remark.   Mr.  Kirwan says that  it requires  7900
times its weight of water at the temperature of 60°, to
dissolve it.
  Experiment  9.   If pure magnesia be exposed to the
air, it will, in time, increase in weight.
  Rationale.  This is owing to the absorption of car-
bonic acid and water. If an acid be added, the former
will be disengaged with  an effervescence.
  Experiment  10.  If carbonate of magnesia be digest-
ed in fresh prepared lime  water, it will be found that
the lime will  have taken the  carbonic acid  from the
magnesia; for the water, on filtering it, will  be found
to have lost all the properties of lime water.
  Experiment  11.   If two parts  of magnesia  and  one
of sulphur be  exposed  to a gentle heat in a  crucible,
union will ensue,  and  sulphuret of magnesia will be
formed.
   Experiment  12.  If muriate of magnesia be dissolved
in alcohol, and the  alcohol then set on  fire, it  will  pro-
 duce a very beautiful orange  coloured flame.
   Remark.  Magnesia combines, with the acids form-
 ing magnesian salts, which will bt noticed hereafter.
 As this  earth  occurs in many  stones, its  separation
 from other earths  is important  in chemical  analysis.
 We shall, therefore, give the processes for separating
 magnesia from other earths.
   Experiment  13.  To a stone, containing  magnesia
 and lime previously pulverised,  add  concentrated sul- 
309
 phuric acid.   Apply a  sand heat  till the acid ceases
 to  rise, and then  raise the  beat  so as to expel the
 excess of  acid.  Weigh  the  div mass,  and digest
 it  in   twice its weight of cold distilled  water.  Fil-
 ter  the fluid,  and  add  to  it carbonate of potash, col-
 lect the  precipitate,   wash  it and expose  it  to  a
 strong heat; its weight will give the quantity of mag-
 nesia in the stone.   The substance which  remains on
 the  filter, when  washed in a  little  water, and dried in
 a low  red heat,  will give  the  quantity of lime by de-
 ducting from its weight 5'J per cent.*
   Rationale.  The sulphuric acid unites with the mag-
 nesia  and lime, forming  sulphate of magnesia, and
 sulphate of lime: on adding water, the former is dis-
 solved, which passes the filter, and the latter remains
 behind.   The  sulphate  of magnesia is then  decom-
 posed  by  carbonate  of potash, by  compound  affinity,
 and the quantity of magnesia ascertained.  By deduct-
 ing  59 per cent, from the  sulphate of lime, will give
 the proportion  of lime.
  Experiment  14.   To  a  stone containing magnesia
 and  alumine add nitric  or muriatic acid, and  effect a
 solution.  To this solution, when cold, add carbonate
 of ammonia, which  will separate the alumine.  The
 remaining fluid, after separating the precipitate, is to
 be treated with carbonate of  potash as before  noticed.
  Rationale.  The solution of  magnesia and alumine,
 when treated with  carbonate of ammonia, is  decom-
 posed :  the alumina is precipitated, and,  as carbonate
 of ammonia in  a lower temperature, does  not decom-
 pose magnesian salts, the magnesia is held in solution.
 Or,
  Experiment 15.  To a solution of the two earths add
 succinate  of soda, and the alumine will be precipitated.
  Remark.  Iron, should it occur, may be separated by
 digesting  the earths in nitric  acid, and exposing the
 solution, previously evaporated to dryness, in a cruci-
ble to a low red heat during one hour.   The iron will
thus be highly oxydized. On  adding diluted nitric acid
it will  remain behind.
         * Kluproth's Analytical Essnys, vol l 76, 
310
  Experiment  15.  If to a solution containing  magne-
sia and manganese,hydrosulphuret of potash be added;
the latter will  be precipitated.
  Remark.   The manganese is precipitated as a hvdi o-
sulphuret, which, when exposed to heat, and weighed,
will give its quantity.  To the remaining solution pot-
ash is to be added, which will separate  the magnesia.
  Magnesia, like lime, is a metallic per-oxyd, to  the
base of wdiich Mr. Davy has given the  name  of mag-
nium.   When moistened magnesia is exposed to  the
action of galvanism in contact with mercury, the earth
is reduced,  and its  base  unites  with  the mercury.
Moistened sulphate  of magnesia succeeds much bet-
ter than the  pure earth.   Magnium  is a white metal,
having the appearance of silver.  When the amalgam
ef magnium is exposed to the air it gradually  absorbs
oxygen, and the magnium is converted into magnesia.
TUie metal decomposes water and generates magnesia.
                SECTION III.

                  OF BARYTES.

  Experiment 1.  Dissolve native carbonate of barytes
in diluted nitric acid, evaporate the solution, and suffer
it to crystallize.  Put the crystals into a china cup, or
silver crucible, and after exposing it to a dull red heat
for at least one hour, transfer the  greenish solid con-
tents into a well stopped bottle.  This is pure barytes.
  Rationale.  The nitric acid decomposes the  • \iibo-
nate of barytes, carbonic acid is disengaged, and ni-
trate of barytes is formed.  On exposing this to the
action  of heat, the nitric acid is separated,  which is
decomposed into its constituent parts, and the barytes
remains behind.
  Experiment 2.  If powdered sulphate of barytes be
boiled  in  a flask,  for about two hours, in a solution 
311
u: twice or three times its weight of carbonate of pot-
ash,  and  the  powder  then  collected,  washed, and
exposed  in a  crucible  to a strong heat, pure  barytes
will be formed.
  Rationale.  The carbonate of potash decomposes the
sulphate  of barytes ; the sulphuric acid  passes to the
potash, forming sulphate of potash, which remains in
solution,  and the carbonic acid  unites with the barytes
forming carbonate of barytes, and  remains in the form
of an  insoluble powder.  When this is exposed  to a
violent heat, the carbonic acid  is expelled in the form
of gas.
  Experiment  3.  If one part of sulphate of barytes be
mixed with eight of charcoal, both reduced to powder,
and exposed in a crucible for  some hours, to a  red
heat, and  the powder then taken and dissolved in di-
luted  nitric acid, the solution filtered, and then treated
in the same manner as Experiment  1, pure  barytes
will be procured.
   Rationale.   The charcoal decomposes the sulphuric
acid of the sulphate, carbonic acid is disengaged, and
sulphuret of barytes is  formed.   On adding  nitric acid
in the state  of dilution, the sulpiuir  will  be  disen-
gaged, sulphuretted hydrogen gas evolved, and nitrate
of barytes will remain in solution.  On  exposing this
to heat  as in  Experiment  1, the  same  effect will
ensue.
   Experiment 4.  Proceed as  in  the last experiment
with  sulphate of barytes and  charcoal; dissolve the
residue in water, filter it,  and  add a solution  of car-
bonate of soda to the filtered liquor.   Collect the pre-
cipitate, and expose it to a strong heat in a crucible,.and
pure barytes will remain.   Or take the powder which
precipitates, and mix it with charcoal powder, make
the mixture into balls, and heat it strongly  as before.
When these  balls are treated with boiling water, -a
portion of barytes is dissolved, which crystallizes as
the water cools.
   Rationale.  The sulphate is decomposed by charcoal
as before.  The  carbonate of soda precipitates  the ba-
rytes, which is exposed to heat  to disengage  the carbo- 
312
, ic acid, or it is mixed  with  charcoal and treated as
before mentioned, by  which  the  barytes is left in a
free state.
   Remark.   Barytes  was discovered by  Scheele in
i774.  The heavy mineral, of a foliated texture and
brittle, which is found in Europe and  America, and
sometimes as a gangue to ores,  was known by  the
name of ponderous spar.   It was  examined  by Gahn,
who discovered that it contained  sulphuric acid, and
the new earth discovered by Scheele.   Bergman con-
firmed the experiments of Gahn, and gave the earth the
name of terra ponderosa.  Morveau called  the  earth
barote, and Kirwan barytes.   Various papers have ap-
peared on this earth.  Barytic  earth has a caustic taste,
and is a violent poison.  It  tinges  vegetable  blues
green, and decomposes the animal bodies like the fixed
alkalies, though with less energy.   Its specific gravity,
according to Fourcroy, is 4.   When heated it becomes
harder.   Before the blow-pipe, on charcoal, it fuses,
bubbles  up, and runs into globules.   Sulphate of ba-
rytes is very plentiful in the Devonshire lead  mines ;
the workmen call it Cauk.  Casciarole, an Italian shoe-
maker, discovered that if sulphate of barytes be calcin-
ed in a peculiar way it will acquire a phosphorescent
quality, and will shine  even in water.  It is known by
the name of bologna phosphorus.   See page  49.
   Barytes has been proposed as a medium for  decom-
posing muriate of soda in a cheap  way.   The  method
of using it may be seen in the Annales de Chimie, tome
xix.  See  also a paper of Vauquelin's on this  subject
in the Journal de Rhys. 1794, p. 297.
   Though this earth has been accounted highly  poi-
sonous, yet Dr. Johnson  says,  that he has seen a deli-
cate female  take thirty  drops of a saturated solution
of muriate of barytes repeatedly in  the course of a day
without even nausea.  He therefore concludes, that it
would require at least 2 or 3 drams to do mischief.
  Barytes is a basis of a  water  paint, which was disco-
vered by Mr. Hume, and  sold under  the name of 
-II .-
o 1 J
Hume's ;■..-„ nnancut white, which it is said, will mix
with any other colour without injury.
  The union of barytes with acids forms  a  class of
salts.   See Salts of Barytes.
  Experiment 5.   Expose barytes  to  the air, it will
attract moisture and carbonic acid, and acquire weight.
  Remark.   In this process the barytes swells  and
emits heat, and, after it is slacked, it attracts carbonic
acid, and increases 0.22 in weight.
  Experiment 6.   Pour water upon barytes, it will ex-
hibit the  same phenomena as quicklime, and be  dis-
solved, forming barytic water.  On evaporating the so-
lution, it will  crystallize  in the form of needles;  but
more commonly in hexagonal prisms, having two broad
sides, with two intervening narrow ones, and terminat-
ed at each end by  a four sided prism.
  Remark.   Water is capable of dissolving 0.05 parts
of its weight of water.  The crystals of barytes con-
tain 53 parts of water, and 47 of barytes.   When ex-
posed  to  heat, they undergo the  watery fusion.   A
stronger heat disengages all the water.   Crystallized
barytes is soluble in 17| parts of water  at the tempe-
rature of 60°.  If the temperature be increased,  the
water will dissolve a larger quantity.   Exposed to the
air the crystals effloresce, and become pulverent.
  Experiment 7.  Add  tincture  of cabbage to barytic
water, and its colour will be changed to  green.
   Experiment 8.  In the same manner mix some tinc-
ture of Brazil wood; the  red colour will be altered to
that of violet.
  Experiment 9.  Immerse a  slip of turmeric  paper,
or add some of the tincture  to barytic water, and a
brown colour will be produced.
   Experiment 10.  Mix one part of olive oil with three
of a concentrated aqueous solution of barytes, they will
unite  into a saponaceous mass, rendering the oil mis-
ciblc  with the water.
  Remark.   These are  the general characters  of ba-
rytes, which answers to the alkalies properly so called.
  Experiment  11.   If a solution of barytes be exposed
to the air, it will  acquire a  pellicle like lime  water, 
314
  ■ihich, when it increases sufficiently,  will fall to the
 bottom of the vessel; or,
   Experiment 12.   Mix  water impregnated with  car-
 bonic acid  with barytic water, and the whole  will be-
 come turbid.
   Rationale.   Barytes diaving a  strong  attraction for
 carbonic acid, when it conies in contact with that acid,
 unites with it, forming carbonate of barytes, which, be-
 ing insoluble, precipitates.
   Experiment 13.  If barytes with half  its weight of
 silica be exposed on charcoal to the action of the heat,
 produced by  a  blow pipe, it will melt with the silex
 and form a globule of glass.
   Experiment  14.  If a  mixture of barytes  and sul-
 phur be exposed  in a crucible to the  action  of heat,
 they will unite, and form sulphuret of  barytes.
   Remark.  The sulphuret of barytes is of a brownish
 colour ;  it decomposes water,  a  portion of sulphuret-
 ted  hydrogen gas is evolved, and a hydroguretted sul-
 phuret is formed.  Boiling water poured upon  the sul-
 puret dissolves it,  and the  solution, on cooling,  depo-
 sits  a great number of  crystals, either  in  six-sided
 prisms or in  hexagonal  plates,  which Berthollet has
 called, from their being composed of sulphuretted hy-
 drogen and barytes, hydrosulphuret of barytes.   The
 liquor still  retaiijs a  portion in solution.
   Experiment 15.   If phosphorus and barytes be intro-
 duced into  a glass  tube close at one end,  and the tube
 heated upon burning coals, as in making phosphuret
 of lime,  a phosphuret of barytes will be formed.
   Remark.  The phosphuret of  barytes decomposes
 water, in the same  manner  as phosphuret of lime.
   Experiment 16.   If a few crystals of barytes  be add-
 ed to alcohol, and,  when the solution has been formed,
*he  alcohol inflamed, it will burn  of a yellow co-
 lour.
   Experiment 17.   If a grain of sulphate of soda be
 dissolved in a wine glass  full of distilled  water, and a
 few  drc$>s of muriate of barytes  added,  a turbidness
 will  ensue,  and  a white precipitate will result.
   Rationale.  The  sulphuric acid unites  with  the ba- 
315
 rytes, forming sulphate of barytes, which,  being in-
 soluble, is precipitated   Hence the  soluble  salts  of
 barytes  have been  used as a test  for sulphuric  acid
 and its  combinations.
   Remark.   Sulphate of barytes is one of the most in-
 solubie substances which chemistry presents, requir-
 ing for its solution about 4300 times its weight of wa-
 ter.  Tim nitrate or muriate of barytes is  generally
 used as  a re-agei.t.
   Experiment  18.   If a  stone which  is supposed to
 contain  barytes, be dissolved  in diluted nitric  acid,
 the solution filtered, and sulphate of soda added, and if
 a white precipitate should be formed, insoluble in water,
 barytes may be inferred.
   Rationale.   The  nitric acid  effects the solution of
 barytes ; and on adding sulphate of soda, it is precipi-
 tated in  the form of sulphate of barytes.
   Remark.   By this means barytes may be known and
 separated from other  earths, but as strontian is  also
 precipitated by sulphuric acid, its  presence may be
 known in the following manner :
   Experiment  19.  If a mixture of  barytes and stron-
 tian exist in the same solution, add sulphate of soda till
 the  precipitate ceases, decant the supernatant liquid,
 waSh the sediment  on a fiiter, and dry it, then digest
 it  in four times its weight of pure carbonate of potash,
 and a sufficient quantity of water,  in*a gentle  heat dur-
 ing three or four hours.  On the powder pour nitric
 acid, of  the specific gravity 1.4, diluted with an equal
 weight of distilled water, which will dissolve  the stron-
 tian, and not the barytes.*
   Rationale.   In this experiment the  sulphuric  acid
 comhincs with  the barytes and strontian, which are pre-
 cipitated in the state of insoluble sulphates. On digest-
 ing the precipitate  in carbonate of potash, the sulphate
 of barytes as well as the sulphate of  strontian, is de-
 composed, a sulphate of potash formed, which remains
in  solution,  and the carbonates of barytes and stron-
 iaii exist in the form of an insoluble  powder.  On add-
* Henry. 
316
ing nitric acid,  the  strontian  is taken up, leaving the
barytes.
   Remark.  Sevcrtil other modes of separating barytes
from strontian maybe seen in  Klap.oth's Essays.
   Mr. Davy has succeeded in decomposing barytes by
the agency of galvanism, and has shown, that it is a me-
tallic per oxyd.   To the metal, which forms its base,
he has given the name of barium.   Its colour is white.
On exposure to the air it becomes tarnished, by absorb-
ing oxygen, and is converted into barytes.   It sinks  in
water, and is about four or five times  heavier than that
liquid. It decomposes water, and emits hydrogen. The
proportion of barium and oxygen  in barytes  has not
been asccrtai. «ed.
                 SECTION  IV.

                OF STRONTIAN.

  Experiment 1.  If carbonate of strontian be exposed
to heat in a crucible, the strontian will be obtained in a
pure state ; or,
  Experiment 2.  If carbonate of strontian be dissolved
in nitric acid, and exposed to heat in the same manner
as stated for obtaining barytes, strontian  will be pro-
cured ; or,
  Experiment^.   If sulphate  of strontian be mixed
with one sixth part of its weight of charcoal powder,
and  kept for some  hours  red  hot in a crucible; the
mass then  dissolved in water, filtered, and  nitric acid
poured into the solution as long as a  precipitate ensues ;
the nitrate of strontian evaporated and crystallized, and
the crystals exposed in a silver crucible to heat till all
the nitric acid is expelled, pure strontian will be pro-
duced.
  Rationale.  In the  first  process the carbonic acid is
disengaged by the heat, leaving the strontian  in tho 
SIT
crucible :  in the second, the carbonate is decomposed
by nitric acid,  which  is afterwards expelled; and in
the third, the sulphuric acid is decomposed by the coal,
carbonic acid is disengaged, and the sulphuret of stron-
tian is decomposed by nitric acid, which is disengaged
by the heat.
  Remark.   Strontian was discovered  in a mineral
brought from  the  lead mines of Strontian in Argyle-
shire, England, a specimen of which was  brought to
Edinburgh in 1787, and was generally considered as a
carbonate of barytes until Dr. Crawford in 1790, in his
treatise  on  muriate of barytes, mentioned that it might
contain  a new earth, from its chemical characters being
in some respects different from those of barytes.   Dr.
Hope instituted some experiments in 1791, which de-
monstrated that the mineral was a compound  of carbo-
nic acid  and a peculiar earth, to which the Doctor gave
the name of strontitcs.
  Klaproth made  some  experiments on it, and drew
the same conclusions as Dr. Hope, though he was. un-
acquainted  with  the experiments  of the Dr.    Mr.
Kirwan  in 1793, discovered many interesting proper-
ties of this  new earth, which afterwards appeared in the
Transactions of the Irish Academy.  Pelletier, Vau-
quelin and  Fourcroy also investigated it. Klaproth gave
to the new  earth the name of strontian.  Strontian is
found abundantly  in many situations, either combined
with carbonic acid or sulphuric acid. Strontian, obtain-
ed according to the foregoing, processes, is of a grayish
white colour,  and of an acrid  and alkaline taste.  Its
specific  gravity is  1.647.   It converts vegetable blues
to green.   Before  the blow pipe it possesses  some pe-
culiar properties.
  Experiment  4.   Strontian sprinkled  with water, be-
comes hot, and falls to powder like lime in the act of
slacking:  on adding more of  that fluid the  strontian
dissolves, forming strontian water.
  Remark.   One part of  strontian will dissolve in 162
parts  of water  at the temperature of 60°.   The solu-
tion  is  transparent, and  converts vegetable  blues to
                     d  d  2 
318
green. If hot water be used it will dissolve it in larger
quantities, and on cooling, it will separate in a crystal-
lized form in thin quadrangular plates.   But the form
of the crystals varies.  They  contain 68  parts in the
hundred  of water, and are soluble in 51.4 parts of water
at the temperature of 60".  On  exposure  to the air,
they effloresce, and absorb carbonic acid.
  Experiment 5.   If sulphur  and strontian be melted
in a crucible, they unite and form sulphuret of stron-
tian.
  Experiment 6. To the sulphuret, thus prepared, add
water, and a solution will be made, which, on evapora-
tion, will afford  crystals of  hydrosulphuret of strontian,
the remaining • liquor will be an hydroguretted sulphu-
ret.
  Remark.  It is evident that when the sulphuret is
added to water, that fluid is in part  decomposed, sul-
phuretted hydrogen is partly  disengaged, and another
portion unites with the strotian forming the compounds
already noticed.
  Experiment 7-   If one part  of phosphorus be mixed
with six  of strontian,  in an iron or earthen tube closed
at one end, and the mixture heated gradually to a dull
red heat, a phosphuret of strontian will  be formed.
  Remark.  This  phosphuret decomposes  water like
the phosphuret of  lime.
  Experiment 8.   If nitrate of strontian be put into al-
cohol, and the alcohol inflamed, it will burn with a car-
mine-red colour.
  Experiment 9. If a mixture of nitrate of strontian and
charcoal powder, in the  proportion of one part of the
former to three of the latter, be inflamed, it  will burn
of a carmine colour.
  Remark.  This  property of producing a flame of a
carmine   colour, is one of the most striking effects  of
this earth.
  Experiment 10.  If sulphuric  acid be  poured into
a solution of  oxymuriate of  strontian, an increase of
temperature takes place, accompanied with an evolu- 
319
tion of light.  If the acid be poured in the dry oxymu-
riate, no light is produced.
  Remark. This singular fact was discovered by Messrs.
Davy and Clayfield.
  Experiment 11.  If strontian be dissolved in nitric
or muriatic  acid, the solution  will be decomposed on
adding sulphuric acid, or the sulphates.
  Remark.   The precipitate which appears when sul-
phuric acid  is added, has rendered  the  solutions of
strontian useful as  re-agents to discover that acid and
its combinations.
  Mr. Davy has decomposed strontian,  and proved
that it has a metallic base which he calls strontium.  It
is a white metal, heavier than  water, and  decomposes
that fluid, absorbing oxygen, and is converted into stron-
tian.
                DIVISION II.

          OF THE EARTHS PROPER.

  The earths proper are five in number, namely, alu-
mina, yttria,  glucina, zirconia and silica,  and differ
from the alkaline earths  in not possessing the charac-
ters of alkali, such  as causticity,  solubility in water,
effect on vegetable colours, and the like.
                 SECTION  I.

                 OF ALUMINA.

  Experiment 1.  If one part of the alum of commerce
be dissolved in six parts of boiling distilled water, and
when cold, liquid ammonia added until no further pre. 
320
cipitate ensues; and the whole then heated, and poured
on a filter, the precipitate washed until the water comes
off tasteless,  then put into a basin, and  muriatic acid
added to it in small quantities at a time till the whole
is dissolved; the solution now  evaporated, till a drop
of it, when suffered to cool on a plate of glass, yields
minute crystals;  these crystals (of alum) separated by
decanting the fluid; this fluid then decomposed by add-
ing to it  liquid ammonia ; and the precipitate thus ob-
tained, when washed and dried will be pure alumina.
  Rationale.  The alum  being a triple salt, consisting
of alumina, potash and sulphuric  acid, is decomposed
by the ammonia, which unites with the acid forming
sulphate of  ammonia,  and precipitates the  alumina.
As the precipitate may contain sulphate of alumina, it is
dissolved in muriatic acid, and the solution (muriate of
alumina) evaporated in order to separate the alum. The
muriate  of alumina is then decomposed  by the ammo-
nia, muriate of ammonia is formed, and the alumina
is precipitated.   By washing  the  precipitate the mu-
riate of ammonia is  separated, as it passes off in solu-
tion.
  Experiment 2.   If to a solution of alum, carbonate of
potash be  added until the precipitate ceases, and the
precipitate collected, washed  and dried, then exposed
to a strong heat for one hour in a -crucible, alumina will
be obtained.
  Rationale.  When carbonate of  potash is  added to a
solution  of alum, the alkali unites with  the sulphuric
acid of that salt, and forms sulphate of potash, whilst the
carbonic acid combines with the alumina, and forms a
precipitate of carbonate of alumina.  When this is ex-
posed to heat, the  carbonic acid is expelled, and the
alumina  remains untouched.
  Remark.   This process, however, is imperfect; for
the alumina thus  procured, when exposed to heat with
charcoal, afterwards treated with a diluted acid, will
emit sulphuretted hydrogen gas.  The former is there- 
321
lore preferred. In order to free alumina from sulphuric
acid, the following method is proposed by Guyton.*
  Experiment 3.  After the precipitate is obtained from
alum by  carbonate of potash, dissolve it in nitric acid ;
add to the solution nitrate of barytes as long as any pre-
cipitate is formed ; separate  the precipitate by the filter,
evaporate the liquor to dryness, and expose it to a strong
heat till all the nitric acid is expelled.
  Rationale.  The nitric acid unites with the alumina,
and the carbonic acid is disengaged.   The  addition of
nitrate of barytes separates the sulphuric acid which
might  remain, by forming  with it sulphate of barytes.
This is  detached by the filter, and the nitric acid is
afterwards expelled by the action of heat.
  Remark.  The earth obtained from alum, was  sup-
posed  by Stahl and  Neuman to be lime ;  but in 1727
Geofroy, junior, proved that the earth of alum consti-
tutes a part of  clay.   Margraff, in  1754, demonstrated
that the  basis of  alum is an earth of a peculiar nature.
Hence it was called argil: it was afterwards named alu-
mina, because it may be obtained from alum.  Macquer,
Bergman, Scheele, and more lately Saussure, have in-
vestigated the propertiesof this earth.
  Saussure gave  it the name of spongy alumina. If the
earthy  salt (alum)  be dissolved  in as little water as
possible, and the alumina then precipitated, the earth
is light, friable,and very spongy, hence its name;  but
if a large quantity of water b,e used to effect the solu-
tion, the alumina is obtained in a brittle transparent
yellow coloured mass, splitting in pieces like roll sul-
phur when held in the hand  In this state it forms the
gelatinous alumina of Saussure,   Alumina  has  little
taste, and, when pure, has no smell;  but if it contains
oxyd of iron, it emits, when breathed upon, a peculiar
odour, which is known by the name of the earthy smell.
Common clays have this property.  The specific gra-
vity of alumina is 2.00.   When  heated, alumina  con-
tacts bv heat.   Mr. Wedgwood took advantage of this
* Ann de Chim. xxxii. 64. 
322
property, and constructed an  instrument called a py-
rometer for measuring high degrees of heat.   See page
61.  This instrument, however, is liable to error.
   Experiment 3.   Pour water  on alumina, and, after
standing some time, filter it off':  it  will be found that
its properties are unaltered.
   Remark.   Water, therefore, has no sensible effect on
alumina; but alumina may be diffused through it with
great facility.  It is said  in its  usual state to be com-
bined with more than its own weight of water.
   Alumina  does not combine with  oxygen or azote.
Charcoal it is said  will combine with  alumina.   This
combination forms a black substance,  which is very
frequently found native.   Alumina and oxyd of iron
often occurs of a yellow colour, which  is known by the
name of ochre.
   Experiment 4.   Mix  fresh prepared lime water and
alumina; if the mixture be iiltered, it  will be found
that the lime is taken from the water.
   Remark.  This experiment proves, that alumina pos-
sesses a strong attraction for lime.  For the fusibility
of different  mixture of alumina and lime, see Kirwan's
Mineralogy, vol. i. 65. Barytes and strontian also combine
with alumina, both when  heated with  it in a crucible,
and  when boiled with it in water : alumina, magnesia,
and  lime, form, when melted, what is called porcelain;
but this is produced in  a particular way.*
   Experiment 5.   If one part of alumina be boiled for
some time with six of potash, soda,  8cc. in a sufficient
quantity of water, a combination will  take place; and,
   Experiment 6.   If to this solution  sulphuric acid be
added, the alumina will  be precipitated.
   Rationale.   The alumina is dissolved by the alkali in
Experiment 1, and, in the second, is precipitated from
its solution  by sulphuric  acid; sulphate of potash is
formed, and the alumina is precipitated.  If more acid
be added, the alumina is dissolved.
* r!ee Kirwan, vol. i. p. 72. 
323
   Experiment 7.   If to a solution of alumina in potash
 we add another of silica in the same alkali, and  suffer
 the  mixture  to  stand  for a  few hours, a precipitate
 composed of alumina and silica will be formed.
   Remark.   A considerable  degree of affinity  exists
 between alumina and silica, and the unsuspected forma-
 tion of this compound  in many analytical experiments
 on minerals has often produced a number of  deceitful
 and embarrassing appearances.  We are indebted to
 the indefatigable Klaproth for shewing, that when to a
 solution of pure silica, in caustic potash, is added a so-
 lution of alumina equally pure in the same menstruum,
 the liquor immediately assumes a reddish brown colour,
 .md after standing an hour or two, coagulates.  By the
 addition of a little warm water, this jelly is resolved in-
 to a fluid, and being thus mixed with muriatic acid -to
 the exact saturation of the alkali, a copious precipitate
 is deposited,  consisting of the two earths in a state of
 combination : if now a  slight excess of acid is dropped
 in, the silica as well as  the alkali will be perfectly dis-
 solved.  Carbonate of potash will again cause the pre-
 cipitate to appear, and this, even separated by the filter
 and dried, will be entirely soluble in diluted sulphuric
 acid, without the smallest deposition of silica.   If the
 sulphuric solution is now gently evaporated, crystals
 of alum will be deposited, and the remainder will as-
 sume the form of a clear jelly.
   Experiment 8.   If one part of alumina and six of pot-
 ash and soda,  with a sufficient quantity of water, be di-
 gested with heat, a solution of the alumina will take
 place.
  Experiment 9.   If to  this solution an acid be added,
 the alumina will be precipitated.
   Rationale.   The alumina is dissolved by the  alkali in
 the first experiment, and then precipitated from the
 solution by the acid in the second;  the acid and alkali
 unite into a peculiar compound.
  Remark.  This is a method sometimes employed tp
prepare  pure alumina.   Alkalized alumina has  been
employed as a preferable mordant to common alum, 
324
 in the fixing of those colours that are  injured by  the
 presence of sulphuric acid.
  Experiment 10.  If to a watery infusion of cochineal,
 fustic, quercitron bark, or madder, a few drops of a so-
 lution of alum be added, the colouring  matter will be
 precipitated in the form  of a lake.
  Remark.  The affinity that subsists between alumina
 and vegetable or animal colouring matter, is  singu-
 larly powerful.  The colouring matter in this experi-
 ment is precipitated with the aluminous base  of  the
 earthy salt, leaving the  supernatant liquor wholly co-
 lourless.   Alumina  unites  with acids, and  forms a
 class of salts.  See Salts of  Alumina.
  Experiment 11.  Put equal parts of brown sugar and
 alum into a crucible, and expose the mixture over a
 fire until it is melted, and reduced to  dryness.  Pul-
 verise the mixture, and introduce it into  a  common
 vial coated with clay, to which  a  glass tube, open at
 each end,  is luted, to allow the escape of the  gases
 that are produced.  Set the vial in a crucible surround-
 ed  by sand,  and  expose the  whole to heat.  When
 the gas or vapour has  ceased to  be evolved,  which
 may be known by  its not taking fire on presenting a
 lighted candle, the crucible may  be removed from the
 fire; and the end of the  tube closed by a little moist
 clay.  The preparation thus formed is pyrophorus.
  Remark.  The pyrophorus, called by some the  pyro-
 phorus of  Homberg, is a black  powder, which  takes
 fire on  exposure to the air.  It is supposed to be a
 compound  of alumina, sulphur,  and charcoal   Gren,
 in his Principles of Chemistry, vol. i. p. 256, accounts
 for  the spontaneous accension of  pyrophorus in the
 following manner s part  of the charcoal decomposes,
 in a red heat, part of the sulphuric acid of the alum,
 and becomes  converted into carbonic acid gas, which
 escapts ; the  sulphuric acid  is thus partly converted
 int© sulphur, which sublimes and burns. During these
 changes, the potash, which is  present in the  alum of
 commerce, unites to a part of the sulphur, and  forms
with it a sulphuret of potash, and there remainsthe super-
fluous part of the coal that had been blended with the 
325
alum.  Dry potash, charcoal  sulphur, and alumina are
therefore the constituent parts of the pyrophorus.  On
exposure to the air, the potash rapidly attracts its mois-
ture, and is  heated with it.  This heat is sufficient to
inflame the  sulphur;  because sulphur is already by
its own nature, when combined with alkaline substances,
by far more disposed to decompose oxygen gas.  This
ignition of the  sulphur in the pyrophorus is commu-
nicated to the coaly particles, that, at the beginning of
its  preparation, were  mingled  with the  sulphate of
alumina.  Thus far is the theory of Mr. Gren.  See
page 51.
  Sauvigny attributed  the  combustibility of pyrophori
to the sulphuric acid, healing by the moist air, and in-
flaming the disengaged sulphur.
   Proust d'-nied the presence of sulphuric acid ;  and
Mr.  Bewly  imputed  it to the attraction  of the  ni-
trous acid from the air, and the heat generated by its
union.  Pyrophori may be made in  a variety of ways,
as follows : Five parts of burnt  alum and  one of char-
coal  intimately mixed ; or  three parts of alum with
one of sugar, honey, or flour, melted  together, and kept
over the fire until it has become blackish, being put
in an earthen bottle, about two thirds full, and kept in
a red hot state, surrounded with sand in a crucible, as
long as a blue flame is perceived at the mouth of the
bottle.
   Bewly obtained  pyrophorus by nearly filling the bowl
 of a tobacco pipe  with two parts of alum, one of char-
 coal,  and one  of  salt  of tartar, pressing it down and
 filling up the bow with fine sand, and exposing it to  a
 heat for three quarters of an hour, a longer time do-
 ing it no injury.  He also obtained  it  from  powdered
 charcoal, with double or treble its  weight of calcined
 blue or green  vitriol,  or of sulphate of zinc, and from
 a mixture of charcoal, well calcined  sulphate of pot-
 ash, or of soda, and from potash and vegetable  or ani-
 mal coal.  A pyrophorus, it is said,  is immediately
 formed by  rubbing together in a mortar 54 grains of
 sulphur, 36 of very dry willow charcoal, and 3 of com-
 mon phosphorus.
                        e e 
32G
   Experiment  12.  If to a solution containing alumina
 and magnesia, malate of potash be added, a white pre-
 cipitate will appear, of difficult  solubility,  which on
 examination, will be found to be a compound of malic
 acid and alumina.
   Rationale. ^  When malate of potash is added to a so-
 lution containing alumina and magnesia,  a double de-
 composition  ensues : the acid which  held the earths
 in solution will unite with the alkali, whilst the  malic
 acid in its turn unites with the alumina and magnesia,
 forming earthy malates ; but as the malate formed with
 the alumina is insoluble, that compound is precipitated,
 whilst the malate of magnesia remains in solution.
   Remark.  Alumina, in the state of common clay, is
 employed for various purposes, on account of its apti-
 tude for moulding into different forms, and its proper-
 ty of hardening in the fire ; such as for making bricks,
 earthen ware, porcelain, crucibles, 8cc.  The subject
 of Pottery will be noticed hereafter.  For securing the
 bottoms and sides  of canals and  reservoirs of water,
 alumina is of much value.  This earth  composes in
 a great measure  those tenaceous earths  called arable
 soils.  In combination, it is employed by the dyer and
 calico-printer, as  a mordant for fixing various colours.
  It was supposed  by Baron,  that alumina was a me-
 tallic oxyd, which l#d to several experiments, and
 much speculation. Sir Humphrey Davy has succeeded
 in decomposing it by  the galvanic influence, and  pro-
 poses to give to its base, as it  is a metal, the name of
aluminum.   Little, however,  is known on  the subject.
                  SECTION II.

                  OF YTTRIA.

  Experiment  1.  Take the mineral called gadolonite,
reduce it  to powder, and add a mixture of nitric and
muriatic acid  till it is  decomposed, evaporate the s»i 
327
lution  nearly  to dryness, and filter it.   To the liquor
thus obtained, add water ; by this means the silica is
left behind.   Filter a,eain, and  evaporate  the fluid to
dryness, and  expose the dry mass for a considerable
time in a close vessel.  Now  dissolve the  mass in
water,  filter the solution, and add to it liquid ammonia;
pure yttria will be precipitated.
  Rationale.   The  nitro-muriatic  acid  dissolves  the
yttria,  which,  after  some intermediate operations, is
precipitated by. ammonia, which takes the place of the
yttria.
  Remark.   This  earth  may also be obtained from a
mineral called yttrotantalite,  which is a compound of
tantalium and  yttria.
  A mineral  was  discovered about the year  1771 by-
Captain Arhenius, in the quarry of Yttcrby in Sweden,
a description  of which  was published in Crell's  An-
nals and Miner's  Lexicon, and was analysed by  pro-
fessor  Gadolin in  1794, who found it to contain a  n :w
earth.   The experiments of this chemist were after-
wards  repeated, and his conclusions confirmed.   Mr.
Ekeberg -gave to  the  new earth  the name  of yttria.
Vauquelin  and Klaproth also repeated the experiment
of the  professor.   Yttria is  a white powder, whose
specific gravity is 4.842. It is precipitated from its
solution in  acids by ammonia and prussiate of potash.
In pure alkalies it is not soluble.  It is precipitated
by tannin.
  It differs from glucina in not being soluble in fixed
alkalies, nor  being precipitated  by  the succinates.
From analogy it is supposed that this earth is a me-
tallic per oxyd.  Ekeberg treated yttria with muriatic
acid, and obtained oxymuriatic  acid gas.   Mr. Davy
is of opinion, that' yttria is not a distinct primitive
earth,  but a modification of some other earth. 
328
                 SECTION  III.

                  OF GLUCINA.

   Experiment 1.  Pulverise the  beryl, or the emerald,
and add to the powder thrice its weight of potash, and
melt  the  mixture in a  crucible.   Dissolve the mass
in muriatic acid, and evaporate the solution to dryness.
To this add  water, and  the silica, which constitutes
more than half the weight of the stone, will remain be-
hind ; add now to the filtered liquor carbonate of pot-
ash, until the precipitate ceases  to appear.  Wash the
precipitate, and  then dissolve  it in  sulphuric  acid.
Add to the solution sulphate of potash ; evaporate it to
the proper  consistency,  and set it by to crystallize.
Alum will gradually form.  To  the fluid now remain-
ing, add a solution ef carbonate  of ammonia in excess,
then filter, and boil the liquid for some time.  A white
powder gradually appers, which is glucina.
   Rationale.   When  the beryl  or emerald is treated
with potash,  the glucina as  well as silica is fused ancf
combines with the alkali. When to  this mass muria-
tic acid is added,  muriate of glucina is formed, and
the silica is separated.  If any other earths be present,
they  are  also dissolved.   All the earths present are
then  precipitated  by  means of  carbonate of  potash,
which takes  place  by compound affinity.  On adding
sulphuric acid, the glucina  and alumina, if it be pre-
sent, are dissolved. When sulphate of potash is added
to this solution, and then evaporated, crystals of alum
or supersulphate  of alumina and potash  will form on
cooling.   After these are separated, as the alumina is
thus detached,  the  addition  of carbonate of ammonia
separates  the glucina gradually in the  form of a white
powder.
   Remark.  Vauquclin is the discoverer of this earth
which he obtained from  the beryl, a transparent stone
of a green colour and a  considerable degree of hard-
ness,  in the year  1798,  when pio^ecuting  some  ex- 
329
periments on  that  stone at the request of the Abbe
Hauy.   To  this newly discovered earth the  name of
glucina was  given.   Klaproth has  since confirmed the
experiments of the French  philosopher.  This earth
has been obtained from  the  emerald as well as from
the beryl or aigue-marine.  It has also been detected
in the  gadolinite.
  Glucina is a light white powder, without either taste-
or smell.  It is infusible by heat.  Its specific gravity
is 2.976.  It is soluble in alkalies ; also in all the acids
except  the  carbonic and  phosphoric, and forms with
them saccharine and slightly astringent salts ; hence
its name from the Greek, which signifies sweet or sac-
charine, because^it gives that taste to the salts it forms,
It is fusible with borax.  It is not precipitated by the
hydro-sulphurets,  nor  by  the prussiate of potash, but
by all the succinates.  Its affinity for acids, which is
intermediate between  magnesia and  alumina may  be
seen in the  table of affinity.
  Sulphuretted hydrogen dissolves it, and forms with
it a  hydrosulphuret   Mr.  Davy has tried to decom-
pose glucina, and, from the result of his experiments
with the galvanic influence, is of opinion, that it is a
metallic per-oxyd, to the metal of which he proposes
to give the  name of glucium.
   Experiment 2.  If equal parts of glucina and alumina:
be dissolved in nitric  acid, two salts will be formed,
which, on evaporation, will shew distinct characters.
The nitrate of glucina has a  saccharine taste; and the.
nitrate of alumina is not sweet, nor does it produce any
precipitate with tincture of galls.
   Experiment 3.   If tartrate  of potash be added  to  a
solution of  nitrate of glucina, no  change will be pro*-
cured;  but,
   Experiment 4.  If the tartrate be added to a solution
of nitrate of alumina, a flaky precipitate will be form-
ed.
   Rationale.  In the first no decomposition ensues, but.
in the second nitrate of potash, and tartrate of alumina
are  formed, the latter of which precipitates.  Hence
the obvious difference between glucina and alumina.
                      E  e 2 
330
  Experiment 5.   To a solution of nitrate  of  glucina
add some oxalate of potash, no change will  take place
even after some days ; but,
  Experiment 6.   On adding  the  same  reagent to ni-
trate of alumina, a very copious white precipitate will
be produced.
  Rationale.  In the first case no decomposition  en-
sues, but in the  second, nitrate of potash and  oxalate
of alumina are formed; the  latter being insoluble, is
precipitated.
  Experiment 7.   To a solution of nitrate  of  glucina
add prussiate of potash, no precipitate will appear ; but,
  Experiment 8.   If  we add prussiata of potash to ni-
trate of alumina, a change will take place.
  Rationale.   Analogous to the preceding.
                 SECTION  IV.

                  OF ZIRCONIA.

  Experiment 1.   Reduce zircon or the hyacinth, to
powder, mix it with thrice its weight of potash, and fuse
it in a crucible.  Wash the mass in pure water, till the
whole of the potash is extracted ; then dissolve the re-
siduum as far as possible in diluted muriatic acid. Boil
the solution to  precipitate any silicia  that  may have
been dissolved, then  filter, and add a quantity of pot-
ash.   The zirconia precipitates in  the state of a fine
powder.
  Rationale.  The fusion of the mineral, with the pot-
ash,  is intended to  separate  principally silica.   For
when the mass is washed in pure  water, the potash as
well as the silica is extracted.  The residuum is treat>
ed with muriatic acid, and the solution is boiled in or-
der to separate any more  silicia  that may  have been
taken up. After this the  addition of potash precipitates 
331
the zirconia, from its solution, as the alkali unites with
the acid, forming muriate of potash.
  Remark.  Klaproth discovered this earth in 1793, in
the zircon or jargon, a gem first brought from Ceylon,
but also found in other countries.   This stone has been
discovered in the United States,  by Mr. Solomon W.
Conrad of this city, a specimen of which he politely pre-
sented me.  Since the experiments of Klaproth, many
others have been made, which confirmed the inferences
of that philosopher.
  Zirconia is a white powder; has  neither  taste nor
odour; and is infusible before  the blow pipe.   Its spe-
cific gravity is 4.3, it is insoluble in water, but has a con-
siderable affinity for that fluid.  It has a strong affinity
for several metallic oxyds, particularly per oxyd of iron ;
it is insoluble in liquid alkalies, neither can it be fused
along with them by means of heat, but it is soluble in
alkaline carbonates.  Zirconia combines with acids and
forms  salts, which  have a peculiar astringent taste;
many of them are insoluble in water.   Mr. Davy has at-
tempted to decompose zirconia, in which he partly suc-
ceeded, and proposes to give  its base, which he sup-
poses to be metallic, the name of zirconium.
  Experiment 2.  If zirconia  be gradually introduced
into diluted  sulphuric acid, it will be  dissolved, and
form a peculiar salt.
  Remark.  This salt is decomposed by heat,  leaving
the zirconia  behind.  Acids  do  not affect it, but al-
kalies and earths decompose  it: charcoal, at a high
temperature, converts it  into a sulphuret, which  when
dissolved  in water and  evaporated, yields crystals  of
hydrosulphuret of zirconia.
  Experiment 3.   If nitric  acid  be added to zirconia,
and digested for some time, a compound called nitrate
of zirconia will be formed.
  Remark.  The nitrate, however, generally exists as
a supernitrate, for the acid in the salt is mostly in ex-
cess.  If the solution be evaporated in a very gentle
heat, and  afterwards exposed, it will shoot into crystals.
The nitrate .is decomposed by sulphuric acid, which 
332
forms with the  earth a white precipitate, soluble in ar.
excess of that acid; by carbonate of ammonia ;  and by
an infusion of galls,  which  affords a white precipitate
soluble in an excess of the  infusion.   The vegetable
acids generally we are told, will take zirconia from the
nitric acid, and form with it insoluble  compounds.
  Experiment 4.   If zirconia be introduced into muri-
atic  acid, it will unite with it, and form muriate of zir-
conia.
  Remark.  Muriate of zirconia is decomposed by sul-
phuric, phosphoric, citric, tartaric, oxalic, and sacco-
lactic acids.  A number of  experiments were institut-
ed by Klaproth and Vauquelin, in which the properties
of zirconia in general are enumerated;  for an account
of these  experiments, see Klaproth's Beitrage,  and
Vauquelin's paper in the  Annales  de Chimie, torn
xxii. p. 179.
                 SECTION V.

                   OF SILICA.

  Experiment 1.  Put into a crucible one part of pound-
ed flint  or quartz, and three parts of potash, previously
mixed,  and apply a heat sufficient to melt them.   Dis-
solve the mass in water, saturate the potash with muria-
tic acid, and evaporate to dryness.   Towards the end of
the evaporation the liquid assumes the form of a jelly;
and when all the  moisture is evaporated, a white mass
remains behind.  After washing this mass with a large
quantity of water, the residue is pure silica.
  Rationale.  When potash is in the proportion of three
or four  to one of flint or quartz, a compound  is formed,-
which is soluble in water.  On dissolving the mass in
water and adding muriatic acid, the alkali is taken from
the silica, muriate of potash is formed, and the silica is
separated. On evaporating the mixture, and afterwards 
333
washing  it well with  water, the muriate of potash is
dissolved and  carried off, whilst the silica remains in a
state of purity.
  Remark.  If gun flints are used they may readily be
pulverised, by heating them red hot and plunging them
into water ; by this means they are rendered brittle. In
precipitating the silica an excess of acid should be used,
in order  that all  the foreign earths which are present
may be separated.  The  mixture of flint and  potash
may be fused  in a silver  crucible, and  the  silica may
be directly separated by dissolving the mass in water,
and adding to  the solution muriatic acid as long as any
precipitate is formed.   This is to be collected, washed,
and dried.  If too much water be used as 24  parts to
one, no precipitation will take place, unless  evapora-
tion be used.  Pure silica may be obtained by separat-
ing it from fluoric acid.
  Silica is found in a variety of stones.  It almost wholly
constitutes quartz  and rock  crystal.   See  the  Table of
Stones.
  Glauber describes this earth.   Different  opinions
were  entertained respecting it; but it was not until the
time of Scheele and Bergman, that its properties were
fully known.
  Silica  is a fine powder, without either taste or smell.
Its specific gravity is 2.66.  It has been exposed to the
action of fire  assisted  by oxygen  gas, without  any al-
teration.   It has been fused, however, by means of the
blow  pipe.  The temperature necessary for  this pur-
pose, is equal to 4043° of Wedgwood.
  Silica is insoluble in water.  When precipitated from
potash by muriatic acid, it retains a considerable quan-
tity of water,  even if exposed to a gentle heat.   Silica
forms a paste  with water, which is not ductile, but con-
stitutes a loose, friable and incoherent mass.  It exists
in a crystallized state in the rock  crystal.  It may ar-
tificially be prepared, by dissolving it  in fluoric  acid,
and suffering the  solution to remain undisturbed. The
crystals, thus obtained, are irregular, but  some of them
 ire in cubes with their angles truncated.   By a similar 

process, Bergman and Seigling obtained crystals from
this earth.   Silica does not combine with oxygen, with
azote, nor with the metals;  but with metallic oxyds it
unites by fusion, and  forms various coloured glasses
and enamels.  These will be noticed in treating of the
metals.
  Experiment 2.   If barytic water be poured  into a
solution of silica  in  potash, a precipitate will appear,
which, on examination, will  be found  to be  composed
of the two earths.
  Experiment 3.  If barytes and  silica be exposed in
a crucible to heat, they will unite, and form a compound
of a greenish colour.
  Remark.  Hence there  is a strong affinity between
barytes and silica.   Mr. Kirwan  has made a number
of experiments on the mixture of these earths.
  Experiment 4.  Silica and strontian exposed to heat,
will unite in the same manner as in the last experi-
ment.
  Experiment 5.  If lime  water be poured into a solu-
tion of silica in potash, a  precipitate is formed, which
is composed of silica and  lime.
  Experiment 6.    Silica  and lime exposed to heat,
forms a peculiar  compound, and if  the quantity of
lime  be inferior to that of  silica, a glass will  be the
result.
  Remark.  Silica and lime have, therefore, a consider-
able affinity for each  other.  Mr. Kirwan has given
several experiments on this subject.
  Experiment 7.  If equal  parts of magnesia and silica,
when melted,  which requires a considerable tempera-
ture,  forms a white enamel.
  Experiment 8.   When  equal portions of silicated
and aluminated potash be mixed,  the  compound will
assume the consistence of jelly.
  Experiment 9.   Silica  and alumina  exposed to a
strong heat, unite, and form a kind of opaque glass, or
rather enamel.
  Remark.   Hence there  is a considerable affinity be-
tween these earths.  Porcelain, stone ware, brick, tile, 
335
 and other  similar mixtures, are composed chiefly of
 this compound.   Silica and alumina, in various pro-
 portions, constitute clays.
   The earths, frequently, when mixed in different pro-
 portions and exposed to heat, are capable of uniting.
   Mr. Davy has rendered it probable, that silica is a
 per oxyd.   This earth was exposed to the  galvanic in-
 fluence, and, from his experiments, he inferred, that itis
 a compound of oxygen and a peculiar metal, to which
 he  has given the name of silicium.   But this conclusion
 is not altogether satisfactory.
  Experiment 10.  If silica, put into a flask, and sul-
 phuric, nitric, muriatic, or acetic acid added, and heat
 applied ; on decanting the  acid, none of  the earth will
 be taken up.  A proof  that the  acid has  dissolved no-
 thing.
  Experiment 11.  If one  part of  silica be put into
 a leaden bottle  with twelve parts of fluoric acid; the
 bottle  closed with a wax  stopper ;  and suffejtod to
 stand for a few days, agitating it frequently, the silica
 will be dissolved.  See the  Properties of Fluoric Acid
 Gas.
  Experiment 12.  If one part  of silica, minutely di-
 vided, and  twenty parts by weight of a concentrated
 solution of potash or soda be boiled in a silver vessel,
 the earth will be dissolved.  See Potash.
  Experiment 13.  If glacial acid of phosphorus and
 silica be  exposed on charcoal to the action of the heat
 produced by a blow pipe,  the mixture will melt, and
 form a globule of transparent glass.
  Experiment  14.  Silica and borax,  treated  in  the
 same manner, will also  produce a compound of a vi-
treous appearance. 
PART  XL
                  OF SOAPS.

                 SECTION  I.

            OF ALKALINE  SOAPS.

  Experiment 1.  If one part of the soda of commerce,
deprived of carbonic  acid  by passing the  solution
through lime, be  boiled with six  parts of olive oil or
tallow, a compound will be formed called  soap of soda,
or hard soap.  Or,
  Experiment  2.   Let one part  of lime, (previously
slacked) and two of soda, be boiled in twelve parts of
water  for half an hour; filter  the lixivium through a
linen cloth, (pouring back the fluid upon the  cloth till
it passes  clear) and  evaporate it till its  specific  gra-
vity be about 1.375,  or, which  is the same, till a vial
which would contain one ounce of water, will hold an
ounce and three eighths of the fluid ; this having been
done, soap may he made by mere mixture of this ley
with olive oil, in the proportion of one part of the for-
mer to two of the  latter, in  a  glass or stone ware
vessel. This mixture being beat up with a wooden spa-
tula, soon becomes consistent, and if left to  stand for
four or five days, forms a white hard soap.   Or,
   Experiment 3.  Prepare a ley from wood ashes, mak-
 ing it caustic by means of lime, and let the ley be suf-
 ficiently strong to float a new laid  egg.   Boil  oil or
 tallow with this ley, until a saponaceous compound is
 formed.  Continue the heat till it acquires a consider-
 able consistence, and seems to be separating from the
 fluid below. Now add a sufficient quantity of muriate
 of soda, or common salt, and boil  the  materials for
 three or four hours, and soap of soda or hard soap will 
337
form on the surface.   1 he liquor on-which it floats I
called waste ley, and is to be drawn off.  The soap is
now melted for the last  time with ley, or even with
water ; it is then allowed to cool for a short time, and
afterwards  cast into wooden frames.   The soap thus
acquires a compact appearance.
  Rationale.  Hard soap is a combination of oil or fatty
matter with soda.  In the first and second experiment
the alkali is united directly with the oil or tallow.   In
the third, it is combined by compound affinity.  The
alkali obtained from wood ashes  is potash.  This  is
first combined with the  tallow,  or fatty matter, and
forms soap of potash or soft soap.   On adding muriate
of soda, or common salt, the muriatic acid unites with
the potash, forming muriate of potash,  which remains
in solution as the waste ley,  whilst the  soda combines
with the oil, or tallow,  in the state of soap of  soda, or
hard soap, and floats on the fluid.
  Remark.   The tallow for making soap is reckoned
good  if 13 cwt. yield  a ton of white soap.  Soap  is
mentioned by Pliny and Galen.  The term is said to
be derived from the old-German word sepe.  The Gauls
and Germans seem to have known this compound for
a long time.  A soap boiler's shop with soap-in it was
discovered  in the  city of  Pompeii,  overwhelmed by
Vesuvius, A. D. 79.  See Miss Starke's Letters from
Italy.
  Whale oil has been tried as a substitute for tallow,
but with little effect.  Tallow is  therefore generally
employed.   In France  and the south of Europe  olive
oil is made use of.   The soap, formed by  the combi-
nation of tallow and soda, is of a  white colour.  The
general properties of soap are too well known to  re-
quire any description.  It  dissolves in alcohol, and is
partly precipitated by  water.   A  specimen  of white
soap analysed by Darcet, Lelievre, and Pelletier, was
found to contain 60.94  oil, 8.56 alkali, and 30.50 water.
  Experiment 4.  If soap,  before it grows  hard,  be
mingled with ley,  so as to disperse it through it, or if
                        f  f 
338
a solution of sulphate of iron be poured into it, the
7.101 tied soap, as it is called, will be formed.
   Rationale.  When  sulphite of iron is used, part of
the alkali quits its combination with the animal oil, and
unites with the sulphuric acid, forming sulphate of
soda, whilst the iron  is deposited in the state of oxyd,
which gives the variegated colour to the soap.
   Experiment 5.   If  to  soap, before  it becomes hard,
rezin be added, a soap of a yellow or brown colour,
will be produced, forming the brown soap.  In making
yellow soap, resin is used  in  the proportion  of about
one  part to three  or  four parts of tallow.  The resin
makes the soap more detersive, and enables  the manu-
facturer to sell it cheaper.
   Experiment 6.   If  to white soap,  in its fluid state,
essential oils, as caraway, rose, bergamot, &c. be added,
the scented soaps of the perfumers will be formed. The
 Windsor soap appears to  be scented with the oil of ca-
raway.
   Experiment 7.   If soap  be prepared with a super-
abundance  of  alkali, a compound  will be  formed,
which has  been sold in this city for the purpose of
removing certain stains from stuffs.
   Experiment 8.   If, by employing an excess of soda,
in the preparation of soap, and giving  it a brown co-
lour; the oriental soap, for washing with sea w7ater, will be
formed.*
   Experiment 9.   If white soap be  dissolved in alco-
 hol,  a solution will  be  prepared similar to the liquid
shaving  soap of the perfumers.
   Remark.  Chaptal has proposed wool in the place of
 oil in the making of soap.   The ley is formed in the
 usual manner, and,  when it  is boiling  hot,  shreds of
 woollen cloth of any kind are  thrown  into it.  They
 are soon dissolved.  Others are thrown in,  and, when
 the ley will dissolve no more, a soap is formed of an
 excellent quality.  The muscles of  fish has been sub-
 stituted for tallow or oil in the manufacture of soap.

   * A specimen of this soap I examined, and found it to contain a
 larger quantity of alkali than the ordinary soap. 
339
   Experiment 10.   If oil, fat, tallow or any unctious
animal substance be boiled with the caustic ley of pot-
ash, prepared  of a  sufficient strength, a saponaceous
compound will be formed, called soap of potash, or soft
soap.
   Remark. Potash, when used in the formation of soap,
has the property of making it fluid.   In the preparation
of ooft soap, some employ whale oil.  A little tallow
is occasionally used, which, by management is dispers-
ed through the soap, forming white spots.
   Experiment  11.  if oil be added  to liciuid ammonia,
a  compound  will be  formed, on mixture, which  is
known by the name of soup ofammrmia ; Or,
   Experiment  12.  If carbonate of ammonia in solution
be mixed with the soap  of lime, the soap of ammonia
will be formed.
   Rationale.   The  carbonic  acid of the carbonate  of
ammonia unites with the lime, forming carbonate  of
lime, whilst the ammonia in its turn combines with the
oil of the soap of lime,  and forms  soap of ammonia ;
or,
  Experiment  13.  If a  solution of sal ammoniac be
poured into another of common soap in water, soap  of
ammonia will be the result.
   Rationale.   The muriatic acid of the muriate of am-
monia combines with the soda of the common  soap,
and forms muriate of soda, whilst the unctious matter
unites with the ammonia, and constitutes the soap  of
Htnmonia.
                SECTION II.

              OF  EARTHY SOAPS.

   Experiment 1.   If lime water be mixed with oil, a
rompound  will be  formed, called the  soap  of lime.
Or. 
340
  Experiment 2.  If to water containing any of the
calcareous  salts, a solution of soap be added, the soap
of lime will be prepared.
  Rationale.  In the first experiment a direct combina-
tion of lime and oil takes  place ;  in the second, it re-
sults from the mutual decomposition.  The acid of the
calcareous  salt, having a greater affinity for the alkali
of the soap, unites with it, whilst the lime in its turn
combines with the oil, forming the soap of lime.
  Experiment 3.  If the solutions of sulphate of mag-
nesia and common soap be mixed, the soap of magnesia
will be prepared.
  Rationale.  The sulphuric acid of the sulphate unites
with the alkali of the soap, and the magnesia combines
with the  oil, forming the soap of magnesia.
  Experiment 4.  If to a solution of common soap,
another of  alum be  added, the soap of alumina will be
the result.
  Rationale.  The sulphuric acid of the alum unites
with the alkali of the soap, and the alumina, thus  dis-
engaged, combines with the oil, as in the  former expe-
riments.
  Remark.  Any of the earthy soaps may be formed,
by pouring the  solution of the earth into another  of
common soap.   Hence the reason that all waters hold-
ing an earthy salt in solution are  unfit  for washing.
They decompose the soap, and form  one insoluble  in
water.  Such waters are called hard.   Hence  the use
of a solution of soap as a  re-agent.
  Earthy salts are insoluble in alcohol, except soap of
magnesia,  which dissolves both in alcohol and fixed
oils. 
341
                 SECTION IIr.

             OF METALLIC SOAPS.

  Experiment I.  If to a solution of corrosive muriate
of mercury, another of common soap be added, the soap
of mercury will be formed, and gradually precipitate.
  Rationale.   The muriatic acid of  the muriate unites
with the soda of the  soap, forming muriate of soda, and
the  oil in its turn combines with the oxyd of mercury,
forming the soap of mercury.
  Experiment 2.  If the  solutions of sulphate  of zinc
and soap be mixed, the soap of zinc will be prepared.
  Rationale.  The sulphuric acid of the sulphate unites
with the alkali, and the oxyd of zinc combines with the
oil.
  Experiment 3.  If nitrate of cobalt and soap be mix-
ed in the same manner, the soap of cobalt will result. -*-
  Experiment 4.  A solution  of. tin added to another cf
soap, forms the soap of tin.
  Exfic: iment 3.   A solution of sulphate of iron treated
in the same manner, produces the soap of iron.
  Experiment 6.  Sulphate of copper mixed  in  the
same manner, gives the soap of copper.
  Fxfu riment 7.  Acetate of lead treated as before, af-
fords the soap of lead.
  Experiment 8.  Nitrate of  silver used in the same.
manner, forms the soap of silver.
  Experiment 9.  Muriate of gold  treated as  before,
will yield the soap of gold.
  Experiment 10.   Sulphate  of manganese with soap,
will afford the soap  of manganese.      »
  Rationale.   The theory of  all these experiments, is..
analogous to  the first.
* F3 
PART  XII.
                OF STONE WARE.

   Clay vessels consist of alumina and siiw.-a, in various
 proportions, as clays are composed essentially of these
 earths.  By stone ware we  would include,  by  way of
 system, all the different kinds of pottery, such as bricks
 and tiles, pots and crucibles, the stone ware so called,
 and porcelain.
                 1. B ticks and Tiles.
   The oblong masses of baked clay, used as a substitute
 for stones in building, are known by the name of bricks,
 and tiles, which are  much  thinner,  arc  prepared for
 covering the roofs of houses. Bricks have been know n
 from time immemorial.                      *
   In  the making of brick, the common blue  clay h
 mostly used;  the goodness of the brick depends upon
 the clay.  If the clay contains too little sand,  the bricks
 are liable to crack in cooling;  too much, on the contra-
 ry, prevents the proper degree of cohesion. The manu-
 facture of bricks is too well known to require descrip-
 tion.   The red colour of the brick depends upon iron
 which the clay contains.
   Dr. John Pennington, in his Chemical and Economi-
 cal Essays, page  34, observes, that he analysed a portion
of the Potters' clay of Philadelphia, and found it to contaui
               51 Silica,
               26 Alumina,
                3  Lime,
                \7  Iron.
              100
               2. Pots and Crucibles.
  In various processes  it is necessary to employ ves«
sels of a particular kind, as in the fusion of glass, metals,
and the like.   Crucibles are used for many chemical
operations.  These are of  various  sizes.   The large 
3-13
crucibles are generally conical, with a small spout, for
the convenience of pouring out; the small  ones  are
truncated triangular pyramids, and are commonly sold
in nests. The Hessian crucibles are composed of clay
and sand, and when good,  will  withstand  an intense
heat for  many hours, without softening or meltin°\
Those which ring clearly when struck, and  are  of an
uniform thickness, and have a  reddish  brown colour,
without black spots, are reckoned  the  best.  Wedg-
wood's crucibles  are made of clay, mixed with baked
clay finely pounded, and are superior to  the  Hessian.
The black lead crucibles, formed of clay and plumbago,
are very durable, resist sudden changes of temperature,
and may be repeatedly used.
            3.  Differ -nt kinds cf Pottery.
   Earthen ware is of ancient date.  According- to  the
Old Testament, it was known at an early period to the
Jews.  The art of manufacturing clay  vessels, seems
to have originated among the  Asiatic nations.  Stone
ware  vessels differ from each other in their fineness;
hence it is distinguished by a variety of  names, such
as flint ware, yellow  ware,  queens  ware, IVedgwcod's
we/re, isfc
   There are two parts of which vessels of stone ware
consist. 1. The body  of the vessel, called  the biscuit.
2. The glassy covering  with which it is  coated, called
the glaze.  The biscuit is composed of two ingredients:
the first is a fine white clay, known by the name of to-
bacco pipe clay, and potter*' clay, and the  second a fine
white sand.   The particular manner of managing the
clay would be unnecessary to notice; suffice it to say,
that it is formed into vessels and burnt,  when it forms
the biscuit ware.   This resembles a tobacco pipe in ap-
pearance, and like it absorbs water with avidity.  Hence
it could not be used before it is glazed. Ordinary pottery
is glazed with oxyd of lead, or by throwing common
wait over it in the fu rnace.  Galena, or sulphuret of lead,
is employed to  glaze tiles and other coarser pottery, as
well as the oxyd  of lead; for when  laid  upon the  bis-
cuit, and exposed to the proper temperature, the  sul-
phur is dissipated and the lead oxydized.  This oxyd, 
344
then vitrifies, and in that state  has a tendency to com-
bine with the earthy bodies.  The brown glaze on the
coarse stone ware, is nothing more than glass of lead.
Common salt, or muriate of soda, is employed to glaze
the surface of fine stone ware vessels.  When the bis-
cuit is sufficiently baked, a quantity of common salt is
introduced into  the kiln.  The heat converts this salt
into a vapour; it penetrates the seggars through holes
left on purpose, and surrounds  the biscuit with an at-
mosphere of salt.  The salt, by combining  with the
surface of the biscuit, disposes  it to vitrification.
, The method of glazing stone ware with salt, was in-
troduced into England, by two brothers  from Holland,
of the name of Elers, about the  year 1700.  The use of
flint, in the manufacture of white stone ware, was intro-
duced according to Parke, in  the following manner:
about the year  172), a potter travelling to  London on
horseback, had occasion, at Dunstable, to seek a reme-
dy for a disorder in his horse's  eyes ; and the ostler of
the inn, by burning a flint stone, reduced it to  a  fine
powder, which he blew into them.  The potter, observ-
ing the beautiful white colour of the flint, after calcina-
tion, instantly conceived the uses to which it  might be
applied in  his art, and  then introducing into use the
white pipe  clay,  instead of  the  irony  clays,  he  readily
produced a white stone ware.
  Enamel is nothing mot e than  an opaque glass, melted
over the surface of the biscuit.  It consists essentially
of various proportions of oxyd of leadr mixed with sand
and glass.   Wedgwood's enamel consists of a mixture
of the oxyd of lead and tin, silica, talc and muriate of
soda.   The  yellow glaze  is composed  of whte  lead,
ground flint, and flint glass.  The whiteness of an ena-
mel depends on the proportion  of tin ; its fusibility upon
the  lead.
  Porcelain, or china, is a finer kind of stone ware, and is
a semi-vitrified earthen  ware,   of an intermediate na-
ture, between common wares and  glass.  Porcelain is
more capable of  resisting the action of chemical agents,
on account of the purity of the substances of which it is 
345
composed, and the nature of the enamel with which it
is covered.  It was known in the east at an early pe-
riod, but the discovery of the art  of miking it in Eu-
rope is of a much later date.  Specimens were brought
t© modern  Europe, and were  much admired.*
   Accident led to the discovery, in Germany, about the
beginning of the 18th century.  A chemist in Saxony,
during a set of experiments in'order to ascertain the best
mixtures for making crucibles, stumbled upon a com-
pound which yielded a porcelain similar to the Eastern.
   A number of experiments  have been made on the
mixture of different  earths, in order  to obtain porce-
lain by exposure to heat.  Reaumur published his dis-
sertations on the subject of making porcelain in 1727
and 1729.  Father Entrecolles, a missionary to China,
had sent an  account of the  Chinese  mode of making
porcelain, which coincided exactly with this ingenious
thought  of Reaumur.  The ingredients, according  to
him, are a hard stone called petuntze9 which they grind
to powder,  and a white  earth called  kaolin,  which  is
intimately mixed with it.  Reaumur found the petuntze
fusible,  and the kaolin infusible,  when exposed sepa-
rately  to a violent heat.

  * Porcelain vessels were known tc*he Romans. They were first
brought to Rome by Pompey, after die defeat of Mithridates, as
we are informed by Pliny, (xxxvii. 2)  The  Romans were igno-
rant of the mode of manufacturing them, but imported them from
Poutus  and Porthia. After the taking of Alexandria, a vessel of
Porcelain  was the only part of the spoil retained by Augustus.
That die vasa murchina of the Romans, were the same as our por-
celain vessels, has been ascertained, as Whitaker informs us, by
the porcelain found in the ruins of the ancient Lyons.  The name
porcelain,  if we believe Whitaker, came by the French name of
the plant portulaca oleracea or purslain, which has a purple co-
loured flower. It got that name because the  porcelain of the  an.
i-ients, was always of a purple colour. See Whitaker's Course of
Hannibal over the Alps, i. 55.
  For the  description of the most superb specimen of ancient pot-
tery, which modern art has not yet equalled, the Portland vase, see
Darwin's Botanic Garden. 
346
  The porcelain clay  of Limoges, according; to  the
analysis of Hassenfratz, is composed of
                      62 silica
                      19 alumina
                      12 magnesia
                       7 barytes
                      100
  The porcelain clay of Cornwall, which dobs not ac-
quire transparency without addition,  yielded to Mr.
Wedgwood,
                      60 alumina                 *.'
                      20 silica
                      12 moisture
                       8 loss

                     100
  The kaolin  of  the Chinese  very much  resembles
what is called the earthy or  disintegrated feldspar.
This is found in  many  places  in  the United  States,
and is derived from the disintegration of granite rocks.
The petuntze of China, according  to Rozen, is a feld-
spar which has lost a portion of potash  naturally be-
longing to it; but, not having been reduced to a com-
pletely earthy state,  stilV retains traces of a laminated
structure: and that  the kaolin  of China differs  from
the  petuntze  in having undergone decomposition to
a greater  extent;  and having been in consequence al-
most entirely deprived of the  potash originally  con-
tained in  it: that in the composition of China these
two  ingredients  are  mixed; the proportion of potash
present in the mixed mass giving that degree of fusi-
bility which is just  sufficient to cement the particles
together without vitrifying the  porcelain: that the pe-
tuntze by  itself would be too fusible for the purpose
intended ; and that the kaolin is too refractory to acquire
a sufficient degree of cohesion between its particles.
Equal parts of grand feldspar and porcelain clay, accord-
ing to an  anonymous German writer, forms the Saxon
porcelain. 
347
  The gkize used  for  porcelain is merely  feldspar,
which is composed essentially of silica and alumina
united to some potash, to which the  fusibility is to be
ascribed.  This is the glaze used in Saxony, and at the
manufactory of Sevres, near Paris.
  The method of colouring porcelain, may  be found
in the Philosophical Magazine,  vol.  xiii, page  342.
The flux, for the colour, is sometimes feldspar.  The
purple colour is  given by  means  of the purple oxyd
of gold ; the red by oxyd of iron ; the yellow by the
oxyd of silver, lead, or antimony,  with sand; green by
the oxyd of copper ; blue,  by the  oxyd of cobalt,  and
violet, by the oxyd of manganese.   For the  gilding on
porcelain, which  is performed nearly in the same man-
ner  as that of painting, see Nicholson's Journal, vii.
28 6. 
PART  X11I.
                   OF GLASS.

   We have before noticed, that glass is made by mix-
ing sihca with a proper proportion of some flux, as pot-
ash, or soda, and exposing this mixture to a violent heat.
   The method of making glass is of ancient date.
Pliny informs  us, that some merchants, with a ship
load of soda from Egypt, had  cast anchor at the mouth
of the river Belus in Phoenicia, and were dressing
their dinner on the sand.  They made  use of large
lumps of soda to support their  kettles, and  lighted
fires  under them.   The  heat melted the  soda and
siliceous  earth together, and the  result  was glass.
For some time the manufacture of glass was confined
to the river Belus.   The  ancients carried this manu-
facture to much perfection.  They mention drinking
glasses, glass prisms, and coloured glasses.  Nero gave
30,000/. for two glass cups with handles; as white glass,
of which they were made, was considered very valua-
ble.   The  materials of glass was melted into  a black
mass, called ammonitrum, which was purified by refi-
ners.   Glass panes were  introduced  about the third
century,  but it was some  time after before they came
into common use.
   There are several kinds of glass in use, as the plate
glass, of which looking glasses are made, crown glass,
bottle glass, 8cc. which are composed  of different pro-
portions of silica and alkali, with occasionally other in-
gredients.
   The following facts and observations respecting glass
are given by Accum.  When silica and alkali are com-
pletely fused  and have acquired a certain degree of
heat, which is known by the fluidity of the mass, part
of the melted matter is taken out at the end of a long
hollow tube, which is dipped  into it, and turned about 
349
until a sufficient quantity is taken up; the workman at
each turn rolling it gently upon a piece of iron, to unite
it more intimately.  He then blows through the tube,
till the melted mass at the extremity swells like  a bub-
ble; after which he rolls it again on a smooth surface
to polish it, and repeats the blowing  until the glass is
brought as near the size and form of the vessel requir-
ed, as he thinks necessary..
   If it be a common  bottle, the melted matter at  the
end of the tube is put into a mould of  the exact size
and shape of its body, and the neck is  formed on the
outside by drawing out the  ductile glass.
   If it be a vessel with a large or wide orifice,  the
glass in its melted state is opened and widened with an
iron tool; after which  being again heated, it is whirled
about with a circular motion, and by means of the cen*
trifugal force thus produced is extended to the size re-
quired.  Should a handle,  foot, or any thing else of the
kind be required, these are made separately, and stuck
on in its melted state.
   Window-glass is made in a similar manner, except
that the mass at the end of the tube is  formed into a
cylindrical shape, which being  cut longitudinally, by
scissors or shears, is gradually  bent back until it  be-
comes a flat plate.
  Large plate-glass for looking  glasses, &c. is  made
by suffering  the mass  in a state of complete fusion to
flow upon a casting table,  with iron ledges to confine
the melted matter, and as  it cools  a metallic roller js
passed over  it to reduce  it  to  a  uniform thickness.
There are different kinds of glass manufactured  for
different purposes ; the prineipal of  these are flint-glass,.
crown-glass, and bottle-glass.
  Flint-glass is the  densest, most transparent, colour-
less, and  beautiful.  It is  often called  crystal.  The
best kind is said to be manufactured in this capital from
120 parts of white siliceous sand, 40 parts of pearl-ash,
35 of red oxyd of lead, 13 of nitrate of potash, and 25
of black oxyd of manganese.
G g 
350
  This is the most fusible glass.  It is used for bot-
tles and other utensils intended to be cut and polished,
and for various ornamental purposes.
  Crown-glass differs  from the preceding in containing
no lead.  It is manufactured of soda  and fine sand.
This kind is used for  panes of windows, 8cc.
  Bottle-glass is the coarsest of all.   It is made of soda
arid common sand.   Its green colour is owing to iron.
It is the least fusible.
  Glass is often coloured by mixing with it, while in a
fluid state, various metallic oxyds.   It is coloured blue
by the oxyd of cobalt; red by the oxyd of gold; green
by the oxyd of copper or iron;  ye/low by the  oxyd ol
silver or antimony; and violet by the oxyd of mangan-
ese.
  The properties of  glass are  well known.  Its hard-
ness is very considerable; its  gravity varies from  2.3
to 4, according to the quantity  of metallic oxyd which
entered into its composition.   Though glass when cold
is brittle, it is  one of the most ductile bodies known.
If a thread  of melted glass be  drawn out and fastened
to a reel, the whole of the glass can be  spun off on  the
reel,  and by  cutting the threads at a  certain length,
there  is obtained a sort of silver feather  of glass.   A
thread of glass, when red hot, may  be  drawn  or spun
so fine as to be scarcely visible to  the  nuked eye.   It
is almost perfectly  elastic, and of course is one of  the
most  sonorous bodies.   Fluoric acid  dissolves it at
common  temperatures,  and alkalies at high  degrees
of heat.  These are  the only agents known which act
wpon it.
   Glass utensils, unless very small and  thin, require to
T>e gradually cooled in all oven.   This operation is call-
ed annealing, and is necessary to prevent their cracking
by change of temperature, wiping,  or slight accidental
scratches.
   There are two toys made of uuanncaled glass, which,
though commonly used for the amusement of children,
exhibit phenomena which justly interest the curiosity 
351
of the philosopher, we mean prince Rupert's drop, and
the Bologna flask, or philosophical phial.
  Prince  Rupert's drop is  made  by letting drops of
melted glass fall into water; the drop assumes by that
means an oval form, with a tail or neck resembling a
retort.  These drops are said to have been invented by
prince Rupert, and  are therefore called by his name,
They possess the singular property, that if a small por-
tion of the tail is broken off, the whole bursts into pow-
der, with a kind of explosion, and  a considerable shock
is communicated  to the hand  that  grasps it.  Their
explosion in the dark is said to be  attended with a flash
of light;  this,  however, is a mistake: a flash of light
indeed is produced  if the drop be broken in a glass
receiver, but in that case the flash proceeds from the
action of  the  projected  particles,  forcibly  striking
against the body of  the glass;  but no such phenome-
non  takes place if the drop be broken in free space.
  The Bologna, or philosophical phial, is a small  cylindri-
cal  vessel of glass which has been  suddenly cooled]
open at the upper end, and rounded at the bottom.  It
is generally made so thick  at  the bottom, that it  will
bear a smart blow against a hard  body  without break-
ing ; but if a little pebble or piece of flint is let fall in-
to it, it immediately cracks, and the bottom falls into
pieces.
  Concerning  the cause of the  phenomena  of both
these bodies,  different opinions have been advanced.
The most general is founded on the assumption, that
the dimensions of bodies, which are suddenly cooled,
remain shorter than if the cooling  had been  more
gradual.   The dimensions,  therefore,  of  the  smooth
external surface of these  glasses, which are suddenly
cooled, arc supposed to be shorter than is adapted to
the accurate envelopcment of the  internal  part, which
is necessarily  cooled in a  more  gradual  manner; if,
therefore, by a crack or fissure, a solution of  the con-
tinuity takes place in the external  coat, the sudden ao
ipn  of the parts which remained  in a state of tension 
352
to recover that of perfect expansion, is supposed to ef-
fect the destruction of the mass.
  Other philosophers again have been inclined to sus-
pect that the phenomenon arises from a quantity of air
being included in the  substance of the  glass which
rushes suddenly out, if the surface which incarcerates
it becomes  broken.   Mr. Lambert, on the  contrary,
maintains an opinion diametrically opposite to this : he
supposes, that during the sudden cooling of the glass,
vacuities are formed between its particles, and that
they are sealed up by the smooth surface of the exter-
nal  covering, so that on  the continuity of that surface
being interrupted,  the air suddenly rushing in occa-
sions the bursting of the drop. 
PART XIV.
           OF HYDROSULPHURETS.

  Experiment 1.   If potash be saturated with  sulphu-
retted hydrogen, which may be accomplished by pass-
ing that gas through the solution of the alkali, a com-
pound will be formed, called hydrosulphuret of potash.
Or,
  Experiment 2*   If sulphuret of potash be dissolved    ,;
in water,  and the  solution evaporated, hydrosulphuret-   .;
of potash will be produced, on standing, in large pris-   :'-\s
matic crystals.
  Rationale  In the first experiment a direct combina-
tion of the gas and alkali ensues: in the second that
compound is formed by the decomposition of the wa-
ter, for the oxygen unites with a portion of the sulphu-    ^
ret, converting it into sulphate of potash, whilst the hy-
drogen unites with another portion, forming hydrosul-
phuret of potash.
  Remark.  V"€n.i«j«oii» fano i«xvijr »ioc/?rihfcd the pro-
perties of this substance.  It is transparent and colour-
less, and  may be obtained in the form of crystals.  Its
taste is alkaline. On exposure to the air it deliquesces.
The crystals have no smell, but either by their deli-  .'^.
quescence, or the addition of  acids, they emit sulphu- :.tfkf-
retted hydrogen gas.                                -;,>
   Experiment 3.  If soda be treated with sulphuretted
hydrogen as before, or if the sulphuret be dissolved in
water, the hydrosulphuret of soda will be formed.
   Rationale.  Analogous to the preceding.
   Remark.   The  hydrosulphuret of  soda crystallizes
in four sided prisms, terminated by quadrangular pyra-
mids.   Berthollet and Vauquelin have  examined its
properties which are similar to  the other hydrosul-
phuret. 
354
   Experiment 4.  When water impregnated with sul-
 phuretted hydrogen is mixed with  liquid sulphite  of
 soda, and the fluid then  evaporated a triple  salt  is ob-
 tained of sulphuretted hydrogen, sulphurous acid, and
 soda.
   Remark.   Although sulphurous acid and  sulphuret-
 ted hydrogen mutually  decompose each other when
 both are uncombined, yet if the sulphurous  acid  be
 first combined with soda, and then suffered to come
 in  contact with sulphuretted hydrogen, a salt is found,
 which appears to be a  compound of the sulphuretted
 hydrogen and sulphite.
   Experiment 5.  If sulphuretted hydrogen be passed
 through liquid ammonia, which is easily accomplished,
 the liquid will assume a greenish yellow colour, form-
• ing hydrosulphuret of ammonia.
   Experiment 6.  If equal parts of lime, muriate of
 ammonia, and sulphur be distilled,  the same  product
 will be obtained, or the fuming liquor of Boyle.
,;  Rationale.   The first is a direct  combination of sul-
 phuretted hydrogen and ammonia ;  the  second is pro-
 duced from the decomposition of the muriate of am-
 monia by means of the lime,  and  the subsequent union
 of  the  sulphur wirh th*» ammonin. thus dUpngaged
 from the muriate.  Some moisture is decomposed ;
 hence the conversion of the sulphuret into an hydro-
 sulphuret.   See Sulphur.
   Experiment 7.  If the  sulphuret  of barytes,  which
 may be formed  by decomposing the sulphate by means
 of charcoal in a crucible, be put into boiling water, the
 solution filtered while hot, and  afterwards evaporated
 crystals of hydrosulphuret of barytes will be  formed ;
 Or,
   Experiment 8.  If barytes and sulphur be heated to-
 gether in  a  crucible, and the compound  dissolved in
 water,  the same product will be  obtained.
   Rationale.   Analogous to the former.
   Experiment 8.  If sulphuret of strontian, be treated
 in  the  same manner as sulphuret of barytes, hydrosul-
 jtburet of strontian will be forme.d. 
355
  Rationale.  Analtgous to the preceding.
  Experiment 9.  If a current of sulphuretted hydro-
gen gas, be passed through lime, suspended in water, the
lime will be dissolved, and form a hydrosulphuret of lime.
This  solution is colourless, and  has  an acrid bitter
taste.                                              .^v;;
  Rationale.  The  sulphuretted hydrogen  gas unitesS^V..
with the lime by direct combination.
  Experiment 10. If magnesia be dissolved in water, im-
pregnated with sulphuretted hydrogen gas, it will form
the hydrosulphuret of magnesia.
  Rationale.  Analogous to the preceding.
  Remark. It is supposed  that glucina and yttria will
combine with sulphuretted hydrogen gas; but neither
alumina nor zirconia possess this property.  Hence the
hydrosulphurets  precipitate their  earth from acids.    '*yji
  When the alkalies  or alkaline earths are mixed with   ;%
sulphur and water, and boiled in a glass vessel,  brown
coloured solutions are obtained, which have lately been
called hydroguretted sulphurets,  but  formerly  liquid;; j&V
livers of sulphur.                                    'v-^5r
  Hydroguretted sulphurets are compounds of abase,  ■■ ,
with sulphur and sulphuretted hydrogen gas, and arc
therefore considered as triple compounds. The proces-
ses for preparing the hydroguretted sulphurets, are si-
milar to the former.  Thus hydroguretted sulphuret of
potash, is formed by boiling sulphur with a solution of
potash, or by dissolving sulphuret of potash in  water ; ;.--•,.*..
hydroguretted  sulphuret of lime, by boiling a mixture
of sulphur and lime  in water, &c.
   The   hydrosulphurets  precipitate almost  all the
metals from their solutions.  The precipitates vary in
their colour according  to  the  metal.  The following
table, given by Thomson, exhibits a view of the colours
of the various precipitates in these cases, as far as. the
subject has been investigated- 
356
Metals.		Precipitated by	
	Hydrosulphuret		Hydroguretted sulphuret
		of potash.	of potash.
'■■- Gold - -	-	Black - -	- Black
^Platinum	-	Black - -	- Black
\ Silver	-	Black - -	- Black
Mercury	-	Brown black	- Brown, becoming black
Palladium	-	Black - -	.
Copper -	-	Black - -	- Brown
■'< . Iron - -	-	Black - -	- Black, becoming yellow
Nickel -	-	Black - -	- Black
v'-^'Tin - -	-	Black - -	- Black
Lead *• -	-	Black - -	- White, becoming black
Zinc - -	-	White -	- White
Bismuth -	-	Black - -	- Black .
Antimony	-	Orange -	- Orange yellow
Tellurium	-	Black - -	- Deep brown or black
'r>:JM',Arsenic -	-	Yellow -	- Yellow
Cobalt -	-	Black - -	- Black
Manganese	-	White -	- White
^'Chromium	•	Green	.
. Molybdenum		Reddish brown	
Uranium	-	Brown - -	- Brownish colour
Titanium	-	Bottle green	- Bluish green
Columbium		Chocolate	-
Cerium -	-	Brown	-
END  OF VOL. T. 
 
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■.-•I.