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UNITED STATES OF AMERICA
WASHINGTON,  D. C.
GPO  16—67244-1 
 
 
            DISCOURSE


                   ON THE


         CONNEXION BETWEEN


CHEMISTRY  AND  MEDICINE.

                  DELIVERED

    IN THE UNIVERSITY OF PENNSYLVANIA,


               Nov. 5,  1818.
l\   33~
       By Thomas  Cooper, Esq. M, D.

PROFESSOR OF CHEMISTRY IN THE FACtJlTI OF ARTS IS THE TWITER*
                 SITT OF FENNSYLVANIA.
  Un ouvrage dans lequel on discute le mode d'action de quelques medica-
mens d'apres les proprietes qae la chimie leur assigne, doit singulierement
deplaire a des hommes qui paraissent redouter pardessus  tout, de voir le
marche de l'experience introduire dans le medicine. On a pu craindre pen-
dant quelque teras que ces partisans d'un aveugle empiricisme et des plus
vagues hypotheses, ne nuissent aax progres de la science: mais en dirigeant
leur attaques trop haut, ils ont perdu tout credit. Qui neseraitflatte de leur
critiques, depuis qu'on les a vus employer les expressions du mepris en par-
lant de travaux de Wottaston at Berzelius ? Review of Dr. Majendie's
Treatise on the Gravely in the Annates de Chime for April, 1818, p. $867'„






                 PHILADELPHIA:       *Mr -1 on ,*%

    PRINTED AND PUBLISHED BY ABRAHAM SMALL

               JVU  112, Cliesnut Street.
1818. 
 
DEDICATION.
To the Trustees and Professors of the  University
                 of New York.
GEN"T#EMEN,
     I DO not  submit to your consideration the
following discourse, because I suppose the con-
nexion between chemistry and medicine is not duly
appreciated and well taught  in your University—
for, while my excellent friend,  Dr. M'Neven,  fills
the chair of  chemistry, all that is necessary to be
taught in theory, and illustrated by experiment, in
this department of chemical  science, will be fully
given.   But I am anxious to seize the first public
opportunity  of expressing my obligations  for  the
degree of Doctor in Medicine, which your partiali-
ty has been pleased to confer on me; and to assure
you, that this public mark of approbation on your
part, shall operate as a continual excitement to those
exertions by which it has been earned.
   Accept, gentlemen, I pray you,  my sincere pro-
fessions of gratitude and respect.
                  THOMAS COOPER,  M. D.
   November, 1818. 
 
PREFACE.
    DR. RUSH, whose talents, industry, and ac-
quirements, gave him deservedly a very high stand-
ing among his fellow citizens,  set his face against
the utility of  classical learning in what he deemed
the present improved state of education.  Unfortu-
nately, his opinions have had too much weight in
this country;  and  this genuine source of correct
taste, and sure foundation of elegant  literature, is
now undervalued by the parents and the  youth of
America; who can discover no use in wasting so
many years in the  acquirement of dead languages,
which are forgotten, when the real pursuits of busi-
ness imperiously lay claim on our time.  It is true,
Latin and Greek, imperfectly taught and imperfectly
learnt, are soon forgotten: it must also be conceded,
that these languages aid little in judging of the qua-
lities of merchandise, or in the arrangement of the
finance of a  compting-house:  but it is not easy to
see, how a Lawyer or a Physician can occupy a
respectable standing without them; nor,  how the
charms  of polished society can be enjoyed, with-
out a reasonable knowledge of the languages, which
for so many centuries have formed the passports to
literary acquirement, and the subjects of allusion in
almost every  literary work.  In Europe—in Eng-
land and  in  Germany particularly,  these studies 
IV
PREFACE.
are considered not merely as the useful, but the in-
dispensible parts of polite education; nor is a know-
ledge of ancient classic authors in good society
there, less common than a knowledge of the  most
popular publications in the language of the country.
Many of our best legal and medical authors—very
many of the indispensible books of science—almost
all our legal, and medical terms and phrases—the
treatises of foreign  jurists,  the prescriptions of fo-
reign physicians—are comprised in the dead  lan-
guages : for they have not yet ceased to be the com-
mon means of communication  in the republic of
Letters.  These sentiments are universally preva-
lent  among what is  usually called  good society
in Europe; and they are falling into great disrepute
in what is called good society in this country.
   It would be well, if we  confined  our neglect to
ancient  erudition; but the most useful parts of mo-
dern science also seem to fall into contempt here,
in proportion as they rise in reputation elsewhere.
   During the late discussions previous to the elec-
tion of Dr. Hare to the Chair of Chemistry in the
Faculty of  Medicine  of  this University,  two opi-
nions appear to have been advanced by the medical
faculty :* 1st. That the Chair of Chemistry ought
not, or at least need not, be filled by a medical cha-
racter;  because  the chair of chemistry was not ne-
cessary to,  and ought to be separated from, the fa-
culty of medicine.  This I know to  have been the
opinion of  Dr. Dorsey, whose  premature decease
* With the exception, perhaps, of Dr. Cost-. 
PREFACE.
V
we have so much reason to deplore.  This gentle-
man strongly advocated the election  of  Dr. Hare,
against whom the objection was urged, that he had
no pretensions whatever to medical knowledge.  A
second opinion was, that no  person  but one  who
had received a medical education,  ought to be ap-
pointed to the chair of chemistry; because, in his
capacity of  Professor, he would have to pass upon
the merits of candidates for a Degree in Medicine:
this was Dr. Chapman's  opinion: this gentleman
went further; and, considering chemical knowledge
rather as an ornamental than an  indispensible, or
even useful part of medical education,  he thought
the chair of chemistry ought to be separated from
the medical faculty; and  that the students should
be exonerated from  the necessity of attending to
this branch of knowledge, when they had so many
other branches to attend to, which were absolutely
indispensible.  This appears to have been the ge-
neral sentiments of the medical faculty of the Uni-
 versity of Pennsylvania;  for having applied to Dr.
 Hare, they persuaded him to relinquish his privilege
 and his duty, of passing upon the qualifications of
 the medical  students when they came forward to
 be examined for a degree, and of signing their di-
 plomas ;  confining himself simply to the examina-
 tion of the students—in  chemistry only—the rest
 of the faculty, reserving to themselves the exclusive
 right of deciding upon the result of such examina-
 tion, which was to take place in their presence. To
 this proposal it  was  understood, and indeed an-
 nounced, that Dr. Hare  had assented.  Whether 
VI
PREFACE.
 the Trustees of the Institution will assent to it also,
 time only can shew.
   This general opinion of the inutility of chemistry
 to medicine was not confined to the medical faculty
 in the University. On the very morning of the day
 that I delivered the ensuing discourse, my friend Dr.
 Caldwell, whose general talents and standing as a
 physician, is among the very first class in this city, and
 whose sentiments are generally understood to coin-
 cide with Dr. Chapman's on this subject, took occa-
 sion, in a lecture before the students of medicine, to
 express an opinion that chemistry had  been intro-
 duced into physiology without any benefit whatever
 to the former branch  of medicine;  and that it was
 hardly applicable to the doctrine of disease, though
 it might be considered useful in the preparation  of
medicines to be exhibited in the cure of disorders.
   In this state of things, I deemed it an allowable
 use of my situation as Professor of Chemistry in
 the Faculty of the Arts,  to shew, that there is a
 connexion between medicine and chemistry, and to
 trace an outline of that connexion.   It appeared to
 me, that the heresy in question ought  to be corn-
batted by  some one, and I found no one likely to
do it,  if I did not.
   It is not difficult to account for  the prevailing
opinion;  but it appears to me impossible to approve
 it.  When the gentlemen who are now professors,
received  their medical education twenty years ago,
the science of chemistry was truly of very little use
or application to physiology or pathology. It is no
 wonder therefore that the opinion then formed of it, 
PREFACE.
Ml
when they first entered on the practice of medicine,
should  prevail  among them  now—or  that they
should think lighdy of a branch of science whose
progress they  have  not traced,  and whose present
importance they  are not  sufficiendy apprised  of.
How can  they  duly appreciate  that  knowledge
which they have been at no pains to acquire, or
inculcate its necessity upon others, when they can-
not feel that necessity themselves?
   But twenty years has changed the whole face of
chemistry, in  its theory, in its practice, in its appli-
 cation.    The physicians of Europe pursue it with
 increasing ardour, and the bands of alliance between
 chemistry and medicine are  growing  every  day
 more indissoluble.   Nor is there a school of medi-
 cine in Europe where a minute attention to medi-
 cal  chemistry is not considered as absolutely indis-
 pensible to a  medical degree:  and  I  consider  it  as
 a deplorable defect in the medical education of this
 place,  that the same sentiments are not inculcated
 on the young gentlemen who study medicine here.*
   » Extract from a Review of Dr. Marcet's  Essay on Calculous Disorders,
 in the London Medical Repository.—«It is  truly gratifying to contemplate
 ««the change of opinion which the last twenty years have produced with re-
 « spect to the importance of chemical scienco as a collateral branch of me-
 « dical educatiou.  It is now generally and minutely studied; and the patho-
 logist willingly admits, that chemistry, in aiding his labours, has, like irri-
 «< gation, fertilised a soil, which, if hitherto unproductive, was so only, from
 «the deficiency of  knowledge in the cultivators to draw forth its riches. In
 « no part of medical science, however, has the influence of chemistry  been
 «moie conspicuously displayed, than in the light it has thrown upon the
 " nature  of calculi; and the consequent improvements which have resulted
 « in the treatment  of these disorders.  Hence the great value of every -work
 «that can render this species of knowledge more familiar to the practitioner:
 « a fact which must plead  our apology for bringing before our readers this
 «< TOlume so immediately after its publication, while many interesting works 
V1U
PREFACE.
   Let us consider, what will be the consequence?
 The prodigious extent to which chemistry is appli-
 cable in the arts, trades,  manufactures, and domes-
 tic economy of life,  renders it each  day more po-
 pular than the past.   Every man is alive to its im-
 portance,  who has an opportunity of reflecting on
 its uses.  The students of chemistry now are con-
 fined to no class of society:  it is no  longer regard-
 ed merely as an ornament—an accomplishment:
 every body is expected to know somewhat about it.
 This progress of attention to chemical knowledge
 is manifestly gaining ground  in this country gene-
 rally.  Hence, in ten years time, chemistry will be
 better known to every class of society in America,
 than it will be to the practitioners of medicine pour-
 ed out from the school of Philadelphia:  for at this
 day. they  are  led to consider it  as  a very inferior
 branch of medical knowledge; and they see before
 them continually,  gentlemen of acknowledged ta-
 lents, who regard it in the same light. It cannot be
 expected  that young men thus instructed  should
 devote themselves to chemistry.  But I would ask,
 how can a physician educated in these opinions meet
 a jury of his country on a case of poison, or a case of
 nuisance affecting the public health?  How will he
 be able to maintain the high ground  that a  physi-
 cian ought to take, as a member of the most scien-
 tific portion of the general community to which he
 belongs?  He cannot.

" of prior date still remain unexamined." See the New England Journa:
of Medicine and Surgery, No. III. of vol. vii. 1818. 
PREFACE.
ix
   In Europe, in addition to the dead languages
and chemistry,  botany also is expected to be one
among a physician's attainments.   It ought to be
so here.   But when the knowledge expected in  a
physician is designedly pared down to the smallest
possible portion that will give colour  to the title,
how can our medical men preserve their due rank
in the estimation of society? a rank founded on  a
presumption, and a general persuasion, of superior
knowledge connected with the profession?
   Whatever may be the opinions  of  the medical
school here—opinions  not founded on knowledge
of the inutility of chemistry to medicine,  but on
ignorance of its utility—I earnestly hope  for the
honour of science in this country, that they will not
be supported by the Trustees of this  University;
who at  some  future  time  may feel  themselves
obliged  by the advice  which  I   now take the
liberty to offer;  viz. that a full  share  of chemical
knowledge be  exacted from each student who ap-
plies for a degree.
   To such of  the  students  who may peruse this
pamphlet, I would beg permission to suggest, that
every physician is by pretention and profession, a
man of science and a gentleman:  in his manners
and deportment—in his modes and habits of think-
ing and   of  acting—well versed   in  every  use-
ful and every liberal kind of  knowledge that  may
serve to  qualify him, not merely for  the practice
of his profession,  but for his intercourse with the
more polished grades of civilised society,  and for
the instruction of the neighbourhood where he may
                       B 
X
PREFACE.
  be placed. The people expect from him all the results
  of a finished education: he cannot support the ho-
  nour of his profession  if he should be deficient in
  this respect.  Even, therefore, if the acquirements
  I recommend were not necessary,  but ornamental
  merely, they ought to be cultivated by medical
  students in particular.   I  hope, however, to prove,
  that no man can be considered as  a well educated
  physician who is not well versed in medical chemis-
  try :  and that this is a branch of science of the first
  necessity in a medical  education.
    I well know how much a student has to learn,
  and how little time he affords himself to learn it in.
  If chemistry be not attended to for want of time  at
 the University,  it must be attended to afterwards
 with fewer opportunities of instruction. For it is  in
 vain to conceal  the  truth.  Chemistry has forced
 itself into public notice: it cannot be pretermitted:
 and ten years hence,  a  physician will assuredly be
 degraded who is not well informed on  the subject.
 No man of sense will  permit himself to be defi-
 cient in a branch of knowledge, which every physi-
 cian in Europe is anxious to attain, and to give evi-
 dence that he has attained  it. If the present portion
 of time allowed be not  sufficient (and assuredly it is
 not)  another year of study ought  to  be  exacted.
 How often is it,  that young men graduate  before
 they are of age ?* Opium, mercury, and the lancet,
  * The late Dr. Dorsey graduated at nineteen years of age, or thereabout.
No credit to the Institution that turned him loose on  the world at that early
period of life, regularly licenced to tamper with the  lives of his fellow citi-
zens. His own good sense, however, corrected the fault: he went to Europe
and attended the Lectures at London and Paris, before  he adventured to
practice it home. 
PREFACE.
xi
are instruments too dangerous to be committed thus
early into such young hands.  Students may rely,
that their emoluments as well as their character in
public estimation, would be greatly enhanced by an
additional year of study and attention. They would
have more confidence in themselves, and the public
with great reason would have more confidence in
them.  It is melancholy to reflect that we live in an
age thus strongly characterised by superficial ac-
quirement !
   I know not how these notions will be received:
but I well know that whatever  may be their fate
now, they will be better thought of the longer they
are reflected on, and the more they undergo the test
of years  and experience.  The reader to whom they
are submitted, must judge for himself.
                   THOMAS COOPER, M. D.
 & I have just received a note from Dr. Caldwell,
     of which the following is an extract, viz.

 Dear  Sir,

    The following is a correct copy  of that portion
 of my  late Introductory Lecture, which relates to
 the connexion between Chemistry and Medicine.

 Chemistry, Botany,  Materia Medica, and  Pharmacy, ought to occupy
two full years of a student's life : Anatomy, Surgery, Midwifery, and the
theory and practice of Physic, two  full  years more. Perhaps the present
circumstances of the country will not afford a quadrennial course of study ;
but if the reputation of the profession is to be maintained before the public,
uc  must adopt this period ultimately 
XU               PREFACE.

   " To some of you, it may, perhaps, appear ex-
traordinary,  that I have represented chemistry, as
only a collateral element of medicine.  It is, how-
ever, indisputably, nothing more.   When strictly
scrutinised,  I am at a loss to perceive, wherein it
is more intimately connected with medical science,
than zoology, botany,  or mineralogy.  Nor can  I
recognise any propriety in the expression,  " medi-
cal chemistry," beyond that  of " medical  botany,
zoology, or mineralogy."   The three departments
of nature, to which those branches  of science  re-
late, furnish the physician with many of his reme-
dies : and, with an immediate reference to his pro-
fession, chemistry, unquestionably, does  nothing
more.
   " Shall I be told, that chemistry aids,  in the ex-
plication of any of the phenomena or laws of  the
living body, either in a healthy or a diseased state?
—that it sheds light on physiology, pathology, or
therapeutics?  From the most correct and  satisfac-
tory views I have been able  to form on this  sub-
ject, I feel myself compelled to deny the position.
As far as chemistry has mingled in discussions of
this nature, it has not only darkened them, but fill-
ed them with error.  It has superadded corruption
to what it found already sufficiently corrupt.
   "Chemistry  is, notwithstanding,  a branch of
science, of such high moment and extensive utility,
that it should never be neglected by those who are
in pursuit of a  liberal education.   Whether  the
destination  of the individual  be  law or  politics,
theology or physic,  his mind will be illuminated, 
PREFACE.
xiii
and his views expanded, by  a knowledge of this
interesting science.  That no  professional character
may be ignorant of it, its elements ought, in all our
higher seats of instruction, to be regularly incul-
cated, as a collegiate study."

   I am much obliged to Dr. Caldwell for this ex-
tract : his  opinions are manifestly formed on a past,
not on the present state  of  chemical  science.  As
applied to medicine, that science, I acknowledge,
is yet in its infancy;  but it  is the infancy of Her-
cules.   In its infancy it would continue to the end
of time, if such depressing,  paralysing sentiments
were to prevail.   Happily, although  they may yet
prevail here, they  are  fast declining elsewhere.*
Medical chemistry  has, in  fact, just commenced its
 career; but such has been its promise of utility,
that ten years  have increased its votaries at least
tenfold. '                                 T.C.
  • They are  supported, to a certain degree, in France, by the Doctors
Richerand, Rcgnaut, Coutanceau;  and in Spain, by Dr. Carbonel. 
CONTENTS.
  Introduction.—Brief History  of Medical Theories.—
Uumoural Pathology.^-Application of Chemistry to Phy-
siology.r-*Pathology.—Poisons and Nuisances.—Materia
Medica.—Adulteration of Medicines.^—Pharmacy.—Pre-
scriptions.—Conclusion. 
A DISCOURSE, $c.
Gentlemen,

     MY peculiar province in this University is to
Lecture on Chemistry with its  application  to  Agri-
culture  and the Arts:  its application to Medicine
properly belongs to  the  Professor of Chemistry at-
tached to the i acuity of  Medicine.   But on the ap-
plication of  chemistry to the arts, I have so little to
urge that I have not urged already—and I am so un-
willing to believe that my years of labour bestowed
on  the  propagation  of chemical knowledge  in  this
country have been so far thrown away, that it is ne-
cessary at the present day to  press the reality of this
application, and to demonstrate the connexion between
chemical knowledge and agriculture, arts and manu-
factures—that I am glad of an opportunity of turning
my own attention as well as yours, to a topic less ob-
vious and still disputed;  and to shew that chemistry
is not only applicable to medicine also, but that it is
indispensible to a medical education.  I am the more
induced to take this  course on the present occasion,
because I know that the  importance of chemistry to a
medical student, has been, and now is, greatly under-
valued by gentlemen of acknowledged talents, and of
high standing in this University—whose  sentiments
on  this subject will be regarded by you with great de-
ference and respect—whose advice will  guide your
studies here, and contribute mainly to form your cha-
racter,  and act  upon your reputation in future  life.
 Addressing you, therefore, on a difference of  opinion 
16
 between myself and gentlemen thus deservedly high
 in your estimation,  it becomes me to lay before you
 the grounds of my  own opinion, and  I am prepared
 on the present occasion so to do.
   I hardly know of any opinions that may be consi-
 dered as forming a school of medicine until the time
 of Paracelsus and Van Helmont.   The aphorisms of
 Hippocrates, the writings of Galen, the chemistry of
 the Arabian physicians—can hardly be considered as
 doctrines peculiar to any class  of medical men : they
 are more practical  than theoretical:   the doctrines
 were  mere notes of  practical observations  in  patho-
 logy, and the medicines exhibited were empirical;
 not prescribed under any theory of their modus ope-
 randi, but because under certain symptoms they had
 been found beneficial in their effects.  Something like
 exception may appear,  but not sufficient to invalidate
 the general remark.
  The chemical notions of  Paracelsus and Van Hel-
 mont, and the Archseus of the latter,  first introduced
 decided theory into medicine. Cures were considered
 as performed by chemical  operation,  and Archaeus
 furnished notice by  symptoms  and  indications of the
 approach and invasion of disease.   This Archseus of
 Van Helmont, the governor and director of the  human
 frame, is  not in  any essential respect  different from
 the Soul of Stahl, or the Vis Medicatrix of modern
 schools.   I know no sufficient  proof of the one or the
 other. Vis Vitae, when confined to the source of ex-
 citability in the solids of the organised body, whatever
 that source may be, is a different thing.
  To these notions succeeded the  humoural and
 chemical theories of lentor and thinness of the blood,
fermentations,  acidity and alkalescence—constituting
 cacochymia of the fluids, and introducing the irritating
 spiculae of saline substances.  This inundation of in-
 distinct and unfounded notions and phrases, could not
 long maintain its ground, though supported in  part or 
17
in whole by Boerhaave, Sydenham,  Willis,  Floyer,
Fernelius, and other eminent men of great  merit in
practice, if not in theory.  Stahl, the German, though
the founder of  the  chemical theory of Phlogiston,
which maintained its ground till the time of Lavoisier,
was so sensible of the inutility of the chemical doc-
trines of the day, that he was tempted, though an ex-
cellent chemist himself, to deny the useful application
of chemistry to medicine.   His notion was,  that the
body,  both in health and  disease,  was under the go-
vernment and superintendence of the soul; an opinion
in its  general form and  outline,  so like to the anima
mundi of Plato,  the *§**<» <?»«< of Hippocrates, and the
Archeus of  Van Helmont,  that it is not worth while
to dwell on the distinction.
  Then came the iatro-mechanical physicians, Dionis,
Borelli,  Baglivi, Bernouilli, Pitcairne,   Sir Clifton
Wintrmgham, Keil, and  Mead, whose physiological
explanations were founded on the laws of mechanics.
  Hoffman suggested morbid action and spasm of the
solids as the causes of disease,  but without rejecting
the humoural  pathology entirely.  Cullen adopted and
extended this  doctrine,  and applied it to the whole of
pathology, gout excepted.
  Building on an expression of Cullen's, Brown found-
ed  his theory of excitability, accumulated during rest,
and exhausted by stimulus, natural or artificial.  Ac-
cording to him,  life is a forced state; and health con-
sists in excitability  perpetually renewed by food and
sleep,  and gradually used up  or consumed, by the
moderate action of  natural stimuli applied to the ani-
mal fibre.   When  the  excitability or the stimulus is
in over proportion, sthenic disease is produced: when
excitability is  deficient,  then there is asthenic diathe-
sis ; when excitability is  too much exhausted by the
application of stimuli, we have indirect debility,  or
asthenia.  Hence, Therapeutics,  with  Brown, were
                         c 
18
guided by four indications only,  excess or  defect of
excitability—excess or defect of stimulus.
  The excitability of Brown does not seem materially
to differ from the irritability of the  muscular and the
sensibility of  the nervous fibre, on  which  Haller,
Whytt, and Girtanner, have laboured so successfully.
Nor does it differ from the sensorial power of Dar-
win; for Brown also derived his excitability from the
nervous fibre and medulla.
  Darwin modified the former theories by rejecting
altogether the humoural pathology, and ascribing the
phenomena of health and disease to irritative, sensitive,
voluntary, and associated motions  in the sensory,—
and correspondent motions in the muscular and other
fibres: herein connecting the theories dependent on
irritability and sensibility, with  the  association and
catenation of motions, first explained and illustrated
by Dr. David Hartley in his most important book on
the association of ideas.
  Thus stood the state of medical science about 20
years  ago; the doctrines of the school of Edinburgh,
as taught by Cullen, maintaining the predominance;
the followers of Brown and Darwin being numerous,
but forming no  separate and  distinct school;  such
also was the case with the medical school of Phila-
delphia, the leading feature of  Dr.  Rush's theory be-
ing,  that pathology is reducible  to the morbid action
of the living solids.   The humoural pathology, with
its cacochymia,  lentors, fermentations,  and spiculae,
could no longer  be  supported by the imperfect che-
mistry of the day.   In Edinburgh, in London, and in
Philadelphia, almost  every body was willing to sub-
scribe to Stahl's opinion,  Chemia  in  medicina, fere
nullus est usus.
  Is it any wonder then,  that  gentlemen educated at
a period when chemistry was regarded as a visionary
branch  of medicine, and  the numoural pathology
founded on it, banished from the schools by common 
19
consent, should retain their prejudices against studies
that they were led to consider as useless and absurd?
  But although this neglect of medical chemistry may
be well accounted for, certain it is, that no such ob-
jections exist at present among those members of the
medical profession who have taken due care to keep
due pace with the knowledge  of the day;  and who
have qualified themselves, to understand and to teach,
what has now become indispensible for a student to
learn.   Professors and practitioners of medicine, in
every part of Europe,  are now alive to the claims of
chemistry, too imperious in its present improved state
to be neglected.  The time has arrived,  when, how-
ever reluctantly, we must retrace our steps:  nor  is it
difficult to shew that even the humoural pathology,
stands upon much  higher  ground than those  who
smile at the application of chemistry to medicine, are
willing to allow, or able to deny.
   I well know that the sentiment I now  advance has
been rejected in Europe  for near half a century:  I
know that it is heresy to the ears of all who are now
present.   But I know too the  ground I stand upon;
and having reflected on the subject, though aware of
contradiction, I am in no fear of confutation.
   The modern doctrine  in  this country is, that the
cause of disease must be sought for alone in the  irre-
gular and unnatural action of  the  living solids, and
never in the fluids of the body.
   I am well aware, that the living fibre of the animal
system, possesses properties that no chemical or me-
chanical philosophy can explain: that  the sensibility,
the irritability, the vitality of the living fibre, are not
chemical properties,  though liable to  be called into
action, deranged, and destroyed, by chemical as well
as by other stimuli:  that health and disease depend
chiefly on the regular and natural, or on the irregular
and disturbed action  of the animal fibres,  whether
separately, or  collected into an QTgpuse&CM&nes: 
20
that the condition of the fluids absorbed, and the fluids
secreted, depends mainly on the condition of the ab-
sorbing and  secreting vessels: and if morbid fluids
and humours appear,  they are very frequently, if not
generally, the consequence of morbid action in the
solids.
  I am well  aware too, of the mutual  and  specific
connexion of the solids with each other  in  various
parts of the body.   I do not ascribe to chemistry the
sympathy of  the skin with the stomach, or the head-
ach of indigestion, or the pain down  the thigh when
the kidneys and  ureters are affected, or the gout in the
toe  on drinking a pint of claret or champaign, or the
affection of the  left shoulder in hepatic obstructions,
or the connexion of the digestive organs, or of animal
heat, with the nervous energy—or a hundred more in-
stances, that demonstrate the association and catena-
tion of morbid sympathies,  too strongly to be doubt-
ed. The position I assume is, that when the humoural
pathology  prevailed,  it sunk  under  the task of ac-
counting for every morbid phenomenon: when it was
rejected for  morbid action in the living solids, the
theorists who rejected it, did not understand it tho-
roughly, or they would  not have  rejected it in toto :
that the present  fashionable  doctrine of morbid action
will in its turn sink under the weight imposed on it,
of  explaining every appearance of disease; and that
there is too much  truth  both in the one doctrine and
the other, to  reject either altogether.
  An instance to  illustrate this morbid action  (if I
may so call it) of medical theory on our opinions, may
be  taken from the gout.
  At first, this  disorder was supposed to arise  from
morbid acrimony contained in the fluids of the body
and therefore venesection, cathartics, and diaphoretics'
were  resorted to.  Well, who can doubt of morbid
acrimony,  who  has  seen the  deposition of lithat  of
soda called chalk stones? 
21
  Then it was supposed to arise from the irritation of
acid spiculae  deposited on the inflamed part.  Well,
who doubts in the present day of a morbid secretion
and formation of acid in the gout?
  Then it was supposed to arise from a  morbid ac-
cumulation of lithic and uric acids in the  system, aid-
ed  by stimulating and acid drinks? Well, who doubts
this who knows that the  substance called urea is not
secreted in usual proportion in a gouty diathesis, and
that acids taken into the stomach uniformly promote
the disease?
   Then it was supposed to arise from a plethora in
 the system of the vena portarum, affecting the secre-
 tions of the liver! Well, can it be doubted for a mo-
 ment whether gout be attended with venous plethora?
    Lately it has been ascribed to morbid sympathy
 with the overloaded state of the stomach and bowels!
 Well, who can doubt this entering into the sources of
 gout,  who knows how frequently a fit  is prevented,
 and how certainly it is shortened by due attention to
 the state of the stomach and intestines?
    It is intolerance that is the  bane of  improvement.
 Intolerance in politics, intolerance in religion, intoler-
 ance in medicine.  Those who deem themselves en-
 titled to  the patent right of a system, will admit of no
 competitor and no sharer. Every thing must be done
 and explained by the sole instrumentality of  their ex-
 clusive method.
    Hence these, my  admissions of modern claims, do
 not exclude the doctrine in question.  The fault of all
 system-makers is exclusiveness.   New theories ex-
 plain every thing: new remedies are panaceas: hence
 the propensity in all of us, to reject what  is useful,
 from its occasional  alliance with unfounded preten-
  sion.
     But the humoural pathology, which admits that the
  causes of disease may exist in the fluids as well as in
  the solids of the body, stands, as  I suppose, upor
  ground  too firm to be shaken. 
22
   The animal solids act when they are stimulated to
 act:  I admit that disease does consist in  morbid  ac-
 tion.  Admitting this, I proceed to the argument.
   1. Such as the fluids are, such are the solids:  for
 they are all formed out of the fluids; and their tenden-
 cy to obey the action of appropriate stimuli, depends on
 their composition, i. e, on the constituents of the fluids.
   2.  All the solids  are  stimulated into action by the
 fluids: the action thus produced will follow  the cha-
 racter of the  producing cause.
   3.  All the secretions will follow the kind and de-
 gree  of  stimulus applied to the solids which secrete
 them; but that stimulus is contained  in the  fluids of
 the body.
   4.  All the  natural stimuli that excite the organs of
 involuntary motion  are contained in the  blood: that
 blood is formed from the chyle; the chyle from chyme
 of the food mixed with the juices of the pancreas and
 the liver.  Such as the food is,  such is the chyle, and
 such  is the blood; and  such is the stimulus to the
 living fibre.  Is not this manifestly  the case in sea-
 scurvy, gout, &c. ?
   5.  The living fibre is liable to be stimulated artifi-
 cially, by all saline  chemical substances, by  alkalies,
 by acids, by earthy  and metallic neutrals,  by galvan-
 ism, by common electricity, by the  gases.
   6.  The quantity and kind of these saline stimulants
 in the blood,  depend greatly on the nature of the food.
   7.  Chemical changes, compositions, and decompo-
 sitions, acid,  alkaline and neutral, do  in fact continu-
 ally take place in and from the fluids of the body,
 such as the lactic, phosphoric,  muriatic, fluoric, sul-
phuric,  and lithic acids,  and their  compounds with
soda, potash,  lime, magnesia, and ammonia.
   8.  The whole mass  of  fluids as  indicated by the
urine  and perspirable matter, can in three or four days
be altered in character from acid to alkaline, and vice
versa: their  stimulant properties must be altered in
proportion. 
23
  9. This  heterogeneous  mass  of saline  chemical
stimuli, of chyle, and of carbonated blood, is mingled
together in the left subclavian vein, and is ultimately
animalised by decarbonisation in its passage through
the bronchial vessels of the lungs: then, and not be-
fore,  it becomes,  when thus mingled and combined,
a stimulus to the left ventricle of the heart, as Good-
wyn has rendered  probable.   The kind  and  degree
of its stimulating power must depend on its composi-
tion : that  is, whether it stimulate too much or too lit-
tle, morbidly or healthily, depends on its composition:
that is, the locality of the source of morbid action, is
in this compound fluid.
   10. The  living fluid blood is not only a stimulus
to the living solid  fibre, but it is itself capable of be-
ing stimulated, and of being formed into a vascular
body: as in the healthy process, where it unites living
parts;  and in the  morbid process, of the last stage of
cynanche trachealis.
    11.  Sir E. Homes's late experiments tend to shew
that medicines act in many, if not in most instances,
 by being received into the mass of circulating fluids:
and  they corroborate the observations to the  same
purpose of Mr. J. Hunter, illustrated by his  case of
 Morgan the painter: and  still later by the discolora-
 tion from nitrate of  silver, related  by Dr. Albers and
 Dr. Roget, 7 Med.  Chir. Trans. 284.*
    12.  Many poisons  act  on  the  solids while  com-
 mingled with the  fluids, as in the variolous, siphilitic,
 the scrophulous,  the cancerous,  when absorbed into
 the system; whether general or lymphatic.
    Lastly, all medicines, in fact, are either stimuli, in-

   • The same position is supported hv a numerous collection of facts in the In-
 augural Dissertation of Dr. Edward Darrel Smith, of Charleston, S. Carolina,
 now Professor of Chemistry in S. C. College.  See also Dr. George Cheyne ,
 case of the absorption of mercury, in his treatise on the English Malady, p.
 343, and Dr. Egan's cases of absorption m the Royal In«h Transactions, anC
 in vol. xxiii. of Tilloch's Phil. Mag. 
24
 creasing action,  or sedatives, diminishing action of
 the living fibre:  and they are always, if possible, ex-
 hibited in a fluid form, in conformity with the  chemi-
 cal axiom, corpora non agunt nisi soluta.
   But nothing is more frequent or notorious than that
 they sometimes act too violently, and increase the dis-
 order : that is, the fluids thrown into the  system fre-
 quently excite to morbid action; that is, they are the
 exciting cause of disease.
   All these arguments might be dilated on and illus-
 trated by cases, but the space of an  introductory lec-
 ture admits only  of an outline: an outline, howeverj
 that sufficiently proves the fluids of the body may be
 diseased themselves, and may produce morbid action
 in the solids.
   Hence, without  denying the effect of vitality, it
 may well  be maintained that the  chemical affinities
 and the stimulating properties of the substances that
 compose the animal fluids, are not annihilated; on
 the contrary, they exert their  full effect  within  the
 body: for  if their  action be  modified by  the  vital
 powers, they in return modify the vital powers them-
 selves.  This may require illustration.   It is an uni-
 versal law that action and reaction are equal and con-
 trary.   Thus, suppose chemical attraction be coun-
 teracted by the attraction of cohesion: the attraction
 of cohesion is proportionably weakened by its resist-
 ance to the tendency of chemical affinity: the same
 law takes place as in the quiescent and divellent forces
 of the component parts of two  chemical compounds.
 So, when chemical affinity is counteracted by the ac-
 tion of the galvanic  fluid, that fluid is expended in the
process.   When  chemical  affinity is modified by the
polarity that produces crystallisation, an  alteration in
 the form of the crystal  is  occasioned by the chemi-
 cal attraction of the molecules:  hence, in mineralogy,
the varieties of form, in substances apparently similar
 in composition.   So in the animal  body;  chemical 
25
affinity in the fluids is counteracted,  1st.  By the per-
petual flux of the particles whereof the body is com-
posed, their absorption, secretion, renewal by assimila-
tion, &c.:  so that in most cases the necessary portion
of time for the attractions to take effect is not allowed.
2d, By galvanic and vital action; which are probably
nearly allied.
   In return, these properties of living matter are mo-
dified by the chemical affinities of the substances sub-
jected to their action: but all this may take place (ac-
cording to the circumstances) either within or without
the limits of healthy action: and in the latter case, the
fluid will contain the causa morbi,  and originate dis-
ease.
   To those who have studied the  laws  of chemical
affinity in connexion with the laws of the animal eco-
nomy, these conclusions are too plain to be doubted:
but to those who have rested content with the imper-
fect knowledge of past times, and  who have despised
animal chemistry too much to study it, these conclu-
sions will be inadmissible, because they  will be unin-
telligible.
   I proceed now to shew  the more  immediate con-
nexion of chemistry  with  medicine, in its relation to
physiology:  pathology, semeiology and  therapeutics:
poisons: 'mineral materia medica:  vegetable materia
medica:  the  adulteration  of  medicines: pharmacy:
and prescription.
   1st. Physiology: wherein we may consider briefly
the doctrine of respiration: of animal  heat:  of  the
circulating fluids: of the bile: of the urinary secretion
of the bones or skeleton: of the coats of the arteries:
of the circulating fluids generally.
   Respiration.   Of respiration and its  uses, nothing
was  known, until the fine experiment of Dr. Priest-
ley, shewing  the disappearance of oxygen when  ex-
posed to venous blood inclosed in a thin bladder, and
the florid colour thus produced.   At present,  how-
                         D 
26
ever, we know tolerably well, that the air inspired is
little changed in quantity:  that  the oxygen is con-
verted into carbonic acid: that  a small quantity of
additional moisture is contained  in  the expired air;
and that it is  thus  fitted  for stimulating the left ven-
tricle of the heart.   At this period, and not sooner,
does the chyle assume  the  properties of the  Wood;
whether a repetition  of this process be necessary to
furnish  a full  share of vitality to the chyle is not yet
fully known.   But it is certain, that the chemical for-
mation of albumen and  fibrin from their elements in
the chyle, does  not  fully take place till this fluid be
acted upon by respiration  and assimilated with  the
blood in the arterial system. So that without a know-
ledge of the chemical composition of the chyle and of
the blood, and the chemical effects of respiration on
these  fluids,  we must remain in utter darkness as to
the processes taking place.  Whatever is known of
these processes,  we owe to chemistry, and to chemis-
try exclusively.
  Animal heat. The first experiments that threw light
on this difficult subject were those of Dr. Black and
Dr. Crawford.   These experiments,  with  some late
ones of Sir H. Davy, inform us, that, not only the
specific heat, but the temperature of arterial is greater
than that of venous blood.  That Crawford was mis-
taken in supposing oxygen to be absorbed because it
disappears, is now well  known; but the facts above
stated are considered as  established.  As in the case
of all other theories,  the  heat of the  animal  system
was, in his day, explained exclusively from the caloric
deposited during  the  course of arterial circulation.
The general  chemical law was  unnoticed, teaching
us, that whenever  a fluid  is converted into a solid,
caloric is given out; so that the  renewal of each par-
ticle of the solid parts of the body must prove a per-
petual source of animal heat. But although this seems
to be a full, an adequate, a reasonable source for the
supply of warmth  to the  animal  system,  it is not ex- 
27
clusively so.  The late  experiments of Le Gallois,
Wilson Philips, Brodie, and Earle,* shew decisively
the influence of the nervous energy over the secretions
and other functions of the body: and that mere che-
mical considerations, though indispensible to account
for animal heat,  will not suffice  alone to explain the
phenomena:  unless,  indeed, the  nervous  energy
should hereafter prove to  be  a galvanic process, of
which the evidence, as yet, is incomplete.
   Of the Blood.  All we know  as yet of the process
of sanguification, and the contents of this compound
fluid, we owe to chemical investigations.  We know
that it contains much  albumen and fibrin,  of which
we can trace little in the chyle until its entrance into
the left subclavian, at its  junction with the carotid;
and but traces of it supplied by the lymph, even there
we know that the colouring matter of the blood alone
absorbs oxygen; and that the serum carries with it
fibrin to renew the waste  of parts it is destined  to
supply (Berzel. An. Ch. 36—46).  Indeed every se-
creting gland is a chemical laboratory;  nor is it pos-
sible to refer the changes that take place in the fluid
that enters a gland, to any other than chemical and
galvanic agency: for decomposition takes place, new
compositions appear, with perfectly different proper-
ties, and with different chemical  elements, and caloric
is given out in almost every case.  We know that the
play of chemical affinities can do this, and we know
of no other power competent to it.   These changes
constitute  the  essential  characters of chemical affi-
nity.
   In considering the serum of the blood in a chemical
point of view,  it is worth observation  that though it
contains fibrin and albumen for  the  purpose  of sup-
plying the wants of solid parts,  it contains no gelatin.
This Bostock  and Berzelius have  shewn.  But the
skin,  the  cartilage, and various  membranes of thf
• 7 Med. Chir. Trans. 284. 
28
body, do contain  gelatin; hence from  five to six per
cent,  of carbon must be separated  chemically from
albumen and fibrin, to convert them into gelatin.   A
direct and incontrovertible proof, among a hundred
others,  that the play of chemical affinities goes  on
perpetually within the body, without interruption from
vital power.
   Of the Bile.  This is secreted by the action of the
liver from the blood which the vena portarum brings
to that viscus.  The bile is described to be, a yellow,
or greenish, and sometimes a colourless fluid.  I shall
venture the assertion, that it never is greenish, or co-
lourless, but in consequence of a morbid state of the
blood brought to the liver,  or morbid  action  of  the
liver itself upon the fluid  thus supplied.   I am per-
suaded  from many experiments  of my own and of
others,  that green bile,  in the stomach,  in the intes-
tines, or in the bladder, is in all cases owing to the
chemical action upon the bile  of  an  acid introduced
too largely in the food,  or morbidly formed,  or  se-
creted,  and in either case chemically combining with
the yellow bile. A remark of very great practical con-
sequence, as I deem it,  and  as I shall note again, in
the semeiology of disease.*
   Urine.  This secretion would demand a volume to
treat all the important questions  concerning it at full
length.  To' chemistry, we owe our knowledge of the
general  composition of healthy urine: and to chemis-
try, we owe all that is known of the variations  that
take place when urine is secreted, either from animal
fluids that are morbid stimuli, or  by morbid action of
the kidneys from healthy fluids.  When we find this
secretion composed of urea, of uric acid, of muriatic,
•lactic, and phosphoric acids,' of combinations of these
in the form of saline neutrals with soda, potash, mag-
nesia,  lime, ammonia,—and in  disease, albumen,
  * On the use of chemistry, as applied to the bile, see Dr. W. Saunders on
the Liver. 
29
gelatin, mucus,  and sugar—and that these vary in
their proportions according to the state of sickness or
health of the  person  secreting this  fluid—when we
have no means of ascertaining the differences of its
composition  but chemical analysis—and when those
differences indicate various conditions of health or dis-
ease,  we may surely be permitted to say  that an accu-
rate knowledge of animal chemistry  is indeed  neces-
sary to the medical profession.
   Of the Bones.  It is principally to Scheele we owe
our knowledge of the chemical composition of these
substances;   consisting  chiefly  of  phosphate, and
slightly of carbonate of lime; and in the  enamel  of
the teeth, of fluate of lime; besides  the fat, the gela-
tin, the cartilage and the water, entering into the com-
position of bone.  To his experiments also we proba-
bly owe die knowledge we possess of Rachitis,  its
proximate cause and probable remedies.
    Of the arterial coats.   It was for a long time sup-
 posed, and I dotibt  whether there  be  yet a  general
 agreement on the question,  that beside  the  elastic
 coat  of the arteries, a muscular coat also accompanied
 these vessels, whose alternate contraction and dilata-
 tion aided the systole and diastole of the heart.  From
 the application of the usual chemical stimuli that ex-
 cite  action in the muscular fibre, no effect was pro-
 duced on  the supposed muscular coat of the arteries
 in the experiments of Bichat.   Hence, it is probable
 that the arterial coats are endued with an elastic power
 only, and  not with the contractility usually observed
 in muscular fibre.   I remark this solely for the sake
 of illustrating, how variously chemical  agency can be
 employed, in determining physiological questions.
    Of the circulating fluids generally.   All these are
 formed out of four principal  fluids  that compose the
 chyle as it enters the venous circulation.   1st. Of the
 chyme formed  in  the  stomach from the food thrown
 in. This must of course depend on the nature of that 
30
 food.  The decomposition of that food, and the new
 compositions formed out of it, cannot take place but
 in consequence of chemical affinities of the substances
 thus acted on,  aided by the vital power  of the sto-
 mach itself.   The diathesis, whether of health or dis-
 ease, must of course greatly depend on the nature of
 the food employed, to satisfy the calls of appetite.  In
 fact we find it so.   An American Indian who lives
 upon animal food, and an East Indian who is sustain-
 ed by rice, have very different temperaments, dispo-
 sitions, and habits.
   2d. Of the pancreatic juice: 3d. Of the bile: 4th.
 Of the lymph.   Each of these fluids before mixture,
 and their combination afterwards, must greatly depend
 on the chemical nature of these separate fluid  sub-
 stances,  and particularly of  the chyle.  For we well
 know that saline substances taken into the stomach,
 whether alkaline, acid,  or neutral, will frequently re-
 tain their composition and properties unchanged: and
 in odier cases, will be subjected to decomposition and
 new arrangements of their  elements.   It is on this
 principle we  exhibit  alkaline and earthy absorbents.
 But all saline substances are stimuli more or less in
 degree, to the living fibre; and therefore the action of
 the living fibre will greatly depend on the nature of
 the food taken in,  and the nature of the chyme form-
 ed out of it.
   That saline substances, acid  and alkaline, may pass
 through the course of circulation, unchanged as to
 their acid or alkaline character, is certain, if there be
 not a double  passage  to the bladder; a fact suspected
 but not ascertained.   Whether the ingenious experi-
ments lately devised by Dr.  Dorsey,  will settle this
long litigated question, we shall know when he thinks
 fit to lay them before  the public*

  • Since this Discourse was delivered we  have to lament thn premature
 decease of this amiable and very ingenious man, whose talents promised <c
much benifit to the Institution to which he belonged. 
31
  Dr. Chapman (Therapeut. vi. p. 284) expresses
himself thus: "My present  view of the subject  is
" perfectly consistent with the doctrine I delivered in
" the early part of these discourses, that no substance
" enters the circulation with a retention of its original
" powers.   To me it is still most manifest,  that the
" process of the assimilation, whether performed by
" the chylopositic viscera, or by any part of the ab-
" sorbent apparatus, completely animalises all articles
" subjected to its influence,  and however various  in
" their  composition,  reduces them  to  one  homoge-
" neous fluid, bland in its nature, and fit for the pur-
" poses of nutrition.  But in the secretions and ex-
" cretions, being removed beyond the sphere  of  the
" vital powers, chemical action takes place, by which
" those substances are in part or entirely regenerated."
   Dr. Chapman's known and acknowledged talents,
which no one is better aware of than myself—the me-
rit of the book in question—and the high standing he
bears in this University, render his opinions of great
importance. The conjectures here quoted are directly
opposed to the numerous facts collected by Dr. Ed-
ward D. Smith; to the case I have cited from Cheyne
and John Hunter, and to the effects of nitrate of silver
related by Dr. Albers and Dr. Roget in the Medico-
 Chirurgical Transactions.
   2dly. There  is  no proof whatever for this strange
 and novel opinion, that the processes of secretion and
excretion are removed beyond the sphere of the vital
powers; but directly the reverse.  3dly. We know
of no process by which any acrid substance decom-
posed and rendered bland by assimilation,  can be in
part or entirely regenerated by the processes of secre-
tion or excretion.   There is not one solitary fact in
support of this opinion.  4thly. If it be so, then the
vital powers of assimilation are  employed in decom-
posing chemical  substances and  rendering them
bland; and the secretory and excretory powers (which 
32
 according to Dr. Chapman are not vital, but removed
 beyond  the  sphere  of vital action)  in  recomposing
 these chemical substances, and restoring their original
 properties.  It is not my business to contend for the
 truth of  these opinions of Dr. Chapman, but if  they
 be true, then is the organised body, even according to
 Dr.  Chapman  himself,  a chemical  laboratory;  and
 nothing but the laws  of chemical affinity can explain
 the phenomena.
   For my own part,  I am well persuaded that  acid
 and alkaline substances  do pass the usual course of
 the fluids unchanged, because by a course of alkaline
 remedies for gouty diathesis, I have repeatedly in the
 course of three days, changed the  character not  only
 of the urinary  secretion, but also of the perspirable
 matter, as appeared when subjected to the test of blue
 litmus paper.   Hence I suspect it as a law in the ani-
 mal  economy,  that the healthy action of the living
 fibre in the organs of the body effects no decomposi-
 tion or new composition of chemical elements, but such
 as the wants of the animal economy call for: such as
 the separation of calcareous earth and phosphoric  acid
 for the use of the bones:  of  gelatin for the cartilage
 and skin  : of albumen and fibrin for the muscles: of
 mucous and synovia  for the  mucous membranes and
joints, &c.: but when that action is morbid,  whether
from a primary disease in the organ or fibre, or from
 the stimulus of  acrid  fluid exciting it to unhealthy ac-
 tion, then secretions and formations of morbid matter
 occur; as in acrid effusions  into the  stomach, intes-
 tines, and lymphatics—ichorous secretions from ill
 conditioned sores—excrescences of various descrip-
tions.
   In all these processes, whether of health or disease,
 not only the vital principle appertaining  to the living
 fibre of the animal body, but the chemical affinities
 of the substances brought within the sphere of action
 of the vital principle, are equally concerned.   This I 
33
consider as demonstrated, 1st. Because the existence
of the vital principle, whatever it may be, is undenia-
ble : 2dly, because the chemical affinities  of the in-
organic matter taken within the body are equally un-
deniable: and, 3dly, Because the  effects  produced
cannot possibly be accounted for without taking both
sets of action into view.
   Hence, also, it follows with equal force, that a know
ledge of physiology depends at least as much on the
effects of animal chemistry,  as  on the laws of ex-
citability and vital action.
   It is manifest that in this brief and hasty sketch of
the connexion of chemistry with physiology, innume-
rable  facts of illustration must  be passed over  for
want of time: and  the  same apology must be made
for the slight outline to which I must confine myself
in the subsequent parts of this discourse.
   I proceed then to  chemistry as connected with pa-
thology, merely touching upon a few of the morbid af-
fections of the body, to shew in what way  chemistry
bears upon the subject.  Always premising,  that when
I propose to shew the use of animal chemistry,  and
thence to deduce its absolute necessity as a part of me-
dical education, I certainly mean, that the well known
properties of the living solids constitute a  branch of
study equally necessary. I agree too, that much useful
knowledge of the  theory and practice  of  medicine
may be obtained, consistently with even a moderate
attention to the  chemistry of the animal body.   In
like manner  much knowledge of empirical practice
can be acquired,  without any just views of the phy-
siology and pathology of the  system.   In  this way,
a man may pass through life with tolerable  eclat as a
village practitioner, just as a knowledge of the minu-
tiae of legal practice may suffice for a county-court
lawyer: but no branch  of the profession will be ne-
glected by those who feel it their duty to stand upon
higher ground; and  to  make the best use of the op-
                        E 
34
 portunities which it  is the  duty of  every medical
 school to afford.
   The yellow and bilious fevers form a prominent fea-
 ture among the diseases of the warm climates of the
 United States.   A hot sun, acting upon a plethoric
 system, either conjoined or unconnected with marsh
 miasmata, may be considered as the exciting cause of
 these diseases,  of which the more immediate seat is
 the liver.  In all these cases, the effects  of intense
 heat and miasmata,  are greatly aided by the venous
 plethora of the  vessels that supply the liver.  Hence,
 persons of a sanguine  temperament and full habit, are
 most liable to danger.  In this  case the liver secretes
 morbidly: by over excitement  in the first instance,
 and by indirect  debility afterwards. But the effect of
 these causes operating upon the liver,  induces also a
 morbid  secretion of acid  in  the stomach, probably
 sympathetic.  In which  case,  a train of  symptoms
 come on, that  ultimately form  the most serious part
 of the disease.
  Chemical experiments shew,  that the acids formed
 in the human body when strong, have this effect upon
the bile.   1st, They turn it of a green colour: 2dly,
They precipitate from it a resin,  insoluble in the fluids
of the body, and soluble in alcohol. (Berzel. 66.)
  By degrees, in the higher stages of the bilious type
of fever, such as the yellow fever, this acid forms the
most constant, the most distressing, the most painful,
and the most dangerous part of  the disease. It is this
concentrated acid, setting the teeth on edge,* and ex-
coriating the lips, that acts on the stomach in yellow-
fever, disorganising and destroying the coats of that
organ, and converting them into the dead matter of
the black vomit.

  • In the report of the Physicians of New Orleans respecting the yellow
fever that prevailed in that city in the summer of 1817, they describe the acid
of the stomach  as agacant les dents : excoriant le bouche : and die ejections
as green. 
35
   This peculiar symptom of morbid acid  has been
 greatly neglected in the cure of these disorders,  par-
 ticularly by the foreign physicians who have practised
 here.   A habit of considering the phenomena chemi-
 cally,  would have  substituted alkaline diluents for
 acidulated ptisans;  and by  counteracting that symp-
 tom which ultimately forms the most serious part of
 the  disease, have saved  many who have  probably
 been injured by the acid medicines meant to promote
 their cure.   This I have observed particularly in the
 reports of cases from New Orleans.*
   These remarks apply in a less degree to the milder
 forms of bilious fever, in all of which, insoluble resin-
 ous matter precipitated in the primsevige, and morbid
 acid formed in the stomach  and intestines, produce a
 train of symptoms that a recurrence to the known
 facts of chemical affinity will alone be  competent to
 combat.  The same  observations  will  apply to  the
 numerous forms of dyspepsia:  one of the most trou-
 blesome symptoms of this proteous disease,  being a
 morbid secretion of acid in the stomach, which in its
 turn acts  not only upon the contents of the intestines,
 but on the mouths of the vessels that open into them,
 either to pour out their contents  from  the  pancreas
 and liver, or to absorb the fluids of the intestines into
 the lacteals.   It is upon this principle only, that we
 can account for the use  of magnesia, soda, and lime,
 in dyspepsia and its attendant symptom cardialgia.
   The same secretion of morbid acid takes place in
 diarrhoea, in dysentery, and in cholera: hence, in these
 diseases,  the manifest use of alkaline remedies,  and
particularly of the chalk mixture: for  although the
symptom  be not the disease, it may when neglected,

   * When the yellow fever is at its highest grade,  little hopes  are to be en-
tertained.  Probably, if called in early, the best general treatment is, full
bleeding: strong purges of calomel and jalap in doses to ensure the speedy
effect: then cold affusions over the whole body; and afterwards saline cathar-
tics, and alkaline ptisans. 
36
 and it frequently does become a disease itself, equal
 in importance to the cause that gave it birth.
   In dysentery,  the astringent remedies of terra  ja-
 ponica and  kino  are  sometimes  usefully  given.*
 There  is every  probability that  these remedies act
 upon the same chemical principles which forms out
 of the  body  the substance called leather: viz. the
 tannin precipitates and combines with the gelatinous
 and albuminous  secretions of this disorder, and closes
 the mouths of the vessels that morbidly secrete them.
   It is surprising that the obvious source of chlorosis
 has never been considered in a chemical point of view.
 I  am not disposed to deny hysteric sympathy acting
 on the stomach;  but it is in  the  stomach and intes-
 tines that this disorder is located.   Is not this obvious
 from the craving of the depraved  appetite  for chalk
 and absorbent earths? Does not this morbid appetite
 point out the acid source of the immediate symptoms?
 and does not  the name  itself indicate  the  chemical
 action of acid on the bile?
   Those who have attended or experienced  cases  of
 hemorrhoid, well know the burning pain that annoys
 the patient in  the region of the rectum:  a pain whose
 cause is the acid nature of the fecal  discharge; and
 which  is severely felt when it passes over the inflamed
 tumours that  characterise this  disease.  Is it not evi-
 dent that chemistry must  supply the remedies to neu-
 tralise this morbid and distressing secretion ?
   I have seen so many  cases of hysteria  to  which
 these remarks apply, that I consider it as a species  of
 dyspepsia, and to be so treated, whether it originate
 in the primae viae, or whether this part of the system
 be affected by uterine sympathy.

   • There are three modes of combating dysentery. 1st, By ipecacuanha
 and emetic tartar, determining to the skin.  2dly, After bleeding, and alkaline
purgatives if indicated by the pulse and primx viae, the exhibition oi'cafchu
 (terra japonica) as an astringent. 3dly, By the exhibition of saline purgatives
 and alkaline remedies during the day, and the injection of laudanum in the
evening.  I have seen them all succeed. 
37
  Indeed, the more I see of disease, the more I am
led to agree with Femelius in his treatise on the gene-
ral method of curing fevers,  and who thus comprises
the sum and substance of die ratio medendi suggested
by the humoural pathology,  of which he was a distin-
guished advocate.   Omnis enim cacochymia, et humo-
rum impuritas, aut ex vitiosd viscerum affectione, aut
ex improba vivendi ratione,  rarb aliis ex causis, pro-
ficiscitur.   That is, all morbid concoction and impu-
rity of the humours of the body, proceeds either from
a diseased  affection of the  stomach and viscera,  or
from a gross and faulty diet. In fact, the most recent
and the most eminent  of  the English physicians,
Hamilton,  Scudamore, Wilson of Kelso,  and Car-
lisle, consider the stomach and bowels as the imme-
diate source of almost all the disorders to which man-
kind are subject;  and that  diseases apparently of a
very different origin arise from the morbid sympathies
 that take place from the acrimonious contents  of the
 primae viae  and the intestinal canal.
   Of Gout.  I have already enumerated the theories
 to  which  this disorder  has given  rise: all of them
 telling us the truth; none of them telling us the whole
 truth.
   The facts hitherto observed seem to establish, that
 this disorder may arise, 1st, From hereditary diathe-
 sis ; inducing a tendency to venous plethora and its
 consequences; viz. morbid action  in the  liver, and
 morbid action in the stomach, causing acid secretion.
   2d. From morbid action in  these viscera, the con-
 sequence of a similar diathesis brought on by habi-
 tual indulgence in too much rich food, and stimulat-
 ing drink.
   3d. From these exciting  causes operating particu-
 larly at the middle age and decline of life,  when  the
 vital energy becomes too weak to  overcome the  op-
 pression of daily  indulgence.
    4th. That acid wines, and  all kinds  of fermented 
38
 liquors, received into the system, are there converted
 into lithic and uric  acids, giving  rise  not merely to
 morbid and arthritic acrimony in the fluids, but to the
 separation  of lithates and urates in the joints and in
 the bladder: a fact  which cannot be denied,  because
 the chalk stones of  the joints, and the calculi of the
 bladder, are  visibly separated from the  circulating
 fluids;  chalk stones, moreover, have been dissolved
 by caustic  alkali,  and again carried into the circula-
 tion.
   All that we know of the composition and formation
 of these productions of gout and  gravel,  we owe to
 chemistry alone: and, cathartics excepted, all the re-
 medies  hitherto suggested, have been furnished by
 chemistry, on chemical considerations:  the same may
 be said not merely of the remedies but of the prophy-
 lactics  also.  In  fact,  without chemistry,  nothing
 would have been known of  the theory or the cure of
 gout, stone, and  gravel; although, as  I allow, other
 considerations may  enter into our view, as gastritis,
 hepatitis, and nephritis, whether  owing to  original
 affection, to metastasis, or to sympathy.
   Dr. Chapman, in  his Therapeutics, when treating
 of the calculus of the bladder, after giving some credit
 to the discoveries  of chemistry on  this subject,  ob-
 serves thus: " Of the many difficulties incident to the
 " case,  not the least  is to determine the composition
 " of the existing stone in  order to  select the appro-
 " priate solvent.   As we  have no  precise mode of
 " doing this, we shall be compelled  to practice empi-
 " rically, experimenting with  one  and  another sub-
 " stance, without rule  or  principle, till we hit upon
 " some one which may answer the purpose."   Chap-
man's Therapeutics,  vol. i. p. 280.
  I believe Dr. Marcet's modes of  analysing urinary-
calculi had not then appeared, which removes almost
entirelythe difficulty  Dr. Chapman complains of.
  How  absolutely necessary it is with  a view to this 
39
disorder and its relations to the gravel and the stone,
to know how to analyse the bile,  and the urine,  as
well as the various kinds of calculi, is made evident
in the last edition of Dr. Scudamore's treatise on the
gout, beyond all doubt the most satisfactory that has
yet appeared.* Owing to the want of chemical as well
as pathological knowledge generally, patients in this
disorder have been from time immemorial the prey of
quacks out of the profession and empirics within it.
But whether the remedy of the day be Mrs. Stephens's
medicine, which is the best  of them, or the Portland
powder, which is the  worst of them, or the Eau Me-
decinale and infusion  of colchicum, which are of the
same grade—whether prescribed by  M. Husson in
France, or Sir E. Home,  or Dr. Want, or Dr.  Wil-
son in England, or by Mr. any body in America, they
are  quackeries—useless in the hands  of skilful  men,
and most dangerous  in the  hands of common men :
the  best opinions and  observations agree that, in every
 case whatever, if they shorten the  paroxysm,  they
 lengthen the disease.   As it appears to me, no physi-
 cian is justified in prescribing a remedy for any dis-
 order whatever,  but  on enlarged views of the patho-
 logy as connected with the physiology of the system;
 either, on  the known properties of the living organ
 when stimulated into action—or on just views of the
 chemical decompositions and combinations that may
 reasonably be expected within the system,  from the
 exhibition  of  the remedy proposed.  The time has
 been, but  it has passed, when empirical  remedies
 might have been excusably prescribed; but I  doubt
 whether  they are allowable in the present improved
 state of medical science.  I forbear to apply chemis-
 try to the gravel and the stone in the bladder, in this
 brief lecture,  because excepting the symptoms pro-
 duced by nephritis, every thing we know of the cause,
  the symptoms, and the cure of these disorders, we are
* See also Sanders on the Liver. 
40
 indebted to chemistry for, exclusively; and the time
 occupied by this lecture would hardly suffice for even
 a brief review of this single  branch of our  general
 subject.  Dr. Chapman's  observations on these dis-
 orders, however, (Therapeutics, vol. i.  p. 281) induce
 me to remark, 1st. Dr. Hale's experiments shew that
 the stone of the bladder, tried by him, was easily dis-
 solved by caustic alkali:  2dly. That Dr. Chitty's
 broth, which contained only caustic alkali as a reme-
 dy, was indubitably of service in calculous disorders:
 so was Mrs. Stephens's medicine acting on the same
 principle.  3dly. That I have no  -doubt  of alkaline
 remedies passing unchanged into the bladder from my
 own repeated experience.
   Diabetes mellitus. Dr. Henry, in the 2d vol. of the
 Med. Chir. Trans, remarks from the experiments  of
 Messrs. Nicholas  and Guadeville,  as  well as from
 tiiose of Dr.  Wollastbn, that  the  serum of diabetic
 blood does not contain sugar.  Hence the kidneys do
 not separate the saccharine fluid, but it is chemically
 formed during the passage of the blood  through these
 organs.  Farina is a common article of every body's
 food; and we know from the experiments of Kirchoff
 repeated on a large scale m my laboratory, that farina
 is converted into sugar by  digesting it  with an acid.
 Dr. Rollo has certainly struck upon the chemical re-
 medy which suits this  theory, as well as the disease
 itself, viz. the deoxygenising property of animal diet,
 and die alkaline sulphurets.   The  experiments  and
 analyses of Dr. Henry are  of great importance  to the
pathology of diabetes and dropsy.
   Pthisis. I fear we know of no cure for this disorder,
 when  decidedly characterised, and combined as  it
 usually is with  scrophula.   Hydrogen  has certainly
 relieved the  symptoms; but it is  of importance to
 know when the disorder is in reality well characteris-
 ed : and when the expectorated matter proceeds from
 tubercules already formed, or merely from an increas-
 ed secretion of mucus owing to incipient inflamma- 
41
tion.   On this point, as on many others among surgi-
cal cases, the experiments of Drs. Pearson, Bostock,
and Berzelius, on  the  distinction between pus and
mucus, deserve great consideration.
   In Rachitis we know that a due proportion of phos-
phate of lime is not secreted and deposited where na-
ture calls for it; but I dare not say that chemistry has
yet discovered the remedy, though she has made us
better acquainted with the disease.
   I cannot, and you cannot, afford the time necessary
to enable me to run even hastily  through the whole
system of nosology, to point out  each particular dis-
ease v\ hereof chemistry has ascertained the cause, the
nature, or the cure. The general  view I have already
taken, comprehends so  many varieties of morbid af-
fection, that I fancy it may by this time be considered
as proven, that a knowledge of medical  chemistry is
at least highly desirable, if not absolutely needful to
the physician.  But we have not yet done.
   Poisons are either mineral, vegetable, or  animal.
Few of these are given, and  few are taken, except
the mineral poisons.  For the vegetable poisons, after
emetics, strong vegetable acids seem the  most proper
as a general class  of medicines:  they seem  power-
fully to counteract the narcotic class of poisons;  and
I have repeatedly eaten  in substance as a pickle,  this
summer, the momordica elaterium, whereof one grain
of the extract is a drastic dose.
  Of the animal poisons, and of  the poisons indeed
generally, we  know nothing but  what chemistry has
furnished us. Dr. Mead, Dr. Ramsay, the Abbe Fon-
tana, Mr. Russel, and Mr. Brodie, have thrown light
upon  some vegetable and some animal  poisons  and
their modus operandi:  but it is with the mineral poi-
sons,  arsenic,  sublimate, copper, and lead, that phy-
sicians have most frequently to deal.   Are there  any
means,  except those which chemistry affords, of alle-
viating the sufferings of a poisoned patient during life,
                        F 
42
or of detecting the nature of the poison after death ?
Some physicians have  pretended to ascertain the ex
istence of poison, and the nature of the poison by the
morbid appearances on dissection.   But these me-
thods of  discovery, when relied on alone, have been
so decidedly shewn to be equivocal and ambiguous,
that I fancy no physician who has a character to lose,
would hazard it by such testimony.  Moreover,  all
who hear me, are liable at one time or other  of their
lives,  to  sit as jurymen upon a case of poison,  or to
be called on as physicians to give testimony in such a
case,  upon oath.  I will  suppose  a physician thus
brought before a coroner's inquest, or a traverse jury
on an indictment.  He will  probably be asked,  and
he will be expected to answer: did  you attend the
patient while living?  what remedies  did  you pre-
scribe? on what principles? did  you  examine the
body  after death?  what were the appearances on dis-
section, in the brain, in the viscera of the thorax, in
the intestinal canal? what reason have you to suppose
that these were the appearances of poison exhibited ?
of what kind of poison? what are the characteristic
appearances,  if any, of each  kind of poison? were
there  any actual appearances of poison in substance ?
did you collect any? what tests did you apply to dis-
cover the existence of  poison?  do you know the me-
thods of detecting the various kinds of mineral poi-
sons? what are they,  and how did you apply them?
Let us see you perform the experiment: this, in many
cases, may be required; for though considerable and
accurate knowledge of chemistry is necessary for the
purpose, any of the  poisons  can be detected with
very great approach to certainty by a small apparatus
and in a short time; arsenic, for instance,  either  in
Mr. Hume, Dr. Marcet's method by alkali and nitrate
of  silver, or in  Scheele's method by copper, or in my
own method by chromate of potash.
   Chemistry is so useful, so  extensively applicable, 
43
 so generally studied,  and so generally understood,
 that the probabilities  are  greatly in favour of some
 judge on the bench, or juryman in the box,  being
 competent  to ask the necessary questions, and  to
 judge of the propriety of the answers.  I should be
 greatly  grieved  to  witness  a physician thus called
 upon in public before a jury of his country, unable to
 give the necessary information.  But how is a man to
 give this information who is unacquainted w ith medi-
 cal chemistry, in practice as well as in theory ? Doubt-
 less a physician who would confess ignorance, or ex-
 hibit ignorance on such an occasion, would meet with
 something like strong disapprobation from those who
 had a right to his professional testimony. Moreover,
 how often is it,  that the healthiness  or unhealthiness
 of particular trades and pursuits come into play, un-
 der the legal doctrine of nuisance! In all these cases,
 physicians are called in to  give  their testimony and
 their reasons for it.  Almost all these legal discussions
 are chemical: and the questions  asked relate for the
 most part to medical chemistry.
   I deem it unnecessary to dilate on this subject; I
 quit it, therefore, and proceed to another  branch of
 the present enquiry.
   All Remedies for disease are drawn from the mine-
 ral, the vegetable, or the animal kingdom. Few from
 the latter. I would ask, is it possible for a physician
 to prescribe  satisfactorily to himself or to his patient,
 who is unacquainted with the medicine  he  thinks fit
 to prescribe?  Are  not the great class  of remedies
 drawn from  the mineral kingdom? Are they not all
 chemical preparations, acting  as  chemical stimuli to
 the living fibre, and undergoing themselves chemical
changes within the body—changes that vary with the
condition of the  body itself and its  fluid  contents?
For instance, calomel  very often  lays for a long time
absolutely inert in the body: sometimes it meets with
phosphoric acid, and becomes a most drastic prepara- 
11
tion. Sublimate to the amount of one-fourth of a grain
is frequently given in alcoholic  solution,  but the eat-
ing of an egg may destroy its effect.   The oxides of
mercury will, in  some instances where the action of
the stomach is healthy, produce the effect  intended
in the usual doses: where acid  is morbidly secreted
in the stomach or intestines, the  oxide  is dissolved,
and a drastic neutral salt is produced,  whose  opera-
tion cannot be counted upon, but will depend on the
nature of the acid it meets  with.  Similar observa-
tions may be made on the preparations of silver, cop-
per,  tin, lead, antimony,  bismuth,  zinc,  &c. whose
numerous  chemical metamorphoses  form so conspi-
cuous a page in the  catalogue  of materia medica.
Can a physician who is not a chemist be qualified to
prescribe these?
   Nor  is  there  less  need  of chemistry  with  re-
spect to the vegetable materia medica.   Are  not
the articles of  this class, very fevv excepted, pre-
pared either by  decoction,  infusion, inspissated ex-
tract, alcoholic resinous  extract,  tincture,  or other
chemical solution? Can any of these be satisfactorily
prescribed without knowing the virtues of the prepa-
ration, as well as  of the simple article? How many
salts, extracts, infusions,  and tinctures, simple and
compound, have we of cinchona? It is dubious,  in-
deed, whether any or all of them be equal to the bark
in substance.  Yet all these are necessary to be well
understood before they can be judiciously prescribed.
Can that man be  a good  workman who is not well
acquainted with  his tools? Can a  physician  safely
tamper  with chemical remedies, who is himself igno-
rant of  chemistry? Again : all the medicines liable to
be prescribed by  a physician, are liable also to gross
adulterations: for instance, calomel is frequently con-
taminated  with sublimate or white lead: red precipi-
tate with red lead : mercury with bismuth: magnesia
with lime: ether  with alcohol: the volatile oils with 
45
turpentine:  the mineral acids are  generally com-
pounds :  carbonate of soda is found mixed with com-
mon and glauber's salt, &c. &c.
   Surely it is desirable for a physician to be able to
detect these  mixtures, which he cannot do if he be
not a chemist also.
   I have said nothing of the  medicinal exhibition of
the  gases, because  when  first introduced to public
notice, they were expected, like all new nostrums, to
perform  every thing.   Physicians found that it re-
quired too much trouble and too much skill to exhi-
bit the gases; and they have been cried down. Now,
that their pretensions are lowered  to a reasonable
standard, and that physicians now are expected to be
chemists, they  deserve a fuller trial  than they  have
had yet.  That hydrogen has prolonged life in con-
firmed pthisis—that oxygen  has  been of service in
typhoid diseases—that nitrous oxide is well calculated
so to be—are assertions not  beyond the reasonable
limits of medical probability.  (See Professor  Silli-
man's Journal of Science, No. J. p. 95.)
   But this is not all: suppose a physician well ground-
ed in the essential doctrines of life and disease, so far
as they are dependent upon the properties of the liv-
ing solid: suppose his medicines  good, and the indi-
cations by which his  prescriptions are to be guided,
clear and unambiguous—I deny that he is fully com-
petent to prescribe,  unless he be  also well versed in
medical chemistry.   Two remedies, each of them
answerirtg a manifest indication  and proper for the
disease, may destroy each other's  efficacy when com-
pounded.  For instance, the sulphate of soda  is a
very common cathartic: prepared chalk, prescribed
as an absorbent, acts also as a cathartic:  when mixed
together, they will  form a compound perfectly inert
as a medicine, and a deleterious load in the stomach.
 Aromatic vinegar is a good  stimulus to  the nerves,
 whether held to the nostrils or taken on a lump of su- 
46
 gar: so is volatile alkali: but the compound is the
 spirits  of mindererus, a mild and weak diaphoretic.
 Sublimed oxide of  zinc is a safe and mild tonic:  so
 is oxide of bismuth: so is  sulphuric  add;  but the
 combinations of sulphuric acid with  these substances
 rank among the poisonous emetics.   Again:  vinegar
 of squills is an efficacious expectorant;  so is carbonate
 of ammonia: join  them in a  prescription,  and the
 compound is an inert neutral salt, the acetate of am-
 monia.   Sulphuric acid is a  tonic,  but the lead it
 usually contains is a poison.
   In making the mineral solution for the ague, the
 dose may fail from  the  frequency of arsenic being
 adulterated with white calcareous spar.  I have  seen
 the effervescent mixture, prescribed and made in my
 presence  at the apothecaries shop.   I have seen the
 lixivium of hickory  ashes preferred  to salt of tartar.
 Nor is there a chemist who hears me, but must have
 known  prescriptions rendered inert, by the composi-
 tion of two or three medicines, each answering a com-
 mon indication.
   It is not possible for a physician to stir in his prac-
 tice,  without employing his knowledge of medical
 chemistry if he has it, or without lamenting the want
 of it, if he have it not.  Hence it is,  that not only the
 best chemists, but the best physicians of Europe, have
 been alive of late years to thejmprovement of medical
 chemistry; and to the prodigious importance  of  this
 branch of knowledge in medical practice.   Where  is
 the scientific journal devoted to medical pur^iits,  that
 does not overflow  with  chemical disquisitions  con-
 nected with medical practice?  Of living chemists in
 Sweden, Gahn and Berzelius: in Italy, Fontana, Sco-
 poli, Brugnatelli, Morichini:  in  France, Parmentier,
 Deyeux, Gay-Lussac, Thenard, Vauquelin, Majendie,
Margueron, and a crowd of others: in England, Davy,
Bostock, Henry, Roget, Hatchett, Home, Wollaston,
Marcet, Scudamore,  Carlisle, and fifty others of the 
47
medical profession, are engaged in it: every day in-
creases the ardour with which this branch of science
is  pursued, and the votaries  attached to its pursuit,
because every day brings its  vast importance more
fully into view.  Is this the favourable opportunity to
decry the  study of it here?  to deny  the necessary
connexion of chemistry with medicine, and to regard
it merely as an ornamental branch of medical educa-
tion? Is this the time, when the obsolete arguments
of twenty  years back, are to be brought forward as
the medical axioms of the  present  day?  Doubtless
such opinions are  natural from gentlemen whose at-
tention has not been alive to  medical improvement,
or whose limited information on this particular  sub-
ject has not permitted them to keep up with it:  but
whatever  strange  and desultory opinions may have
prevailed on this subject, in this city, one thing I take
for granted, which we have all to be thankful for, that
the medical school of  Philadelphia has not yet ven-
tured upon their adoption.*
   A few words more on the method of teaching me-
dical chemistry, and I have done.
   The brilliant and imposing experiments usually de-
vised to gratify  the sight rather  than  inform the un-
derstanding, and to attract the ignorant  and inexpe-
rienced,  are misplaced here.  A complicated and ex-
pensive apparatus is  unnecessary,  and therefore  is
misplaced here.   After a few lectures in illustration of
the general doctrines of chemical affinity,  the experi-
ments shbuld be strictly confined to the subject mat-
ter; and brilliancy should  be sacrificed to utility.  I
agree with that most able physician and chemist, Dr.
Marcet  (2 Med. and Chir. "Trans, p. 358) that the
large and dismal  subterraneous laboratory of the old
 chemists,  is now changed for the fire side of a com-
 fortable study;  and that under the auspices of Dr.

   * Dr. Coxe, l know, agrees in opinion with me on the general subject of
 this discourse. 
48
 YVollaston and two or three more of the British che-
 mists, the anal} sis of small quantities of matter with
 neatness and accuracy, promises to give an essential
 impulse to the progress of analytical chemistry.  In
 fact, the  apparatus  for experiments in medical che-
 mistry  ought to  occupy no  more  space than the
 drawer of a book case, and the required investigations
 may be prosecuted without  injury to a mahogany ta-
 ble by the fire side.
   It is a wise dispensation of  Providence, that death
 should periodically remove the generations of the hu-
 man race:  were it not so, the progress of improve-
 ment would be stopt: for  it is hard to  convince our-
 selves as we advance in years, that the world  of the
 present day can be much wiser than the world of our
 youth; and those who have  neglected  to keep pace
 with the progress of knowledge, never will be con-
 vinced of it.
   I hope,  however,  that on this subject I have been
 able to produce facts and arguments  of sufficient co-
 gency, to shew,  that whatever might have been the
 state of medical chemistry when my cotemporaries
 were young,  it  holds a present rank  among  the
 branches of useful science with claims far superior,
 and too imperious  to be slighted:  and  that I do not
express myself too strongly  when  I  say, that  it is a
branch of science indispensible to medicine.
THE END. 
 
 
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