No. 1285.

APRIL 15, 1848.

LecturesON

THE CHEMISTRY OF PATHOLOGYAND THERAPEUTICS.

SHOWING THE

Application of the Science of Chemistry to the Dis-covery, Treatment, and Cure of Disease.

DELIVERED BY

ALFRED B. GARROD, M.D.LOND.,ASSISTANT PHYSICIAN TO UNIVERSITY COLLEGE HOSPITAL; LECTURER

ON MATERIA MEDICA AND THERAPEUTICS, ETC.

LECTURE III.

Introductory. Nutrition in Carnivora continued; exercise re-

quired by these animals. Nutrition in Herbivora; principlesnecessary for the formation of their tissues contained in Vege-tables ; also Amylaceous and other principles; food for Respi-ration ; less motion required to 8ustain animal temperature;formation of Bile in Car2zivora; in Herbivora, not an ex-crementitial fluid; Bile an element of Respiration, formed bythe metamorphosis of the tissues. A -4-fized Diet suited to ffan;alteration in,from habits &,c.; Milk contains everything essential Ifor Nutrition; all Diet should resemble JJlilk in composition; ’,Theine, Cafeine, and Theobromine.: probable use in the economy; Ichiefly taken by those who use much Amylaceous matters in their jdiet; peculiar composition of these principles. Principles of ’iChemistry: elementary bodies; number of; compound bodies;mode of arrangement of elements in; doctrine of equivalent orcombining proportions; of multiple proportions. Atomic

theory ; symbols andformulce; method of employing; use andimportance of.

WE were speaking, at the termination of our last lecture, ofthe mode in which the process of nutrition takes place incarnivora; and I stated to you, that their food was identicalin composition with their bodies, and that the ultimate resultsof the decomposing action of their systems were the produc-tion of carbonic acid, water, and nitrogenized bodies allied toammoniacal salts; that animal heat was produced by thisoxidizing action. Now, we at once see that for the purposeof keeping up their temperature a considerable decompositionmust be constantly going on, and as the amount of fat con-tained in the bodies of their prey is usually not very large,this must be at the expense of their albuminous tissues-asthe muscular and other systems. To effect this, it appearsthat motion is required, and the habits of animals are foundto have a close relation to the nature of their food-thosethat live on the bodies of animals or carnivora having to usemuch muscular exertion in seeking after their prey. Whensuch animals are confined, this necessity for exercise is shownin the constant state of motion which they exhibit in theirdens.Nutrition in the Herbivora.-If we now turn our attention

to the nutrition of the herbivora, at first little resemblance isseen between the composition of their food and of their ownbodies; but on closer examination it is found that the vegetableproductions which constitute their food contains all the proxi-mate principles required for the formation of their frame, andin addition to these, a large amount of amylaceous or starchycompounds, which we shall find to act as food for respiration.In vegetables, as I told you in the last lecture, an albuminousclass of compounds exists, of which many of the members areidentical with those found in the animal body, and theirnutritive power may be generally estimated by the amountof these principles; they contain, in addition, the varioussalts which are essential to the animal-as the phosphateof lime and magnesia, the potash soda, and iron salts. Toobtain the same quantity of flesh-forming material, a muchlarger amount of vegetable food is required, as the proportionof these principles is usually small, the bulk being composed iof amylaceous matter, and water. But as the amylaceous com- Ipounds, when taken, do not form part of the system, nor ;are eliminated from it, as such, by any of the excreting iorgans, being converted into carbonic acid and water, andthus thrown out, it is evident that a large amount of respira-tion can take place without the disintegration or wasting ofthe nitrogenized or albuminous structures; and hence in theseanimals the necessity of motion is less urgent than in thecarnivora.The organs concerned in digestion are also very different inN. 1,)Qtr

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these two classes of animals: in the herbivora, we find a verycomplex alimentary canal, destined to extract all the nutril-tive matter from a large amount of useless material. Liebigsupposes that in carnivora (a serpent, for example) the actionof oxygen, taken in during respiration, causes the disintegra-tion of the tissues, which are first resolved into urate of am-monia and bile; that these enter the blood in a state of solu-tion, and are separated by the action of the kidneys and liver,the former being thrown out of the system in the form ofurate of ammonia, (the semi-solid urine of these animals;) thelatter passing from the gall-bladder into the intestine, whereit becomes again absorbed, and serves as food for respiration,having first performed an important office in the process ofdigestion. To illustrate this view, he shows that the organicsolid portion of the blood or muscle, with the addition ofoxygen, has the composition of urate of ammonia and bile,and proves that the true bile is never found in the fseces whenthe animal is in a state of health. The colouring and fattymatters contained in this fluid are, however, excreted by thealimentary canal. When the true bile has been again ab-sorbed, it is further decomposed into carbonic acidwater, andurea, the two first being thrown off by the lungs, the last bythe kidneys.But in many carnivora we find the urine very rich in urea,

and containing but a small quantity of urate of ammonia.This he explains by supposing that in such animals the oxi-dizing power of the system has been more intense, and theurate of ammonia, previous to its excretion, has been furtherbroken up into urea, carbonic acid, and water. To show thatthe bile and urine are not formed from the food, but by themetamorphosis of the tissues of the animal, it has been foundthat when in a state of starvation, or when no nitrogenizedfood has been given, these fluids are still formed.To explain the changes which take place in the herbivora,

whose food contains so large an amount of non-nitrogenizedmatters, Liebig supposes that bile can be formed by otherprocesses than the metamorphoses of the tissues, and thatthe amylaceous part of their diet, by uniting with nitro-genized principles met with in the system, as urea, &c., andalso some contained in their food, will thus form bile. Heshows, also, that the composition of bile is not unlike that ofstarch with urea. With regard to the statements involvedin this hypothesis, there is no doubt that most of them arecorrect; it is certainly true that the elements of the urineand bile are formed in the blood, and simply excreted-notproduced-by the special organs by which they are eliminated;it is also true that these elements are formed generally fromthe disintegration of the tissues, and not directly from thefood. When, however, more nutriment is taken than requiredby the system, it seems probable that it may be broken upwithout first becoming a part of the animal tissues. Thispoint, however, is at present undetermined. It is true, also,that the bile is not, as formerly supposed, merely an excre-mentitial fluid, as only a very small portion of it-viz., thecolouring and fatty matters-are thrown out in the excre-ments in the healthy state, most of it becoming reabsorbed;and it is very probable, also, that this reabsorbed portion ofthe bile becomes an element of respiration; but it has notbeen proved that in the carnivora all the respiratory elementsfirst assume the form of bile, or that in herbivora, the amy-laceous principles are thus converted previous to their beingthrown off as carbonic acid and water.On reviewing the structure and functions of the human

body, we shall find that, as far as structure is concerned, manis essentially an animal fitted for a mixed diet. This is seenin the form of his digestive apparatus. Such a diet appearsalso best calculated to produce the full development both ofhis bodily and mental powers; and to such his instinctivepropensities generally lead him. We see, however, thatpeculiarities of habits, occupation, and climate, are generallyaccompanied by an alteration in the nature of his food-thesavage hunting nations living almost entirely on animal flesh;while some of the Hindoo races make rice, which consistsalmost entirely of starch, the chief ingredient of their diet.A model for the construction of a diet suited for man is seen

in a single article, (milk,) which, forming, as it does for a time,the only food of the animal, must contain all the substanceswhich are essential for its nutrition.

If this fluid be examined, it is found to contain, dissolved orsuspended in the watery portion, an albuminous principlecalled casein, containing carbon, hydrogen, oxygen, nitrogen,and sulphur-a substance from which the albuminous, fibrinous,and gelatinous tissues can be produced; also fatty principles,in the form of cream ; starchy principles, in the form of milk.

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sugar-these two last serving for the production of animalheat and the deposition of fat; and we find also in this fluid allthe salts required by the system,-phosphate of lime, for theformation of bone, and the salts of soda, potash, magnesia,and iron, essential for the formation of the blood and varioustissues of the body. All diets suited to the adult must moreor less resemble this fluid, and a proper mixture of meat,

bread, and vegetables, will be found to contain these prin-ciples in about the same proportions. In disease, a knowledgeof this subject becomes very important, as we are thenceenabled, by regulation of diet, to diminish such principles asmay be injurious, or to increase those required in greaterabundance; but on this point we shall enlarge when on thesubject of food.

Before leaving this topic I will speak a few words on thealmost universal practice amongst civilized nations of takingcertain vegetable substances, as tea, coffee, cocoa, in the formof hot infusions or decoctions, and on the curious circum-stance of all of them containing either the same or almostidentical principles which are peculiar in composition as com-pared with most other vegetable substances.Now in’the leaves of the tea shrub is found a substance

named theine, which, when pure, assumes the form of beau-tiful crystals, remarkable for the large amount of nitrogen intheir composition. Coffee also contains this principle, at firstcalled caffeine, but which has been since discovered to beidentical with theine. This circumstance is remarkable, asno botanical relation exists between the two plants. Thesame principle has also been found in the leaves of the ilexparaguensis, a species of holly (but not in the common holly-leaves) employed forthesame purposes by the South Americans,and called Paraguay tea; also in guarana, a substance used bythe Mexicans; and lastly, in the cacoa theobroma, whichyields the cacoa nuts, an allied principle, theobromine, is con-tained. Now as these principles do not give to coffee, tea, orcocoa, the properties for which they are chosen as aliments,-viz., their odour, flavour, &c., for’these’depend on’other’prin-ciples contained in’ the different plants, and as they have sopeculiar a composition, with no relation to the albuminousclass of compounds, and therefore cannot act as nutritiveprinciples, strictly so called,-the question is-Of what use arethey are in the animal economy ? Liebig supposes that theyassist in the formation of the bile, where the diet contains alarge amount of amylaceous principles, by uniting with thesein.the blood; and it is found that these substances containingsuch principles are chiefly used by nations whose habits aresedentary, and who take a large amount of such diet; but theyare not employed by. hunting nations, or those who live chieflyon flesh. In the food of the herbivora, Liebig supposes thatasparagin and allied compounds serve the same purpose.There are many objections to this hypothesis; but we mustreserve the discussion of these until such time as we speak ofthe composition of bile.

Principles of Clae7nistry.-In a former lecture I stated that Ishould assume that my hearers were conversant with theprinciples of inorganic and organic chemistry, and that theywere also acquainted with the properties of the most importantelementary substances and compounds. With a view, how-ever, of refreshing your memories with such knowledge as willbe necessary to bear in mind while studying the applicationof .this science to medicine, I will, at the risk, of being con-sidered tedious by some, pass shortly under review some ofthe principal laws which govern, the combination’of the ele- ’,ments, both in inorganic and organic compounds.’ Chemists Irecognise fifty-nine bodies, which as yet. they have beenunable to decompose, and.have therefore- styled them ele-ments. The greater number of these possess properties incommon, to which the name metallic has been,applied; someof them exist in their simple uncombined form: thus we findoxygen and nitrogen in the atmosphere in a state of simplemixture; again, carbon in the form of the diamond; also, gold,silver, and several other metals, in a similar free condition.This, however, is by no means generally the case, most of thesubstances with which we are familiar being composed oftwo or more of these elements in a state of chemical combina-tion. Thus, in water, we find two-oxygen and hydrogen,which in their free state assume the form of gases. We canresolve, again, a piece of flint or rock crystal into oxygen, oneof the constituents of water, and an element called silicon,baving properties somewhat -resembling charcoal or carbon.To give an example of a body still more complex in its con-stitution, let us take a piece of Iceland spar, this we can easily

. separate into two bodies-carbonic acid in the form of gas,and lime, a well-known earthy substance; we can also furtherdecompose each of these bodies into two others, the carbonic

acid into charcoal and oxygen, the lime into a metal calledcalcium, and into oxygen. The substances we have given as ex-amples belong to one division only of the material world orthe inorganic kingdom. If we take organic substances as ourexamples, we shall find that they also can be broken up into afew simple elements; but their mode of combination with eachother, as I shall shortly show you, is very different from whatholds good in the first-mentioned class of bodies. It will bereadily understood from these instances, that elementarybodies will combine with each other in various quantities; but.at the same time we shall discover that these are by no meansindefinite, but that each elementary substance has a particularproportion, in which, or in some multiple of which, it alwaysunites with all other bodies; and hence the doctrine of equi-valent or multiple proportions, of which I shall now endeavourto give you a slight sketch.

Combining equivalents or propm.tions.- We find that the com-position of all chemical compounds is fixed and invariable.100 parts of water are uniformly composed of 11.1 parts, byweight of hydrogen, and 88.9 parts of oxygen; the same holdsgood with all other definite compounds; but although thesame body always contains the same elements united, in un-varying proportions, yet the converse is far from being true,for we not unfrequently find, in organized bodies, the sameelements combining in the sameproportions,without generatingthe same substance, owing to a different arrangement; this,however, does not appear to be the case in the inorganic king-dom of Nature. If we take a class of bodies having oneelement in common,-as, for example, the class of oxides, sul-phurets, or chlorides,-and estimate their composition in 100parts, no relation is found between the oxygen, sulphur, orchlorine, and the other constituents. Thus water is composedof 88.9 parts of oxygen and 11.1 of hydrogen; oxide of copper,of 20.2 of oxygen and 79.8 of copper; oxide of lead, (litharge,)of 7.2 parts of oxygen and 92.8 lead. But if, instead of takingthe composition in 100 parts, we assume a certain number foroxygen—viz., 100, we then find that 12.5 parts of hydrogen,396 parts of copper, and 1294 parts of lead, combine with 100parts of oxygen; and on examining sulphurets and chlorides,the same proportion of hydrogen, copper, and lead, will befound to combine with 200 parts of sulphur, or 443.75 parts ofchlorine. These numbers are characteristic of the substancesto which they are attached, and each of the other elementshas likewise a number which expresses the proportion inwhich it unites with 100 parts of oxygen, 200 of sulphur, or443.75 of chlorine. As oxygen combines with almost all theother elementary. bodies, continental chemists have repre-sented it by 100, or have taken its combining proportion as theunit,-but of course we can assume that number for. any. otherelement,-and as hydrogen enters into combination in less pro-portion than any other substance, in England, hydrogen ismade to represent the unit of the scale, and the .nuinbers Ihave just mentioned, as characteristic of oxygen, copper, lead,sulphur, and chlorine, have only to be divided, by 12.5, to re-duce them to this (the hydrogen) scale. Oxygen will then be8; sulphur, 16; copper, 31; chlorine, 35; lead, 102; (thedecimals being omitted;) and the combining proportion of anyelement will be that amount which unites with 8 parts ofoxygen to form. its,protoxide.As a beautiful example of the law of combination in multiple

proportions, we have only to take the five compounds thatnitrogen forms with oxygen:-

Thus we find that one.equivalent of nitrogen (14) will combinewith 1, 2).3, 4, or equivalents of oxygen, but in no interme-diate proportions. _-

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The same is the case when compound bodies unite witheach other, the law being that the " combining number of acompound body is always the sum of the combining numbersof its constituents"-for example, potassium, eq. 40, uniteswith oxygen, eq. 8, to form the protoxide or potash, andsulphur, eq. 16, unites with three equivalents of oxygen, 24,to form sulphuric acid; and then if the potash combines withthe sulphuric acid, we have a salt called the sulphate of potash,produced by the union of 48 parts of potash with 40 parts ofsulphuric acid, which proves the law I have just stated.Compounds also unite among themselves in multiples of theircombining proportions, as well as in single equivalents.Potash, for instance, with carbonic acid in two proportions, toform the carbonate and bi-carbonate, the amount of carbonic

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acid being twice as great in the latter body as in the former;and even the most complex organic substances, as, for ex-ample, quina, (which is composed of 20 eq. of carbon, 12 eq.of hydrogen, 1 eq. of nitrogen, and 2 eq. of oxygen;) when itunites with the acids, as in the production of its salts, entersinto these bodies in the proportion of the sum of the equi-valents of all these elements. When bodies replace eachother, the same law holds good-thus, if we put a piece ofzinc into a solution of hydrochloric acid, we have hydrogengas given off, and a chloride of zinc formed; and if we estimatethe amount of hydrogen which is displaced, we find that whencompared with the weight of zinc dissolved, it is exactly inthe proportion of their equivalent numbers, or as 1 to 32.5.Our knowledge of the combining proportions of different

bodies will also enable us to explain the phenomena of doubledecomposition: if, for example, we add sulphate of soda to asolution of nitrate of barytes, we find that the liquid still re-mains neutral, although there has been complete interchangeof elements with the production of the insoluble sulphate ofbaryta and the soluble nitrate of soda, because both the oldand new salts are composed of single equivalents of acid andbase, the amount of soda originally combined with an equi-valent of sulphuric acid being that which will neutralize anequivalent of nitric acid; such is also the case with the baryta.What we have already stated, with regard to the equi-

valents of bodies, involves no hypothesis, as the results arederived from experimental inquiry; but if in place of the termequivalent proportion we use that of atomic weight, we makean assumption which leads us at once to the consideration ofthe atomic theory of Dalton.Atomic Theory.-Is matter infinitely divisible, or is it com-posed of particles which can be no further divided-that is, ofatoms ? This is a question which engaged the attention ofthe ancient philosophers, but one which has never been satis-factorily solved. Dalton made the assumption that all matterconsisted of atoms, and that these atoms differ in weight indifferent kinds of matter, being in the same relation to each.other as their equivalent combining proportions. This theoryenables us at once to explain the doctrine of equivalent andmultiple proportions; for compounds must be formed by theunion of atoms of different bodies in the relation of 1 to 1, or1 to 2, or some other simple proportion, and the atom of acompound must always be equal to the sum of the atoms ofits components.Symbols and I1’ornxalcr.-As symbols and formulae will be

constantly used in this course of lectures, perhaps it will beadvisable for me to give you a short explanation of the modein which they are employed, and the advantages resultingfrom them. In the present nomenclature, for which we areindebted to Lavoisier and Berzelius, the elementary bodiesare represented usually by the first letter of their Latinnames, but as the names of many begin alike, the first letteris frequently conjoined with a small one, contained also inthe word, the most characteristic being selected. Carbon isthus represented by C.; potassium, (kalium,) by K.; iodine,by I.; magnesium, by Mg.; lead, (plumbum,) by Pb. It mustbe fully understood that these symbols are not mere con-tractions, but are used to represent an equivalent of eachelement. Thus the letter K’ does not express kalium or

potassium in the abstract, but compared with the symbol ofhydrogen, (Eq. 1,) it represents forty-eight parts by weight.When we wish to express any number of equivalents, thismay be effected either by putting the number before thesymbol, like an algebraic co-efficient; or above and to theright, as an exponent; or a little below and to the right; thus,4 eqs. of carbon can be represented in each of the followingways,-4 C, C4 or C4. Compounds can be represented eitherby the juxtaposition of the symbols; or by the interpositionof a comma, or the sign of addition; thus, the composition ofpotash may be expressed by K 0, or K, 0, or K + 0; and inmore complex combinations, these different methods are usedto signify different degrees of intimacy among the com-ponents : thus, the formulae for nitrate of copper is Cu 0,N 05 z- 3 II 0. In this we find expressed, the intimateunion of the copper and oxygen, to form the oxide of copper;also, of the nitrogen and hydrogen with oxygen, to formnitric acid, and water; in it also is shown the union of thenitric acid with the oxide of copper, which is next in theorder of intimacy; and lastly, we see the water of crystal-lization attached only by the connecting sign of addition.By means of this excessively complete nomenclature, we areenabled, at a glance, to see the intimate composition of themost complex compound.

I shall next proceed to speak of the arrangement of elements,and the difference between morganic and organic combinations.

Lectures

ON PARTURITION,AND THE

PRINCIPLES & PRACTICE OF OBSTETRICY.BY W. TYLER SMITH, M.B. LOND.

LECTURER ON MIDWIFERY, ETC.

LECTURE X.

Abortion a Branch of Spinal Pathology.-Excentric Causes ofAbortion.-Irritation of the Mammary, Trifacial, Vesical,Ovarian, Rectal, Vaginal, and Uterine Nerves.-CentricCauses of Abortion.-Blood-poisons.- The Exanthenzata,Syphilis, Scrofula, 111erezcrialization, Carbonic A cid, Specific.—Uterine Excitants.—Emotion.

IRRITATION of the extremities of Excitor Nerves, and irrita-tion of the Spinal Centre, are the two classes of causes, whichmust be studied in all their forms and varieties, in order toobtain a knowledge of the true nature of Abortion. In thissubject we deal only with surface-pathology, unless we reco-gnise the paramount influence of the nervous system.

EX-CE:8TRIC CAUSES OF ABORTION.

Irritation of the Mai7-imary nerves may produce abortion.This cause is seen in operation in cases of undue lactation,complicated with a second pregnancy. Cases occur in which,during prolonged lactation, two or three conceptions andabortions follow each other, the latter being caused by theirritation of constant suckling. The question naturally sug-gests itself,-whether it is not the constitutional debility,rather than the local irritation, which induces abortion inthese cases; and there can be no doubt that this, like manyother anaemic conditions, may help to produce the accident.There is, however, over and above this, mammary irritationas a distinct cause. I have observed cases in which, owing tothe synergic action between the uterus and the breasts, thesecretion of milk had been almost entirely arrested by con-ception-the infant being chiefly supported by feeding. Thechild would still suck most vigorously, in its attempts to obtainmilk, until the uterus was excited to the expulsion of theovum. and after the abortion has occurred. the secretionof milk returns abundantly. Such cases are very dif-ferent from those in which the breasts are dried up fromdebility. If the synergic relations between the mammaeand the uterus required any more obvious proof, I mightrefer to cases on record in which actual metritis has beencaused by the application of sinapisms to the breasts inamenorrhcea. It is important to recognise mammary irrita-tion as a cause of abortion in the early months, because itmay be mistaken for a profuse menstruation; and the woman,misled by the subsequent profusion of milk, may allow of itsrecurrence, and so suffer considerable constitutional injury.It is curious that irritation of the stomach, between whichand the uterus there is such a distinct relation, should notproduce abortion. After parturition, the slightest gastricirritation will excite contractions of the uterus; but duringpregnancy, gastric irritation, and sickness, even to death, mayoccur without disturbing the foetus in utero; on the contrary,sickness seems positively favourable to the continuance of utero-gestation. The synergies between the lungs and the uterusare equally remarkable. The uterine phenomena of utero-gestation retard the progress of pulmonary disease, but if themost extensive disease of the lungs exist; it does not exciteabortion. An amount of pulmonary disease sufficient tocause death a few days after delivery may exist, without anyinterruption to the natural duration of pregnancy.

Irritation of the Prifacial nerve will sometimes excite abor-tion. It happens when no other cause can be recognised butthe appearance of the dens sapientise, and this phase of den-tition is well known to produce considerable local and consti-tutional disturbance. General convulsions may, in fact, beexcited from this source, either in the male or female subject.The reflexion of irritation from the trifacial upon the uterinenerves, in young pregnant women, is no more remarkablethan the strangury. excited by teething in the infant. Ex-traction of decayed teeth during pregnancy is another cause ofabortion in which the trifacial is concerned. There is a well-known synergy between the uterine system and the teethduring pregnancy, leading to toothach and caries; and thereis also a tendency to reflex action in the direction from theteeth to the uterus. These facts and their rationale requireto be borne in mind in the management of pregnancy.