j!5s? ? .effecr tus. Ge"- N E W-Y O R K: *U '/*fP Printed by T. and J. Swords, Printers to the Faculty of Phyfic of Columbia College, No. 27, William-Street. — 1793.— I Imprimatur. William Pitt Smith. WM. .: ■• . - CIA JOSEPH YOUNG, PHYSICIAN; WILLIAM PITT SMITH, PROFESSOR OF MATERIA MEDICA IN COLUMBIA COLLEGE: INDEBTED to you for the foundation of the fmall Medical SuperftrucJure, which, through Providence, I have been enabled to ere5l—having piloted my little Bark to the Haven of her Dejire-, if any thing in the following pages fhall be found worthy of attention, Permit them to be dedicated to you, With every mark of esteem and respect, By your Friend and Pupil, The AUTHOR. C- * ^' f- gation of this phenomenon of being. Notwith- standing it has engaged the attention of Phyficians and Philofophers of every age, nothing has beea written on the fubjecT:, till within a few years, which is worthy of attention. The rapid improvements in the fcience of Aerology, of which Doctor Priestly is the difcoverer, have enabled the moderns to view the fubjecl: in a more juft manner than the anrients could poffibly have done. Air is necefTary to the exiftence of all organized beings. We fryi none exifting where they are not admitted to its contact -, even plants, as well as ani- mals, are found by experiment to die in vacm. Nature ( 6 ) Nature has taken great pains to provide animals, even of the moft insignificant kind, with organs for bringing their blood fufficiendy in contact with the fluid in which they Jive. This is inftanced in a manner remarkably curious in infects, in their diffe- rent modes of exiftence. From numerous obferva- tions it appears, that air is more effential to animal life than aliment. It forms a great part of the food of plants, and probably alfo of animals; but each of thofe clafTes of being requires it of different kinds: that which is the moft falubrious to plants being noxious to animals; and that which is emitted as excrementitious by the former, moft falutary to the latter. Thus, by an unequalled defign, are thofe two kingdoms made to labour for each other, and, the balance between the components of our atmos- phere preferved.—The death of animals, by fubr merfion, ftrangulation, and fuffocation, is produced by a privation of this all-vivifying fluid. We may be eafily convinced of its eflentiality to life, by vor luntarily fufpending refpiration a few moments. The vaft aerial ocean in which we continually move, although apparently a Ample fluid, is in fact a very heterogeneous mafs. It is compofed of the various fubftances which are capable of being vola- tilized at the temperature at which it exifts, and which it can by its folvent power fufpend. Monf. Lavoisier has proved, fynthetically and analytically, that it is compofed of ovigenous gas, and mephetic airs, in the proportions of 27 and 73 to the 100 parts. This C 1 ) This mepbetis confifts chiefly of azolic, although it contains a fmall portion of carbonic and hydroge- nous gafes.* That carbonic gas enters as an ingredient in the compofition of our atmofphere, has been proved to a derhonftration. It is fufhcient for this purpofe to mention, that lime water expofed to the air is ren- dered turbid, the lime becoming precipitated; and that cauftic alkalies (pure alkalies) are carbonated, or rendered efFervefcent. That hydrogenous gas exifts in the atmofphere, has not fo generally been allowed: but whoever will confider what a yaft quantity of this gas is exhaled from marines, mines, putrifying animal and ve- getable fubftances, will not have a doubt remaining on this head. The airs, then, which compofe our atmofphere, are, the oxigenous, azotic, carbonic, and hydrogenous.-j- Now, * The oxigenous, azotic, carbonic, and hydrogenous gafes of the French Cbemifh, are fynonymous with the dephlogifticated, phlogifticated, fixed, and inflammable airs of Priestly. -f The mechanical propertiesof the atmofphere have, till very lately, entirely attracted the notice of Philofophers. The attention of men of the greateft eminence is now turned towards its compofition. The propor- tions of the ingredients in this fluid muft vary according to a variety of circumftances and fituations. The analyfis of the accurate Lavoisier, already mentioned, is about the medium, and may be moft relied upon, as his abilities and apparatus enable him to do juftice to the inquiry. The proportion of carbonic gas is generally eftimated at anhundreth part, that of the hydrogenous is not afcertained. Probably neither are effential to the compofition of atmofpheric air, as the azotic gas is fufficient to qua- lify the aclion of th« ox"genous. ( 8 ) Now, as animals cannot live without air, it muft be fbrne one of thefe components of the atmofphere in particular, which fupports their exiftence, or the whole collectively. Azotic gas (as its name Signifies) is noxious to animal life. " It cannot be breathed by animals, neither will it admit of the combuftion of inflamma- ble bodies, nor of the calcination of metals.'* If common air be infpired into the lungs, and again ex- pired into a receiver, the volume becomes diminish- ed, while the azotic gas remains the fame both in quantity and quality. It is, therefore* unfit for the pufpofes of refpitationi Hereafter it will appear, that refpiration is not merely a paflive function; that it is not confined to the mere reception and emiflion of air. The unrefpirability of carbonic gas Was long fince ftiewn by Van Helmont, and has fince been proved by Hales, Priestly, and others. It is manifefted by the experiments which have been made on dogs in the grotto del cano, and by accidents which happen in breweries, cellars, and places where the procefs of fermentation is going on. It is this gas which produces the fatal effects that follow from the com- buftion of charcoal in confined places. The expe- riments which have been made on animals in the air exhaling from mineral waters, prove the fame fact. It is further corroborated by the actual experiments of the Abbe Nollet, and the intrepid Pilatre de Rosier, ( 9 ) Rosier, who breathed it at the hazard of life: De Rosier had not taken more than two or three infpi- rations, before he was feized with all the fymptoms of apoplexy. Bergman obferves, that it kills ani- mals inftantaneoufly, and that the hearts of animals fo deftroyed are entirely deprived of their irritability. Hydrogenous gas is likewife incapable of fupport- ing refpiration. " Birds, placed fucceflively in a veflel filled with this air, died without producing the fmalleft perceptible change in it." M. Chaptal fays, that he refpired it himfelf, and found that the fame air might be taken into the lungs feveral times without danger; and that it was not in the leaft vi- tiated or dimimfhed after the experiment. De Rosier likewife infpired it feveral times with impu- nity. From thefe fads it appears that hydrogenous gas is incapable of being decompounded in the kings: It is then merely a paflive fubftance in refpi- ration, producing death by a negation of fome other principle which can fupport this procefs.* Having afcertained that neither azotic, carbonic^ nor hydrogenous gas can fupport refpiration, it there- fore follows, that the oxigenous is the only one fit for B this * From the experiments of feveral eminent perfonson this gas, it would appear, that it exerts a pofitive operation in the lungs, and that it is in itfelf deleterious. The Abbe Fontana found extreme difficulty in tak- ing three infpirations of it. Thefe apparent contradictions will reconcile themfelve, when we confider the power which this gas pofleffes of diflblving charcoal, fulphur, phofphorus, and feveral of the metals.—-One pofitive? experiment, like thoft mentioned in the text, ought to have more weight than an hundred negative ones. C 10 ) this purpofe; for the exiftence of any other in our atmofphere is not afcertained. This gas, like every other, is a compound iub- ftance. It is formed of a radicle or bafe, called oxi- gene, held in folution by caloric (heat, fire, igneous fluid, matter of heat) to the point of faturation, which conftitutes its principle of elasticity. . From the numerous experiments which have been made, it appears that oxigenous gas is capable of fupporting refpiration only a certain time; and that air is refpirable in proportion to the quantity of this gas contained in it. Count Morozzo placed ten fparrows fucceflively under a glafs filled with oxige- nous gas; the firft died in five hours and twenty- three minutes, and the air became confiderably dimi- nifhed in quantity; the Second died in two hours and ten minutes, the third in lefs time, and fo on; the duration of their exiftence diminifhing in proportion to the diminution and vitiation of the air. Others, that were placed in atmofpherical air, died much fooner than thofe in oxigenous gas; the collective duration of the exiftence of three fparrows placed fucceflively in the latter, being three times greater than in the former; correfponding with the propor- tion of oxigenous gas prefent. Chaptal fays, that air in which five fparrows had died, yielded only feventeen hundreths of vital air.—As we have fhewn, that none of the gafeous parts of the atmofphere are capable of fupporting refpiration except ( II ) except the oxigenous, it muft be from a diminution of this that breathing becomes difficult in crouded aflemblies without free ventilation. The above cited experiments fhew that air is di- minifhed by animal refpiration. The lofs in one hour, by the breathing of a man, is 3 60* cubic inches, which will contain, according to the experiments of Lavoisier, 130 grains of folid oxigene. Now, it is impoflible for this gas to be diminished in bulk, unlefs by cold or by preflure, without decompofi- tion; and in order that fuch decomposition may take place, it is necefiary that fome fubftance mould come in contact with it, for which its oxigene has a ftronger attraction than it has for its caloric: Such a fubftance exifts in the lungs of animals, and Shall be pointed out in its proper place. As oxigenous gas is decompounded in the lungs, refpiration may be confidered properly a fpecies of oxigenation. Accordingly, it is found that the fame changes take place in the air during calcination, combuftion, and fermentation, as in refpiration. Thefe procefles require Similar circumftances to favour them, and produce feveral phenomena com- mon to each. 1. Oxigenous gas is required. 2. Caloric is difengaged. 3. Oxigene becomes fixed. 4. The * " M. De. la Metkerie has proved that 360 cubic inches of vital air are abforbed in an hour. My experiments have not fliewn fo great a. lofs." Chaptal's Chemistry. Thejeftimate of the lofs of air in an hour by Hales, is the fame as that pf la Matkekie. See his Staticks. C 12 ) 4. The augmentation of the weight of the products is equal to the weight of oxigenous gas employed. If refpiration is a fpecies of oxigenation or com- buftion, why does not the difengaged caloric manifeft itfelf in the form of light and flame ? The reafon is readily afligned.—The procefs of oxigenation va- ries according to a variety of circumftances. In order that it may go on in a rapid manner, it is ne- cefiary that the fubftance to which the oxigene is at- tached fhould have a ftrong attraction for it, and that it fhould be in a temperature moft favourable to fuch an attraction. It is likewife neceflary that it fhould be concentrated, and not diffufed through a mafs of incombuftible matter. There is but one of thofe favourable circumftances exifting in the lungs of animals: the fubftance by which oxigene is at- tracted there, has indeed a ftrong affinity for it, as fhall be fhewn; but it is diffufed through a fluid unfufceptible of combuftion. The temperature of animal bodies is probably not the moft favourable to a rapid procefs. The difengaged caloric will, under thefe circumftances, confequently, be invisible, a fuf- ficient quantity not being evolved in any given fpace of time to manifeft itfelf by the properties of flame and light. Moreover, as foon as the caloric is let loofe in the lungs, it is communicated to the forma- tion of the vapour and carbonic acid gas which are continually exhaling from the lungs.* As • Whether the vapour exhaling from the lungs of animals is formed . there, by the union of hydrogene patting from the blood with the oxigene ( 13 ) ' As the diminution of oxigenous gas by animal re- fpiration is conftant and fucceflive, we muft look for fome fubftance in the lungs to which its bafe becomes attached. We know of no other matter there which has an attraction for oxigene Sufficient to difengage it from it's caloric, except the blood: In refpiration1, therefore, the Solid matter of oxigenous ga'S muft unite with this fluid. I am of opinion, that the oxi- gene of all the gas which is decompounded in the lungs pafles into the blood. The from the air, or whether it be a fluid exhaled from veflels already formed, is doubtful. The latter conjecture I think the moft probable ; for Chap- tal fays, that when hydrogenous gas is taken into the lungs of animals repeatedly, it does not alter either its quantity or quality : If hydrogene is" coriftantly exhaling from the blood, ought not the volume of gas td have been augmented?--1 intend hereafter to determine this point, by placing animals in hydrogenous gas j if this aqueous fluid is then exhaled, it muft be fecreted from the blood. From a cat which I faw Profeflor Kemp place in a tolerably good vacuum, this halitus was exhaled^ and manifefted itfelf by condenGng upon the fides of the receiver.—This fluid appears to. poflcfs the properties of water, and muft'therefore be formed in the exhalant arteries; for I do not know of a drop of water,- q_UA aojua, in the ani- mal body. It is tranfparent, alnjoft taftejef>, and evaporates by heat without coagulation or leaving any refiduum. That carbonic acid gas exifts in greater quantity in the air expired from the lungs of animals than it did previous to infpiration,' is proved by its rendering lime-water turbid, reddening the tinfture of turnlble, and by carbonating alkalies when caufed to pafs through them. See Gooowyn's inaug. diflert. Priestly on air. Chaptal's Chem.—I am inclined to believe that the compound radicle of this gas is formed in the blood, and not in the veficles of the lungs j for, " according to the experiments of the Count De Milly, and the obfervations of Fouojiet," carbonic gas is conftantly palling off from the flcin as well at the lungs. If " air be placed in contadt with blood, it acquires the property of precipitating lime-water." Whether the aqueous matter and carbonic acid are formed in the lungs or not, they require a large quantity of caloric to convert them into the gafeous ftate ; and muft, no doubt, take up all the caloric which is extri- cated from the oxigenous gas in the lungs.. ( 14 ) The decompofition of fuch a quantity of oxigenous gas as takes place in refpiration, muft produce fome corresponding change in the blood; for experiments fhew that this fubftance is a very general and power- ful agent in nature. It was long fince obferved by Lower, that the blood which flowed from the put"- monary veins was more florid than that which flowed from the artery. The fame fact has been fince taken notice of by Boerhaave, Haller, Cigna, Hew- son, Goodwyn, &c. &c. The blood, then, ac- quires a more florid appearance during its paiTage through the lungs. The caufe of this florid appearance has been made the fubject of the prize queftions of many learned fbcieties. It was a long time attributed to nitre in the air, from the property which this fubftance has of communicating a red colour to blood out of the body. Boerhaave attributes it to texture; Hal- ler to a mixture of oily and ferrugenous matter; Hales to fulphur; Hewson to the efficacy of the fpleen and lymphatic glands I The fact is, there have been as many conjectures refpecting the caufe of it, as there have authors written on the fubject.—It was left for the immortal Priestly to prove that the blood is indebted to what he calls aephlogijiicated air for its red colour.* He * The Doctor does not appear to have had an idea of the decompofition •f this gas in refpiration; he fuppofes it moft fit for this purpofe of any of the airs, becaufe " it contains the leaft phlagifton;" and therefore, according to his idea, it is the beft folvent or menftruum for that principle. Hence, fays he, refpiration is a " phlogiftic procefs, the ufe of the lungs ( i5 ) He expofed a quantity of venal blood to common air, and found that by agitation it immediately be- came red; but this was more eminently the cafe when oxigenous gas was ufed, and in a fhorter time.* Blood rendered florid in this manner, and blood ta- ken from an animal in this ftate, were expofed to hydrogenous, azotic and carbonic gafes; the florid co- lour immediately difappeared, and the blood became black; but upon expofure to oxigenous gas, it fooh relumed its former appearance. Blood becomes red in proportion to the quantity of oxigenous gas con*- tained in the air to which it is expofed. Hewson being to difcharge that phlogifton which had been taken into the fyftem with the aliment." But as all the phaenomena which the Stahlians afcribe to the difengagement of phlogifton, are produced by combinations with oxi- gene, the experiments of Dr. P. are equally applicable to our purpofe, as if they were made upon the principles of the French Chemiftry. * Here it will be pertinent to remark, that as blood is rendered fluid fooner, and in a greater degree out of the body, by expofure to oxigenous gas than to atmofpherical air, it is certainly preferable, in cafes of fufpended animation, to inflate the lungs with it. Goodwyn found by ufing this inftead of common air that he could reftore animals fooner. This gas I conceive, might be exhibited with great advantage in fevers of the typhoid kind, in dropfies, chlorofis, and other difeafes of debility. It is eafily procured, and is not a very dear remedy, as ixoo cubic inches can be obtained from one pound of nitre; and one pint from an ounce of minium. It is a grand defideratum to find a mode for obtaining it from water. Mint, lavender, and many other fragrant plants emit it in co- pious quantities, and might be placed in a fick room with great advantage; they would be pleafing to the eye, grateful to the fmell, afford a ftimulus tto the hear*, and would abforb the unrefpirable part of the air. Chap- tal relates a cafe or two of its beneficial influence in pthifis pulmon. The breathing of this air " diffufes an agreeable warmth in the breaft, infpires cheerfulnefs, renders the patient happy ■— In defperate cafes, it muft certainly be a precious remedy which can fpread flowers on the bor- ders of the tomb, and prepare us in the gentleft manner for the laft dread- ful effort of nature. e *t ) Hewson fays, that he injected air into a vein be- tween two ligatures, and found that the contained Wood aSTumed a more florid appearance. Beccaria expofed blood in vacuo; it immediately became black. Priestly fays, that he repeated the expe- riment with the fame refult. The blood does not come in actual contact with the air in the lungs. That oxigenous gas can acT; through membranes apparently more denfe and im- permeable to air than the veficles of the lungs* is evident from the following experiment of Doctor Priestly. A quantity of black blood was inclofed in a bladder, and expofed to the air; when it was ex- amined, it exhibited the fame florid appearance as if k had been in actual contact with that fluid, the bladder appearing to be no obstruction to the procefs of fioridation. It is a curious and .interesting fact, that oxigenous gas can act on blood although it be covered with a Stratum of ferum of the depth of two inches and an half: whereas the flighteft covering of oil, faliva, or water, effectually prevents its action. As florid blood becomes black in vacuo, or when expofed to any of the unrefpirable gafes; as this co- lour is reftored by expofing it to oxigenous gas, which at the fame time becomes diminished; as blood is changed from black to red by oxigene out of the body, whether it be imparted to it from acids, neutral falts, oxigenous gas, or gafes containing a portion C '*? ) portion of this; we may fafely conclude, that this principle is the immediate caufe of the fame change* which the blood undergoes in the lungs. Priestly found by experiment, that if fucceflive quantities of florid blood were placed in contact with a quantity of hydrogenous or azotic gafes, they be- came in a degree refpirable, and that nitrous air be- came lefTened in bulk, at the fame time lofing its power of diminifning oxigenous gas.—Thefe phe- nomena, according to his theory, he afcribes to the abforption of phlogifton, by the blood, from the air: but any perfon verfed in the doctrines of the new chemistry will perceive, that they are owing to an emiffion of oxigenous gas, the bafe of which exifts in the blood.—This view of the fubject affords an eafy and Satisfactory anfwer to the unphilofophical queftion, whether air exifts in the blood in an elaftic form ? That the bafe of air exifts in the blood, and that it will eafily aflume the gafeous ftate, is evinced from the experiments juft mentioned; but if a vein be taken out of an animal with a ligature pafied round each end, and it be placed under an exhaufted receiver, it will not fwell; or if an artery or vein is punctured under water, not even the fmalleft bubble of air afcends. If air was to be injected into the veins of an animal, it would deftroy its life; for we muft be convinced from the analogy of the blood veflels to hydraulic tubes, that a fmall quantity of air in any of their fuperior flexures would effectually obftruct the circulation of the blood. C The C 18 ) The blood of fifhes, of the foetus in utero, and of the chick in ovo, is red. Are not thefe objections to the theory which fuppofes that oxigene is the florid- ifying principle of blood ? That aquatic animals require air for the continu- ance of their exiftence as well as the terrene, is ren- dered furficientiy evident from the well known fact, that fifh in the winter will rufh in crowds to holes which form or are formed in the ice—an artifice fre- quently ufed for taking thofe animals. This pofi- tion is further corroborated by the following experi- ments. If a few fifhes are placed in a veflel of water, and the air be effectually excluded, they will foon die. The fame takes place in vacuo. Thefe creatures feem to fuffer the fame inconve- nience from being crowded together in a fmall quan- tity of water, as men or other land animals do, when in confined places—the water probably not being fufficiently permeable to air to afford them neceffary fupplies. The experiments of Priestly throw great light on this part of our fubject, and furnifh Sufficient data to prove, that oxigene is neceflary to the florid- ification of the blood of fifhes.—He inclofed a num- ber of thefe animals in different veffels, containing water, with atmofpheres of nitrous, hydrogenous, azotic and carbonic gafes •, under which circumftances they died in a fhort time—in the carbonic gas they expired convulfcd. He likewife placed two fmall fifhes ( i9 ) fifhes in a pail of water: after they had been in twenty-four hours, he found that the water had loft its property of purifying air. In repeating the ex- periment with water which contained air of great purity, he found, after the fifh had died in it, that the air which it contained had not only become di- minifhed in quantity, but alfo that its quality was worfe than that in which a candle goes cut. From thefe experiments it appears, that the gafes which are noxious to land animals, are unfit for the refpiration of fifhes. From the diminution of the quantity of pure air in the water in which thefe ani- mals had been, it is evident that they decompound oxigenous gas, and that, like terrene animals, they Want conftant Supplies of frefh air, With refpect to the young of animals in.utero, it is now rendered fufficiently evident, that they are fupplied with arterial (oxigenated) blood by the umbi- lical vein.—Whether the veflels of the placenta have a power of taking up chiefly that part of the blood in which oxigene refides, or whether the arteries of the uterus tranfmit to the veins of the placenta chiefly that part, is doubtful. Probably this will not appear neceflary when we advert to the well afcer- tained fact, that the blood of women during preg- nancy, and probably of other animals, manifefts a highly florid colour.-—So wifely has Nature adapted means to ends, and upon Such beautiful principles has fhe constituted the animal ceconomy, that the irritability ( 20 ) irritability and tone communicated to the fyftem by a diftention of the uterus, fhould act as a phyfical caufe in increasing the power of Oxigenating blood, in order that the foetus may be fupplied without in- juring the mother. " The gen'ral Order fince the whole began, ♦ < Is kept in Nature, and is kept in Man." That oxigenation is neceflary to the blood of the chick in ovo, is manifefted from the fact, that if the communication between the membranous lining of an egg-fhell and the external air be cut off, it is inca- pable of being hatched. If I had time Sufficient for the purpofe before me, I would try if it Was pbflible to hatch chickens in any of the unfeSpirable airs, and whether oxigenous gas would facilitate that procefs. That their fhells are permeable to oxigenous gas, may be inferred from the putrefaction of eggs. When animal fubftances putrify, carbonic acid gas is exhaled; and from analogy I conclude this to be the cafe with them. Oxigene is eSTential to the for- mation of carbonic acid, and if it could not pene- trate their fhells, it is probable that they would never putrify. It is a notorious fact, that if they are coated with, or immerfed in any fubftance which will exclude the air from them, they may be pre- ferved from putrefaction, even during the warmeft feafons, for a long time. The membrane which lines the internal Surface of the fhells of eggs, is found to be turgid with blood in advanced incuba- tion •, probably it performs the office of oxigenation for the chick whofe lungs are inactive. Here ( 21 ) Here arifes a curious and important queftion—*• important, becaufe, if it could be fatisfactorily an- •fweredj we fhould be in poSTeflion of a never-failing mean of increasing the energy of the fanguiferous fyftem:—To which of the component parts of the blood does the oxigene become united, and what is its nature and properties ? The. inferences drawn from the experiments of Priestly and others * fhew that oxigene is the florid- ifying principle of the blood; but what is the nature of that principle which is capable of being floridified, remains to be determined by experiment, i. It muft refide particularly in the colouring part of the blood. 2. It muft be common to the blood of all red blooded animals. 3. It muft have a great affi- nity for oxigene at a moderate temperature. Iron, as a principle always prefent in red blood, feems to promife a happy explanation of this phseno- menon. The arguments which prefent in favour of this being the floridifiable principle, are, 1. It is al- ways prefent in the blood of animals. 2. It is found in the greateft quantity in the colouring* part. 3. It has an univerfal agency in nature, " in colouring clays and ftones from the darkeft brown to the moft beautiful red." 4. The union of this fubftance with oxigene * The blood is here fuppoled diftinguilhable into three feparate partf, ferum, coagulable lymph, or fibrous portion, and colouring part.—Ac- cording to the moft accurate analyfis of the blood, iron refiJes exdti- fively'in the colouring part. C 22 ) oxigene produces a colour Similar to that of the blood, 5. It is a fubftance friendly to animal bodies, increaf- ing the denfity, floridity, and circulation of the blood. 6. It is one of the moft combuftible of the metals, and eafily reduced to an oxide (calx) by oxigene.— Does not the quantity of iron in blood accord with the degree of its floridity ? Thefe arguments do not appear Sufficiently cogent to afford full fatisfaction. The attraction of iron for oxigene at the temperature of animals, is not fufficiently great to account for that inftantaneous change which the blood undergoes in the lungs, or when expofed to oxigenous gas out of the body. The proportion of iron found in blood, does not ap- pear fufncient to account for its florid appearance; but when we confider how much colour depends upon texture, this objection will not militate fo ftrongly. A quantity of red oxide of iron, equal in weight to that which is obtained from a given weight of blood, will not diffuSe that beautiful red appearance through fo large a mafs of water as the colouring matter from an equal quantity of blood. Red oxide* of iron does not remain in folution, in water, like the colouring part of the blood. Upon the principles of this theory, iron Should be a more certain * Tie oxides of iron differ in colour according to their degrees of ox, igenation; fome containing not more than from twenty to twenty-five parts of oxigene to the hundred} while others have this principle in the proportion of thirty-two or thirty-four hundreths; in which laft ftate theyfjrm a beautiful red, like carmine. Fourcroy, to!, i. p. 413, ( 23 ) certain remedy, always increasing the quantity of co- louring matter, and confequently the floridity.* Upon the whole, the prefence of iron in red blood is not Sufficient to account for all the changes which take place in the lungs of animals. It is, therefore, neceflary to call in the aid of fome other of the com- ponent parts of the blood, by which we Shall be able, either Singly or conjunctly with iron, to account for them in a Satisfactory manner. Phofphorus, as another never-failing principle in the composition of red blood, will afford much af- Slftance in the folution of this difficulty. The cir- cumftances, which a priori appear in favour of this fubftance, are, i. That it is always found in the blood of animals. 2. That its attraction for oxigene is very ftrong, and that at a low temperature. 3. Hu- man * Chalybeates probably do not produce any great effect till they are taken into the circulating mafs. They then form a bafe, or increafe the • power of fome other fubftance exifting in the blood for the attachment of oxigene in the lungs. The blood, being more highly oxigenated, will ftimulate the extreme arteries of the fyftem to greater aftion; and a greater' quantity of caloric will be evolved from the combined ftate in a given time. Heat being one of the greateft ftimuli of animated nature, will further excite arterial action even to the moft minute ramifications. Ac- cordingly we find, that iron is " confidered one of the moft powerful tonics. It increafes the force of the heart, acts upon the fecreting powers, improves digeftion, and invigorates the whole fyftem." (Moore's Mat. Med.) That iron does enter into the blood by the lacleals, is proved by its being prefent in a preternatural quantity in the urine of perfons who have been under the ufe of it, and by their blood being of a more florid colour, containing more than a natural quantity of this fubftance. (MenGhini quoted by Fourcroy and Chaptal.)—This explana- tion, of the operation of iron, accounts for its good effects in cachexies, and Ihews how and why it is fo effectual in reftoring the floridity of the countenance and frefh colour of the whole body.—May not iron be given in conjunction with phofphorus, or the phofphoric acid with advantage ? ( 24 ) man calculi become of a florid red, as docs alio thd blood, if oxigene be communicated to $hem by the nitrous acid. 4. Animal fubftances receive the red dye better than aiiy other^ Probably thefe two phe- nomena are not only produced through the interven- tion of phofphorus, but alfo of iron, as both arc prefent.* A great quantity of phofphoric acid is formed in the animal body. It .enters largely into the compo- fition of bone. It exifts in a naked ftate in the gaftric juice. It is found in the blood. In fact, it enters as an ingredient in almoft all the parts of ani- mal bodies. Large quantities are daily evacuated from the fyftem through the urinary organs, and by the Skin. As oxigene is the great acidifying principle through nature, phofphorus can only be brought into the acid ftate through the intervention of this principle; and as it is impolfible to conceive of any other way in which oxigene can have accefs to the blood but by the lungs, it is evident that this fubftance muft ac- quire its oxigene directly from the air during the paf- fage of the blood through that vifcus, or indirectly from fome fubftance which had previoufly undergone the * Whether thefe fubftances are formed in the bodies of animals or not, a not to the prefent purpofe to inquiie ; -it is fufficient to have afcrrtained that they are never-tailing ingredients in red blood. If they are formed in animal and vegetable bodies, they are not fimple fubftances, as they ar* at prefent efteemed. The chemiftry of nature is not fufficiently attended to. The marine acid radicle, alkali, and probably calcarious earth can be formed in the bodies of animals. ( 25 ) the procefs of oxigenation there.-—There is no fub- ftance in the blood from which phofphorus could re- ceive oxigene in this indirect manner except iron. As the attraction of phofphorus for oxigene at the temperature of animal bodies is greater than that of iron, and as they are equally expofed to the influence of this principle in the lungs, the former muft heceflariiy undergo the greateft change. Thefe considerations induce me to believe that the florid colour of blood is owing to iron and phof- phorus, brought into a ftate of union by oxigene,' I am inclined to believe that thefe fubftances are united in the blood, becaitfe oxigene is the bond of union between acids and metals, and becaufe the che- miftiy of art can unite them through the interven- tion of carbone (pure coal.) Every circumftance favourable to their union exifts in the blood, toge- ther with the more fublime operations of the che- mistry of nature. The idea then of the procefs, to which I have been conducted by this courfe of induction, is fimply this. During the paflage of the blood through the minute branches of the pulmonary artery oxigene becomes united to phofphorus and forms the phofphorlc* acid. The iron is reduced to the ftate of red oxide, partly by the oxigene which it receives in the lungs, D and • Nature appears ftudious to accomplifh this object, by expofing the gteateft pofllble quantity of furface to the oxigenous gas; the area of the air vefides of the lungs being at leaft equal to t/.c furface o« the whole body. ( 26 ) and partly by a communication from the aci How can the production of thefe various fluid fub- ftances from folids be explained, unlefs it is allowed that caloric, under certain circumftances, can take the folid form; and that the fame caloric, in confe- quence of an alteration taking place in the fubftance by which it is held in chemical union, fhall afliime another State, and be the caufe of liquidity and elafti^ fluidity ? ~ Caloric is, no doubt, in a degree condenfed in the natural State of the air; for if thinglafs bubbles, filled with air, be placed under the receiver of an air-pump^ they will burft; bladders, partly filled with air, under fimilar circumftances, immediately- fwejl—the latter fact takes place with bladders partly filled with, ah? when taken to the tops of high mountains-. Mr. Boyle found air to expand in vacuo one hundred and fifty- times; but this falls vaftly Short of the bulk which it is capable of occupying. -n It as impoffible to limit the bounds of the con- denfation of air. Boyle made it thirteen times more -denfc than it was before he applied the preffure. :;-t.. Halley ( 30 ) Halley fays that he has feen it comprefied into one-- fixtieth of its natural fpace. Hales condenfed it thirty-eight times. It has been lately made to occupy one hundred and twenty-eighth part of its former bulk. It is evident, that in the condenfatiOn of air, ca- loric is not fqueezed put, for it inftantaneoufly re- turns to \ts former condition when the condenfing power is removed, as may be feen in the familiar in- Trance of the air-gun. It would not only return to its former volume, but would actually pafs infinitely beyond it, was it not for the mechanical preffure of the contiguous atmofpherical column. If in the compreflion of air caloric was forced from between its folid particles, it would be in a free or difengaged State, andcqnfequently would rnanifeft itfelf by heat. In the expanfion or condehfation of air there lis neither an addition nor diminution of caloric,' there cannot be of the folid matter, caloric can then be made to occupy a greater or lefler fpace than it naturally does in air; its particles cannot be in contact even in the moft condenfed ftate of air. If caloric is matter, and if it be fubject to the laws of the che- mical attractions, and can exift in bodies not only as water does in a Sponge, but alfo in combination ; why may it not become part of their folid fubftance ? From what has been advanced above, it appears that oxigenous gas is decompounded in the lungs. That its folid matter, oxigene, becomes the floridify- ing ( 3i ) mg principle of the blood, and that iron and phof- phorus are the fubftances capable of being floridined. It was then rendered probable from the nature of fluid and folid, and from feveral phenomena explica- ble upon no other principles, that thetbafesof gafes when affumingthe folid form carry caloric with them. I now think it probable, that the caloric.thus united with the oxigene* in the blood, js evolved in the extreme arteries, and is the greateft fource of heat to animal bodies. In maintaining an opinion that heat is not com- municated to animals by the blood from the lungs, but that it is evolved in every point of the body which contains arteries, I know that I fhall act irt oppofition to the fentiments of great names—Ami- cus Plato fed arnica Veritas magis. Although we do not know in what manner arteries evolve combined caloric into the free or fenfible State, yet that its evolution is connected with the action of the arterial fyftem is an obvious truth. But whether this depends upon the action of the ar- teries, or upon that caufe by which arterial ac- tion is directly produced, will be difficult to deter- mine. * 4t One hundred parts of phofphorus require one hundred and fifty- four parti of oxigene for faturation." It has been already obferved, -thai the proportion of oxigene in the red oxide of iron is as thirty-four to one hundred. If one hundred and thirty grains of OxigeWe are combined with the blood in one hour, three thoufand one hundred and twenty muft be fixed in the courfe of one day, which appears to me to carry combined caloric fuffkient to be adrgiute to the effect of the heat of the human bod j. C 32 ) mine. ' We certainly know, that arteries poffefs the power of decompounding the blood, and of recom- pounding it again, as in the various fecretory organs1 of the fyftem. Analogous to this, is that change which the blood undergoes from arterial to venal, as it paffes through the extreme arteries into their an-' aftamofing veins. As the affinities of bodies for caloric, and capacity for containing it, are changed when they undergo any chemical alteration, it is eafy to conceive that bloody when it undergoes the change juft mentioned, Shall throw out a quantity of its combined calorie, which will manifeft itSelf in the fenfible form. During this change of blood from red to black, difengaged oxigene may unite to its car- bone, and form the carbonic acid which is exhaled in fuch quantities from the lungs and fkin.—The blood being deprived of its oxigene, by its union with carbone, by a quantity of phofphoric acid going to the formation of bones and other purpofes, and by a portion of this acid conftantly paffing off by the kidnCys and Skin; the fyftem at the fame time continually generating phofphorus; it is again pre*- pared to attract oxigene in the lungs, and thus is kept up the perpetual round of changes in the blood from venal to arterial, and from arterial to venal during the exiftence of animals. The idea of animal heat, which is deduced from the theory of refpiration already given, is Simply this. By the decompofition of oxigenous gas in the lungs, a quantity of oxigene is communicated to the blood. ( 33 ) blood. The oxigene thus combined carries a large portion of its caloric with it; which is gradually ewtving by the oxigene forming new combinations during the circulation, and which becomes more com- pletely evolved in the extreme arteries by that power which changes blood from arterial to venal. This idea of animal heat refts on the following obfervations, and its eafy application to the explanation of phenomena. The heat of animals is in propor- tion to the extent, perfection, and vigour of their lungs: thus birds are warmer than terrene animals; thefe latter are warmer than the amphibious, and thefe Still more fo than fifhes, whofe temperature is fcarcely above that of the element in which they live. Animals appear to deftroy oxigenous gas in propor- tion to their temperatures. The blood of animals is found to correfpond with their lungs; that of land animals containing a greater quantity of crauamen- tum, and being more florid than thofe which live both on land and in water, and thefe latter again more fo than fifhes, whofe blood is pale, aqueous, and in fmall quantity. The ftate of the blood does not only differ in the different claffes and fpecies of animals, but alfo in individuals of the fame fpecies: " in in- fants, delicate women, and weakly men, it is paler, and lefs difpofed to coagulate, than in robuft healthy perfons. The blood is thin and pale coloured in cachexies, but in difeafes of an oppofite diathefis it is highly florid, and contains a large proportion of crafTamentum, correfponding with the weaknefs or E Strength ( 34 ) ftrength of the pulfe. Any caufe increasing the energy and action of the arteries, increafes heat. Every part of the body containing arteries, is fuf- ceptible of inflammation,* or an increafed genera- tion of heat, even the vafa vaforum of the lymphatics; and that in proportion to vafcularity and fenfibility. Inflammations are generally circumfcribed, which Would not be the cafe if heat was communicated through the body by a mere diffusion from the lungs. Every part of the body is capable, in a certain de- gree, of fupplying itfelf with heat, according to its exigencies. Children have been born with marks of the fmall-pox, the fuppuratory procefs of which difeafe implies inflammation. If * inflammation is confined to the extreme arteries. The phaenomena of this difeafe all concur in fhowing that there is an increafed impetus of the blood in the veflels of the part affected; and, as at the fame time the action of the heart is not evidently increafed, this is fufficient reafon to conclude that the increafe of heat in the part is owing to an increafed action of the veflels independent of the heart. An increafe of action in any fet of veflels produces preternatural heat. Active inflammation may there*. fore be defined an augmentation op that power by which ca- tORlC IS EVOLVED PROM THE COMBINED TO THE FREE STATE. A topical accumulation of excitability or ftimulability will render the vef- lels of that particular part more fufceptible of the adVion of the oxigenatej blood, by which means their action will be increafed (not their energy), and confequently a greater quantity of blood will circulate through the part in a given time than in health, and by this means a greater quantity of heat be evolved. Inflammation may thus continue by the part generating its own ftimulos, till nature relieves the veflels by resolution or fuppuration; hut if the excitement of the part be railed too high by the ftimulant opera. tion of heat, that principle upon which the ftimulusacts will be worn out j the part being thus deprived of that principle, which, when prefent, mo- dified the agency.flif feptic powers, it will confequently be left to the de- ftructive action of external agents, decompofition will eufue, and the components of the fkin, mufcular fibres, &c. form binary combinations, which conftitutes fphacelus.—Upon this principleof a part generating its own heat, the continuance of inflammation can be accounted for, without fuppofing a fpafm to exift in the extieme ends of arteries to fupport their aclion, or without recurring to a vis medicatkix for its. formation. ( 35 ) Tf the heat of animal bodies was all evolved in the?r lungs, the following propofitions would be found to be juft. i. The parts of the animal body would be cool according to their diftance from this fuppof- ed centre; for it is an eftablifhed law in Nature, that heat fhall decreafe as it recedes from the fource from which it originated. 2. No part would be fufcep- tible of an jncreafed degree of heat. 3. No part could refift the topical application of cold, 4. The foetus in utero would generate no heat, and confe- quently would be unfufceptible of inflammation. The accurate obferver of the phaenomena of animal bodies will perceive that the reverfe of thefe is the fact. If the animal body had not the power of preferv- ing itfejf nearly at one uniform temperature, it would be impoffible for it to exift. Heat is an agent which regulates chemical attractions: if the body was raifed much above, or funk much below its natural ftandard, the chemical operations which it performs would be varied, new combinations formed, and death enfue. It was, therefore, neceflary that the temperature of animal bodies fhould be nearly equa- ble, whether they were expofed to the cold of Sibe- ria, or to the burning heat of the torid zone, To fupport this regularity, Nature has made abundant provision. In the frozen regions of the earth, and during cold feafons of the year, atmof- pheric air contains a greater quantity of oxigenous gas ( 3^ ) gas under a given volume, than it does in warm climates and feafons; and, according to the idea, P- 3°» a greater quantity of caloric is contained in condenfed than in rarefied air, and moft certainly more oxigene. Under thefe circumftances a greater quantity of oxigenous gas will be decompounded in the lungs, in a given time, than in warm climates and feafons, and confequently a greater quantity of oxigene fixed in the blood. If this fluid is Stimulant to the fanguifcrous fyftem in proportion to its degree of oxigenation, the animal fyftem will be able to pre- serve one uniform temperature, whether it be ex- pofed to an atmofphere at the freezing point of mercury or at the boiling point of water.* When the atmofphere is cold, and confequently the animal body deprived of a great quantity of heat by its mechanical contact, the air is moft replete with ox- igene and caloric, which are the great caufes of ani- mal heat. The contrary takes place when animals are Surrounded by a warm atmofphere. According to my arrangement of this fubject, I have only to mention the effect of refpiration on the action of the heart. The connection between the ftate of the -breathing and the pulfe has been noted by Boerhaave, Haller, Zimmerman, M'Bride, Gregory, and every other writer on phyfiology and pathology. * It Is a well known fact, that the human body is not colder in the northern regions, where mercury has been known to freeze ; and the ex- periments of Bt.AGb.BN and Fordyce fliew that Its temperature is not much increafed when expofed to air where Farenheit's Thermometer ftoOU above two hundted and forty degrees. ( 37 ) pathology. This natural connection between thefe two vital functions has been brought to account for the fuccefs of Hipprocates in curing difeafes; who, it is faid, almoft neglected the pulfe, but attended particularly to the ftate of the breathing. Goodwyn fuppofes that the heart is indebted only to the chemical change which the blood under- goes in the lungs for the fupport of its inceflant ac- tion. He therefore denies that the dilatation of the thorax is the final caufe of refpiration; and aflerts that the circulation of the blood through the lungs, even in the moft perfect ftate of expiration, is fufli- cient to fupport the life and health of animals. The death of animals by drowning and Strangulation, he fuppofes to be owing to venal blood paffing from the right to the left ventricle of the heart unchanged. Hales and Haller fuppofe that the dilatation of the lungs is neceflary to the free tranfmiffion of blood through them. The former of thefe authors goes fo far as to fuppofe that this is the only ufe of refpiration. It appears to me that the truth (as ufual) lies be- tween thefe two extremes: the blood not only ap- pearing to ftimulate the heart in confequence of be- ing oxigenated in the lungs, but alfo by mechani- cally diftending it. If the conclusion of Goodwyn was founded in Nature, would there be that intimate connection be- tween C 38 ) tween the frequency and force of the heart's action and the frequency and fullnefs of refpiration? Would the fuSpenfion of refpiration produce that turgefcence and rednefs of the face which it is inva- riably found to do ? From Hales's account of his experiments on dogs, it appears that the circulation of the blood was fupported in a kind of mechanical manner, by forcibly distending the lungs with air, which muft have been much vitiated by its having been frequently taken into the lungs of the animal. Cullen obferves, that " the tone of the arterial fyf- tem depends upon its tenfion." I know of no rea- fbn why this will not apply to the heart in fome mea- fure. The right or anterior ventricle of the heart acts without the ftimulus of arterial or oxigenated blood. This Goodwyn fays is becaufe the venal blood is its proper ftimulus. Does it not act by the ftimulus of oxigenated blood in the foetus ftate ?—- According to Goodwyn's idea, a different organi- zation is implied in the ventricles of the heart, to render each fufceptible of its peculiar ftimulus, which is not proved. Upon the whole, I am induced to conclude, that the uninterrupted action of the heart is owing to the evolution of caloric from the oxigene of the blood as it paffes from the lungs to the heart, to the oxi- gene which changes the blood from venal to arterial, and to the mechanical action of the blood. Is ( 39 ) Is the tenacity of the hearts of animals, for their vis infita or irritability, increafed in proportion to the diminution of the power of their refpiratory organs in decompounding oxigenous gas ?—and do their temperatures decreafe in the fame ratio ? From the doubts, difficulties, and uncertainties which occur in attempting to explain the phaenomena of refpiration (and indeed of almoft every other function of the animal oeconomy) I am convinced that much more is Still to be done. There are not yet a Sufficient number of facts collected, and experi- ments made, to constitute the bans, or ferve as data for reafoning in a Satisfactory manner; I have no doubt, and I have analogy in my favour, that this will foon be done. A genuine fpirit of investigation prevails—Revolutions are taking place in every fpecies of knowledge—Medicine does not remain ftationary; and from the unbounded profpects which chemiftry opens to view, I have no doubt but that a period is commencing which will mark a glorious aera in the history of this fcience. FINIS. hed, Hist, 3/7 0 1713 c -1 JfJ* H1 &,J% /A •^~*r -^^^ir ^"< *rv*^