Dr. Cheyne, on this important head, badly fortified by his inconteftable remark, page 97, that Providence has wifely ordained, that a Vegetable Diet chiefly falls to the share of the most strong and laborious.' Our Author having, in this chapter, candidly acknowleged the improvement, which Medicine may have received from Dr. Pringle's accurate experiments and obfervations, with regard to antifeptic fubftances; and from his having fhewn, that Volatile Alcaline Salts, which were formerly fuppofed to promote Putrefaction, are really powerful Antifeptics; very judicioufly diftinguishes foon after, That as Antifeptics of a quite oppofite nature prevent putrefaction in dead flefh, and flagnating animal fluids, it is difficult to determine in what manner they operate, and how differently they may act in circulating fluids: adding afterwards, p. 104, That this can only be determined by further experiments and ob- ' fervations, as animal circulating fluids are only fufceptible of a weaker degree of putrefaction, and from caufes different from thofe, which produce it in stagnating fluids and dead flesh-fuch fluids,' he alfo juftly obferves, may acqu're a certain degree of putrefaction from a circulation too languid, or too much increased,' immediately adding, In the former cafe the volatile alcaline falts, and the more warm aromatic Antifeptics; in the latter the acid and neu'tral faline and refrigerating, will be most effectual in preventing its progrefs.'-We have been the more particular on this material practical diftinction, as we are apprehenfive, or, indeed, rather convinced, that for want of having made it, fome Practitioners confidering the ftrongest alcalies (in confequence of Dr. Pringle's experiments) only in the general view of ftrong Antifeptics, have directed them as fuch, in that mode of putrefaction refulting from a circu lation too much increafed, which they muft ftill further pro→ mote. The first confideration [not to multiply our own here] that would occur to us, after feeing the antiseptic ef fects of volatile alkalies on dead fleth or membranes (fuppofex the ftomach of fome quadruped) would be, what effect they would be most likely to have on the human ftomach in its na tural and in its different morbid ftates; fince, in fome, our Author rationally imagines, that even the Salt of! Wormwood [un-neutralized] might act, in fome degrec,: as a cauftic.' We have really known an inftance, where.1 a robuft laborious man fwallowed about an ounce of volatile*! fpirits, undiluted, (miftaking it for a dram) and though he almoft immediately plunged his head into a hogfhead of wa ter, of which he fwallowed largely, puked up a little, and ་ ་ fwallowed 1 fwallowed more water, (to allay his burning heat, as he call! ed it) the confequence was a very great hoarienefs, and a lan gour even to his death, which enfued within a month or two. Neither is it improbable, that the cooling antifeptics may. have been as erronenoufly, tho' not fo often, applied in a tendency to putrefaction from a languid circulation: fuch mistakes being not unlikely to refult from general principles and experiments, confiderably founded in truth; but not sufficiently explained and diftinguished, to fuggeft only the safe and falutary practice in different cafes. This, however, Dr. Barry feems to have effected in the prefent important point; [which we could not decline remarking and recommending] the natural ftrength of his mind not fuffering him to acquiefce in remote and poffible causes, when he could difcern mechanical and ftriking ones. Having afferted, in the courfe of this chapter, that a diet on the flesh of fuch animals as fubfift on the flesh of others, will be more apt to give a putrid difpofition to the fluids, than a diet on those who are nourished by vegetable food, he gives the following curious example of it. This way of reafoning was confirmed by an experiment made on a foldier, who was hired to live entirely for fome days on wild fowl, with water only for drink: he received in the beginning his reward, and diet, with great chearfulnefs; but this was foon fucceeded by a Naufea, Thirft, and a difpofition to a putrid Dyfentery, which was with fome difficulty prevented from making a further progrefs, by the Phyfician who tried the experiment." As the Doctor immediately infers from hence, That Seafalt, in a fufficient quantity, is a useful corrector of an animal diet,' it fhould feem as if the foldier was prohibited from using it with his wild-fowl; which is not mentioned, and may be a typographical omiffion. He proceeds, however, to affirm Sea-falt, in that refpect, to be an Antifcorbutic, and exposes the vulgar error of its caufing the Sea-fcurvy, (tho' he thinks a muriatic acrimony may arife from its excefs) infifting, that the continuance of fresh animal food, with their putrid water and bread, and without acids or vegetables, would fooner increase the putrid ftate of the blood," than found and well-falted meat in the fame circumstances. In confirmation of which he gives the following cafe and inftance, 'from his own knowlege. I knew an eminent Lawyer, who, by the advice of Dr. • Woodward, abstained for fome years entirely from Salt, drank. chiefly chiefly Water, and used freely an animal Diet, and by that means acquired a violentScurvy: he was in fome time relieved by a strict Regimen of Diet, and Medicine; and afterwards used Salt, and Vegetables, with an animal Food, < drank Wine more freely, and never had any Return of that Disorder. I knew another perfon, who drank nothing but. Water, and lived freely on an animal Food; and on askC ing him if he was not fond of Salt, he faid, he generally • eat ten times as much as any one in company; Nature thus directing him to guard against that tendency which his Humours had to Putrefaction. This laft inftance we have feen exactly verified in a Water-drinker of our acquaintance. In treating of the Third Digeftion, chap. V. which, he fays, is finished when healthy Serum is fo far gradually attenuated by the action of the veffels on it, as to be capable of entering their smallest series, he makes a parallel between the effect of the Heat of the incubating Hen on the White of the Egg, and that of the Human Body and Circulation on the Serum, as elaborated by the Second Digeftion; proving " thefe two fluids to be exactly fimilar in every appearance and experiment. His defcription of the Humours and Membranes in Ovo, for which Malpighi is referred to, is very accurate; and evinces, that although each of these fluids contains all the materials neceffary for Nutrition, yet a further attenuation of them by heat, is a neceffary circumstance to qualify them for being admitted into those fine vessels, where Nutrition is chiefly performed. The formation of the red globules, fuppofed, from microscopical obfervations, to confift of fix ferous globules, cannot be confidered as a Digestion, which feems in Phyfics to imply fome degree or mode of comminution; but is rather a compofition or condensation effected by the force and mechanism of the vital Oeconomy, and fome mode of attraction, perhaps, which we do not recollect to have feen hitherto fatisfactorily explained. We find, however, that Haller fuppofes them, from their inflammable nature, to contain fome oil or Adeps, which may poffibly ferve as a kind of cement to their compofition. The fection of Nutrition, methodically fucceeds the account of the third Digeftion, which was fo neceffary to it. This difcuffion of that fecret and indifpenfable operation of human bodies, is truly rational, and replete with medical learning and reflection. He premises here, that the body will grow as long as the impelling force of the Heart is fu-. perior to the refiftance of the Arteries; that it will remain at a ftand on their enfuing Equilibrium; and that old 'age age will advance in proportion to the increafe of their fu perior refiftance; when,' as our ingenious Author obferves, the man may be faid to grow back again. And having added, that when a perfon dies of the increafed' rigidity and fuccumbing contraction of the Heart, he may more properly be faid to ceafe to live, than to die,' the Doctor deduces the following curious calculation of the different extent of Life, in different human circulations and habits of living. Hence it is evident, that a human body muft gradually be deftroyed, by the fame caufes which fupport it; that the more quick the motion of the blood is, the fooner old age will advance; and that (cæteris paribus) the number of years, to which all men may attain, will be in a reciprocat Ratio to the Velocity of their Pulfes. Thus allowing 70, or f years for the common age of man, and 60, or b Pulfes in a minute, for the common Measure of Pulfes in a temperate Perfon; and putting c for the number of minutes in a year, then c, b, f, 2209032000, the number of Pulfes in his whole life: but if another, by intemperance, forces his Blood into fuch a motion, as may give 75, or z Pulfes ← in a minute, then cbfbf 56, the number of years, in which fuch a one will run out the same number of Pulses, which, by the former computation, would laft to Threefcore Years and Ten; by which means he will finish his • limited number of Pulfes, or Years, fourteen Years fooner bf, than otherwise; and univerfally z: b:: f: Z After many other ingenious and practical deductions on this fubject, he gives us no incompetent idea of that appofition in which Nutrition confifts, as follows. The only difference between the Solids, and the nourishing parts of the Fluids, is, that the former are more at rest, and have a stronger cohefion; the latter are more eafily feparated, and in perpetual motion; for if a thoufand finall globules be fupposed to move in a proper vehicle, through a canal compofed of the fame materials, though they are then to be confidered as a Fluid; yet if one of them should be preffed into a fmall vacant pore of the canal, it ftops there, and becomes folid, or a part of it; and by being at first prominent, fuftains in that point, the whole force of the circulating Fluid, which was before fuftained by several points of that canal, (as is evident from the doctrine of Hy • draulics) ' draulics) by which means it becomes fixed, and conftitutes a particle exactly like that which has been abraded." Having noted Dr. Keil's error, in concluding from the indelible marks of Scars, the Small-pox, &c. "that the Solids of the body never fuffered any decay, nor received "any addition ;" and Dr. Lower's miftaken calculation, for determining the time in which the whole mass circu"lated through the body, from the given quantity of the blood, and of the quantity paffing through the Heart in a "given time;" without his having adverted to the great difference of the revolution of the blood through the Coronary Arteries, and those of the extremities; this, with feveral other unattainable investigations, making Dr. Barry confider a just refolution of this Problem as impoffible, he fubjoins the following pertinent Query concerning Nutrition. Is not the manner of Nutrition, and the materials of Nourishment the fame in all Animals, as in Plants? and is not the reason why all cannot be nourished by the fame Food owing to the different Strength of the Vellels, and of the circulating Humours, rather than to a Difference of the • Materials required? fince from the frongest Animal, to the most tender Vegetable, the Strength of the Food is always proportioned to the Strength of the Veffels, and Nature of the circulating Humours; and that whatever is used for Diet, from the ftrongest Food, to Water depurated by repeated diftillations, by a chymical analyfis examined, affords the fame terreftrial, folid parts for Nourishment, though in a different quantity,' Finally, as he judges a due quantity of animal Spirits inftrumental to perfect Nutrition, tho' not containing the materials of it, he has annexed to this chapter a fection concerning this evanefcent fluid, which fome Writers on the Animal Oeconomy have denied; but whofe exiftence our Author subscribes to, from much the fame anatomical obfervations, and phyfical analogy, on which the ingenious Haller, and others, feem to have irrefragably established it. He diffents, however, from Borelli and Malpighi, who fuppofed this nervous fluid vifible, and coagulable by fire, from having feen fuch a liquor diftil from a Nerve cut tranfverfely, and placed in an air-pump; which liquor Dr. Barry reasonably concludes, to have iffued from the wounded Lymphatics, plentifully diftributed on the coats of the Nerves. He differs as judicioufly from fome other eminent Writers, who imagined they had difcovered the nervous Cavities in a dried Nerve, tranfverfly cut; and, indeed, clearly fhews, that • the |