Milk. will in a fhort time get the better of them, and prevent the future growth. In Auguft the feeds will ripen, when the plant must be cut down, and the feeds beaten out, as is practifed for other grain; but if it is not protected from birds, they will devour it as foon as it begins to ripen.

Mat. Med.

MILK, a well-known fluid, prepared by nature in the breafts of women, and the udders of other animals, for the nourishment of their young.-According Leon, to Dr Cullen *, milk is a connecting and intermediate fubftance between animals and vegetables. It feems immediately to be fecreted from the chyle, both being a white liquor of the fame confiftence: it is most copiously fecreted after meals, and of an acefcent nature. In most animals who lives on vegetables, the milk is acefcent; and it is uncertain, though at the fame time no obfervation proves the contrary, whether it is not fo likewife in carnivorous animals. But, whatever be in this, it is certain, that the milk of all animals who live on vegetables is acefcent. Milk being derived from the chyle, we thence conclude its vegetable nature; for in those who live on both promifcuously, more milk is got, and more quickly, from the vegetable than the animal food. Milk, however, is not purely vegetable; though we have a vegetable liquor that refembles its tafte, confiftence, colour, acefcency, and the feparability of the oily part, viz. an emulfion of the nuces oleofe and farinaceous fubftances. But thefe want the coagulable part of milk, which feems to be of animal-nature, approaching to that of the coagulable lymph of the blood. Milk, then, feems to be of an intermediate nature, between chyle taken up from the intestines and the fully elaborated animalfluid.

Its contents are of three kinds: firft, an oily part, which, whatever may be faid concerning the origin of other oils in the body, is certainly immediately derived from the oil of the vegetables taken in, as with these it agrees very exactly in its nature, and would entirely if we could feparate it fully from the coagulable part. Another mark of their agreement is the feparability, which proves that the mixture has been lately attempted, but not fully performed. 2dly, Befides this oily, there is a proper coagulable part: And, 3dly, Much water accompanies both, in which there is diffolved a faline faccharine substance. These three can be got feparate in cheese, butter, and whey; but never perfectly fo, a part of each being always blended with every other part.

Nothing is more common, from what has been faid of its immediate nature, than to fuppofe that it re quires no affimilation; and hence has been deduced the reafon of its exhibition in the moft weakly ftate of the human body. But wherever we can examine milk, we always find that it coagulates, fuffers a decompofition, and becomes acefcent. Again, infants, who feed entirely on milk, are always troubled with eructations, which every body obferves are not of the fame quality with the food taken; and therefore it appears, that, like all other food, milk turns naturally acefcent in the ftomach, and only enters the chyle and blood in confequence of a new recompofition. Itapproaches then to the nature of vegetable aliment, but is not capable of its noxious vinous fermentation, and therefore has an advantage over it; neither from this quality, like VOL. XII. Part I.

animal-food, is it heating in the ftomach, and pro- Milk, ductive of fever; though at the fame time, from its quantity of coagulable matter, it is more flourishing than vegetables.

Milk is the food moft univerfally fuited to all ages and states of the body; but it seems chiefly defigned by nature as the food of infants. When animals are in the foetus-ftate, their folids are a perfect jelly, incapable of an affimilatory power. In fuch ftate nature has perfectly affimilated food, as the albumen ovi in the oviparous, and in the viviparous animals certainly fomewhat of the fame kind, as it was necessary the veffels fhould be filled with fuch a fluid as would make way for an after-affimilation. When the infant has attained a confiderable degree of firmnefs, as when it is feparated from the mother, yet fuch a degree of weakness ftill remains as makes fomewhat of the fame indication neceflary, it behoves the infant to have an alkalefcent food ready prepared, and at the fame time its noxious tendency to be avoided. Milk then is given, which is alkalefcent, and, at the fame time, has a fufficient quantity of acidity to correct that alkalefcency. As the body advances in growth, and the alkalefcent tendency is greater, the animal, to obviate that tendency, is led to take vegetable food, as more fuited to its strength of affimilation.

Dr Cullen obferves, that milk is almoft fuited to all temperaments; and it is even fo to ftomachs difpofed to acescency, more than those substances which have undergone the vinous fermentation; nay, it even cures the heart-burn, checks vinous fermentation, and precipitates the lees, when, by renewal of fermentation, the wine happens to be fouled. It therefore very properly accompanies a great deal of vegetable aliment; although fometimes its acefcency is troublefome, either from a large proportion taken in, or from the degree of it; for, according to certain unaccountable circumftances, different acids are formed in the ftomach in, different ftates of the body; in a healthy body, e. g. a mild one; in the hypochondriac difeafe, one fometimes as corrofive as the foffil acid. When the acidity of milk is carried to a great degree, it may prove remarkably refrigerent, and occalion cold crudities, and the recurrence of intermittent fevers. To take the common notion of its paffing unchanged into the blood, it can fuffer no folution. But if we admit its coagulum in the ftomach, then it may be reckoned among foluble or infoluble foods, according as that coagulum is more or lefs tenacious. Formerly rennet, which is employed to coagulate milk, was thought an acid; but, from late obfervations, it appears, that, if it be an acid, it is very different from other acids, and that its coagulum is ftronger than that produced by acids. It has been imagined, that a rennet is to be found in the ftomachs of all animals, which caufes coagulation of milk; but to Dr Cullen the coagulation of milk feems to be owing to a weak acid in the ftomach, the relicts of our vegetable food, inducing, in healthy perfons, a weak and foluble coagulum: but in different ftomachs this may be very different, in these becoming heavy and lefs foluble food, and sometimes even evacuated in a coagulated undiffolved state both by ftomach and ftool.

As milk is acefcent, it may be rendered fometimes purgative by mixing with the bile; and fome examples C

of

Hoffman, in his experiments on milk, found that all kinds of it contained much water; and when this was diffipated, found the refiduum very different in their folubility. But we muft not thence conclude, that the fame infolubility takes place in the ftomach; for extracts made from vegetables with water are often very infoluble fubftances, and hardly diffufible through water itself: therefore, in Hoffman's extracts, if we may fo call them, of milk, fomewhat of the fame kind might have appeared; and these fubitances, which in their natural ftate were not fo, might appear very infoluble. However, we may allow that milk is always somehow infoluble in the intestines, as it is of a drying nature, and as cheefe, &c. is very coftive. And this effect shows that milk is always coagulated in the ftomach for if it remained fluid, no fæces would be produced, whereas fometimes very hard ones are obferved. In the blood-vessels, from its animal-nature, may be confidered as nutritious; but when we confider its vegetable contents, and acefcency in the prime viæ, we find that, like animal-food, it does not excite that degree of fever in the time of digeftion, and that from its acefcency it will refift putrefaction. Hence its use in hectic fevers, which, whatever be their caufe, appear only to be exacerbations of natural feverish paroxyfms, which occur twice every day, commonly after meals, and at night. To obviate these, therefore, we give fuch an aliment as produces the leaft exacer. bation of these fevers: and of this nature is milk, on account of its acefcent vegetable nature.

it

There appears alfo fomewhat peculiar to milk, which requires only a small exertion of the animal-powers in order to its affimilation; and befides, in hectic complaints there is wanted an oily, bland food, approach ing to the animal-nature; fo that on all these accounts milk is a diet peculiarly adapted to them, and, in general, to moft convalefcents, and to thofe of inflammatory temperaments. So far of milk in general. We fhall now fpeak of the particular kinds which are in common ufe.

The milk of women, mares, and affes, agree very much in their qualities, being very dilute, having little folid contents, and, when evaporated to dryness, having these very foluble, containing much faccharine matter, of a very ready acefcency, and, when coagulated, their coagulum being tender and eafily broke down. From this view they have lefs oil, and seem to have lefs coagulable matter than the rest.

The milk of cows, fheep, and goats, agree in oppofite qualities to the three juft mentioned; but here there is fomewhat more of gradation. Cows milk comes nearest to the former milk: goats milk is lefs fluid, lefs sweet, lefs flatulent, has the largest proportion of infoluble part after coagulation, and indeed the largeft proportion of coagulable part; its oily and coagulable parts are not fpontaneously feparable, never throwing out a cream, or allowing butter to be readily extracted from it. Hence the virtues of these milks are obvious, being more nourishing, though at the same time less easily foluble in weak ftomachs, than the three first, lefs acescent than these, and fo more rarely laxative, and peculiarly fitted for the diet of conva

Thefe qualities, in particular milks, are confiderably. diverfified by different circumftances. First, Different animals, living on the fame diet, give a confiderably different milk; for there feems to be fomething in the conftitution, abftracting from the aliment, which conftitutes a confiderable diverfity of milk, not only in the fame fpecies of animals, but alfo in the fame animal, at different ages, and at different diftances after delivery: this applies to the choice of nurfes. Secondly, Milk follows the nature of the aliment more than any other juice in the human body, being more or lefs fluid and dilute, more or lefs folid and nourishing, in proportion as these qualities are more or lefs in the ali ment. The nature of the aliment differs according to its time of growth, e. g. old grafs being always found. more nourishing than young. Aliment, too, is always varied according to the season, as that is warm or dry, moift or cloudy.

The milk of each particular kind of animal is fitter for particular purposes, when fed on proper food.Thus the cow delights in the fucculent herbage of the vale: if the sheep be fed there he certainly rots, but on the higher and more dry fide of the mountain he feeds pleasantly and healthy; while the goat never ftops near the bottom, but afcends to the craggy fummit: and certainly the milks of thefe animals are always beft on their proper foil, and that of goats is bett on a mountainous country. From a differtation of Linnæus, we have many obfervations concerning the diverfity of plants on which each animal chooses to feed. All the Swedish plants which could be collect ed together, were prefented alternately to domestic animals, and then it appeared that the goat lived on the greatest variety, and even on many which were poifonous to the reft; that the cow chofe the first fucculent fhoots of the plant, and neglected the fructifica tion; which laft was preferred by the goat. Hence may be deduced rules concerning the pafturage of dif ferent animals; e. g. Farmers find, that, in a pasture which was only fit to feed a certain number of fheep, an equal number of goats may be introduced, while the fheep are no lefs nourished than before.

It is not easy to affign the difference between milk fresh-drawn and that detained in the open air for fome time: but certainly there is fome material one, otherwife nature univerfally would not have directed infants to fucking; and indeed it seems, better than the other, fitted for digeftion and nourishment. Phyficians have fuppofed that this depended on the evaporation of fome fpt. redor: but our author cannot conceive any such, except common water here; and befides, thefe volatile parts can hardly be nutritious. A more plaufible account feems deducible from mixture: milk new-drawn has been but lately mixed, and is exposed to spontaneous feparation, a circumftance hurtful to digestion; none of the parts being, by themselves, fo eafily affimilated as when they are all taken together. Hence, then, milk new-drawn is more intimately blended, and therefore then is most proper to the weakly and infants.

Another difference in the ufe of milk exposed for fome time to the air, is taking it boiled or unboiled.

Phyficians

cheefy matter, and may be collected from it in a white Milk. cryftalline form, by boiling the whey til all remains of the curdled fubftance have fallen to the bottom; then filtering, evaporating to a due confiftence, fetting it to shoot, and purifying the cryftals by folution in water and a fecond cryftallization. Much has been faid of the medicinal virtues of this fugar of milk, but it does not feem to have any confiderable ones: It is from cows milk that it has been generally prepared; and the crystals obtained from this kind of milk have but little sweetness.

Milk. Phyficians have generally recommended the former; but the reafon is not eafily affigned. Perhaps it is this: Milk kept for fome time expofed to the air has gone fo far to a fpontaneous feparation; whereas the heat thoroughly blends the whole, and hence its refolution is not fo easy in the ftomach; and thus boiled milk is more coftive than raw, and gives more fæces. Again, when milk is boiled, a confiderable quantity of air is detached, as appears from the froth on the furface; and air is the chief inftrument of fermentation in bodies; fo that after this procefs it is not liable to acefcency: for these reasons it is proper for the robuft and vigorous.

Another difference of milk is, according as it is fluid or coagulated. The coagulated is of two kinds, as induced by rennet, or the natural acefcency of the milk. The former preparation makes the firmer and lefs eafily foluble coagulum; though, when taken with the whey unfeparated, it is lefs difficult of folution, though more fo than any other coagulum in the fame cafe. Many nations use the latter form, which is cafier foluble, but very much acefcent, and therefore, in point of folution, fhould be confined to the vigorous, in point of acefcency, to thofe who live on alkalefcent, food; and in the last case, the Laplanders use it as their chief acefcent condiment. From the fame confiderations it is more cooling, and in its other effects like all other acefcent vegetables.

Milk by evaporation yields a fweet faline matter, of which Dr Lewis gives the following proportions: From which water ex

Twelve. ounces of

Cows milk . Goats milk

Human milk
Affes milk

Left of dry tracted a sweet faline fubftance amounting to

matter

The faline fubftance extracted from affes milk was white, and sweet as fugar; thofe of the others brown or yellow, and confiderably lefs fweet; that from cows milk had the leaft fweetnefs of any.

On diftilling 12 quarts of milk in balneo marie, at leaft nine quarts of pure phlegm were obtained: the liquor which afterwards arofe was acidulous, and by degrees grew fenfibly more and more acid as the diftillation was continued. After this came over a little fpirit, and at last an empyreumatic oil. The remaining folid matter adhered to the bottom of the retort, in the form of elegant fhining black flowers, which being calcined and elixated yielded a portion of fixed alkaline falt.

Milks fet in a warm place, throws up to the furface an unctuous cream, from which, by agitation, the butter is eafily feparated. The addition of alkaline falts prevents this feparation, not (as fome have fuppofed) by abforbing an acid from the milk, but by virtue of their property of intimately uniting oily bodies with watery liquors. Sugar, another grand intermedium betwixt oils and water, has this effect in a greater degree, though that concrete is by no means alkaline, or an abforbent of acids.

The fweet faccharine part of the milk remains diffolved in the whey after the feparation of the curd or

When milk is fuffered to coagulate fpontaneously, the whey proves acid, and on ftanding grows more and more fo till the putrefactive ftate commences. Sour whey is ufed as an acid, preferably to the directly vegetable or the mineral acids, in fome of the che mical arts; as for diffolving iron in order to the staining of linen and leather. This acid was commonly made ufe of in the bleaching of linen, for diffolving and extracting the earthy particles left in the cloth by the alkaline falts and lime employed for cleanting and whitening it. Butter-milk is preferred to plain fourmilk or four-whey: This laft is fuppofed to give the cloth a yellow colour. Dr Home, in his ingenious treatife on this fubject, recommends water acidulated with spirit of vitriol (in the proportion of about half an ounce, or at most three quarters of an ounce, to a gallon), as preferable in many respects to the acid of milk, or of the more directly vegetable substances. He obferves, that the latter are often difficultly procurable, abound with oleaginous particles, and haften to corruption; whilft the vitriolic acid is cheap, and pure, and indifpofed to putrefy: That milk takes five days to perform its office, whilft the vitriolic acid does it in as many hours, perhaps in as many minutes: That this acid contributes alfo to whiten the cloth, and does not make it weaker though the cloth be kept in it for months. He finds, that acids as well as alkalies, extract an oily matter from the cloth, and lofe their acidity and alkalicity. Since this treatise appeared, the ufe of four-milk is very generally fuperfeded by oil of vitriol.

It is obfervable, that affes milk is greatly disposed, on standing for a little time, to become thick and ropy. Iu the Breslau collection for the year 1720, there is a remarkable account of milk (which probably was that of the afs) grown fo thick and tenacious as to be drawn out into long ftrings, which, when dried, were quite brittle.

New cows milk, fuffered to ftand for fome days on the leaves of butterwort or fun-dew, becomes uniformly thick, flippery, and coherent, and of an agreeable fweet tafte, without any feparation of its parts. Fresh milk, added to this, is thickened in the fame manner, and this fucceffively. In fome parts of Sweden, as we are informed in the Swedish Memoirs, milk is thus prepared for food.

New milk has a degree of glutinous quality, fo as to be used for joining broken ftone-ware. There is a far greater tenacity in cheese properly prepared.

Milk, when examined by a microscope, appears compofed of numerous globules fwimming in a tranfparent fluid. It boils in nearly the fame degree of heat with common water; fome forts rather fooner, and fome a lile later: after boiling, it is lefs dif

C 2

pofed

Milk. pofed to grow four than in its natural ftate. It is coagulated by acids both mineral and vegetable, and by alkalies both fixed and volatile. The coagulum made by acids falls to the bottom of the ferum; that made by alkalies fwims on the furface, commonly forming (efpecially with volatile alkalies) a thick coriaccous fkin. The ferum, with alkalies, proves green or fanious; with acids, it differs little in appearance from the whey that feparates fpontaneously. The coagulum formed by acids is diffolved by alkalies, and that formed by alkalies is rediffolved by acids; but the milk does not in either cafe refume its original properties. It is coagulated by moft of the middle falts, whofe bafis is an earth or a metallic body; as folution. of alum, fixed fal ammoniac, fugar of lead, green and blue vitriol; but not by the chalybeate or purging mineral waters, nor by the bitter falt extracted from the purging waters. Among the neutral falts that have been tried, there is not one that produces any coagulation. They all dilute the milk, and make it lefs difpofed to coagulate with acids or alkalies: Nitre feems to have this effect in a greater degree than the other neutral falts. It is inftantly coagulated by highlyrectified fpirit of wine, but fcarcely by a phlegmatic fpirit. It does not mingle with expreffed oils. All the coagula are diffolved by gall.

It has generally been fuppofed by medical authors, that the milk of animals is of the fame nature with chyle, and that the human milk always coagulates on the ftomach of infants; but in a late differtation upon the fubject by Mr Clarke, member of the royal Irish academy, we find both thefe pofitions controverted. According to him, woman's milk, in an healthy ftate, contains no coagulable, mucilaginous, or cheefy principle, in its compofition; or it contains fo little, that it can not admit of any fenfible proof. Dr Rutty ftates, that it does not afford even a fixth part of the curd which is yielded by cows milk; and Dr Young denies that it is at all coagulable either by rennets or acids. This is confirmed by Dr Ferris, who in 1782 gained the Harveian prize-medal at Edinburgh by a differtation upTrife Tranf. on milk. Mr Clarke informs us, that he has made a For 1788. vaft number of experiments upon woman's milk with a view to determine this point. He made ufe of ardent spirits, all the different acids, infufions of infants ftomachs, and procured the milk of a great many different women; but in no inftance, excepting one or two, did he perceive any thing like curd. This took place in confequence of a fpontaneous acefcency; and only a fmall quantity of foft flaky matter was formed, which floated in the ferum. This he looked upon to be a morbid appearance.

The general opinion that woman's milk is coagulable, has arifen from a fingle circumftance, viz. that infants frequently vomit the milk they fuck in a ftate of apparent coagulation. This greatly perplexed Dr Young; who, after having tried in vain to coagulate human milk artificially, concluded, that the process took place spontaneoufly in the ftomach; and that it would always do fo if the milk were allowed to remain in a degree of heat equal to about 6 degrees of Fahrenheit. Mr Clarke took equal quantities of three different kinds of milk, and put them into bottles flightly corked, and these bottles into water, the temperature of which was kept up by a fpirit-of-wine

lamp as near as poffible to 96° of Fahrenheit: but after frequently examining each bottle during the course of the experiment, at the expiration of feveral hours there was not the fmalleft tendency towards coagulation to be perceived in any of them; the cream was only thrown to the furface in a thick and adhesive form, and entirely feparated from the fluid below, which had fomething of a grey and wheyifh appearance. As the matter vomited by infants is fometimes more adhefive than we can fuppofe cream to be, Mr Clarke fuppofed that the curd might be fo entangled with the cream, as to be with difficulty feparated from it; but having collected a quantity of rich cream from the milk of different women, he repeated the experi ment with precifely the fame event, not being able in any one inftance to produce the smalleft quantity of curd. To determine, however, what effects might be produced upon milk by the ftomach of an infant, Mr Clarke made the following experiment: Having taken out the ftomach of a fetus which had been deprived of life by the use of inftruments, he infufed it in a fmall quantity of hot water, fo as to make a ftrong infufion. He added a tea-spoonful of this infufion to equal quantities of cows and human milk; the confe quence of which was, that the cow's milk was firmly coagulated in a fhort time, but the human milk was not altered in the leaft; neither was the least coagulation produced by adding a fecond and third spoonful to the human milk. "Upon the whole, then, (fays Mr Clarke), I am perfuaded it will be found, that human milk, in an healthy ftate, contains little or no curd, and that the general opinion of its nature and properties is founded upon fallacious analogy and fu perficial obfervations made on the matter vomited by infants. We may prefume, that the cream of woman's milk, by its inferior specific gravity, will fwim on the furface of the contents of the ftomach; and being of an oily nature, that it will be of more difficult digeftion than any other conflituent part of milk. When an infant then fucka very plentifully, fo as to over-diftend the ftomach, or labours under any weakness in the powers of digeftion, it cannot appear unreasonable to fuppofe, that the cream fhall be first rejected by vomiting. Analogous to this, we know that adults affected with dyfpepfra often bring up greasy fluids from the ftomach by eructation, and this efpecially after eating fat meat. We have, in some instances, known this to blaze when thrown into the fire like spirit of wine or oil." Our author derives a confirmation of his opinion from the following observation, viz. that curds vomited by infants of a few days old are yellow, while they become white in a fortnight or three weeks. This he accounts for from the yellow colour of the cream thrown up by the milk of women during the first four or five days after delivery.

Mr Clarke likewife controverts that common opinion of the human milk being fo prone to acidity, that a great number of the diseases of children are to be accounted for from that principle. "Whoever (fays he) takes the trouble of attentively eomparing human milk with that of ruminant animals, will foon find it to be much less prone to run into the acefcent or acid procefs. I have very often exposed equal quantities of human and cows milk in degrees of temperature, varying from the common fummer heat, or 65° to 100°;

and

this to be the cafe, we have plenty of mild absorbents, Milk. capable of deftroying all the acid which can be fuppofed to be generated in the bowels of an infant; yet many children are obferved to die in confequence of these diseases supposed to arise from acidity. 5. Tho' the milk of all ruminant animals is of a much more acefcent nature than that of the human species, yet the young of these animals never suffer any thing like the difeafes attributed to acidity in infants. 7. Hiftory informs us, that whole nations use four curdled milk as a confiderable part of their food without feeling any inconvenience; which, however, muft have been the cafe, if acidity in the ftomach were productive of fuch deleterious effects as has been fup posed.

Milk. and I have conftantly found that cows milk acquires a greater degree of acidity in 36 hours than the human did in many days: cows milk becomes offenfively putrid in four or five days; a change which healthy human milk, exposed in the fame manner, will not undergo many weeks, nay fometimes in many months. I once kept a few ounces of a nurse's milk, delivered about fix or seven days, for more than two years in a bottle moderately corked. It ftood on the chimneypiece, and was frequently opened to be examined. At the end of this period it showed evident marks of moderate acidity, whether examined by the tafte, fmell, or paper ftained by vegetable blues or purples; the latter it changed to a florid red colour, whereas cows milk kept a few days changed the colour of the fame paper to a green, thereby clearly fhowing its putrefcent tendency."

Our author next goes on to confider of the probability there is of milk becoming fo frequently and ftrongly acid as to occafion most of the diseases of infants. He begins with an attempt to fhow, that the phenomena commonly looked upon to be indications of acrimony are by no means certain. Curdled milk has already been shown to be no fign of acidity; and the other appearance, which has commonly been thought to be fo certain, viz. green fæces, is, in the opinion of Mr Clarke, equally fallacious. In fupport of this he quotes a letter from Dr Sydenham to Dr Cole; in which he fays that the green matter vomited by hyfterical women is not any proof of acrid humours being the caufe of that disease, for fea-fick people do the fame. The opinion of green fæces being an effect of acidity, proceeds on the fuppofition that a mixture of bile with an acid produces a green colour; but it is found, that the vegetable acid, which only can exift in the human body, is unable to produce this change of colour, though it can be effected by the ftrong mineral acids. As nothing equivalent to any of these acids can be supposed to exift in the bowels of infants, we must therefore take some other method of accounting for the green fæces frequently evacuated by them. "Why fhould four milk, granting its existence, give rife to them in infants and not in adults? Have butter milk, fummer-fruits of the most acescent kind, lemon or orange juice, always this effect in adults by their admixture with bile? This is a queftion which, I believe, cannot be answered in the affirmative."

On the whole, Dr Clarke confiders the disease of acidity in the bowels, though fo frequently mentioned, to be by no means common. He owns, indeed, that it may fometimes occur in infancy as well as in adults, from weakness of the ftomach, coftiveness, or improper food; and an indubitable evidence is afforded by faces which ftain the blue or purple colour of vegetables to a red, though nothing can be inferred with certainty from the colour or smell.

The Doctor next proceeds to ftate feveral reasons for his opinion, that the greater number of infantile diseases are not owing to acidity: 1. Woman's milk in an healthy ftate contains little or no coagulable matter or curd. 2. It shows lefs tendency out of the body to become acescent than many other kinds of milk. 3. The appearances which have been generally fuppofed to characterise its acidity do not afford fatisfactory evidence of such a morbid cause. 4. Granting

The reasoning of Dr Clarke feems here to be very plaufible, and nothing has as yet been offered to con tradict it. The reviewers in taking notice of the treas the only obferve, that the Doctor's pofitions are fupported by great probability; yet "they have seen them, or think they have feen them, contradicted by the appearance of difcafes and the effects of medi cines;" fo that they must leave the subject to farther examination.

In a memoir by Meffrs Parmentier and Deyeux, members of the royal college of pharmacy, &c. in Paris, we have a great number of experiments on the milk of affes, cows, goats, sheep, and mares, as well as women. The experiments on cows milk were made with a view to determine whether any change was made in the milk by the different kinds of food eaten by the animal. For this purpofe fome were fed with the leaves of mais or Turkey wheat; fome with cabbage; others with fmall potatoes; and others with common grafs. The milk of those fed with the mais or Turkey wheat was extremely fweet; that from the potatoes and common grafs much more ferous and infipid; and that from the cabbages the most disagreeable of all. By diftillation only eight ounces of a colour lefs fluid were obtained from as many pounds of each of thefe milks; which from those who fed upon grafs had an aromatic flavour; a disagreeable one from cab bage; and none at all from the potatoes and Turkey wheat. This liquid became fetid in the space of a month whatever fubftance the animal had been fed with, acquiring at the fame time a vifcidity and be coming turbid; that from cabbage generally, but not al→ ways, becoming first putrid. All of them separated a filamentous matter, and became clear on being expofed to the heat of 25° of Reamur's thermometer. In the refiduums of the diftillations no difference whatever could be perceived. As the only difference therefore exifting in cow's milk lies in the volatile part, our authors conclude, that it is improper to boil milk, either for common or medicinal purpofes. They ob. ferved also, that any fudden change of food, even from a worfe to a better kind, was attended by a very remarkable diminution in the quantity of milk. All the refiduums of the diftillations yielded, in a strong fire, a yellow oil, an acid, a thick and black empyreumatic oil, a volatile alkali, and towards the end a quantity of inflammable air, and at laft a coal remained containing fome fixed alkali with muriatic acid.

On agitating, in long bottles, the creams from the milk of cows fed with different fubftances, all of them

were