with silver, insoluble in boiling nitric acid. It is possible, therefore, in the experiments of Dr. Prout, who determined the total amount of chlorine in the gastric fluid by supersaturating with potash, igniting and precipitating with nitrate of silver, that he had formed cyanide of potassium, which would precipitate cyanide of silver along with the chloride, unless the precaution were taken not merely to add nitric acid, but to boil the solution after the addition of the acid, since cyanide of silver is insoluble, or at least not wholly decomposed by cold nitric acid. I offer this explanation, originally proposed by Leuret and Lassaigne, because, from my knowledge of Dr. Prout, I am quite certain his experiments were most accurately made. Indeed, the testimony of all succeeding experimenters who have obtained the same results is sufficient to establish his accuracy without the addition of any confirmation on my part. It is even possible that, in cases where the food is different, the acid may be of the nature described by Dr. Prout.

"The experiments which have been detailed seem to demonstrate that no free hydrochloric acid existed in the stomach of the animal under the circumstances described, since no acid could be distilled over at a temperature greatly above that at which this acid boils when sufficiently concentrated, while the fluid in the retort became more intensely acid in proportion as the distillation proceeded. A portion of the liquid from the retort was evaporated to dryness, and heated to a temperature exceeding 300° without giving out acid fumes; the residue was digested in water, and still retained an acid reaction. The solution of this residue was easily saturated by carbonate of lime, and was not precipitated by chloride of calcium, indicating the absence of biphosphate of lime (contrary to the views of Blondlot) and likewise of free sulphuric acid.

"In another experiment the gastric juice was evaporated to dryness in the water-bath, and treated with alcohol and oxide of zinc with the necessary precautions: prismatic crystals were obtained corresponding with lactate of zinc, but in too minute quantity to admit of analysis, the only demonstrative argument. The preceding experiments appear to shew, however, that the free acid of the stomach, in the digestion of vegetable matter, at least, of all the known acids, alone corresponds with the lactic. To determine the nature of the volatile acid, which, however, appears to be

present always in minute quantity, a portion of gastric fluid was distilled, and the product was obtained in three distinct receivers. Their characters, as determined by infusion of litmus, were as follow :

:

'From these observations, it would therefore appear that the greatest amount of volatile acid was carried over at first, and that as the distillation proceeded its amount in the retort gradually diminished, indicating that the acidity was not due to the decomposition of lactic acid or its eduction by the vapour, but rather to the presence of acetic acid. The quantity present was, however, trifling, since the distilled product of a large amount of gastric fluid could never be detected in a state of effervescence on the addition of carbonate of soda.

"Dextrin and Soluble Starch found in the Stomach in the Digestion of Starch.-I have already stated, in a previous part of this paper, that I was unable to detect any traces of starch in the serum of the blood; it was therefore necessary to return to the stomach, and to observe the chemical changes to which the starch was subjected in that viscus. When an animal is fed on porridge, if water be added to the contents of the stomach, the mixture wellstirred and then allowed to stand at rest, the supernatant liquor produces a blue colour with tincture of iodine; but if the liquid be filtered, the colour obtained by mixing the solution of iodine with the filtered liquor is red, indicative of the presence of dextrin, or one of the varieties of soluble starch. I have sometimes found, however, that starch has existed in solution in the gastric fluid even when neither a blue nor a red colour was indicated by iodine. This substance I have isolated by boiling the gastric fluid in order to coagulate the albumen, evaporating to dryness in the water-bath, and then removing the sugar and oil by means of alcohol. The substance thus obtained gave no decided indications with tincture of iodine previous to isolation when dissolved in water, and therefore corresponds with that variety of soluble starch which has frequently been described by chemical writers. It appeared a

point of some importance to ascertain whether the transition of starch into dextrin takes place at once in the stomach, or whether the change commences before the food is swallowed. I accordingly prepared a quantity of porridge by boiling it for upwards of half an hour with distilled water, and on filtering it I obtained distinct evidence of the presence of dextrin in the filtered liquid. It may perhaps, therefore, be legitimate to infer that one of the important purposes to be acquired by cooking starch is to facilitate its conversion into soluble dextrin, and that other form of soluble starch already described; and hence the importance of the boiling being continued for a considerable space of time, when some of the harder species of amylaceous food, as rice, sago, tapioca, are used as articles of diet, and especially when they are administered to the delicate stomachs of the sick.

"The soluble starch was separated in the manner already detailed, and was found to possess the following constitution when subjected to organic analysis :

'The result of these analyses per cent. is as follows:

"This composition does not agree with that of starch, except with wheat starch, in the carbon before that substance has been dried; but, according to the analyses of Prout, the hydrogen in wheat starch is greater in amount than in the present case. The carbon in the substance under consideration agrees with that of sugar of starch, but the hydrogen is much inferior; and the three experiments detailed agree so closely in reference to the hydrogen, that there can be little doubt of the accuracy of the results, more especially as the last analysis was made with oxide of copper and chlorate of potash, and the matter subjected to analysis appeared to be completely burned. The substance appears to have possessed some intermediate characters between those of sugar and starch." Philosophical Magazine.

ON THE ADVANTAGE OF REDUCING THE FOOD OF ANIMALS BEFORE

GIVING IT.

By A. GYDE.

Two horses in good health, in daily work, and as nearly as possible equal in size and age, were selected for the experiment. They were each allowed 5 lbs. of oats (42 lbs. per bushel), and a sufficiency of good hay, of which they consumed about 17 lbs. per diem each horse. The only difference in the feeding consisted in one horse having the oats thoroughly crushed, and the other being allowed the oats uncrushed. On the fourth day of the above mode of feeding the solid excrements of each horse were examined. 100 parts of the dung from the horse fed on crushed oats were found to be deprived of all the nutritious matter contained in the food, and to consist of woody fibre, mixed with the animal secretions and some salts; while 100 parts of the dung from the horse fed on uncrushed oats were found to contain 1.4 per cent. of nutritive matter, consisting of starch and gluten, which had not been acted on by the stomach, mixed with the ordinary constituents of the solid excrements of the animal-this arising from the inability of the horse to perform perfect mastication, and must vary with circumstances, such as age and rapidity of feeding. The same horses were then fed with cut and uncut food, consisting of hay cut into chaff, and hay uncut. At the expiration of the third day the excrements were examined, but no chemical difference in their composition was detected: the food in both instances was found to be equally exhausted of its nutritive matter. The shorter period occupied by the horse in filling its stomach, and consequently greater amount of rest obtained, and the means of mixing food and preventing waste by cutting it into chaff, require no observation from me, but will be material points in this mode of feeding.

Agricultural Gazette.

A NEW SPECIES OF CALCULUS FOUND IN THE KIDNEYS AND
URETERS OF A BITCH.

By M. LASSAIGNE, H.A.V.M.A.

THE author of this memoir published in the "Journal de Chimie Médicale for 1828, a detail of the analyses of various urinary concretions occurring in the dog. He shewed that many of these were analogous in composition to those found in the human bladder; and inferred from thence a manifest conformity as regards the different functions of man and certain of the lower animals of similar organization. The remarkable feature in the present research is, that the calculus consisted of two organic principles, one belonging exclusively to the products of the renal or urinary secretion, the other only met with heretofore as a secretion of the liver. He has, therefore, very properly called it urino-biliary calculus. This fact, which seems unique in the history of concretions, merits the attention both of the medical practitioner and of the physiologist.

The animal which formed the subject of this observation was a bitch of large size, a sort of bull mastiff, which died in the hospital of the school at Alfort, from dropsy.

The cadaveric inspection was made by M. Prudhomme, who discovered in the kidneys, the ureters, and the bladder, a considerable number of small calculi, very irregular in shape, of a beautiful grass-green colour. Among other changes, it was remarked that the renal substance presented a faint yellowish tint: the liver contained in its texture little whitish granulations of phosphate of lime, and small well-defined cysts, of the bigness of a pea, filled with a soft matter of a greyish green, formed of half coagulated albumen, mixed with a little of the green principle of the bile, phosphate and carbonate of lime.

A portion of these calculi was carefully dried and pulverized; the powder emitted a slight urinous smell, and had a marked greenish yellow hue. In this comminuted state even boiling alcohol did not seem to act sensibly as a solvent, although the liquid assumed a pale green colour. Sulphuric ether afforded the same result. In order to determine the nature of the substance held in