led to another. Calculus of a to contain lime will not be formed on the addition of sulphuric acid,, cess. It may have been in consequence of this oversight, that mistake on that subject has occurred in the succeeding vo lume of the Transactions. A calculus is there described, which had been taken by dog supposed Mr. Thomas from the bladder of a dog; and a series of experiments are related, from which it was inferred to consist of superphosphate of lime, and phosphate of ammonia. But from the appearance of this calculus (which was exhibited to the society at the time when the paper was read) I was much inclined to think, that the nature of it was mistaken; and upon full consideration of the experiments, they did not appear to me conclusive. was afterward I therefore obtained a portion of the calculus, and, by proved to be a the following process, the earth contained in it was proved to compound of consist almost wholly of magnesia. magnesia. Superphos It was dissolved, with the exception of a very small residuum, by distilled vinegar. The whole of the phosphoric acid was then precipitated by acetate of lead added to excess. The liquor was then poured off, and sulphuric acid was added, which precipitated the excess of lead, and at the same time formed sulphate of magnesia in solution. By evaporation to dryness, the acetic acid was removed, and by subsequent increase of heat, the sulphate of ammonia, and excess of sulphuric acid were expelled. The residuum being then dissolved in water, and the liquor suffered to crystallize by spontaneous evaporation, there remained a quantity of sulphate of magnesia, that weighed rather more than the quantity of calculus taken for the experiment. It was evident, therefore, that in this instance the calphate of lime culus examined did not consist of superphosphate of lime; perhaps never and there is some reason to doubt, whether a compound, exists in a calculus. that is so very soluble in water, ever forms a part of urinary concretions. Prevention of Although the treatment of diseases is not in general a calculous.com- fit subject to occupy the time of this society, there is neverPlaints. theless theless one suggestion, with respect to the prevention of calculous complaints, so nearly connected with my present subject, that I think it may deserve to be recorded. birds Since the white matter contained in the urine of birds, Uric acid which is voided along with their dung, has been remarked the dung of by Mr. Vauquelin, to consist principally of uric acid, I have paid some attention to the different proportion in which this matter is voided by different species of birds, to see how far it accorded with the different qualities of their food. And I found, that in the dung of the goose, feeding wholly seems proon grass, the proportion did not seem so much as of portional to the quantity the whole dung. In that of a pheasant kept in a cage, and of animal food fed on barley alone, it was about part. In that of a they take, hen, having the range of a garden and farm yard, and consequently procuring insects, and possibly other animal food, the proportion was manifestly much greater, and combined with lime. In the dung of a hawk, fed upon flesh alone, the quantity of matter voided in a solid state bears but a small proportion to the residuum of uric acid, that is, left by the urine when dry. And in the gannet, feeding particularly of solely on fish, I have observed the evacuations in some in- fish. stances to be mere urine, for it contained no solid matter excepting the uric acid. persons should It seems, consequently, deserving of inquiry, what changes Hence calenmight be produced in the urine of any one animal, by such lous and gouty alterations of diet, as its constitution would permit; for as prefer a vege far as any inference can be drawn from these varieties, which table diet. naturally occur, it would appear, that persons subject to calculi, consisting of uric acid, as well as gouty persons, in whom there is a redundance of the same matter, have much reason to prefer vegetable diet: but that the preference usually given to fish above other kinds of animal food is probably erroneous. Effects of heat IX. Comparative Analysis of Gum Resins: by Mr. HENRY (Continued from vol. XXVII, p. 370.) ART. II. Analysis of Gamboge. Sect. I. IF gamboge be exposed to the flame of a candle, on gamboge. it swells up; and burns like a resin. Heated in a capsule it emits a peculiar smell, softens, and is decomposed before distillation. it melts. Products of its Fifty gram. [772 grs.] exposed to distillation produced 1st, a brown water, containing empyreumatic acetic acid: 2d, a email quantity of a light oil: Coal. Gamboge treated with alcohol, 3d, afterward came over in considerable quantity another oil, heavy, thick, and brown. In the retort remained a light coal, weighing 8 gram. [123.5 grs]. It was incinerated with difficulty, and left 5 decig. [7.7 grs] of ashes, which yielded 2 cent. [0·3 of a gr.[ of potash in part sulphated, 4 cent. [0.6 of a gr.] of phosphate of lime, 6 cent. [0·9 of a gr.] of carbonate of lime, and 3 dec. [4.6 grs] of quartz sand, containing a little charcoal, and some traces of oxide of iron. No ammonia was found in the liquid products. Sect. II. Twenty gram. [309 grs] were treated with hot alcohol and filtered. What remained on the filter, after being well washed with alcohol, was a grayish substance, that dried with difficulty, and was then brittle. In this state it weighed exactly 4 gram. [617 grs]; had a faint taste, or was nearly insipid; and dissolved entirely in water, except a decig. [15 gr.] of impurities. The solution reddened litmus. Evaporated to dryness it left a transparent, friable residuum, resembling the high coloured gum of the plumtree, burning like it with little flame, and leaving a considerable quantity of a compact coal, in which was some phosphate of lime. The alcoholic solution was red. Evaporated to dryness it afforded 16 gram. [247 grs] of resin. This was transparent, red, without any perceptible taste, and pretty decidedly electric by friction. When powdered it emitted a peculiar smell, and assumed a bright yellow colour. On pouring water into a saturated solution of this resin precipitated by in alcohol, there is a sensible evolution of heat, and a uni- water, form, yellowish, milky liquid is produced; while most other resins are precipitated from alcohol in clots. Sect. III. Solution of potash acts very quickly on the and acted on resin of gamboge, particularly if heated. The result is a by potash. red liquid of an oily appearance, in which the properties of the potash are neutralized. On evaporating this com pound almost to dryness, it crystallizes like the solution of aloes. The soap or saponule of this resin is of a deep red ap- Soap from it. proaching to black, and feels greasy between the fingers. When dried it is friable, and resembles a resin. It has the taste of rancid fat, leaving a slight sensation of acrimony at the root of the tongue. It is easily soluble in water, without rendering it turbid. Acids precipitate this solution in such abundance, that the whole becomes a thick coagulum of a fine yellow colour. Lime-water throws down from it a fine orange coloured precipitate. Earthy salts and most solutions of the white metals likewise produce yellow precipitates in it. It precipitates sulphate of iron brown, and nitrate of copper green. treated with nitric acid. Sect. IV. Ten gram. [154-4 grs] of the resin of gamboge The resin were put into a retort with 80 parts of strong nitric acid of the shops. As soon as the retort felt the heat of the fire, red vapours arose, the intensity of which soon disappeared. The first product was returned into the retort, and the operation continued, till the matter was dissolved, and the solution reduced to the consistence of a sirup*. On cooling a mass of lamellar crystals was formed, enveloped in a vis The product of this distillation, being thoroughly saturated with Product of chalk, and distilled anew, yielded a slightly acid liquor, of a very pun- the distillagent smell, and bitter to the taste. Alkalis gave it a light yellow tinge. tion. On adding sulphate of iron to this mixture a precipitate was formed, which was completely soluble in acids; so that there was no prussic acid in this liquid, but I am not fully acquainted with its nature, Product. cid matter. The whole being diluted with a quantity of water, a sediment was formed, which, when well washed and dried, weighed 13 gram. [20 grs]. It This matter is of a yellowish colour, and bitter taste. is partly soluble in boiling water. On cooling the solution grows turbid, and lets fall a portion. The filtered solution is of a reddish yellow, froths when shaken, reddens infusion of litmus, is rendered of a deeper colour by the addition of an alkali, and forms a slight precipitate after some time with sulphate of iron. On burning coals this substance does not melt so easily as the resin, diffuses a fragrant smell, and leaves a great deal of coal. It combines very well with potash and spirit of wine, forming with them transparent red solutions. Nitric acid, heated gently with it, dissolve it, without occasioning any sensible alteration. Water produces a copious white coagulum in the solution. A resinoamer. From these properties I think I may fairly consider this substance as a particular species of soluble factitious resinoamer, combined with a yellowish resiniform substance insoluble in water. Produce of the mother waters. The resin act muriatic gas. The acid liquor and waters of elutriation were boiled down, to drive off any nitric acid that might remain; and the residuum was diluted with water, in which a small quantity of potash was dissolved, which separated 4 dec. [6 grs] of the yellow resiniform substance. The liquor being again boiled down, then treated with alcohol, and filtered, left 1 gram. [154 grs] of very white superoxalate of potash. The alcoholic solution produced on evaporation 3 gram. [46'3 grs] of bitter matter, soluble in water, and containing malic acid. Sect. V. I diluted some of the resin of gamboge in fine ed on by oxi powder with water; and passed into it a stream of oximuriatic acid gas, to try its effect on the colour; and in fact it destroyed its fine yellow. The milky liquor being boiled down, then diluted with water, and filtered, left on the filter a substance, which was washed with boiling water, till what came off would no longer redden litmus, The following were its properties. |