268 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. 



lime, composes superphosphate of lime, a very fusible substance. The phosphate 

 of ammonia being dissolved out by water, or caustic alkaline lye, the remaining 

 matter is infusible, being phosphate of lime. A very hard, brittle, and blackish 

 intestinal calculus of a dog, from Mr. Wilson, was found to be of greater spe- 

 cific gravity than human urinary calculi, and to have the same composition as that 

 of the dog above described. This also was found to be the composition of a 

 white, smooth, round, intestinal calculus of a horse, the specific gravity of which 

 was 1.791. The same composition was discovered, on examining a very hard, 

 grey, brittle, laminated, quadrilateral concretion, said to be from the urinary 

 bladder, but which, I think, was more probably from the intestines, of a horse. 



2. On a calculus from the urinary bladder of a rabbit. — This is also a curiosity, 

 being the only instance I have seen. I am also indebted to Mr. Thomas for this 

 specimen, which he very kindly sent me, fitted up as a preparation, included in 

 the bladder itself. Mr. Thomas found this concretion, on dissecting a perfectly 

 healthy and very fat rabbit. This specimen is spherical, and of the size of a small 

 nutmeg. It is of a dark brown colour, has a smooth surface, is hard, brittle, and 

 heavy. When broken, it appeared to consist of concentric laminae. Its specific 

 gravity was 2. 1; Under the blow-pipe it became black, and emitted the smell of 

 animal matter while burning; at last it ceased to emit any smell; and urged with 

 the intensest fire, showed no signs of fusibility. 2. It readily dissolved, with 

 effervescence, like marble, in both muriatic and nitric acids, giving clear solutions. 

 3. The nitric solution (2) being evaporated partly to dryness, and partly to the 

 consistence of extract, the dry residuary matter was white; and the extract-like 

 matter, which was bitter, could not be fused under the blow-pipe; but, when 

 brought to the state of a powder, its particles were made to cohere loosely toge- 

 ther into one mass. 4. On dropping sulphuric acid into the muriatic solution (2), 

 turbidness, and a copious white precipitation, immediately ensued, from the com- 

 position of sulphate of lime. 



From these experiments it is warrantable to conclude, that the above urinary 

 calculus of a rabbit consisted principally of carbonate of lime and common animal 

 matter, with perhaps a very small proportion of phosphoric acid: it certainly con- 

 tained no uric oxide. I examined, in the same manner, a concretion which was 

 said to be from the stomach of a monkey ; but I have not evidence of its origin 

 equally satisfactory as that of the last 2 calculi. Its composition was found to be 

 similar to that of the calculus of the rabbit, viz. carbonate of lime and animal 

 matter. Its obvious properties were also the same, it was of the size of the largest 

 nutmeg 



3. On urinary concretions of the horse. — I examined several specimens in cabi- 

 nets, said to be vesical calculi of the horse, and found none of them to contain 

 the uric oxide above described; but that they consisted, as well as the calculi from 

 the stomach and intestines of the same animal, of phosphate of lime, phosphate 

 of ammonia, and common animal matter, which melted like superphosphate of 



