64 Analysis of the Coprolites of Birds. 



g. Phosphate and carbonate of soda produces in the watery 

 solution an immediate and copious white precipitate. This is 

 greater than could be due to a decomposed sulphate of lime, 

 which exists in the solution, and is probably due to the decom- 

 position of urate of ammonia, and the formation of less soluble 

 urate of soda. 



h. A portion of the watery solution being left to spontaneous 

 evaporation, a creeping mass of dendritic crystals was obtained, 

 partly soluble in a small quantity of water. This gave no indi- 

 cation of sulphuric acid by muriate of barytes. The crystals 

 solved in nitric acid, but gave no indication of sulphuric acid by 

 nitrate of barytes. The nitric solution, by evaporation and agi- 

 tation, deposited crystals. They cannot be phosphate of lime 

 therefore ; and yet their solution in water is precipitated by oxa- 

 late of lime. I conclude they are in part urate of lime. 



i. Whatever care be taken in filtering and evaporating the wa- 

 ter of solution, the dry white crust with a tinge of yellow here 

 and there, always solves with effervescence in dilute nitric acid. 

 This may arise from the presence of soluble alkaline carbon- 

 ates or carbonate of lime, produced by their action on a soluble 

 salt of lime — or more probably, from the certain presence of uric 

 acid, which may exist as a hi-urate. This effervescence is not 

 confined to the bottom of the evaporating dish, where any car- 

 bonate of lime would be deposited, but is manifested in every 

 part of the white crust, from the edge to the bottom of the dish. 

 I have not, from want of material, pursued my inquiries so far on 

 this residuum as is desirable. It is however abundantly evident, 

 that it consists in part of soluble urates. It chars by gentle heat, 

 its solution in water is precipitated by sulphuric acid, and this 

 precipitate also chars ; its habitudes with nitrate of silver, falling 

 in yellow brown flocks, insoluble in pure ammonia, easily redu- 

 ced to metallic silver by gentle heat, and producing a pinky salt 

 when treated with nitric acid — all demonstrate the presence of 

 uric acid. 



I have attempted to estimate the quantity of urates present in 

 the coprolite : here I find great difficulty, and we must be con- 

 tent with an approximation. From the amount of what I have 

 considered only as muriate of soda, solved by alcohol, is to be de- 

 ducted the small portion of urates which I have since found that 

 solution to contain. My former estimate of 0-51 per cent, mu- 



