304 On the Boa Constrictor. 



nient, part of which he very obligingly gave me. Not being aware 

 that tliis substance had been analysed, I submitted it to such a 

 chemical examination as the very limited quantity in my possession 

 would allow. And as I presume there is some little novelty of 

 result in my experiments, I beg leave to give you an account of 

 them, with a view to their insertion in your valuable Magazine. 



Properties and Composition of the solid Excrement. 



1. This excrement when voided was soft, but it became hard 

 by exposure to the air. In the state in which I saw it, it was 

 rather larger than a pigeon's egg, of an amorphous form, and ex- 

 hibited on its surface a number of irregular elevations and de- 

 pressions. It was grayish white, and resembled chalk in colour 

 and fracture ; but it was more easily frangible than chalk, and its 

 powder had a slight greasy feel. It had a slight odour, which was 

 rather fragrant and agreeable. Its specific gravity could not dif- 

 fer much from that of chalk, for five grains of each in an impal- 

 pable powder occupied about the same space. 



2. When heated by a spirit lamp on a slip of platinum, the ex- 

 crement first became brown, and then black ; it exhaled an am- 

 moniacal smell, and the odour of decomposing animal matter. 

 By keeping it at a red heat for a few minutes, it consumed with- 

 out flame, leaving only a very minute grayish residuum, which 

 deliquesced in the air, rendered turmeric brown, and dissolved 

 with effervescence in muriatic acid. The muriatic solution was 

 rendered blue by prussiate of potash, and gave with ammonia a 

 little light coloured flocculent precipitate. These experiments 

 seem to show that the minute portion of grayish residuum was 

 composed of subcarbonate of soda, phosphate of lime, and oxide 

 of iron. 



3. The excrement was insoluble in water, in alcohol, and in 

 muriatic acid, at a boiling heat. It dissolved slowly in sulphuric 

 acid, with the evolution of minute globules of gas. 



4. It readily dissolved with effervescence in strong nitric acid, 

 the air disengaged appeared to be nitrous gas, as it produced red 

 fumes on coming in contact with the atmosphere. Diluted nitric 

 acid also dissolved the excrement, and a little gas was evolved. 

 The nitric solution, when eva])orated to dryness, assumed a fine 

 pink colour; and on adding a little water, the fluid became of a 

 carmine hue, and presently a reddish substance precipitated, leav- 

 ing the fluid colourless. These experiments prove the existence 

 of uric acid in the excrement, and the pink or reddish substance 

 appeared to be the compound of purpuric acid and ammonia de- 

 scribed by Dr. Prout*. 



5. In an instance when five grains of the excrement were dis- 



• Philosophical Transactions 1818. 



solved 



