74 DR. YELLOLY'S REMARKS ON THE 



One of the most able and experienced of our English chemists, Professor 

 Bhande, has been induced to infer, that the evolution of ammonia from calculi, 

 which were regarded as consisting of lithate of ammonia, depends, in all 

 instances, on the decomposition of the ammoniacal salts contained in such 

 calculi, and more especially of the aramoniaco-magnesian phosphate, with 

 which the lithic acid is united. As this is an interesting point in the history of 

 those substances, I have made it a particular object of attention; and the fol- 

 lowing is the result of my observations. 



After exposing calculi bearing the character of lithate of ammonia, either to 

 alcohol or distilled water, whether cold or heated, I have never found that by 

 the abstraction of any substance from them, which those fluids were able to 

 carry off, the development of ammonia was at all diminished, on subjecting the 

 remainder to the action of pure potash. When a portion of such calculi, either 

 before or after exposure to alcohol or distilled water, was submitted to the 

 action of acetic acid, none of the crystals of triple phosphate were to be ob- 

 served on the addition of carbonate of ammonia to the filtered liquor, though 

 the existence of that salt is capable of being detected, by this process, in the 

 most minute quantity. By adding pure potash to the dried deposit which is 

 obtained by evaporation from a solution of lithate of ammonia in boiling water, 

 a copious development of ammonia took place, and the deposit itself was ca- 

 pable of undergoing complete solution in pure potash. It does not therefore 

 appear, that in those instances, the evolution of ammonia depended on the de- 

 composition of triple phosphate. 



Mr. Brande has shown, that muriate of ammonia is capable of being ob- 

 tained from lithate of ammonia ; and hence, he thinks, that this substance is 

 one of those, which may afford the ammonia supposed to characterize the 

 lithate of ammonia calculus*. My experiments coincide entirely with those of 

 Mr. Brande, as to muriate of ammonia being a constant component part of that 

 description of calculus ; but besides that this substance is in too small a quan- 

 tity to give rise to the elicitment of ammonia, which occurs on the addition of 

 pure potash to a lithate of ammonia calculus, the disengagement of ammonia 



• A Letter on the differences in the structure of calculi which arise from their being formed in dif- 

 ferent parts of the urinary passages, and on the effects that are produced upon them by tlie internal 

 use of solvent medicines, from Mr. William Brande to Everard Home, Esq. F.R.S. Phil. Trans, 

 for 1808. p. 231. 



