74 
DR. YELLOLY’S REMARKS ON THE 
One of the most able and experienced of our English chemists. Professor 
Brande, 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 ammoniaco-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 potasli 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 the internal 
use of solvent medicines, from Mr. William Brande to Everard Home, Esq. F.R.S. Phil. Trans, 
for 1808. p. 231. 
