72 
DR. YELLOLY’S REMARKS ON THE 
actions two years before*, it is not a matter of surprise, that the labours of 
these very eminent chemical philosophers, did not, in this department, obtain 
an authority in this country, which an appearance of greater candour would 
unquestionably have ensured them. Feeling, however, as I do, that Dr. Wol- 
laston’s paper, even after a lapse of above thirty years of the most active and 
successful period of chemical investigation, is not only to be regarded as a model 
of elegant and accurate deduction, but as containing nearly every thing of im- 
portance which is yet known on the subject of urinary calculi, I must still do 
Messrs. Fourcroy and Vauquelin the justice to state my conviction, that their 
operations were independent of those of our distinguished countryman. They 
were the first to notice lithate of ammonia ; and their claim to originality may 
even derive some degree of support, from their having overlooked the most 
striking characteristic of the fusible calculus, noticed in Dr. Wollaston’s com- 
munication, — ready fusibility, notwithstanding they were aware of the existence, 
as separate substances, of both the sets of materials of which it is composed, 
and knew also, that these substances are frequently united. The subject, it is 
also to be observed, was not a new one with them ; for it appears from a paper 
which was published in the Annales de Chimie for the year 1793-j~, that M. 
Fourcroy had been engaged, at various periods since the year 1787, in pro- 
secuting researches into the nature of animal concretions, during which he 
materially enlarged the bounds of our acquaintance with those substances. 
Several of the specimens in the Norwich collection, bear a close resemblance 
to the plate which M. Fourcroy gives of a calculus of lithate of ammonia^. 
They are small, gray, and laminated ; and in addition to the usual characters 
of lithic acid, elicit ammonia copiously, on the addition of pure potash. Like 
those mentioned by Messrs. Fourcroy and Vauquelin, they are likewise gene- 
rally derived from young subjects. 
The combination of ammonia with lithic acid, is not, however, confined to 
small calculi, or to those which occur at an early period of life. It is to be 
found in calculi of all sizes, and belonging to all ages. But in such cases, am- 
monia invariably communicates a lighter colour, and diminishes the cohesion 
• On Gouty and Urinary Concretions: Philosophical Transactions for 1797. 
q Analyse Comparec dcs differentes Especes des Concretions Animales et Vegetales, tom.xvi. p. 23. 
+ Annales du Museum dTIistoire Naturelle, tom. i. pi. vii. 
