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 counti-jonan. 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- 

 nmnication, — 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 l/OS-f-, 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:j:. 

 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. 



t Analyse Comparee des differentes Especes des Concretions Animales et Vegetales, torn. xvi. p. 23. 



% Annales du Museum d'Histoire Naturelle, torn. i. pi. yii. 



