240 



While, in the state of gravel, it is ever the same, whe- 

 ther passed immediately with the urine, or spontaneously 

 deposited, or precipitated from it: a circumstance that, 

 for a long time, continued to give me much surprize, con- 

 sidering the variety of calculi; but of the truth of which 

 I was convinced, by the examination of many hundred 

 specimens, for many years back. 



I was, therefore, pleased to find, that Fourcroy, for the 

 first time, in his Connoissances Chimiques, asserts, " les 

 " sables des reins sont presque toujours de I'acide urique." 

 And, in another place, he says, speaking of the uric acid, 

 " cfet lui qui forme les sables, qui se crystallize et s'at- 

 " tache aux parrois de vaissaux." 



No wonder, then, that calculi of this kind should be of 

 most frequent occurrence; and that, of five hundred, ana- 

 lyzed by Fourcroy, one fourth should entirely consist of 

 it, besides its occasional admixture with the remamder: 

 and, of three hundred, examined by Pearson, the greater 

 number were found to be of this nature. 



Having premised these necessary observations, we have 

 now to consider, to what circumstances we may attribute 

 its separation, in a crystallized or aggregate state, from 

 its natural solvent: the only condition, in which it can 

 be productive of inconvenience, or diseases of this kind. 

 And first; I would observe, that, being a natural secre- 

 tion, of which the urine is only the vehicle, destined to 

 carry it out of the system, it must be subject to the 

 same derangements, with the other secretions of the human 



body; 



