76 DR. yelloly's remarks on the 



from the decomposition of an accessary ingredient, as in the specimens ana- 

 lysed by Mr. Brande. 



Lithate of ammonia, whether natural or artificial, bears a temperature much 

 above that of boiling water without decomposition ; for it does not part with 

 its ammonia when exposed to the heat of melted tin, which requires a tempe- 

 rature of about 440° for its liquefaction. Its ammonia, or at least the greater 

 part of it, is, however, readily yielded to any dilute acid, particularly on the 

 application of heat ; and from the nature and amount of the saline compound 

 which is formed, the quantity of ammonia existing in the lithate, might, I pre- 

 sume, be ascertained. 



ITie lithic calculi form, as is usual, the most numerous class of concretions 

 in the Norfolk collection, where they amount to nearly a third of the whole 

 number analysed. But when, in addition, we take those into account, which 

 have lithic acid, or lithate of ammonia as a nucleus, it appears that nearly three- 

 fourths of such number (namely 238 out of 328) either consist of the lithates, 

 or have those substances as their nuclei. 



The same observation may be made as to about two-thirds, or 27 out of 41, 

 of the calculi belonging to the Cambridge Hospital, of which the kindness of 

 Dr. Havii/AND, the Regius Professor of Physic, and my other medical friends of 

 that flourishing and well-regulated establishment, allowed me the particular 

 inspection. 



In the collection of calculi belonging to the University of Leyden, which I 

 had an opportunity of examining about two years since, by the courtesy of Pro- 

 fessor Sandiford, 38 out of 49 specimens which it contained, or three-fourths 

 of the whole, bore the character which I have just mentioned. 



Dr. Henry, of Manchester, published a valuable analysis in the Medico- 

 Chimrgical Transactions some years since,- of 187 calculi ; and of those, 168, 

 or five-sixths, were also either lithic calculi, or had lithic nuclei*. The evi- 

 dence, therefore, which is derived from places far distant from each other, 

 agrees as to the similarity in nature, of the primordia, of by far the larger pro- 

 poi'tion of urinaiy calculi ; and evinces, that in appreciating the tendency to 

 calculous disorders, and the means by which it is to be obviated, the attention 



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