URINARY CALCULI. 435 



buiation,the third body, in (lead of cfiecYmg the 

 reparation of the twoprcvioufly combined, often 

 added itfelf as a new ingredient in the compofi- 

 tion ; I was induced tofufpecl that in the pre- 

 font indunce a fimilar event took place, and 

 uith the greater confidence, as 1 was certain 

 fomc, although but a very fmall, portion of unc- 

 Uioiu matter was always joined with fugar. The 

 facl confirmed my conjecture. For by the tho- 

 rougii combuftion of urinary calculi, 1 obtained 

 a white aib, evidently calcareous, which ctter- 

 vefccd with acids, and acquired on tlic infulion of 

 \itriolic acid, a gypfcous characler ; was ealily 

 prccipitablc by faccharinc acid, and was to a 

 certain degree, folublc in water, c. There 

 Aill remains, however, nearly an hundredth part 

 which is infolublc in nitrous acid. But the rcfi. 

 due above-mentioned, forms in conjunction with 

 the concrete acid, the fubilancc of the calculus. 

 The matter of the calculus may be obtained by 

 evaporation from a nitrous folution of it; and if 

 burnt to whitencfs, will allbrd a calcareous pow- 

 der. 



Pure vitriolic acid not being contaminated 

 with any unctuous matter, 1 hoped to fuccced 

 in examining the calx with it: and it proved fo. 

 For on pouring into a nitrous folution of calculi 

 a few drops of flrong and limpid vitriolic acid, 

 I perceived a few cryilals detached, which upon 

 a particular examination, and chiefly by prcci- 

 K e 2 cipitation 



