ESSAY IX. 



ANALYSIS OF THE CALCULUS VESICLE. 1776. 



HAVING collected a sufficient number of calculi, taken 

 from persons of both sexes, I undertook an inquiry into their 

 nature, and I now communicate some observations, which, to 

 my knowledge, have not hitherto been communicated to the 

 public. 



All the calculi which I have examined, whether Hat and 

 polished, or rough and angular, were of the same nature, and 

 consisted of the same constituent parts. 



SECTION I. 



I put a quantity of calculus, reduced to powder, into a 

 small glass retort, poured some diluted vitriolic acid upon it, 

 and exposed it to digestion, but the powder was not at all 

 attacked. After the humidity was abstracted by distillation, 

 the concentrated acid began to attack the powder, and the 

 stone was dissolved. After the acid was abstracted to dryness 

 by an increased heat, a black coal remained ; the liquid which 

 passed over was vitriolic acid with a strong smell of the 

 volatile acid of sulphur. 



SECTION II. 



Neither concentrated nor diluted muriatic acid had any 

 effect upon the calculus, not even when boiled with it. 

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