556 MORBID CONCRETIONS. 



Dr George Monteath of Glasgow, which I examined particular- 

 ly, there were no fewer than six calculi composed either of urate 

 of ammonia, or of a mixture of uric acid and urate of ammonia. 

 These calculi were all extracted from young children. They 

 were small ; but had been a source of such uneasiness while in 

 the bladder, that the noise produced by opening or shutting a 

 door was apt to throw the child into convulsions. 



In 1810,* Dr Wollaston discovered a new calculus, to which 

 he gave the name of cystic oxide. It was subjected to an ulti- 

 mate analysis by Dr Prout. 



Proust stated that in some urinary calculi which he examined, 

 he found a quantity of carbonate of lime. This statement was 

 at first called in question, because Fourcroy and Vauquelin found 

 no such substance in the numerous calculi which they examined. 

 But it has been confirmed by subsequent researches. In Dr 

 George Monteath's collection, there was a calculus extracted from 

 a Highlander of 26 years of age. It was white, but not friable ; 

 nor did it stain the fingers. It was composed of about one part 

 of carbonate of lime and two parts of phosphate of lime ; and con- 

 tained, besides, crystals of ammonia-phosphate of magnesia. 



In 1817, Dr Marcet published his Essay on the Chemical 

 History and Medical Treatment of Calculous Disorders. In this 

 work he gave an account of two new species of urinary calculi. 

 The first of these he called from its colour xanthic oxide.\ It 

 was subjected to a chemical analysis by Wohler and Liebig, who 

 showed that it differed from uric acid by containing two atoms 

 less of oxygen. The second calculus was composed entirely of 

 animal matter, possessing the characters of fibrin. Marcet gave 

 it the name oijibrinous calculus. J 



Berzelius informs us that Lindbergson analyzed a urinary 

 calculus composed of urate of soda and carbonate of magnesia. 

 It was therefore analogous to the gouty concretions analyzed by 

 Dr Wollaston. 



Urinary calculi are most commonly ellipsoidal or egg-shaped. 

 They vary very much in size ; sometimes being not larger than 

 the head of a pin, and sometimes almost as large as a moderate 

 sized fist. I have seen one which was extracted after death from 



* Phil. Trans. 1810, p. 223. f Essay, p. 95. \ Ibid. p. 101. 



Traite de Chimie, vii. 413. 



