560 



MORBID CONCRETIONS. 



pointed out by Proust. I have only met with one such calculus. 

 It was in the collection of the late Dr George Monteath, and had 

 been extracted from Hugh M'Lean from Cowal in Argyleshire, 

 a young man of twenty-six years of age. The calculus was not 

 large. It was white, but not friable, nor did it stain the fingers. 

 Its nucleus was crystalline, and composed almost entirely of am- 

 monia-phosphate of magnesia. The calculus itself, if we do not 

 reckon the animal matter, which was but small, consisted of one 

 part carbonate and two parts phosphate of lime. Bergman 

 also analyzed a calculus consisting chiefly of carbonate of lime. 

 It was of a dirty-white colour, or in some places yellow. It 

 readily separated into small concretions about the size of a pin- 

 head, which had a crystalline structure. They were soft. This 

 calculus consisted chiefly of carbonate of lime with an animal mat- 

 ter, which cemented the particles together. It contained no uric 

 acid, nor phosphoric acid, nor oxalic acid ; nor indeed could any 

 other acid be detected except carbonic.* Marchand found two 

 carbonate of lime calculi in the Berlin Museum. These he sub- 

 jected to analysis, and found them composed of 



Carbonate of lime, utivu- 96 '50 



Phosphate of lime, Jw,\> 2-05 



Oxide of iron, .'// 0*05 



Animal matter, rlvn 1*40 



100-OOf 



7. Mulberry calculi. This calculus, which is not unfrequent, 

 is usually hard, of a dark dirty-greenish or brownish colour, and 

 with a tuberculated surface, in consequence of which it got the 

 name of mulberry calculus. Dr Wollaston first subj ected this kind 

 of calculus to examination, and extracted from it oxalic acid and 

 lime. Hence he concluded that it consisted of oxalate of lime 

 mixed with some uric acid and phosphate of lime. But there 

 can scarcely be a doubt that the true constituent is oxalurate of 

 lime, 



Wohler and Liebig have shown that oxaluric acid is a com- 

 pound of 



2 atoms oxalic acid, . C 4 O 6 



1 atom urea, C 2 H 4 Az 2 O 2 



C 6 H 4 Az 2 O 8 



* Poggendorfs Annalen, xix 556- f Ann. der Pharm. xxxii. 323- 



