URINARY CALCULI. 563 



tion was precipitated yellow by prussiate of potash.* The gen* 

 tleman who passed this calculus was from fifty to fifty-five years 

 of age. He had been labouring under symptoms of urinary cal- 

 culi for two years, recurring in the form of severe paroxysms. 

 He never had any pain in the kidneys or ureters, but during the 

 paroxysms there was great pain about the neck of the bladder, 

 with bloody urine, and frequent difficulty in passing it. Under 

 these circumstances, he passed three fibrinous calculi at three 

 different times, f 



12. Ferruginous calculi. Only a single calculus of this de- 

 scription has been met with. It had been formed in the kidney, 

 and was passed by a lady in Bogota, and subjected to analysis by 

 M. Boussingault It weighed 17 grains, and was about the size 

 of a hazelnut. Its form was irregular, though in some parts it 

 had a lamellated structure. Its colour was not uniform, being 

 in some parts ochre-yellow, in others deep-brown. It had great 

 resemblance to bog-iron ore, and had a specific gravity of 2 '886. 

 Its constituents, as determined by the analysis of Boussingault, 

 were, 



Peroxide of iron, . 38-81 

 Alumina, . . 23-00 



Silica, . . 17-25 



Lime, . . 8-02 



Water, . . 10-89 



98-17J 



If no deception was practised, this must be allowed to be a 

 most extraordinary concretion from the bladder of a woman. 



Such are the different species of human urinary calculi hitherto 

 observed and examined. It is hardly necessary to remark, that 

 the species of more frequent occurrence are often mixed together 

 in the same calculus usually in concentric coats. The most com- 

 mon nucleus is uric acid and oxalurate of lime. When the stone 

 is large, and has remained long in the bladder, the outermost 

 coats in general consist of fusible calculus ; for it is a remarka- 

 ble fact, and well deserving the attention of medical men, that 

 whenever the bladder becomes diseased from irritation, the quan- 

 tity of phosphate of lime and ammonia-phosphate of magnesia in 



* Marcet's Essay, p. 101. f Ibid, p 103. 



\ Jour, de Pliann. xi. 153. 



