Treatment of Calculous Disorders. 209 



somewhat tough when cut, and has a pecuhar greasy lustre. 

 It is usually of a pale fawn colour bordering upon straw yellow, 

 and of an irregularly crystalline texture*. 



The calculi which have now been described may all be con- 

 sidered as of renal origin, that is, as formed upon nuclei that 

 have passed from the kidneys into the bladder, where they have 

 lodged and increased in bulk, that increase depending at times 

 upon a morbid state of urine, and at times being the simple 

 consequences of an extraneous substance lodged in the urinary 

 passages ; in the former case it is uric acid, or oxalate of lime, 

 or cystic oxide ; and in the latter, generally speaking, phos- 

 phate of lime, or ammonio-magnesian phosphate, or the mixed 

 fusible phosphate 



Independent, however, of the ordinary disposition of the urine 

 in its healthy state to deposit the phosphates upon any ex- 

 traneous matter in the passages, it often acquires a greatly in- 

 creased tendency to do so in consequence of general disease or 

 local injury. There are, as has already been stated, particular 

 states of stomach and bowels, or of the general health, that 

 favour the formation of the phosphates ; local injury of the spine 

 produces an alcaline urine ; and when, from any cause, such as 

 stricture, or diseased prostate gland, or calculus, the bladder 

 does not quite empty itself, the remaining portion of urine is 



* Dr. Marcet, in his Essay on Calculi, has mentioned two nondescript 

 substances forming concretions in the bladder. One of these he has 

 termed Xanthic oxide, from the yellow-coloured compound which it pro- 

 duces when acted on by nitric acid ; it is more soluble in water than uric 

 acid, and is distinguished from cystic oxide by its inferior solubility in acids. 



The other is called a Fibrinous Calculus, aud appeared to consist of 

 hardened albuminous matter. 



1 once met with a calculus having a nucleus of albuminous matfer, 

 probably analogous to that described by Dr. Marcet ; the specimen I gave 

 to Mr. Wilson, and is, I believe, preserved in the Museum in VViudniill- 

 slrcet. I attributed the origin of this stone to a clot of blood having been 

 rcUiued in the bladder during the voiding of a large ([uautity of uric 

 gravel, which had produced copious ha-morrhagc ; but I do not think tluvt 

 calculi can often result from such a cause, in conscqueuce of the facility 

 with which any coagulu ol blood are generally sol'teneil aud voided. 



