ON THE STRUCTURE OF CALCULI. 51 



of the calculus, so that, while of a very small form, it may- 

 be voided by the urethra. 



VIII. 



Some Observations on Mr. Brande's Paper on Calculi. By 

 Everard Home, Esq. F. R* 5*. 



JL HAT calculi in the human bladder are not dissolved by Inefficacy of 

 the internal use of alkaline medicines, is an opinion which cines" 6 "^ 

 1 have long entertained, but the grounds of failure, so clearly 

 pointed out by Mr. W. Brande, were not known to me: I 

 only knew from expeiu-mce, that, to whatever extent the 

 medicines are given, no such effect: takes place. The cir- Ground of the 

 cumstance of the exterior laminae of calculi extracted from nton^ ° P 

 patients, who had persevered in a course of alkaline prepar- 

 ations, having been found softer than the parts towards the 

 centre, has always been considered as a proof of the action of 

 the medicines upon the calculus, and led to the belief,- that 

 where the stone was small, it might be wholly dissolved. 

 This, however, Mr. W. Brande has now proved to be a de- a deception, 

 ception, and that the soft part is not a portion of the original 

 calculus, but a newly formed substance, in which the uric 

 acid is not deposited in crystals, but mechanically mixed 

 with the phosphates and the animal mucus in the urine. 



Having met with cases, which confirm Mr. W. Brande's Cases confirm 

 observations, it will be satisfactory to state them, as they l 1S * 

 may assist in doing away many erroneous notions generally 

 entertained on this subject. 



The opinion, that calculi in the human bladder have been Apparently 

 entirely dissolved, has received its principal support from dencf ^^ 

 instances having occurred, and those by no means few in 

 number, where the symptoms went entirely away while the 

 patients were using alkaline medicines, and never afterward 

 returned. This evidence appears to be very strong, but it a mere fallacy, 

 will be found from the following cases, that it is not so in 

 reality; since the fallacy has been detected in all the in- 

 stances in which an opportunity was afforded of examining 



* Phil. Trans, for 1808, p. 244. 



E 2 the 



