50 



ON THE STRUCTURE OF CALCULI. 



Vse of acids. 



•tate to a calculus in the bladder ; they favour the deposi- 



tion of the phosphates. 



They reach the It cannot be doubted, that the alkalis reach the bladder, 

 bladder. . ' 



since in cases where large doses of subcarbonate of petash 



have been exhibited, I have seen evident traces of it in the 



urine. 



Where the phosphates only are voided, it has been pro* 

 posed to dissolve the calculus by the exhibition of acids, and 

 more especially the muriatic acid. 



During the use of the muriatic acid, the phosphates are 

 either diminished or disappear altogether ; and even some- 

 times the urine acquires an additional acidity ; a solution of 

 that part of the calculus, which consists of the phosphates, 

 might therefore be expected; but even then the nucleus of 

 uric acid would remain, and thus a great deal of time would 

 be lost without any permanent advantage. 



I have also occasionally remarked, that during the use of 

 acids, the uric acid reappears, and even seems to be aug- 

 mented in quantity. 



Attempts have been made at different times to effect the 

 solution of calculi, by the injection of solvents into the blad- 

 der. This subject has been more lately revived by Four- 

 croy and Vauquelin, who, in their paper on the composition 

 of calculi, lay down rules for its practice. Independent, how- 

 ever, of the impossibility of ascertaining the composition of 

 the calculus with sufficient accuracy, it is obvious, that were 

 the composition of the surface of the calculus known, the 

 frequent introduction of an instrument into the bladder, and 

 the long continuance of the process which would be neces- 

 sary, even where the calculi are small, are insurmountable 

 objections; and whenever this mode of treatment has been 

 adopted,, it has speedily been relinquished, as it always ag- 

 gravates the sufferings of the patient. 



It has been shown, that, in the majority of cases, the nu- 



Injection of 

 solvents. 



Seal use of al- 

 kalis. 



clei of calculi originate in the kidnies, and that of these nu- 

 clei by far the greater number consist of uric acid; the good 

 effects therefore, so frequently observed during the use of an 

 alkali, arise, not from any actual solution of calculous mat- 

 ter, but from the power which it possesses of diminishing the 

 secretion of uric acid, and thus preventing the enlargement 



of 



