242 Afr. W, Brande on the Differences 
posed to dissolve the calculus by the exhibition of acids, ancl 
more especially the muriatic acid. 
During the use of the muriatic acid, the phosphates are 
either diminished or disappear altogether ; and even sometimes 
the urine acquires an additional acidity : a solution of that part 
of the calculus which consists of the phosphates might there- 
fore 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 re-appears, 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 fre- 
quent 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 aggra- 
vates the sufferings of the patient. 
It has been shewn that in the majority of cases, the nuclei 
of calculi originate in the kidnies, and that of these nuclei by 
far the greater number consist of uric acid ; the good effects 
