470 



The second is an instance of the beneficial effects of magnesia in 

 correcting the formation of uric acid, where alkalies had relieved but 

 could not be continued. It also exhibits the prejudicial effects of both 

 when too long persisted in, by causing a redundance of an opposite 

 nature in the urine, and a consequent deposit of earthy phosphates 

 as white sand. 



The object of the second section of this paper is to ascertain what 

 acids may be employed with most advantage in those cases where 

 the ammoniacal phosphate of magnesia prevails in the urine, either 

 naturally or by an injudicious use of alkaline medicines. For though 

 the use of acids was pointed out fifteen years since by the same 

 chemist who originally analysed this species of calculus, Mr. Brande 

 is not aware that in the course of that time any experiments have 

 been made to illustrate the mode of action of different acids. 



The first case related is that of a gentleman who had been cut for 

 the stone ten years before, and was again attacked with symptoms 

 of calculus. By the use of a brisk purge in the first instance, one 

 calculus was passed, but he still suffered pain in bis kidneys, that 

 was aggravated by the use of soda water, which increased the pro- 

 portion of triple phosphate in his urine. Ten drops of muriatic acid 

 were then taken three times a day, which removed the white sand ; 

 but as this acid tended to increase the quantity of red sand, it was 

 exchanged for carbonic acid, with decided relief to all the symptoms. 



The second case was that of a boy, from whom four calculi had 

 been extracted by the usual operation of lithotomy. These consisted 

 principally of the triple phosphate of magnesia ; and his urine con- 

 tinued after the operation to be loaded with a deposit of this sub- 

 stance, in the form of a white sand. The acid employed in this in- 

 stance was citric acid, to the amount of twenty grains three times a 

 day. As the effect of this remedy upon the disorder was found to be 

 decisive, and the consequence of any omission was observable in less 

 than twenty-four hours, it was persevered in for nearly three months, 

 when the disposition to deposit the earthy phosphates was found to 

 have ceased altogether, and the lad remained apparently free from 

 disease. 



Two other cases are also related : the first of which was relieved 

 by citric acid taken twice every day, together with vinegar and other 

 acid articles of diet ; and the second by carbonic acid, taken as an 

 effervescing draught, which prevented the formation of white sand, 

 and removed an irritation of the bladder, occasioned by that deposit. 



As the general results of these trials, the author infers, 



That where alkalies fail to correct the redundant secretion of red 

 sand, magnesia is generally effectual. 



That when either of these is improperly continued, they are liable 

 to occasion the deposit of the earthy phosphates, in the form of white 

 sand. 



That the mineral acids prevent this deposition, but are apt to in- 

 duce a return of red gravel, consisting of uric acid. 



That vegetable acids, especially the citric and tartaric, are less 



