Prof. E. D. Smith on Calculous Affections. 803 



Admitting, however, that satisfaction has been obtained 

 with regard to the peculiar nature of the disease, a question 

 of much importance still remains to be discussed. 



In the case of a tendency to form uric calculi, which are 

 supposed to be the most common, it is not a matter of in- 

 difference what particular alkali is used to counteract this 

 tendency. "Mr. Brande clearly shows that an alkali, ad- 

 ministered to a calculous patient, stands no chance of reach- 

 ing the uric concretion in a caustic state; for the urine con- 

 tains both phosphoric and carbonic acid uncombined. But 

 experiment clearly shows that neither carbonates nor sub- 

 carbonates exert any sensible action on uric acid : in other 

 words the affinity of the uric acid for alkalies is weaker tha!a 

 the affinity of carbonic acid for the same bodies : therefore 

 alkaline liquors cannot act as solvents of the uric calculi."" 



Experiments made upon healthy urine, tend to show that 

 the internal use of sub-carbonates of pot-ash and soda oc- 

 casions a considerable and speedy deposition of the phos- 

 phates (a circumstance, that ought to excite a caution in the 

 fashionable use of soda-water, by persons in health) proba- 

 bly by neutralizing the free acids, which hold these salts in 

 solution ; while the similar use of the alkaline earth, mag- 

 nesia, does not produce this effect but in a very hmited de- 

 gree. Hence the inference has been drawn, that in calcu- 

 lous cases, which need alkaline remedies, magnesia is to be 

 preferred ; and the particular mode of its action has been 

 accounted for, both by the assumption that the disposition 

 to generate uric acid in undue quantity commences in the 

 stomach, and by the fact, that magnesia from its insoluble 

 nature, will remain in the stomach long enough to combine 

 with any acid that may be formed there — if this acid does 

 not exist in the stomach, the use of the sub-carbonates of 

 potash and soda does little good ; because, from their great 

 solubility, they are carried too rapidly out of the seat of 

 disease and being conveyed into the bladder, may pro- 

 duce injury there by causing a deposition, which would nor 

 otherwise have taken place, while magnesia, retarded by its 

 insolubility, acts efficaciously upon the acid and is totally 

 neutralized by it. In case of no acid existing, then both 

 the sub-carbonated alkalies and magnesia will be injurious, 



* Edinburgh Review. November 1820- 



