108 



found that alkaline urates do not precipitate 

 riat of magnesia, which earth consequently pro-? 

 duces with this acid a salt easily soluble, pro- 

 posed that an experiment should be made with 

 magnesia ; which experiment, according to 

 BRANDE'S statement, completely succeeded, so 

 that after using, for two w r eeks, from fifteen to 

 twenty grains of magnesia, morning and evening, 

 all the superfluous uric acid was removed, and 

 the patient became completely cured. This dis- 

 covery is as yet too recent to be considered as 

 sufficiently confirmed by experience*. 



* Dr. Wollaston has described, in the Philosophical trans- 

 actions for 1810, a rare species of calculus, containing a sub- 

 stance to "which he has given the name of the cystic oxyd. 

 These calcali are in the form of a mass " confusedly crystalli- 

 zed," yellowish, and semitransparent : they are insoluble in 

 alcohol, and in the acetic, tartaric, and citric acids, nor are they 

 affected by the saturated carbonate of ammonia : but they are 

 dissolved by the stronger acids and alkalis : with the acids they 

 afford slender spicular crystals, radiating from a centre ; with the 

 alkalis small granular crystals ; and their peculiar substance 

 seems to be exhibited alone in the form of hexagonal plates, 

 when slowly precipated from a solution in pot-ash, by distilled 

 vinegar. Dr. Wollaston finds a greater quantity of uric acid in 

 the dung of birds, in proportion as they feed more on animal 

 food ; and hence suggests, that the tendency to deposit the uric 

 calculus, or to form gouty concretions, might very possibly be 

 obviated by a vegetable diet. T. Y. 



