286 



minute intermixed particles of the arnmoniacal magnesian 

 phosphat, weighing fifty-two grains, was suspended, as be- 

 fore, for forty-eight hours, in Nooth's apparatus. After 

 heing taken out and dried, was found to weigh fifty-one 

 grains and a quarter; so that there was here a loss of 

 three quarters of a grain: undoubtedly, of the arnmoni- 

 acal magnesian phosphat. 



EXPERIMENT IV. 



Wishing to see, whether even increased temperature 

 would add to the solvent power of carbonic acid, a frag- 

 ment of calculus, of the uric acid kind, weighing twenty- 

 two grains, was mimersed, as before, for forty-eight hours, 

 in three ounces and a half of highly impregnated carbo- 

 nated water, in a well closed phial, and laid on a sand 

 heat, which did not exceed the temperature of 100 de- 

 grees. Aft€r being taken out, and dried, the weight was 

 formd, as before, twenty-two grains. 



From these experiments, then, Ave may conclude, that 

 calculi, of the uric acid kind, are insoluble in carbonated 

 Avater; and that Dr. Percival, whose character as a philo- 

 sopher, as well as a physician, deservedly stands so high, 

 must have operated upon concretions of a different kind ; 

 more especially as, in his experiments, there was a loss 

 of several grains, in only a few ounces of mephitic water; 

 whilst none appeared in ours, though in several pounds of 



that 



