118 On Gravelly and Calculous Concretions. 



fecting their solution, when they once acquire the aggregate 

 state. The same fragment, in a similar quantity of soda 

 water, in the temperature of from 50 to bb degrees only, 

 sustained no loss, after forty-eight hours. And here we 

 have another proof of the necessity of seriously attending to 

 the degree of temperature in all researches of this kind. 



But it may be observed, as to the internal use of alkaline 

 substances in particular, that their effects must be consi- 

 derably weakened upon their immediate admixture with the. 

 urine; as the small quantity that can be conveyed there 

 must, in the first place, neutralize the uncombined phos- 

 phoric acid in all urine, the benzoic in children's, and de- 

 compose the ammoniacal and magnesian phosphates in that 

 of every period of life. It must be acknowledged its efficacy 

 is partly counteracted bv these circumstances, which should 

 never be overlooked, and always taken into account in prac- 

 tical application. Referring to Fourcroy's instructive essay 

 on this subject. Memoirs of the National Institute, and 

 Co/moissavces Chimiques, let us here once more appeal to 

 the test of experiment. 



Experhnent XVII. 



A fragment of calculus, weighing eighteen grains one, 

 quarter, of the uric acid kind, was suspended, for forty- 

 eight hours, in an alkaline lixivium, consisting of four 

 ounces and a half of recent urine, and twenty drops of a 

 very weak, and partly aerated, caustic lixivium ; medium 

 temperature about 74 degrees. On being taken out, and 

 dried, it was found to have lost one grain three quarters; a 

 considerable quantity from so small a specimen. To the 

 filtered solution were added a few drops of dilute marine 

 acid, whichj after a few minutes, precipitated a reddish cry- 

 stalline matter in a triple proportion of what generally oc- 

 curs in the natural state of urine. 



From the above experiments, therefore, it appears no 

 longer doubtful ; first, that pure lime, even in the small 

 proportion contained in lime water, and the pure alkalies, 

 in an extreme state of dilution, in temperatures even some- 

 what inferior to those of the human system, exert an active 

 solvent power oix calculi of the uric acid kind : secondly, that 



the: 



