287 



that fluid. He must have then operated upon some of a 

 different and highly soluble kind. 



EXPERIMENT V. 



One half of a calculus, of the ammoniacal magnesian 

 kiiid, weighing 100,5 grains, was suspended, as usual, for 

 forty-eight hours, in Nooth's apparatus: temperature 50 

 degrees. Upon being taken out, and dried, was found to 

 weigh 92,63 grains; so that its loss amounted to 7,87, or 

 rather more than seven grains three quarters. And here 

 we have an explanation of the result of Doctor Percivars 

 experiments; by supposing that the calculi he employed 

 must have been of this species: the extreme solubility of 

 which, in so weak and innocent a menstruum, should ex-^ 

 cite the earnest hope of our young gentlemen, in the sur- 

 gical department, of effecting its solution, by injections of 

 carbonated ^vater into the bladder. To such safe trials 

 they must be encouraged, by the pleasing consideration, 

 that this kind forms a large proportion of the human uri- 

 nary calculi. On these occasions, the water should not be 

 too highly impregnated; lest the sudden expansion of the 

 gas, under the human temperature, might excite the blad- 

 der to reject it too quickly. This inconvenience, however, 

 must be in part obviated, by the necessity of previously 

 warming the injection, to about the temperature of 80 de- 

 grees: a precaution never to be omitted. But to return 

 to the alkaline earths and salts. 



o 2 expehimekt 



