CALCULI. SS9 



Erp. IL To sixteen ounces of urine, -were added eight Experiments 

 drops of very dilute sulphuric acid. To a similar quantity, ^jq,^, q^ urine, 

 two scruples of citric acid, to bring them to nearly the ^'c. 

 same standard of acidity. After a very short interval, in 

 that with Bitric acid, the usual appearance of transparent 

 tloating molecular reflecting light, and gradually becoming 

 larger, were observed, and began to adhere to the glass : 

 whilst in the other, after five hours, no such appearajices 

 took place. Yet, after forty-eight, here also a precipita- 

 tion took place, of smaller crystals, and less in quantity; 

 for, being collected on a filter, and carefully dried, they 

 weighed only two grains; whilst the former amounted to 

 three. And this is nearly the largest proportion I ever 

 found the above quantity of healthy urine to contain. 



Exp. 12. As the nitrous acid is one of the most active 

 solvents of this matter, out of the body, I was curious 

 to ascertain, whether, in the very dilute state in which it 

 must reach the kidneys and bladder, (where its action must 

 have been facilitated, by the actual state of solution of this 

 substance,) it would manifest its powers, in preventing its 

 separation. 



To three ounces of urine, rendered a few hours after 

 breakfast, and, of course, scarcely acid, were added five 

 drops of weak nitrous acid ; which did not seem to add 

 very materially to its ascescent properties. 



To a similar quantity were added four scruples of ace- 

 tous acid. In less than an hour, the former deposited a 

 distinct quantity of gravelly matter, in considerable pro- 

 portion. This, perhaps, we should not be surprised at, 

 when we consider how the action of this acid, in that 

 fluid, may be determined by superior affinity* In the lat- 

 ter, the separation did not take place for a considerable 

 time after. We see, then, that the nitrous acid speedily 

 and powerfully precipitates this acid substance* 



Exp. 13. To six ounces of urine, shewing a strong 

 acescent quality, were added only three drops of strong 

 marine acid. A cloudiness and transparent granular pre- 

 cipitation took place, followed by the formation of ex- 

 tremely minute gravelly concretions, which, even after two 

 days standing, did not assume so red a tinge as that with 

 2 D 2 vegetable 



