(270 



of tbis very compovind fluid, give rise to some artificial 

 fbiraation oi" it, on this occasion. 



To the filtered liquor, therefore, of Number 3, were 

 again superadded five drops, which, in twenty-four hours, 

 caused a farther separation of a very few crystals only. 

 It was filteied a third time, and eight drops more added; 

 but without the smallest appearance of a single crystal, 

 after four days. The additional acid, then, only more ef- 

 fectually and speedily determined the separation of the 

 quantity, naturally contaiwd in urine: its more divided 

 pulverulent appearance adding considerably to its volume. 



It now only remained, to demonstrate the identity of 

 these various precipitates, with the naturally deposited 

 matter of gravel. Tor, though it could not be well mis- 

 taken, for any other saline composition in urine; yet, as 

 external characters are, even in the hands of a Rome de 

 Lisle, or an Abbe Haiiy, fallacious, the following, and 

 concluding one, on the. subject of acids, was instituted. 



EXPERIMENT XV. 



To two drachms of this artificial gravelly matter, was 

 gradually added one ounce of nitrous acid; which acted 

 on it, with effervescence, and dissolved the whole, with 

 the exception of some small, floating, floculent, animal 

 particles, so well described by Bergman. 



The evaporated solution reddened the skin, and, after 

 some time, depoeited crystals of oxalic acid ; as happens in 



all 



