of Urinary. Concretions. 5I 
ourices more of gaz came over; and then the retort only 
contained a dark-brown folid matter. 
_ The firft portion of gaz, vzz. 23 ounces, confifted of about 
equal bulks of carbonic acid and atmofpherical air. The 
fecond portion, viz. 23 ounces, was two-thirds of its bulk 
carbonic acid, and the reft nitrogen gaz. The third portion, 
or 3 ounces, was atmofpherical air, with a little carbonic 
acid. 
Nitric acid was poured, in the fame quantity as before, 
into the retort. An effervefcence immediately took place; _ 
which was fucceeded by a tranfparent folution. The diftilla- 
tion yielded gaz of the fame kind as before, but in fmaller 
quantity, with white fumes, and white fublimate. When 
only about 4 drachms, by meafure, of liquid remained in 
the retort, a little of it was evaporated ; and, when reduced 
to a folid matter, it turned black, and took fire, leaying a 
carbonaceous refidue; but, before this, a margin of beautiful 
pink matter appeared. 
Nitric acid was poured, as before, into the retort, for the 
third time, but very little gaz afcended, and much lefs white 
fumes than before. The diftillation proceeded, till zbout ° 
one drachm-meafure of liquid remained in the retort: this 
being left to ftand, prifmatic cryftals were formed in a very 
fmall quantity of liquid. Thefe cryftals did not tafte four, 
but fharp, and they reddened turnfole paper. Adding a 
little foda to a part of them, to fee whether I could form a 
neutral falt, I was furprifed by the extrication of ammoniac. 
To another portion of cryftals I added fulphuric acid, which 
difengaged nitric acid. A third portion of cryftals, being 
expofed oyer a lamp, wholly evaporated, without leaving a 
mark behind. The remaining matter in the retort being 
examined, was found to be nitrate of ammoniac. It was 
plain that the nitric acid had, by parting with oxygen to the 
carbon of the oxide, formed carbonic acid. The carbon 
being thus carried off, of courfe the nitrogen and hydrogen of 
the oxide uniting produce ammioniac; which, uniting with 
to A 1 the 
