98 Dr. Davy on the urinary organs and urine 
flocculent precipitate. Neutral acetate of lead, a copious white 
precipitate. Aqua ammonice had no effect. Oxalate of ammo- 
nia produced a slight cloudiness ; and a faint cloudiness was 
produced by muriate of barytes, which did not disappear on the 
addition of a drop of nitric acid. A portion of this urine, slowly 
evaporated, afforded a brown extract, with a strong urinous 
smell. To a moiety of this extract of a syrupy consistence, 
a drop of nitric acid was added ; the effect produced was just 
the same as if human urine had been the subject of the ex- 
periment ; a crystalline compound was immediately formed, 
which I could not hesitate in pronouncing nitrate of urea. The 
other moiety, decomposed by heat in a close glass tube, 
afforded a considerable quantity of yellow oily fluid, strongly 
impregnated with subcarbonate of ammonia, and a residual 
coal, from which I obtained a large proportion of common salt 
and a little phosphate of lime, and slight traces of a fixed alka- 
line phosphate. 
Another portion of this urine was set aside to undergo 
spontaneous decomposition. It has been kept now eight days. It 
has become slightly turbid, and has acquired a distinct, though 
not strong ammoniacal odour, mixed with another kind of 
odour, not unlike that of cabbage. 
The conclusions to be drawn from the results of these ex- 
periments scarcely need to be pointed out : it is pretty evident, 
now, that the urine of the bull-frog and of the brown-toad 
contains urea, and the latter rather abundantly. Reasoning 
from analogy, the probability is, that the urine of frogs and 
toads in general is of a similar nature, and altogether different 
from that of the other amphibia. 
It is seldom that any very abrupt transitions are to be 
