Memoir on Human Urine. 53 
ion of ammonia, and giving only phofphorus when the” 
whole fufible falt of urine is heated with carbon. 
G. The uric acid, named yery improperly at firft the 
Jithie acid. It eryttallifes by the cooling of urine, and forms 
the red fand which that liquid depofits at the bottom of pots. 
It is more abundant in the urine of difeafed perfons. It may 
be diflolved exceedingly well by the cauftic alkali. 
H. The benzoic acid, more abundant in the urine of 
children; eafy to be obtained from urine evaporated to a 
dyrup; mixed to a tenth with concentrated fulphuric acid, 
and diftilled, 
I. Gelatinous matter and albumen, extremely variable iu 
its proportion inthe different kinds of urine; fhewing iticlf 
in clouds in urine where ammonia is formed, in filaments 
in that over which alkali is poured, in flakes by the evape- 
ration of urine; precipitating itfelf by the tanning principle, 
which. ferves to determiné the proportion ; occafioning a 
{peedy putrefaction of urine, which contains it in abun- 
dance ; appearing by their augmentation to be the firft canfe 
-of the formation of g¢alculi, and furnifhing them with the 
gluten which unites their molecule, and following, in their 
proportion, the energy or weaknefs of the digeftive forces of 
the diftribution of the chilous matter, 
K. The fpecial urinary matter, giving ta@urine its charac- 
teriflic properties really con{tituung it; giving it its odour, 
colour, and favour—its alterability into ammonia, the car- 
bonic and acetous acids, &e. It is the moft abundant of the 
matters contained:in urine; it forms alone the 4% of its 
‘mafters. It has been mproperly confidered by Rouelle the 
younger as a faponaceous extract. To it is owing the almott- 
total cryftallifation of urine evaporated to the confiltence of 
-fyrup; the folid and cryftalline form it aflumes in that {tate 
by the addition of concentrated nitric acid; the eryftallifation 
_ of the muriates of foda and ammonia modified, and im fome 
meafure reverfed—the former from the cube to the octaedron, 
and the Yecond from the o¢tacdron to the cube. This partis 
cular animal matter, which we call ur‘e, will form the qb- 
ject of another Memoir, deitined to ferve as.a fuppleanent d 
rs “ibe 
