Experiments om Urine: 243 
fmoke, leaving a very fmall quantity of a charity refiduum, 
by no means difficult to incinerate; but, when expofed to 
an intenfe heat, they burn with a reddifh flame and a kind 
of detonation fomewhat fimilar to nitrat of ammonia. 
From thefe experiments it would appear that this fub- 
ftance is an animal acid hitherto unknown, and whofe bafis 
exifts in this extractive matter. | 
We {hall now briefly mention the effects produced by 
certain re-agents on the urine, when in a healthy ftate, and 
likewife when altered by fome morbid difpofitions of the 
body. 
- Pure ammonia and the fixed alkalies, dropped into healthy 
recent urine, produce a flight cloud, which, on examination, 
will be found to confift principally of phofphat of lime ; 
about 2 gr. may be obtained in this way from 4 02. of urine. 
Lime-water likewife throws down a precipitate which is 
much more copious, for reafons that muft be obvious. 
Nitrous acid, added to healthy urine, produces a flight 
effervefcence, and gives it more or lefs of a reddith colour, 
but produces no precipitation. In fome difeafes, however, 
particularly general dropfy or anafarea, this re-agent, when 
dropped into the urine, produces a milkinefs, and in fome in- 
ftances a coagulation, fimilar to what would take place if 
added to the ferum of the blood. When bile is mixed with 
this fluid, as in jaundice, the acid renders it green: a fimilar 
effet is produced by the muriatic, and alfo in fome degree 
by the fulphuric acid; for this purpofe, however, the mu- 
riatic is to be preferred. 
The principle of tan, or infufion of oak-bark, deteéts ani- 
mal mucilage or jelly, and the quantity of coagulum thrown 
down will in general bear a certain proportion to the extrac- 
tive matter. Four oz, of healthy urine afforded in this way 
a precipitate of about 4 gr.* 
* ® Seguin remarks, that in every cafe where the action of the ftomach 
and organs of digeftion is much impaired, this infufion produces a co- 
pious precipitate. C. 
R2 The 
