V R E 
ftur. The mineral from which Mr. TClap- 
pth first obtained it is a native sulphvu'et ot 
ranium. 
URANOSCOPUS, star-gazer, a genus of 
Lhes of the order jugulares. The generic 
haracter is, head large, depressed, rough ; 
houth furnished with an internal cirrus ; gill- 
overs edged by a ciliated border; gill-mem- 
irane five-rayed. 
Uranoscopus scaber, bearded star-gazer, 
'he head of this fish is large, squarish, and 
[overed by a strong bony case, roughened by ; 
an infinite number of small warts or protube- j 
ranees : each side of this case is terminated j 
above by two spines, the hindermost of which ; 
is the strongest, and covered by a skin : the 
under part has five spines, smaller than those 
above: the mouth, which is wide, opens in 
an almost vertical direction: the tongue is 
thick, short, and roughened with numerous 
small teeth : near the interior tip of the 
lower jaw is a membranaceous process which 
terminates in along cirrus. or beard extend- 
ing to some distance beyond the lips, which 
are themselves edged with smaller ones: the j 
eyes are situated very near each other on the 
top of the head: the body is of a somewhat 
squarish form as far as the vent, and thence 
becomes cylindric: it is covered with small 
scales, and marked near the back by a lateral 
line composed of small pores or points bend- 
ing from the neck to the pectoral fins on 
each side, and thence in a straight line to 
the tail : on the back are two fins, of which 
the first is liuich shorter than the latter, and 
furnished with stronger spines : the pectoral 
fins are large, with soft rays: the ventral fins 
are small ; the tail of moderate size,, and 
rounded at the end. I lie colour of the body 
is brown, with a whitish or silvery cast to- 
wards the abdomen ; the head, pectoral fins, 
and tail, having a strong ferruginous cast, and 
the first dorsal fin being marked towards its 
hind part by a large black spot. 
The star-gazer is an inhabitant of the Me- 
diterranean and northern seas, chiefly fre- 
quenting the shallow parts near the slioies, 
where it lies concealed in the mud, with tire 
tip of the head alone exposed: in this situa- 
tion it waves ihe beards of the lips, and par- 
ticularly the long cirrus of the mouth, in va- 
I rious directions, thus alluring the smaller 
fishes and marine insects which happen to be 
swimming near, and which mistaking these 
organs for worms, are instantly seized by 
their concealed enemy. The usual length of 
this fish is about twelve inches. It is in no 
| esteem as an article of food, being generally 
considered as coarse and ot an ill Havonr : 
the "all was anciently considered as of pecu- 
liar efficacy in external disorders of the eyes. 
There are only two species, viz. the scaber 
and Japanicus. 
UREA, the constituent and characteristic 
matter of urine, may be obtained by the fol- 
' lowing process: Evaporate by a gentle heat a 
quantity of human urine, voided six or eight 
hours after a meal, till it is reduced to the 
l consistence of a thick syrup. In this state, 
when put by to cool, it concretes into a crys- 
: talline mass. Pour at different times upon 
this mass four times its weight of alcohol, and 
applv a gentle heat ; a great part ot the mass 
will be dissolved, and there will remain only a 
I number of saline substances. Pour the alco- 
■ hoi solution into a., retort,, and distil by the 
U R E 
heat of a sand-bath till the liquid, after boil- 
ing some time, is reduced to the consistence 
of a thick syrup. 1 he whole ot the alcohol 
is now separated, and what remains in the re- 
tort crystallizes as it cools. These crystals 
consist of the substance known by the name 
of urea. 
Urea, obtained in this manner, has the 
form of crystalline plates crossing each other 
in ditferent directions. Its colour is yellowish 
white : it has a fetid smell, somewhat resem- 
bling that of garlic or arsenic ; its taste is 
strong and acrid, resembling that of ammoni- 
acal salts; it is very viscid and difficult to 
cut, and has a good deal ot resemblance to 
thick honey. When exposed to the open 
air, it very soon attracts moisture, and is con- 
verted into a thick brown liquid. It is ex- 
tremely soluble in water ; and during its so- 
lution. a considerable degree of cold is pro- 
duced. Alcohol dissolves it with facility, 
but scarcely in so large a proportion as wa- 
ter. The alcohol solution yields crystals 
much more readily on evaporation than the 
solution in water. 
When nitric acid is dropt into a concen- 
trated solution ot urea in water, a great num- 
ber of bright pearl-coloured crystals are de- 
posited, composed of urea and nitric acid. 
No other acid produces this singular effect. 
Tlve concentrated solution of urea in water is- 
brown, but it becomes yellow when diluted 
with a large quantity of water. 1 ne infusion 
of nut galls gives it a yellowish-brown colour, 
but causes no precipitate-; neither does the 
infusion of tan produce any precipitate. 
When heat is applied to urea, it very soon 
melts, swells up, and evaporates with an in- 
supportably fetid odour. V\ hen distilled, 
there come over first benzoic acid, then car- 
bonat of ammonia in crystals, some carbu- 
reted hydrogen gas, with traces of prussic 
acid and oil ; and there remains behind a 
large residuum, composed ot charcoal, muiiat 
of ammonia, and muriatof soda. The distil- 
lation is accompanied with an almost insup- 
portable fetid alliaceous odour.. Two. hun- 
dred and eighty parts of urea yield by distil- 
lation 200 parts of c.arbonat of ammonia, 10 
parts of carbureted hydrogen gas, 7 parts of 
charcoal, and 68 parts of benzoic acid, mun- 
at of soda, and muriat of ammonia. These 
three last ingredients Fourcroy and Vauque- 
lin consider as foreign substances, separated 
from the urine by the alcohol at the same 
time with the urea. Hence it follows, that 
100 parts of urea, when distilled, yield 
92.027 carbonat of ammonia 
4.608 carbureted hydrogen gas 
3.225 charcoal 
99.860 
Now 200. parts of carbonat of ammonia, ac- 
cording to Fourcroy and Vauquelin, are com- 
posed of 86 ammonia, 90 carbonic acid gas, 
and 24 water. Hence it follows that 100 
parts of urea are composed of 
39.5 oxygen- . 
32.5 azote 
14.7 carbon 
13.3 hydrogen; > 
100,0 
But it caicscarcely be doubted that the water 
U R E 
which was found in the carbonat of ammonia 
existed ready-formed in the urea belore the 
distillation. 
When the solution of urea in water is kept 
in a boiling heat, and new water is added as it 
evaporates, the urea is gradually decompos- 
ed, a very great quantity of carbonat of am- 
monia is disengaged, and at the same time 
acetic acid is formed, and some charcoal pre- 
cipitates. 
When a solution of urea in water is left to 
itself for some time, it is gradually decompo- 
sed. A froth collects on its surface ; and air- 
bubbles are emitted which have a strong disa- 
greeable smell, in which ammonia and acetic 
acid are distinguishable. The liquid contains 
a quantity of acetic acid. 1 lie decomposi- 
tion is much more rapid if a little gelatine is 
added to the solution. In that case more am- 
monia is disengaged, and the proportion of 
acetic acid is not so great. 
When the solution of urea is mixed with 
one-fourth of its weight of diluted sulphuric, 
acid, no effervescence takes place; but, on 
the application of heat, a quantity of oil ap- 
pears on the surface, which concretes upon 
cooling ; the liquid which comes over into 
the receiver contains acetic acid, and a quan- 
tity of sulphat of ammonia remains in the re- 
tort dissolved in the undistilled mass. By 
repeated distillations, the whole of the urea is 
converted into acetic acid and ammonia* 
When nitric acid is poured upon crystal- 
lized urea, a violent effervescence takes place, 
the mixture froths, assumes tli£ form of &• 
dark-red liquid, great quantities of nitrous gas, 
azotic gas, and carbonic acid gas, are disen- 
gaged. When the effervescence is over, 
there remains only a concrete white matter, 
with some drops of reddish liquid. When 
heat is applied to this residuum, it detonates 
like nltrat of ammonia. Into a solution of 
urea, formed by its attracting moisture from 
the atmosphere, an equal quantity of nitric 
acid, of the specific gravity 1.460, diluted 
with twice its weight of water, was added ; a. 
gentle effervescence ensued: a very small 
heat was applied, which supported the effer- 
vescence for two days. There was disengaged 
the first day a great quantity of azotic gas and 
carbonic acid gas; the second day, carbonic 
acid gas; and at last nitrous gas. At the same ' 
time with the nitrous gas the smell of the 
cxyprussic acid of Berthollet was percepti- 
ble. At the end of the second day, the mat- 
ter in the retort, which was become thick, 
took fire, and burnt with a violent explosion. 
The residuum contained traces of prussic acid 
and ammonia. The receiver contained a yel- 
lowish acid liquor, on tire surface of which 
some drops of oil swam. 
Muriatic acid dissolves urea, but does not 
alter it. Oxymuriatic acid gas is absorbed 
very rapidly by a diluted solution of urea ; 
small whitish flakes appear, which soon be- 
come brown, and adhere to the sides of the 
vessel like a concrete oil. • After a consider- 
able quantity of oxymuriatic acid had been 
absorbed, the solution, left to itself, continued 
to effervesce exceedingly slowly, and to emit 
carbonic acid and azotic gas. Alter this ef- 
fervescence was over, the liquid contained, 
muriat and carbonat of ammonia. 
Urea is dissolved very rapidly by a solution 
of potass or soda, and at the same time a 
quantity of ammonia is disengaged; the sums 
