546 URATES. 
UREA. 
with the terminal ones petiolate, have been in-]a stranger could point where the urate com- 
troduced to British gardens from India, China, 
Brazil, and Western Africa; and all love a soil 
of sandy loam and require to be propagated from 
seeds. Several were ranked by Linnezeus and his 
immediate successors among the true hedysa- 
rums. 
URATEHS. Salts of uric or lithic acid. This 
acid is a common constituent of urinary calculi; 
and always occurs in healthy urine, combined 
with some alkali; and is precipitated from urine 
by means of any acid which robs it of the alkali. 
It forms at first in brick-coloured crystals ; but 
when pure, it is white, tasteless, and inodorous. 
It consists of 6 equivalents of carbon, 2 of hydro- 
gen, 3 of oxygen, and 2of nitrogen. It is inso- 
luble in alcohol, and cannot be thoroughly dis- 
solved in less than about 10,000 times its own 
weight of water at 60° Fahr. It reddens litmus 
paper, and combines with alkalies and alkaline 
earths and oxides, but does not effervesce with 
alkaline carbonates. It is decomposed by chlo- 
rine ; and when acted on by nitric acid, it leaves 
a beautiful purple residuum, with distinct acid 
properties. 
The principal urates, or pure salts of uric 
acid, are those of ammonia, potash, and soda. 
Urate of ammonia is soluble to a considerable 
degree in boiling water, but more sparingly in 
cold water. The urates of soda and potash, when 
neutral, are of very sparing solubility; but an 
excess of either of the fixed alkalies takes up a 
large quantity of the acid. See the articles Urna 
and URINE. 
The urate of the manure market is an artificial 
fertilizer prepared by a Company in London; 
and ranks in some respects with special manures, 
and in others with factorial and patent ones. See 
the article Manurz. It is a dry powdery sub- 
stance; and is applied by the drill in the quan- 
tity of about 63 cwts. per acre, and has the repu- 
tation of being a very powerful fertilizer, and 
acts with equal or at least similar effect on 
turnips, tares, rye, wheat, and winter barley. Two 
competent and credible experimentalists report- 
ed as follows respecting it in September, 1841; 
—‘“T applied it broadcast,” said the one, “on 
two acres in the centre of a twelve-acre field of 
sandy land, at the rate of 63 cwts., and at the cost 
of 33s. per acre. The rest of the field I dressed 
with bone-dust at the rate of two quarters, and 
costing 52s. per acre. Up to the present time, I 
perceive no difference whatever between the 
two, the whole field promising to be a very 
good crop. The turnips are drilled at 18 inches 
apart, and set out at the same distance.” “TI 
drilled a ton of urate upon 3 acres, in rows 17 
inches apart,” said the other, “upon a very hot 
gravelly soil. The adjoining portion of the field 
was manured, in the usual way, with 14 loads 
per acre of farm-yard manure. The turnips in 
the urate were fit to hoe 7 days before the other 
manured part ; and from their first appearance, 
menced and ended. The difference is still evi- 
dently in its favour ; both portions were sown the 
same day. I certainly consider it a good artifi- 
ficial dressing, and that its fertilizing qualities 
are great.” 
URCHOLINA. A recently discovered genus 
of ornamental exotic plants, of the amaryllis or- 
der. The name alludes to the pitcher form of the 
flower. The pendulous species, U. pendula, has 
yellow and green flowers, and blooms in June, 
and was introduced to the greenhouses of Bri- 
tain a few years ago from the Andes. 
URE. The udder of a cow or ewe or other mam- 
mal. The word is provincial. 
UREA. A chief and characteristic constituent 
of urine. It can be separated by a somewhat 
easy chemical process; and it forms into crys- 
talline plates, which cross one another in various 
directions or assume the shape of four-sided 
prisms, and which are transparent, yellowish- 
white or almost colourless, and of a slight pearly 
lustre. It is viscid and difficult to cut; it has a 
faint fetid odour, similar to that of garlic or ar- 
senic, and a strong and acrid taste, similar to 
that of ammoniacal salts; it leaves a sensation of 
coldness on the tongue, like that left by salt- 
petre ; it attracts moisture from the atmosphere, 
and deliquesces into a thick brown fluid ; it is 
very soluble in water, and evolves much cold dur- 
ing solution ; it melts at'a temperature of about 
248° Fahr., and decomposes at a rather higher 
temperature, swelling up and evaporating with 
an insufferably fetid odour, and passing into 
carbonate of ammonia and cyanuric acid; it 
dissolves but does not decompose under the 
action of hydrochloric acid; and it effervesces 
and decomposes under the action of nitric acid, 
giving off nitrous, azotic, and carbonic acid 
gases, and leaving a residuum which is white 
and concrete, and which eventually shows tra- 
ces of ammonia and prussic acid. Jt has a 
specific gravity of about 1:35; it consists of 
two equivalents of carbon, four of hydrogen, 
two of oxygen, and two of nitrogen; and it is 
the only animal compound, or animal organic 
secretion, which has yet been artificially formed. 
A pure aqueous solution of urea may be heat- 
ed to the boiling point, or exposed to the atmo- 
sphere for several months, without undergoing 
any change; but an aqueous solution of it con- 
taining the other constituents of urine—in other 
words, aqueously diluted urine, or much more 
urine itself—decomposes by a temperature of 
212 Fahr., or rapidly passes into putrefactive 
decomposition by exposure to the atmosphere, 
and is converted in either case almost wholly 
into carbonate of ammonia. A solution of soda, 
potash, lime, magnesia, or barytes also rapidly 
dissolves and decomposes urea, changing it prin- 
cipally into carbonate of ammonia. The decom- 
position of urea, in any ordinary way, therefore, 
whether as a constituent of urine or of guano or 
