Encyclopaedia Britannica, or, a Dictionary of arts, sciences, and miscellaneous literature : enlarged and improved. Illustrated with nearly six hundred engravings > Volume 5, BUR-CHI

73°
Component
Parts of
Vegetables,
*437
Alkalies.
2438
Compofi-
tion.
G H E M I
the afliflatice of heat ether diffolves wax nearly in the
fame proportion, but on cooling it is alfo precipi-
teitcd* •
Wax is foluble in the fixed oils with the aid of heat.
This compound is known by the name of cerate, which
is much employed to form plafters for dreffing wounds.
It is foluble alfo in fome of the volatile oils, as thole ot
turpentine, with the affiltance of heat. As the folu-
tion cools, part of the wax is precipitated.
6. Wax combines with the fixed alkalies, and forms
with them fubftances fimilar to foap.
7. According to the analyfis of Lavoifier, wax is
compofed of
Carbone, 82.28
Hydrogen, I7-72
100.00
Butter of 8* When wax is diftilled with a temperature above
wax. 2120, water comes over, fome acid, and a little fluid
and odorous oil. The oil in the courfe of the pioccfs
becomes thicker, and at laft affumes the confiftencj of
butter *, and hence it has been called butter of wax.
This fubftance by repeated diftillation is converted
into a volatile oil. A coaly matter remains in the
0 retort.
Obtained 9- Wax is extrafted from a number of plants, pof-
from many fefling different degrees of confiftency, as that from the
plants. cacao, called the butter of cacao; from the croton febi-
fera, called the tallow of croton ; and the myrtle wax
extracted from the myrica cerifera, ox candle-berry
myrtle of America. TL he myrtle wax is obtained from
the berries of this plant. They are colle&ed and put
into a kettle, and covered with water to the depth of
half a foot. Heat is applied, and the berries are pref-
fed againft the fides of the velfel. The wax melts, and
fvvims on the top. It is colleaed, paffed through a
cloth, dried and melted again, and then caft into cakes.
The wax, it appears, exifts chiefly in the outer cover¬
ing of the berries. Myrtle wax is of a pale-green co¬
lour j the fpecific gravity is 1.015. When heated to
the temperature of 109°, it melts j with a ftronger
heat it burns, giving out a white flame with little
fmoke 5 an agreeable aromatic odour is at the fame
time emitted. In its other properties it refembles bees
wax.
Prouft has detefted wax in the rind of plums,
oranges, and fimilar fruits, and in the green fecula of
many plants.
XIV. Of Camphor.
2441
Fxtraction. 3* Camphor is obtained from the laurus camphorata,
a fpecies of laurel which grows in China and Japan.
It is extrafted by fublimation in an iron pot. The Hutch
2442 afterwards purify it by a fecond fublimation.
fjopemes. jt *s a brittle fubftance, poffefiing a hot
acrid tafte. The fpecific gravity is 0.9887. It is not
altered by expofure to the air, but it is fo extremely vo¬
latile, that it difappears entirely if left in an open vef-
fel. It cryftallizes by fublimation in clofe veffels in
the form of hexagonal plates or pyramids. It is info-
luble in water, although at the fame time it communi-
2443 cates fome of its odour.
Action of When a heat about the temperature of 300° is
fuddenly applied, it melts, and then is volatilized. It
S T R Y.
readily catches fire, and burns with a bright flame, with Component
out leaving any refiduum. It even burns on the fur- Partsof
face of water. When a fmall quantity of camphor jn yegetables.
a ftate of inflammation is introduced into a large glafs *
veffel filled with oxygen gas, it burfts out into a vivid
flame ; the infide of the veffel is covered w ith a black
powder, and a great deal of carbonic acid gas is dif-
engaged. If a little water has been previoufly put into
the veffel, it is impregnated with carbonic and campho¬
ric acid. # _ jm*.
4. Camphor is foluble in the acids, but with thead-Acid^
dition of water or an alkali, it is precipitated un¬
changed. Camphor in fulphuric acid forms a red iblu-
tion ; in nitric acid, a yellow folution, which was for¬
merly called oil of camphor. By the repeated diftilla¬
tion of nitric acid off camphor, it is converted into cam¬
phoric acid.
Sulphurous acid, muriatic acid, and fluoric acid, in
the ftate of gas, diffolve camphor. If oxymuriatic
acid gas be made to pafs into a folution of camphor in
nitric acid, it is immediately changed to a rofe colour,
and inftantly afterwards it becomes yellow, which is
permanent during the procefs. When water is added
to the folutions of camphor in acids, it is feparated.
Camphor is alfo foluble in water impregnated with car¬
bonic acid gas, and in acetic acid. The latter com¬
pound conftitutes Henry’s aromatic vinegar..
5. Alcohol readily diffolves camphor, but it is preci¬
pitated with the addition of water. By diluting alco¬
hol which holds camphor in folution with water juft fo
much as not to precipitate the camphor, the latter cry¬
ftallizes in the form of feathers. The fixed and vola¬
tile oils diffolve camphor with the afliftance of heat, but
on cooling the camphor is precipitated, and cryftaU
lized, as in the folution wdth alcohol. _ _ 2445
6. Camphor communicates to the alkalies a little of Alkalies,
its colour, but is not otherwife foluble in thefe bo-
dies. £
7. According to the analyfis of Bouillon Lagrange,Com^
by diftilling one part of camphor with two of alumina,tion.
formed into a pafte with water in a glafs retort, the
component parts of camphor are carbone and hydro¬
gen j the proportion of carbone being much greater
than in oils. 2447
In the courfe of the diftillation, he obtained a vola-oil of cam-
tile oil, of a golden yellow colour, which floated on thephor.
furface of the water in the receiver. It had an acrid
burning tafte, and aromatic odour, fimilar to that of
thyme or rofemary. 2448
8. Camphor has been detedted in many other plants. Found in
It has been extrafted from the roots of thyme and many
fage, and in thefe plants it feems to be combined withPlants’
volatile oil. If the oil be expofed to a temperature be¬
low 540 in the open air, it evaporates, and the camphor
cryftallizes. It may be alfo obtained by diftilling the
oil in a w ater bath, under the temperature of 212°, till
a third part of the oil paffes over. Part of the cam- ^
phor is found cryftallized in the veffel, and by repeat¬
ing the procefs, the whole may be extracted from the
oil. By mixing the camphor with a little dry lime,
and fubliming it, it may be purified.
XV. Of Caoutchouc.
heat.
244^
i. Caoutchouc is a foft elaftic fubftance, chiefly ob-Hiftory.
tained