OIL. 
none o m being either drying in themfelves, or capa 
of beco o by means of litharge and othe Soins. 
Fat, oat to dry diftillation, — . — ise tem- 
perature of about 400°, emits 
agreeable vapour: as the heat increates, ae of the oil 
comes over into the ioral aa th which remains in the 
blackt 
buretted ae and carbonic acid of a 
d ce it is inferred that there is a real difference 
oils, always rancid, are 
for the moit part thick and iitinaas, which renders them 
and fome other ufes to 
at the 
ay be 
ee con fence een be fitnefs for buraing. Ani- 
mal oils are fubftances of ver y great economical importance. 
They are uied as food, and in medicine as the bafis of 
rious unguents: they are largely e employed in the manu- 
facture of foap, and alfo for burning either in lamps or in 
31) 
the form of candles. Akin 
ale oil is much em by — animal 
matters, to which it owes its difagreeable odot It has, 
however, been fo purified as to pollefs lefs fmell and tafte 
than the bett olive oil. 
All the fixed oils are of lefs {pecific gravity than water ; 
and fince they do ore ae the former muft float upon 
the furface of the lat 
e fixed oils came be diftilled oe decompofition. 
which condenfes 
“An in- 
This is 
ae which h lodges in the 
Fixed oils a divided into rs nominee 
(4), drying oils. 
(a). Fat Oils.—Thefe are a as, when expofed to the 
air for a certain time, firft become vifcid, and ultimat ae 
concrete, having the allow, and in every 
pal a fimilar to fat. 
rding to the time exp : it at the fame time acquires a 
dit seceable odour, to which we give the name of rancidity. 
Of thefe kinds we may mention olive oil, almond oil, and 
that extracted from rape feed, called rape oil. This change 
is more rapidly brought about by dilute nitric acid, or an 
fubftance which affords oxygen. It has been fuppofed that 
(a), fat oils, and, 
have not as yet learned from any 
abfolute weight of the oil be increafed or diminifhed by the 
agency of the oxygen. It feems moft plaufible to fuppofe, 
that the oxygen combines with a portion of hydrogen of the 
oil, forming water, leaving the remainder more concrete and 
lefs fufible. Olive oil, by treating it wit — itric acid, may 
be rendered saga infufible with {perm 
The fat oils combine with the allcalies, carte and mott 
metallic oxyds, forming foaps. See Soap. 
They are not mifcible pa water, Sag through the 
medium of fugar, ftarch, or gum. the two latter 
they form compen called emulfions. 
ey do not combine with many o 
of the bi lens 
bodies. They unite with fulphur, forming a Own 
co a difagreeable {mell. O eae me of 
he fulphur is depofited in cryftals. Phofphorus scuibiaes 
with feve f th ie oils. Olive oil, when rubbed with 
ofed to the air, by o 
taining it, becomes very luminons. 
with it fhines for fome time, but no perceptible heat is 
produced. 
When concentrated fulphuric acid is poured upon the 
= oils, decompofition f{peedily enfues. The produds are 
ater, carbon depofited, giving a blac ean The ful- 
shiv is alfo psec os fome meee ~~ form When 
concentrated nitric a ils, ‘he action is 
co era 3 the oil. take fire, and ae, ete {pon 
a ind. If the be dilute, as has been obferved, it 
converts the fat oils i into fat like tallow. 
fixed oils combine with fone of the metals. 
r s 
carriages, and in all inftances in which oil is ufed with | iron to 
leffen fri tion. 
b. Dr 
—Thefe oils poffefs ‘aoa aan eh 
icula he 
aes infte ing an opaque fatty appearance, they re- 
ain their tranfparency, and acquire the flexible property of 
horn. 
The varieties poffefling this property are the oils of nut, 
poppy, and lin 
Thefe oils are lefs fitted for combuftion than hig fat 
oils, but ar ni 
fe) 
i 
a 
om 
oO 
Q 
ro) 
colour, and makes it thicker. Acetat of lead, and other me- 
tallic falts, produce the fame change. 
il is mixed with the black oxyd of manganefe, it 
me time after takes fire. This arifes from amore rapid 
combination of the oxygen of the oxyd with the pyle 
a oil 
compolition of the fixed oils has been given by La- 
voilier, at it is not to be relied upon. He makes it confift 
of 79 carbon, and a1 hydrogen. 
Another f{pecies of oils is found in fome vezetables, 
which have an acrid tafte, and diffolve in alcohol, - Z 
olatile 
