438 
.OIL. 
of acid, and of water, into contact with each other; 
after which it mud be left to fettle. After about a week’s 
reft, the oil fwims above the water, and the water above a 
blackifh fubftance precipitated from the oil by thefulphu- 
ricacid ; which fubftance is the colouringmatterof the oil, 
and prevents it from burningwell. Thus it appears, that 
the whole arranges itfelf into three very diftinft ftrata; the 
upper being oily, the fecond aqueous, containing a little 
fuiphuric acid, and the third carbonic. But, even after this 
period of reft, the oil thatforms theupperftation is farfrom 
being clear, and it would perhaps require twenty days to 
render ittran(parent by reft alone; but, by filtering the oil, 
it immediately becomes perfedfly clear and pellucid. For 
this purpofe, either pounded charcoal, cotton, or wool, 
may be employed. The two laft are preferable, the fame 
cotton and the fame wool fervinga great number of times ; 
but, after a certain interval, they require to be cleared from 
the greafe. By this procefs, carefully purfued, an oil is 
obtained, infinitely more free from colour, tafte, and 
fmell, than that commonly employed, which burns with 
the greateft eafe, and in all refpefts worthy to be com¬ 
pared with the pureft oils Of commerce : add to which, 
that the lofs in quantity is very inconfiderable. 
If it be delired to obtain a ftill whiter oil, it may be 
fubjedfed to a fecond procefs ; but then one part of con¬ 
centrated fuiphuric acid will fuffice for too parts of oil. 
In oil once purified, this acid does not caufe a blackifh 
precipitate, but, on the contrary, of agreyifh-white, and in 
no great quantity. This precipitate feparates lefs eafily 
from the oil than the preceding. 
When the oil has been treated with yg 3 of fuiphuric 
acid, if it be left to d^'eft during twenty-four hours 
with a quarter of its weight of lime, or of carbonate of 
lime or argil, it is rendered almoft as clear as w’ater. 
Neither lime, nor carbonate of lime, but Specially the 
former, could be ufed with advantage, becaufe they would 
occafion too great a wafte of oil: but I am of opinion 
that argil would produce advantageous refults ; for, al¬ 
though it in faft retains a confiderable quantity of oil, 
almoft the whole of it might be extracted by means of a 
prefs. Annates de C/iimie. 
To purify F-iJh - oit .—Take one gallon of crude ftinking 
oil, and put to it a pint of water, poured off from two 
ounces of lime flacked in the air. Stir the mixture up 
feveral times for the firft twenty-four hours ; then let it 
Hand a day, and the lime-water will fink below the oil, 
wdiich muft be carefully feparated from it. 
Another Method .—Take one gallon of crude ftinking 
oil, and mix with it a quarter of an ounce of powdered 
chalk, a quarter of an ounce of lime flacked in the 
air, and half a pint of water; ftir them together; and, 
when they have flood fome hours, add a pint of wa¬ 
ter, and two ounces of pearl-afhes, and place the mix¬ 
ture over a fire that will juft keep it fimmering, till the 
oil appears of a light-amber colour, and has loft all fmell, 
except a hot greafy foap-like fcent. Then fuperadd half 
a pint of water in which one ounce of fait has been dif- 
folved ; and, having boiled it half an hour, pour the 
mixture into a proper veffel, and let it Hand for fome days, 
tiil the oil and water feparate. 
If this operation be repeated feveral times, diminifhing 
--each time the quantity of ingredients one half, the oil 
may—be- brought fo a very light colour, and rendered 
equally fweet with the common fpermaceti-oil. Oil, pu¬ 
rified in this manner, is found to burn much better, and 
to anfwer better the purpofes of the woollen manufacture. 
If oil be wanted thicker and more unftuous, it may be 
rendered fo by the addition of tallow or fat. 
In the year 1814, Mr. Vanderkleet, of High Holborn, 
obtained a patent fora method of fweetening, purifying, 
and refining, Greenland-whale and feal-oil. The oil, in 
its raw ftate, is filtered through bags, about forty-one 
inches long, with circular mouths, extended by a wooden 
hoop, about fifteen inches in diameter, fixed thereto. 
Thefe bags are made of jean, lined with flannel; between' 
which jean and flannel powdered charcoal is placed 
throughout, to a regular thicknefs of about half an inch, 
for the purpofe of retaining the glutinous particles of the 
oil, and ftraining it from impurities; and the bags are 
quilted, to prevent the charcoal from becoming thicker 
in one part than another, and to keep the linings more 
compaft. The oil is pumped into a large funnel, made 
of tin, annexed to the pump through a perpendicular pipe ; 
and pafl’es from the funnel into another pipe, placed over 
the bags horizontally, from whence it is introduced into 
them by cocks. The oil runs from the filtering-bags 
into a ciftern about eight feet long by. four feet broad 
and four and a half deep, made of wood, and lined with 
wood, and containing water at the bottom about the 
depth of five or fix inches, in which are diffolved about 
fix ounces of blue vitriol, for the purpofe of drawing 
down the glutinous and offenfive particles of the oil 
which have efcaped through the charcoal, and thereby 
rendering it clean, and free from the unpleafant fmell 
attendant upon the oil in the raw ftate : and, in order to 
enable the oil thus to run from the bags, they are hung 
in a frame or rack made like a ladder, with the fpokes 
or rails at fuflicient diftances to receive the hoop of the bag 
between two ; and fuch frame or rack 1$ placed in a hori¬ 
zontal pofition over the ciftern. The oil is fuffered to run 
into the ciftern until it Hands to the depth of about two 
feet in the water, and there to remain for three or four 
days, (according to the quality of the oil;) and is then 
drawn off by a cock, wdiich is fixed in the ciftern, a little 
above the water, into a tub or other veffel, when it will 
be found to be confiderably purified and refined ; and 
the oil, after having undergone this operation, may be 
rendered ftill more pure, by pafiing a fecond or third time 
through fimilar bags and cifterns. But the oil, after fuch 
fecond and third procefs, is drawn off into, and filtered 
through, additional bags, made of jean lined with flannel, 
inclofed in other bags made of jean, doubled; when the 
procefs is complete. Monthly Mag. vol. xxxiii. andxxxviii. 
Some curious Properties of Oil. 
The ufe of oil, in flopping the violent ebullition of va¬ 
rious fubftances, may be very great in many occafions of 
life. It is w'ell known, that, if a mixture of fugar, honey, 
or the like, be boiling on the fire, and in danger of rifing 
over the fides of the veffel, the pouring in a little oil im¬ 
mediately makes it fubfide. In many cafes, the marking 
a circle round the infide of a veffel, in which a liquor of 
this kind is to be boiled, with a piece of hard foap, (hall, 
like a magic ring, confine the ebullition to that height, 
and not fuffer it to ftir any farther. This is wholly owing 
to the oil, or fat, contained in the foap ; but there is, 
befides thefe, another-very important ufe of oil, on alike 
occafion, which is the pouring a little of it on any me¬ 
tallic folution, while making; this reftrains the afcent 
of the noxious vapours, preferves the operator from dan¬ 
ger, and, at the fame time, by keeping dovm the evapo¬ 
rating matter, gives redoubled ftrength to the menftruum. 
Pliny has mentioned an extraordinary effedt of oil, in 
Hilling the furface of water when it is agitated with 
waves, and the ufe of it made by the divers for this pur¬ 
pofe. “ Omne,” fays he, “oleo tranquillari,” See. lib. ii. 
cap. 103. and Plutarch, in Quaeft. Natur. afks, “ Cur mare 
oleo confperfum perlucidum fit et tranquillum ?” Pliny’s 
account feems to have been eitherdifereditedordifregarded 
by our writers on experimental philofophy, till it was 
confirmed by feveral curious experiments of Dr. Franklin, 
which were publiflied in the year 1744. 
The property of oil above-mentioned has, however, 
been well known to modern divers and dredgers for oyf- 
ters, at Gibraltar, and elfewhere. The divers in the Me¬ 
diterranean, in particular, defeend, as in Pliny’s time, 
with a little oil in their mouths, which they now and 
then let out, and which, on rifing to the furface of the 
1 fea. 
