IMPROVEMENTS IN THE TREATMENT OF VEGETABLE OILS FOR THE PURPOSE OF AGEING THE SAME
Year: 1880

page_text: LETTERS PATENT to Thomas Henry Gray, of Deptford, in the County of Kent,
Varnish Maker, for an Invention of "IMPROVEMENTS IN THE TREATMENT OF
VEGETABLE OILS FOR THE PURPOSE OF AGEING THE SAME."
PROVISIONAL SPECIFICATION left by the said Thomas Henry Gray at the
Offico of the Commissioners of Patents on the 9th July 1880.
THOMAS HENRY GRAY, of Deptford, in the County of Kent, Varnish Maker.
"IMPROVEMENTS IN THE TREATMENT OF VEGETABLE OILS FOR THE PURPOSE OF
AGEING THE SAME.
"
The object of this Invention is so to treat linseed and other vegetable oils as to
improve their drying quality and render them the better applicable for mixture
with pigments, and for use in the process patented by me on the 23rd June, 1879,
No. 2518, for converting the oil into a semi-solid gum.
To this end I so treat the oil as to remove therefrom a portion of the fatty
substance contained therein and known as oleine, to the prescence of which in its
normal proportion in the oil is due the non drying quality so detrimental to its use
in many branches of the arts.
In attaining this end 1 take, say, 1 ton of linseed or rape oil as ordinarily met
with in commerce, whether refined or not, and place it in a tank, which may be
heated by a steam jacket or otherwise. The oil 1 maintain at a temperature of
about 110° Fahrenheit, agitating it for an hour by means of beaters or in any
other convenient manner from time to time, say, once or twice in every 24 hours, to
facilitate the uniform heating of the oil.
When the oil begins to assume a cloudy or opaque appearance, which it will
usually do at about the 14th day of this treatment, I test a small quantity of
it by means of a saline solution, and if it has arrived at the state desired the oleine
will be precipitated. When the oil has arrived at this state I prepare a saline

page_text: solution containing about 14lb. of salt to every gallon of water, and add it to the
oil in the tank, stirring them well together for an hour or more, after which the
oleine or fatty matter will precipitated to the bottom of the tank, and may be drawn
off in any convenient manner, leaving the pure oil behind.
The pure oil is then washed with cold water, which is afterwards run off, and the
oil is then heated to such a temperature by steam or otherwise as will suffice to
expel the remaining water therefrom. I then remove the salt in the oleine by adding
water in excess and agitating; and I thus obtain a marketable fatty matter. Rape
oil may be treated in the same manner. Old oils may be similarly treated, and
precipitation of the oleine may be effected by other suitable chemicals, such as alum
and white copperas.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Thomas Henry Gray in the Great Seal Patent Office on the 7th
January 1881.
THOMAS HENRY GRAY, of Deptford, in the County of Kent, Varnish Maker.
IMPROVEMENTS IN THE TREATMENT OF VEGETABLE OILS FOR THE PURPOSE OF
AGEING THE SAME."
The object of this Invention is so to treat linseed and rape oils as to improve their
drying quality and render them the better applicable for mixture with pigments and
for use in the process patented by mo on the Twenty-third June, One thousand
eight hundred and seventy nine, No. 2518, for converting the oil into a semi-solid
gum.
To this end I so treat the oil as to remove therefrom a portion of the fatty
substance known as oleine (which is a natural constituent thereof), and to the
presence of which in its normal proportion is due the nondrying quality of the oil,
so detrimental to its use in many branches of the arts. In attaining this end I take,
say, one ton of linseed or rape oil as ordinarily met with in commerco, whether
refined or not, and place it in a tank, which may be heated by a jacket of steam or
otherwise. The oil I maintain at a temperature of about one hundred and ten
degrees Fahrenheit while working, agitating it by means of beaters or in any
other convenient manner from time to time to facilitate the uniform heating of
the oil.
I have found by experience that new linseed oil should be kept in agitation
during the whole of the working hours of the day, say, ten out of the twenty four,
and that this treatment should be continued for some nine days. When howover
old oil is treated, the agitation should be kept up for a longer period, say, fourteen
days.
The heated oil I test from time to time by a saline solution for a precipitate, and
when this is obtained I add to the oil in the tank a saline solution, similar to that
used for testing, and agitate for about two hours, at which time the precipitation of
the olcine will commence. When the precipitation is completed, which will be in
about twenty four hours, the deposit, together with the saline solution, is drawn off
from the bottom of the tank, leaving the clear oil in the tank. I then wash the oil
with pure water, and after agitation for one hour I obtain a second deposit, which is
in like manner removed.
As a guide to the preparation and use of the saline solution, I may state that I
have obtained satisfactory results by employing ninety pounds of common salt
dissolved in sixty gallons of water to the ton of oil treated.
In order to brighten the oil after washing, I heat the oil to about two
bundred degrees, and thus drive off the water left in the oil by the washing
operation.
The yield of oleine from new linseed or rape oil will be about twenty per cent.
by weight of the bulk treated, but old oils will give a somewhat smaller yield. The
oleine obtained as above explained is applicable as a base for soap making.
The purified oil obtained from new oil is applicable wherever linseed or rape oil
is used, preference however is given to that obtained from old oil for mixing with
melted hard guns, such as copal, to produce varnishes.
Instead of using mechanical agitation, I find that I can advantageously employ
heat for effecting the same result; in such case I mix the saline solution at the
outset with the oil, and subject the mixture to a heat sufficient to boil the solution.
This heat I maintain for, say, twenty four hours, and on cooling down the tank the
precipitation of the oleine will take place.

page_text: The oleine I then run off, together with the saline solution, as before explained,
and treat the oil and the oleine as above mentioned to fit the same for the
market.
In this modification of my process I use one-and-a-half pound of common salt
dissolved in twelve gallons of water for every hundredweight and-a-half of oil.
Having now set forth the nature of my Invention of "Improvements in the
Treatment of Vegetable Oils for the Purpose of Ageing the same," and explained the
manner of carrying the same into effect, I wish it to be understood that under the
above in part recited Letters Patent I claim,-
Subjecting linseed and rape oils while in a heated state to the action of a
precipitating solution, in the manner and for the purpose above set forth.
In witness whereof, I, the said Thomas Henry Gray, have hereunto_set my
hand and seal, the Sixth day of January, in the year of our Lord One
thousand eight hundred and eighty one.