IMPROVEMENTS IN THE MODE OF AND APPARATUS FOR REFINING OR PURIFYING OILS
Year: 1872

page_text: LETTERS PATENT to Thomas M°Micking Wilson, of Bergen, in the
Kingdom of Norway, but at present residing at Arundel Hotel,
Arundel Street, in the City of Westminster, Engineer, for the
Invention of "IMPROVEMENTS IN THE MODE OF AND APPARATUS FOR
REFINING OR PURIFYING OILS."
Sealed the 2nd August 1872, and dated the 12th February 1872.
PROVISIONAL SPECIFICATION left by the said Thomas McMicking
Wilson at the Office of the Commissioners of Patents, with his
Petition, on the 12th February 1872.
I, THOMAS MOMICKING WILSON, of Bergen, in the Kingdom of Nor-
way, but at present residing at Arundel Hotel, Arundel Street, in the
City of Westminster, Engineer, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN THE MODE OF AND APPARATUS FOR
REFINING OR PURIFYING OILS," to be as follows:-
The object of this Invention is the refining or purifying of oils so as
to render them, when thick and opaque owing to the presence of solid

page_text: matters, such as spermaceti, stearine, and margarin, fluid and clear.
These solid matters are crystallizable, and it is their crystallization in
a manner that will allow of their separation from the oil by filtration, on
which my Invention is based. This result I attain by two operations
which I denominate, 1st, the cooling operation, and 2nd, the filtering
operation.
The operative details of the Invention are as follows:-
The semi-fluid oil is first to be heated until the solid matters are
melted. The temperature at which this takes place is to be carefully
noted. The oil is now to be allowed to cool to a point about 8° or 10°
Fahr. below the melting point, and the cooling then stopped for a
sufficient length of time to allow the solid matters to precipitate. When
this is effected the cooling is to be allowed to proceed naturally. The
retarding of the cooling is effected by the application to the oil of a
steady heat maintained at the desired temperature.
The method which I recommend as being the most economical and at
the same time giving the most command in the regulation of a specified
temperature is to conduct the cooling operation in a building supplied
with a ventilating and heating apparatus such as is used for heating
drying stoves. Failing this I consider a steam coil in the tanks
is best.
For reasons which will be apparent when the filtering operation is
described, the cooling of the oil must take place in tanks to which the
filter can be attached, so that the oil is not required to undergo any
manipulation between the processes.
The filtering operation I conduct on what may be called the principle
of ascension in contradistinction to the ordinary mode of filtering by
gravitation. When the cooling operation is completed I fix a few inches
below the top of the tank containing the oil, and resting on a ledge pre-
pared to receive it, a stout frame covered with strong coarse wire cloth or
netting, on the under side of which is stretched the filtering cloth. I
then admit water at the bottom of the tank supplied by a force pump or
from a considerable height so as to have the means of pressure at
command. The oil and solid matters float on the water, and as the water
is admitted are lifted and pressed against the filter cloth; the oil is then
forced through it, appearing on the upper side clear and fit to be run

page_text: into the casks. The clear oil passes through without any considerable
obstruction until the solid matters come into contact with the filter,
when the operation proceeds more slowly and with increasing difficulty.
I therefore recommend that for a short time the operation should be
conducted with as little pressure as possible to allow of the water
passing up between the crystals before the mass becomes too much
consolidated by pressure, and afterwards at the full pressure. In this
way the apparatus can be used up to a certain moderate extent of pres-
sure as a press, and the operation of separation is thereby rendered very
effective.
When the operation is completed the solid matters are found con-
solidated into a firm cake adhering to the filter. The fluid oil being now
all run off from the upper side of the filter the water supply is to be
closed, and the water in the tank allowed to escape.
As it escapes a
vacuum is formed and the cake is thereby detached from the filter cloth,
which is left perfectly clear and ready for future use. The filter frame
is now to be taken off and the cake removed from the tank. It should
next be subjected to pressure in a powerful press, as this improves its
quality and expels the last traces of fluid oil or water. It can then
if desirable be melted and formed in moulds for sale.
In some cases I propose to mix with the oil when run into the coolers
a portion of some chemical salt that is free from alkaline reaction on
the oil that has a specific gravity greater than water and that is easily
soluble in water. Of the many salts possessing these properties in a
greater or lesser degree I prefer ground alum. When the oil in the
cooling tanks is at the melting point I stir into it a portion of ground
alum, which has the effect of greatly promoting crystallization, owing to
the alum particles forming a basis for crystallization to take place on,
and by its greater specific gravity it causes the solid matters to precipitate
more quickly and effectually. The alum is taken up by the solid com-
position; therefore to recover it it is necessary to melt the composition
in a suitable vessel, and when melted stir in hot water sufficient to
dissolve out the alum.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thomas McMicking Wilson in the Great Seal
Patent Office on the 12th August 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
McMICKING WILSON, of Bergen, in the Kingdom of Norway, but at
present residing at Arundel Hotel, Arundel Street, in the City of West-
minster, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twelfth day of February, in the
year of our Lord One thousand eight hundred and seventy-two, in
the thirty-fifth year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said Thomas M*Micking
Wilson, Her special licence that I, the said Thomas McMicking
Wilson, my executors, administrators, and assigns, or such others as
I, the said Thomas McMicking Wilson, my executors, adminis-
trators, and assigns, should at any time agree with, and no others,
from time to time and at all times thereafter during the term therein
expressed, should and lawfully might make, use, exercise, and vend,
within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN THE MODE
OF AND APPARATUS FOR REFINING OR PURIFYING OILS," upon the condition
(amongst others) that I, the said Thomas MMicking Wilson, my
executors or administrators, by an instrument in writing under my,
or their, or one of their hands and seals, should particularly describe
and ascertain the nature of the said Invention, and in what manner
the same was to be performed, and cause the same to be filed in the
Great Seal Patent Office within six calendar months next and imme-
diately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Thomas M'Micking Wilson,
do hereby declare the nature of my said Invention, and in what manner
the same is to be performed, to be particularly described and ascertained
in and by the following statement, reference being had to the Drawing
hereunto annexed, and to the letters and figures marked thereon (that
is to say) :-

page_text: render them, when thick and opaque owing to the presence of solid
matters, such as spermaceti, stearine, margarin, fluid and clear, thereby
increasing their commercial value.
The rationale of the process by which the desired object is attained is
very simple, and is derived from careful observation of certain properties
or qualities possessed by the oils upon which this Invention is intended
to operate. It is well known that the want of fluidity and transparency
in such oils is caused by the presence of certain matters derived from the
same sources as the oils themselves, but which, unlike the oils, have the
property of solidifying at ordinary temperatures, but melting at tempera-
tures ranging from about ninety degrees to one hundred and forty-five
degrees Fahrenheit. These substances are generally spermaceti, stearine,
or margarin, either singly or in combination. They are when in bulk
very valuable commercial products, yet they have the effect of decreasing
the value of oils in which they appear. It is therefore evident that if
the solid matters can be extracted by suitable means from semi-fluid
oils without injury or loss of raw material, such oils would be rendered
fluid and clear, and consequently more valuable, and that the extracted
matter would also be a valuable product. This being the case, it of
course follows that the most profitable way of dealing with such oils is to
refine them into two products, viz., fluid oil or olein, and a solid substance
or composition.
This Invention provides, first, a cheaply worked yet efficient process
by which the above object can be attained, and, second, apparatus by
which the process can be carried into effect. Filtering at once suggests
itself as the readiest way of separating solid and fluid matters, but the
experienced oil refiner knows that filtering oils as hitherto conducted is
an impracticable process on a large scale. It is therefore rarely
attempted, and when a separation is wanted between an oil and a solid
fat or grease the usual treatment is to put the oil or fat in bags, and
subject it to powerful pressure. This, although effectual, is a very slow,
troublesome, and expensive process.
When semi-fluid oils are sufficiently heated they become clear and
transparent, but when they cool they resume their former objectionable
state. An observation of this property shews, first, that at a certain
temperature the oils are fluid and clear, but below this temperature they
become more or less thick and opaque. Second, that this temperature
differs in different oils, and is dependent on the nature of the solid

page_text: substances. These substances melt at various temperatures, and an
observation of the melting point is therefore a very good guide to a
determination of the solid matters present in the oils. Experiment
shews that the specific gravity of the solid matters is slightly greater
than that of the fluid. It therefore follows that the solid matters should
precipitate and leave the oil fluid and clear; but this does not in fact
take place, therefore a counteracting influence must be at work. Careful
observation of the oils whilst cooling gives the clue to this counteracting
take place, therefore a counteracting influence must be at work. Careful
observation of the oils whilst cooling gives the clue to this counteracting
influence.
Observation shews, first, that the solid matters do not resolve them-
selves into a uniform semi-fluid grease as might from appearances be
supposed, but on the contrary they have the property of crystallizing
like salts, and are therefore present in the semi-fluid oil as a mass of
pasty soft crystallized matter; second, in crystallizing the crystals
absorb what may be called oil of crystallization, hence their soft and
pasty quality; third, the counteracting influence which prevents the
solid matters precipitating is to be found in the soft pasty nature of the
crystals, combined with the very slight difference in the specific gravity
between the solid and fluid matters; fourth, the difference in the
specific gravity being so small the time occupied by the natural cooling
of the oil is too short to admit of precipitation of the solid matters before
the oil has entirely cooled, and the crystals have been fully formed;
fifth, when the crystallization is completed precipitation of the solid
matters is impossible, because the difference in the specific gravity is too
small to counteract the soft pastiness of the crystals, and these therefore
remain as it were built up on each other in the body of the oil, and
thereby cause the objectionable qualities of semi-fluidity and opaqueness.
This crystaline theory is very clearly proved by the following experi-
ment: Take a small portion of the semi-fluid oil in a clear glass bottle,
add two or three times the bulk of ether. The ether dissolves the
adherent fluid oil leaving the crystals free, so that they can easily be
seen floating about independently of each other. Allow the bottle to
remain at rest for an hour, and it will then be seen that the crystals have
precipitated. Pour off the ether and take the sediment in a cloth, press
it between folds of blotting paper until it has become a cake hard enough
to be handled; break the cake across, and the sides of the fracture will
shew a beautiful crystaline formation. When the experiment is well
conducted the crystals are bright like salt or sugar crystals. It evidently

page_text: follows from these observations that if the semi-fluid oils are heated
beyond the melting point of their solid matters they will become fluid
and clear; but if they are then allowed to cool to a point a little below
the melting point of the solid matters, and the cooling is then arrested
and maintained at that point for a sufficient length of time, the solid
matters will precipitate and leave the fluid oil clear. Experiment shews
conclusively that this is the case, and that the process gives besides
other advantages, as it is found that under this treatment the crystals
form larger than when allowed to form in the ordinary way; the pre-
cipitated matter is also deposited in an increasing ratio of density, which
is most advantageous for the next process of filtering, as conducted on
the system and in the apparatus hereafter described.
My improved process for extracting solid crystallizable substances, such
as spermaceti, stearine, and magarin, from oils or fats in which they
appear, consists therefore of two operations which I denominate, first, the
cooling operation, and, second, the filtering operation. In addition to
these I recommend that the extracted solid substance be submitted to
severe pressure by any of the known appliances in order to improve the
quality, and at the same time expel the last traces of fluid.
The operative details of the Invention are as follows:-
The Cooling Operation.-The semi-fluid oil is first to be heated until
the solid matters are melted. The temperature at which this takes place
is to be carefully noted. The oil is now to be allowed to cool to a point
about eight degrees or ten degrees Fahrenheit below the melting point,
and the cooling is then to be arrested for a sufficient length of time to
allow the solid matters to precipitate. When this is effected the cooling
is to be allowed to proceed naturally. When cold the oil is ready for the
next operation of filtering, which must be effected by the system here-
after described. It is evident that the retarding of the cooling is to be
effected by the application of a steady heat, maintained at the desired
temperature, and that there are many ways by which this can be
effected.
The method which I recommend as being the most economical and at
the same time giving the most command in the regulation of a specified
temperature is to conduct the cooling operation in a building supplied
with a ventilating and heating apparatus such as is used for heating

page_text: HESI CORsider a steam con in the tanks
is best.
For reasons which will be apparent when the filtering operation is
described the cooling of the oil must take place in tanks to which the
filter can be attached, so that the oil is not required to undergo any
manipulation between the processes.
The Filtering Operation.-This I conduct on what may be called the
principle of ascension, in contradistinction to the ordinary mode of
filtering by gravitation. When the cooling operation is completed I fix
a few inches below the top of the tank, resting on a ledge prepared to
receive it, a stout frame covered with strong coarse wire cloth or netting.
On the under side of this I stretch the filtering material, which must be
of some moderately close textile fabric. I then admit water at the
bottom of the tank, supplied by a force pump or from a considerable
height, so as to have the means of pressure at command. The oil and
solid matters float on the water, and as the water is admitted are lifted
and pressed against the filter, then the oil is pressed through it, appearing
on the upper side clear and ready to be run into the casks. The clear
oil passes through without any considerable obstruction until the solid
matters come into contact with the filtering surface, when the operation
proceeds slower and with increasing difficulty as it proceeds. I recom-
mend that for a short time the operation should be conducted with as
little pressure as possible to allow of the water passing up between the
crystals of solid matter before the mass becomes too much consolidated
by pressure. The water is now to be admitted at the full pressure, and
by a well-known hydrostatic law it exerts over the whole surface of the
filter a pressure per square inch equal to the pressure per square inch at
which it is admitted. In this way this machine can be used up to a
certain moderate extent of pressure as a press, and the operation of
separation is thereby rendered very effectual.
When the operation is completed the solid matters will be found to
have consolidated into a firm cake, which adheres to the filter. The fluid
oil being now all drawn off from the upper side of the filter the water
supply is to be closed, and the water in the tank discharged. As it
escapes a vacuum will be formed below the filter frame, the effect of
which will be to detach the cake from the filter, when it will fall to the
bottom of the tank, and leaving the filter perfectly clear and ready for
use on another occasion. The filter frame is now to be taken off, and

page_text: the cake removed and subjected to pressure in a powerful press to expel
the last traces of fluid oil or water. The cake can then, if desired, be
melted and formed in moulds for sale.
In the accompanying Drawing Fig. 1 shews the filtering apparatus in
longitudinal sectional elevation; Fig. 2 is an elevation of the same; and
Fig. 3 is a plan view of the filtering frame detached.
A, A, is a tank of galvanized iron six feet long, two and three-quarter
feet broad, and four feet deep, and is capable of filtering fourteen barrels
at one operation; B, B, is a ledge or rim of angle iron fitted water-tight
all round the inside of the tank, six inches from the top. It supports
the filtering frame when in use, and should be slightly inclined towards
the outlet D so as to drain the filter well. This ledge is provided with
numerous upright screw bolts fitted with nuts for ensuring the firm
attachment of the filtering frame thereto; a packing of felt or other
thick woollen material is placed between the ledge and the filtering frame,
its use being to prevent the escape of any unfiltered oil round the edges
of the frame while the filtering is proceeding; D is the outlet by which
the filtered oil is drawn off, and for convenience should be provided with
a stop-cock; E is the water supply pipe fitted with a stop-cock, and
communicating with a cistern placed about thirty feet above the tank or
with a force pump, so as to ensure a considerable pressure; H is a
branch pipe with its end turned downwards leading from the water
supply pipe E between the stop-cock and the tank. On this branch pipe
is fitted a safety escape valve, which gives the means of regulating the
water pressure inside the tank, as desired. This pipe also serves to dis-
charge the water from the tank at the end of a filtering operation; F is
a glass window or gauge about six or eight inches long, by two inches
broad, of strong plate glass, fitted in the end of the tank just under the
ledge B. Its use is to allow the state of the contents of the tank to be
ascertained towards the end of a filtering operation; C, C, is the filtering
frame, covered with coarse wirecloth or netting to support the filtering
fabric. For convenience in lifting out and in it is provided with handles
as at C, C. If desired, the tank can also be fitted with a coil of steam
pipe running along the foot of it and passing from side to side. In this
case the coil can serve the purpose of melting the oils as well as cooling
them; but for many reasons its use is not so desirable as conducting the
operation in a heated room, and having a separate apparatus to melt
the oils.

page_text: Should a steam coil be used the tank should be six inches deeper, so
as to admit of a layer of water surrounding the steam coil without
detracting from the filtering capacity of the tank. It is of considerable
advantage to convey the heat of the steam pipe in this manner instead of
allowing the oil to come into direct contact with it.
The filtering operation is effected in the above-described apparatus
with great expedition, and it has in conjunction with the cooling opera-
tion several great advantages, viz., the oil requires no manipulation from
the time it is poured into the tank to cool till it is drawn off ready for
market. The filtering operation itself proceeds quickly, owing to the
cooling operation having caused the solid matters to precipitate and form
large crystals. Up to a certain extent this apparatus can be used as a
press as well as a filter. It is self-cleaning, and the textile fabric used
is as clean at the end of an operation as it was at the beginning, which
is a great saving of expense for renewing filters. It will now be seen
that this refining process is, besides being a very effective one, conducted
at a minimum of labour and expense.
The following is a process intended to supplement the cooling opera-
tion. It is however not essential to that operation, but its use is in all
cases advantageous, and in some cases particularly so. It consists in
mixing with the oil when run into the coolers a portion of some
chemical salt possessing certain necessary properties, and in a state
of fine powder. The salts' necessary properties are, first, that it
admits of reduction to fine powder; second, that it is free from alka-
line reaction on the oil; third, that its specific gravity is greater than
water; fourth, that it is easily soluble in water. Many salts possess
these properties in a greater or lesser degree; but none to such a degree
and at so low a cost as common alum. Alum has also the great
advantage that it can be purchased ready for use as an article of trade
in the form of ground alum. I therefore recommend that when the oil
in the cooling tanks is at the melting point a portion of ground alum
should be stirred up along with it. This has the effect of greatly pro-
moting crystallization, owing to the alum particles forming a basis for
crystallization to take place on, and by its greater specific gravity it
causes the solid matters to precipitate more quickly and effectually. The
alum is taken up by the solid composition, therefore to recover it it is
necessary to melt the composition in a suitable vessel, and when melted
to stir in hot water sufficient to dissolve out the alum. Boiling water

page_text: dissolves about half its own weight of alum. The alum is dissolved, and
the composition floats on the water and can be drawn off to cool. This
process entails additional labour and expense, and therefore, although
possessing advantages, but not essential to the success of the cooling
operation, its adoption is a matter for individual opinion and calculation
of profits or loss. It is scarcely necessary to add that the salt used must
be perfectly insoluble in oils or fats.
Having now set forth the nature of my Invention of "Improvements
in the Mode of and Apparatus for Refining or Purifying Oils," 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,
the extraction from oils of the solid crystallizable matters contained
therein, by the means and for the purpose above set forth.
In witness whereof, I, the said Thomas McMicking Wilson, have
hereunto set my hand and seal, the Fifth day of August,
in the year of our Lord One thousand eight hundred and
seventy-two.