_To make Oil of Sweet Almonds._
It is usually made from bitter almonds for cheapness, or from old Jordan almonds, by heat, the oil from which soon grows rank, while that from fresh Barbary almonds, drawn cold, will keep good for some time. The almonds are sometimes blanched by dipping in boiling water, or by soaking some hours in cold water, so as to part with their skin easily, but are more usually ground to a paste, which is put into canvas bags, and pressed between iron plates in a screw press, or by means of a wedge, 1 cwt. of bitter almonds, unblanched, produces 46 lbs. of oil; the cake pays for pressing.
Is obtained from the kernel of the hazelnut, and is very fine. As it will keep better than that of almonds, it has been proposed to be substituted for that oil. It is drunk with tea in China, probably in lieu of cream, and is used by painters, as a superior vehicle for their colors.
_Oil of Mace._
Is obtained from nutmegs by the press. It is buttery, having the smell and color of mace, but grows paler and harder by age; 2 lbs. of nutmegs in Europe will yield 6 oz. of this oil.
_True Oil of Mace by Expression._
This oil is red, remains always liquid or soft, has a strong smell of mace, subacid taste, and is imported in jars or bottles, the lower part being rather thicker than the top; 1 1/2 lbs. of mace will yield in Europe 1 1/2 oz. troy of oil.
_Olive, Salad, or Sweet Oil._
This is the most agreeable of all the oils; it is demulcent, emollient, gently laxative, and is also used as an emetic with warm water; dose, 1 oz. troy, or a large spoonful; also externally, when warm, to the bites of serpents, and, when cold, to tumors and dropsies. Rank oil is best for plasters, but fresh oil makes the best hard soap.
Is made by pressing the beans, cold or slightly warmed. It may be rendered colorless and odorless by filtering through animal charcoal and magnesia. It is soluble in strong alcohol, and is used as the basis of many hairoils. (See PERFUMERY.)
_Oil of Croton._
This oil is extracted from Molucca grains, or purging nuts. In its chemical qualities it agrees with castor oil, but is considerably more active, as a single drop, when the oil is genuine, is a powerful cathartic.
This is made from rape-seed. It dries slowly and makes but a softish soap, fit for ointments. The mucilage it contains may be got rid of, in a great measure, by adding 1/2 ounce of oil of vitriol to 2 pts. of the oil.
_To Purify Rape Oil._
The following is a simple method of rendering rape oil equal to spermaceti oil, for the purposes of illumination:
Begin by washing the oil with spring-water; whicb is effected by agitating the oil violently with a sixth part of the water. This separates the particles of the oil, and mixes those of the water intimately with them. After this operation it looks like the yolk of eggs beat up. In less than 48 hours they separate completely, the oil swimming at the top, the water, with all feculent and extraneous particles, subsiding to the bottom. This may be very much improved, by substituting sea water in the place of fresh-water.
By the process of washing the oil does not lose a hundredth part. The experiment can at all times be made in a glass decanter, or in a churn, with a cock at the bottom, the water to come up very near to the cock, by which all the oil can be drawn off, after it has deposited its impurities.
To 100 parts of oil add 1 1/2 or 2 of concentrated sulphuric acid, and mix the whole well by agitation; when the oil will become turbid, and of a blackish-green color. In about three-quarters of an hour the coloring matter will begin to collect in clots; the agitation should then be discontinued, and clean water, twice the weight of the sulphuric acid, be added. To mix the water with the oil and acid, a further agitation of half an hour will be requisite. The mass may, afterwards, be left to clarify for 8 days, at the end of which time 3 separate fluids will be perceived in the vessel; the upper is the clear oil, the next is the sulphuric acid and water, and the lowest a black mud or fecula. Let the oil then be separated by a syphon from the acid and water, and filtrated through cotton or wool. It will be nearly without color, smell, or taste, and will burn clearly and quietly to the last drop.
_To Purify Vegetable Oil._
To 100 lbs. of oil add 25 oz. of alum, and mix, dissolved in 9 lbs. of boiling water. After stirring it about half an hour, add 15 oz. of nitric acid, still continuing to stir it. Let it stand 48 hours, when the fine oil will swim on the surface, and then draw it off. Such oil is used all over the Continent, and an equal quantity yields double the light of whale and fish-oil without its offensive odor.
_To make Pumpkin Oil._
From the seeds of the pumpkin, which are generally thrown away, an abundance of an excellent oil may be extracted. When peeled they yield much more oil than an equal quantity of flax. This oil burns well, gives a lively light, lasts longer than other oils, and emits very little smoke. It has been used on the Continent for frying fish, etc. The cake remaining after the extraction of the oil may be given to cattle, who eat it with avidity.
_Beech Nut Oil._
Beech-nuts are not only an excellent food for pigs, but they are known to yield an oil, fit for common purposes, by the usual methods of extraction.
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