in flaxseed oil, namely, linolein. When prepared for edible purposes it contains only a small quantity of free acid, is free from rancidity, clear, and brilliant in appearance and has a sweet agreeable taste. The specific gravity of sesamé oil at 15 degrees C. varics from .9225 to .9237. It absorbs from 103 to 108 percent of its weight of iodin and has a refractive index at 15 degrees of about 1.4748.

Adulteration of Sesame Oil.-Some of the other vegetable oils are cheaper than sesamé and are added to it for the purpose of adulteration and cheapening the product. Among the most common oils used for the adulteration of sesamé are poppyseed oil, cottonseed oil, and rape oil. The presence of cottonseed oil in sesame oil is easily distinguished by the Halphen test already given. The presence of poppyseed oil is revealed by the high iodin number and the high degree of heat produced when mixed with sulfuric acid.

Only the best variety of cold-drawn sesamé oil is used for edible purposes and for making oleomargarine. The inferior qualities are used in soap making, the making of perfumes, etc., and the lowest quality of oil is used for burning purposes.

Characteristic Reaction.—A test which is known as Baudouin's is extremely delicate and reliable and is easily applied. It consists in the development of a red color when a small quantity of sesame oil is treated with hydrochloric acid in the presence of furfural. The test is easily carried out as follows: Place a few drops of a two percent solution of furfural in a test-tube with 10 cubic centimeters of sesamé oil or the oil to be tested for sesamé and 10 cubic centimeters of hydrochloric acid of 1.19 specific gravity, and shake the mixture well for half a minute. When the tube is left at rest, if sesamé oil be present the aqueous acid layer which forms will have a distinct crimson color. Any coloration which is produced by other oils is entirely distinct from this one and therefore can be easily distinguished.

Geographical Distribution. The sesamé plant is grown chiefly for commercial purposes in India, China, Japan, and West Africa. The technical preparation of the oil, in so far as is known, is not practiced in the United States. It is pressed and prepared for commerce chiefly in France. The seeds are rich in oil, yielding a larger percentage by pressure or extraction than most of the oil-bearing seeds.

Sunflower Oil.-The oil extracted from the seed of the sunflower is of high quality for edible purposes. Although not in general use in this country, it is very extensively used in Russia and some other parts of Europe. There is every reason to believe that a profitable industry could be established in the preparation of edible oils from sunflower seeds. The plant grows in the greatest luxuriance in nearly all parts of the country, and the yield is sufficiently great to make it an object of more interest to our agricultural population than it is at the present time.

The oil is obtained from the seed of the sunflower (Helianthus annuus L.). It is of a pure amber tint with an agreeable odor and pleasant taste. As has already been said it is grown largely in Russia and also in Indo-China. The seeds are very rich in oil. Before expression the hulls should be removed, since these form a porous substance, and if the seeds are crushed with the hulls large quantities of oil are absorbed and cannot be recovered.

The method of preparation is the same as that for other edible oils, the kernel, after the removal of the hull, being ground and cold-pressed for the highest grade. By heating and renewing pressure lower grades of oil are secured suitable for soap making. Where all the oil is required the extraction with bisulfid of carbon or gasoline is advised. Such oils, however, are not suitable for edible purposes because of the difficulty of removing the last traces of the solvent. The specific gravity of sunflower oil at 15 degrees is approximately .925. It absorbs a very high percentage of iodin, and in this respect it may be classified with the drying oils. Its iodin number ranges from 120 to 130. No specific color reactions have been established by means of which sunflower oil may be readily distinguished from the other edible oils. In fact sunflower oil has not been subjected, by any means, to as critical a study as many other vegetable oils.

VEGETABLE FATS.

The fatty principles in vegetables which are solid at ordinary temperatures are commonly termed fats instead of oils. They present, as a rule, a soft mass, usually of an amber tint and somewhat of the consistence of butter. Only a few of these solid fats or semi-solid fats are used for food. Among them the most important are palm-nut oil or coconut oil or fat, though the fat of the cacao also may be regarded as belonging to this group. These solid or semisolid fats are used to a considerable extent for edible purposes in many parts of the world. Coconut fat and cacao fat are used very extensively in this country either in a pure state or in chocolate or cocoa.

Cacao Butter.-Cacao butter is the semi-solid fat obtained by pressure from cacao beans, the seeds of the cacao tree (Theobroma cacao L.). These beans are extremely rich in fat, the content of which varies from 35 to 50 percent. On a large scale the cacao beans are roasted, ground, and the fat expressed while still hot by hydraulic pressure. In order to remove the free acid which it contains the carbonates of the alkalies are mixed with the material after grinding and before extraction. In these cases the expressed fat naturally does not contain any free acid, though the soaps which are formed by this process are apt to contaminate the expressed fat.

Adulterations. By reason of its high price cacao butter is often adulterated by the addition of various fats usually of a vegetable character. Those most generally employed are the stearin derived from the coconut fat and the palm

COCONUT OIL OR BUTTER.

4II

nut fat. The addition of ordinary edible vegetable oils is easily detected by the usual chemical tests and is especially recognized by the increase in the percentage of iodin absorbed. They also reduce the melting point of cacao butter, and for this reason these oils, with the exception of coconut, are not used very extensively as adulterants. Beeswax and paraffine wax are also used to some extent as adulterants, and when used in connection with vegetable oils they serve to keep the melting point from going too low. Tallow has also been used quite extensively as an adulterant. The detection of these adulterants is so difficult as to be accomplished only by a skilled chemist..

Composition. Cacao butter is composed chiefly of stearin and palmitin, though other fats and oils are present in small quantities. Although it is generally supposed that cacao butter does not tend to become rancid, this is a mistake, since, when exposed to the conditions which favor rancidity, the fermentation which produces this condition takes place in the butter, though somewhat more slowly and more incompletely than in many other fats. The specific gravity of cacao butter at 50 degrees C. is .892. It absorbs about 35 percent of its weight of iodin. It has a much lower melting point than palm fats and even lower than butter. Its melting point varies from 30 to 33 degrees C. Cacao butter has some of the properties of ordinary butter and has been recommended as a substitute therefor, but it is not likely that it will ever come into common use both because it is less desirable than butter and also because of its high price.

Properties.-Cacao butter has a light amber tint and tends to become bleached on long standing. It has a very pleasant flavor, reminding one of the flavor of the preparations of chocolate. At ordinary temperature, 70 degrees F., it is quite solid and sometimes even brittle.

Coconut Oil or Butter. This is a very abundant natural fat and is obtained from the kernel of the coconut, especially the two species Cocos nucifera L. and Cocos butyracea L. At ordinary temperature coconut oil is of the consistency of fat. Its taste is pleasant, and it possesses an odor which is not disagreeable or undesirable. It differs from cacao butter in the ease with which it becomes rancid, at which time it takes on a very disagreeable flavor and taste. The coconut oil of commerce is distinguished by different names, according to the country in which it is made.

Cochin oil is a variety which is regarded as of the finest quality, being almost colorless, and is prepared in Malabar.

Ceylon oil is another very important variety made in the neighborhood of and imported from Ceylon. It is regarded as of somewhat inferior variety to Cochin oil, due probably to less care taken in the cultivation of the plant and the preparation of the oil.

Another variety of coconut oil is known as copra oil. The term "copra” is applied to the sun-dried or kiln-dried kernel of the coconut. In this dried

state the fruit can be shipped in bulk and large quantities of it can be sent to Europe or other countries, where the oil is either obtained by extraction or by compression in a hydraulic press. This is regarded as of the least desirable. quality.

Coconut oil resembles palm-nut oil in its chemical composition, with the exception of the relative porportion of palmitic acid. The specific gravity of coconut oil or fat at 40 degrees C. is about .912 and reduced to 15 degrees C. about .925. Coconut oil absorbs very little iodin, which is one of its principal characteristic chemical properties. The quantity of iodin absorbed may be taken as about eight percent of the weight of the oil. Coconut oil is one of the vegetable fats which resembles butter to some extent in the high content of volatile acid which it contains. If, under given conditions, butter may be regarded as having a volatile acid number of 27, coconut oil will have upon the same scale a volatile acid number of about 7, whereas ordinary vegetable oils and fats will have less than 0.5 on a similar scale. Coconut oil may be regarded as the one edible oil which approximates in constitution ordinary butter. Coconut oil has been used very extensively as an adulterant for oleomargarine, since by reason of its high volatile acid it brings that substance much nearer to the composition of butter or indicates a larger percentage of butter therein than is actually present. While it is used extensively as human food its principal value is for soap making. It appears as an edible fat under various names, such as "vegetable butter," "lactine," "nucoline," "palmin," etc. Coconut oil is also very extensively used in the manufacture of candies and confections. Adulterations.-Coconut oil is rarely adulterated. About the only adulteration of any consequence is that of the admixture with palm-kernel oil, which has properties very much like that of coconut oil. These two oils are ordinarily about the same price and therefore there is no inducement to practice adulteration.

Palm Oil or Fat.-This oil is obtained from the fleshy part of the fruit of the palm tree Elais Guineensis Jacq. and Elais melanococca Gaertn. Extensive groves of these trees are found in Africa and also in the Philippines. In Africa they grow particularly upon the western coast. There is a large number of varieties of palm trees that afford this fat, but the two mentioned are the principal ones. This fat becomes solid at about the temperature of the body. It has a somewhat higher melting point than butter, which becomes liquid at a temperature of from 34 to 36 degrees C. When once solid the fat may be heated to 41 or 42 degrees before it again becomes liquid. Palm oil has rather a pleasant taste and is regarded as an edible fat of high quality, and is largely used as such by Europeans and in Africa and other countries where the fat is produced. The fat also has a very pleasant odor which is said to resemble somewhat that of violets. This pleasant odor is quite persistent and remains even in the fatty acids after they have been converted into

THE ACORN.

413 soap. Palm oil is manufactured in the crudest possible way by the natives, and immense quantities are lost for this reason. By reason of this crude method, which leaves the oil in contact with the putrescible matter, palm oil often comes into the market in a rancid state or at least with a high content of free fatty acid. Appreciable quantities of water are also found in the crude article.

Inasmuch as the natural color of palm oil is somewhat too deep for the taste of the ordinary consumer, ranging from yellow to a dirty red color, it is often bleached in the refining process before being sent into commerce. Ordinary exposure to the air tends to bleach this oil, due probably to the bleaching properties which the air sometimes possesses. Ozone is also employed as a bleaching agent. The bichromate process of bleaching palm oil is very commonly practiced. By this method the oil is freed from its principal impurities and treated with from one to three percent of potassium bichromate and with hydrochloric acid which decomposes the "chrome" liquor, and in the chemical process which attends this reaction decided bleaching effects are produced. The bleaching agents are withdrawn and the oil thoroughly washed with water until all traces of chromate and mineral acid are removed.

Adulterations.-On account of its great cheapness and the fact that the admixture of other oils of lower melting point would detract from its value, palm oil has not been subjected to any extensive adulteration. The most common adulterations are the impurities which are left in the oil in the slovenly method of manufacture employed by the natives of Africa.

Constituents. As would be expected from the name, one of the chief constituents of palm oil is palmitin. If palm oil is saponified and the solid separated from the liquid fatty acid, the former is found to consist almost exclusively of palmitic acid. The specific gravity of palm oil is taken at a high temperature, as much as 50 degrees C. or above. The specific gravity at this temperature is about .893. Palm oil absorbs a little over one half its weight of iodin. The average iodin number may be regarded as varying from 53 to 55. Aside from the limited use of palm oil for human food it is used chiefly in the manufacture of soap and of candles. It is also used extensively in the tin plate industry to spread over the hot iron surface to preserve it from oxidation until it is dipped into the bath of melted tin.

NUTS.

All of

The Acorn.-Many varieties of acorns are used for human food. the nuts of the oak family are edible, but some of the larger and more common varieties contain such a quantity of tannin as to be rather bitter to the taste. The wild acorns were formerly utilized very extensively for the fattening of swine, producing an article of pork of high palatable value but with