The constituents of elaine, as determined by Chevreul, are

as follows:

1 atom oxygen,

10 atoms carbon,

9 atoms hydrogen,

as the true constitution, then we might consider it as a compound of

1 atom carbonic oxide,

1 atom of a carbo-hydrogen, composed of 9 atoms carbon
and 9 atoms hydrogen.

This would reduce the difference between stearine and elaine
to one atom less carbon and hydrogen in the carbo-hydrogen,
of which the latter is chiefly composed.

3. Cetine.

The spermaceti of commerce, from which cetine was extracted by Chevreul, always contains a yellow oil, from which it was freed in the following manner:

50 parts of spermace tifusible at 111° were triturated in 50 Preparation. parts of cold alcohol of the specific gravity 0-816, and the mixture was left for 24 hours at a temperature of about 68° and then filtered. The undissolved residue was treated with 100 parts of boiling alcohol in a flask, and the whole allowed to

Chap. III. cool. The crystals and the undissolved portion were treated with successive portions of boiling alcohol till the alcohol when evaporated ceased to exhibit any traces of oil. The residual matter was considered as pure cetine. It melted at the temperature of 120°.

Properties.

Composition.

On cooling it crystallizes in white brilliant plates. At the temperature of about 680° it may be volatilized without decomposition. It has a very slight smell, but is destitute of taste. It is insoluble in water. 100 parts of alcohol of the specific gravity 0-821 dissolve 2-5 parts of cetine, the greatest part of which is deposited as the solution cools in crystalline plates having a pearly lustre. Cetine produces no change on vegeta

ble blues.

Potash converts it into ethal and margaric and oleic acids. When heated sufficiently in an open dish it takes fire and burns like wax. Sulphuric acid gradually decomposes it when assisted by heat. The action of nitric acid on it is similar to the action of the same acid on stearic acid. The constituents of cetine, as determined by Chevreul, are as follows:

These numbers give us the atomic constitution of cetine as follows:

1. atom oxygen,

19.8 atoms carbon,

18.75 atoms hydrogen.

Perhaps we may adopt the following atoms as coming sufficiently near the result of the analysis,

1 atom carbo-hydrogen, composed of 19 atoms carbon and 19 atoms hydrogen.

Or if we consider the carbo-hydrogen as the same as exists in elaine, then cetine contains only half the oxygen that exists in elaine.

* Sur les corps gras, p. 170.

4. Phocenine.

This substance was extracted by Chevreul from the oil of the delphinus phocæna or common porpoise, in the following

manner:

Sect, VII

200 parts of porpoise oil were mixed with 180 parts of alco- Preparation. hol of the specific gravity 0·797 and slightly heated, the whole was dissolved. After 24 hours the alcohol which swam on the surface of the oil was decanted off and distilled. There remained an acid oil of the specific gravity 0-931 at the temperature of 61°. It was deprived of its acid portion, and then treated with weak cold alcohol. By this means phocenine was obtained.

It is a very fluid oil, having a specific gravity of 0.954. Its Properties. odour is slight, but peculiar, and having some resemblance to that of phocenic acid. It does not act upon vegetable colours. Alcohol dissolves it in great abundance when assisted by heat. When a dilute alcoholic solution is distilled, the phocenine remaining has acid properties; but the quantity of acid formed is very small. When 100 parts of phocenine are treated with potash, they are converted into

Chevreul found, on examining butter, that it contained two distinct oily bodies; besides a solid constituting a variety of stearine. One of these oils possessing peculiar properties, he gave it the name of butyrine. He obtained butyrine by the following process:

The butter was first freed from all traces of buttermilk. It Preparation. was then cooled very slowly in a deep porcelain dish, and kept for some days at a temperature of 66°. By degrees it separated into a granular substance, consisting of stearine, still retaining a certain portion of the two oils of butter, and a liquid consisting of the two oils, still retaining in solution a portion of stearine. This liquid portion being filtered was found to possess the following properties: Its colour was yellow, and its taste and smell similar to that of butter. At 66° its specific gravity was

* By this is meant the sweet principle of oils discovered by Scheele. + Chevreul, sur les corps gras, p. 190.

Chap. III. 0.922.

Properties.

Preparation.

It did not act upon blue vegetable colours. 100 parts of alcohol of 0.821 dissolved 6 parts of it when assisted by a boiling heat.

88 parts of this liquid oil were mixed in a flask with 88 parts of alcohol of the specific gravity 0-796. The mixture was agitated and left to digest for 24 hours in the temperature of 66°. The alcohol was drawn off after 24 hours, and replaced by 176 parts of new alcohol, which was drawn off in its turn after 21 hours, and 176 parts of new alcohol substituted. This last portion dissolved the whole, but when the alcohol was allowed to cool, a portion of oil precipitated. The alcohol was separated from the solution by a cautious distillation. The residual oil contained a little acid, which was removed by digestion with magnesia, and then washing with water. Thus purified it was butyrine in a state of purity.

Butyrine thus obtained is very fluid at 66°, and has a specific gravity of 0.908. It is usually yellow, but this colour is not essential to it, as some butters give a butyrine quite white. It has a smell similar to that of butter. It does not congeal when cooled down to 32°. It has no action on vegetable colours. It is insoluble in water, but alcohol of the specific gravity 0-822 dissolves it in any proportion whatever, at a boiling temperature. A solution of 20 parts of butyrine in 100 alcohol becomes opaque on cooling; but 120 parts of butyrine in 100 of alcohol remains transparent. When the alcoholic solution is distilled the butyrine becomes acid, a small quantity of butyric acid being developed. It is readily saponified, and by the process is converted into butyric acid, margaric acid, and oleic acid; together with about 12.5 per cent. of glycerine.

6. Hircine.

Hircine is a liquid oil, which exists in the tallow of the deer and the sheep. It is it which forms with elaine, the liquid portion of tallow. It is characterized by yielding hircic acid when saponified.*

*

7. Cholesterine.

This name has been given by Chevreul to a fatty matter like spermaceti, which constitutes the principal constituent of biliary calculi, and which Foureroy had distinguished by the name of adipocire. Cholesterine may be obtained by washing human

* Chevreul, sur les corps gras, pp. 151, 195.

biliary calculi with water, and then dissolving them in boiling Sect. VII. hot alcohol. As the solution cools the cholesterine is deposited in crystalline plates. When these are washed in alcohol, and dried, they constitute pure cholesterine.

It is solid, white, and possessed of considerable lustre. It Properties. melts when heated to 278°. When allowed to cool slowly, after being brought into a state of fusion, it crystallizes in radiating plates. It has no taste, and is almost destitute of smell. At 680° it may be volatilized without undergoing decomposition, It is insoluble in water. 100 parts of boiling alcohol of the specific gravity 0-816, dissolve 18 parts of cholesterine. But if the specific gravity of the alcohol be 0.840, it will dissolve only 11-24 of this substance. The alcoholic solutions on cooling, deposite most of the cholesterine in crystals. It has no action on vegetable blues. It gives out no water when heated with protoxide of lead. It cannot be converted into a soap, nor does it undergo any alteration when digested with potash ley. When heated sufficiently in an open dish it burns like wax. Sulphuric acid decomposes it when assisted by heat. It is also decomposed by hot nitric acid. Its constituents, as determined by the analysis of Chevreul, are as follows:

it is obvious that it cannot, like the preceding bodies, be resolved into carbonic oxide and carbo-hydrogen. But it might be resolved into

1 atom carbonic oxide,

1 atom carbo-hydrogen, consisting of 27 atoms carbon and
27 atoms hydrogen,

1 atom super-carburetted-hydrogen, consisting of 8 atoms
carbon, and 4 atoms hydrogen.

* Chevreul, sur les corps gras, p. 153.