DAIRY PRODUCTS. 73 



pie or violet blue coloration. 1 This reaction is characteristic of crude cotton-seed oil. 

 The coloring matter causes crude cotton-seed oil to produce stains, and hence is re- 

 moved by a process of refining. This is usually effected by agitating the crude oil 

 at the ordinary temperature with 10 to 15 per cent, of solution of caustic soda of 1.060 

 specific gravity, when the alkali combines with the coloring matter and saponifies a 

 portion of the oil. The mixture becomes filled with black flocks which deposit on. 

 standing- and leave the oil but slightly colored. The loss in refining is usually from 

 4 to 7 per cent., but occasionally amounts to 12 or 15. Hence it is desirable, before 

 purchasing crude cotton-seed oil for refining, to ascertain, by a laboratory experiment, 

 what the percentage of loss is likely to bo. Frequently the treatment with alkali is 

 only carried far enough to remove the majoi part of the coloring matter, the oil being 

 then boiled with a solution of bleaching powder, and subsequently treated with di- 

 lute sulphuric acid. 3 



Refined cotton-seed oil is of a etraw or golden-yellow color, or, occasionaly, nearly 

 colorless. The density ranges from .922 to .926, and the solidifying point from 1 to 

 10 C. By subjection to cold and pressure a certain proportion of stearine is separated, 

 the melting point of the residual oil being correspondingly lowered. Refined cotton- 

 seed oil is usually very free from acid, and when properly prepared is of pleasant 

 taste and admirably adapted for edible and culinary purposes, for which it is now 

 extensively employed, both with and without its nature being acknowledged. It is 

 now substituted for olive oil in some of the liniments of the United States Pharma- 

 copeia, but its principal applications are in soap making and .the manufacture of fac- 

 titious butter. 



ESTIMATION OF SALT. 



The method employed in this laboratory since 1883 has continued to 

 give satisfaction, and can be recommended as the best in use. 



From 10 to 20 grams of the well-mixed butter or butter substitute 

 are placed in a separatory bulb provided with a closely fitting glass 

 stopper. Add 25 to 50cc. hot distilled water, and after shaking well al- 

 low to stand for a few minutes. The water, which has dissolved most 

 of the salt, is now drawn off through the stoppered tube of the appa- 

 ratus. Fresh hot water is added and this operation repeated until the 



1 " Cotton-seed blue " is stated by Kuhhnaun to have the composition of CnE^Ai. 

 It is amorphous, readily destroyed by oxidizing agents, insoluble in water, diluted 

 acids, and alkalies, sparingly soluble in carbon disulphide and chloroform, but more 

 readily in alcohol and ether, and dissolves with purple color in strong sulphuric acid. 

 The unoxidized coloring matter of cotton-seed oil has been recently examined by J. 

 Longmore, who, in a communication to the author, states that it is a pungent golden- 

 yellow product, insoluble in water, but soluble in alcohol and alkaline solutions, and 

 precipitated from the latter on addition of acids. It dyes well and perfectly fast on 

 both wool and silk. 



3 The deposit thus formed, consisting of coloring and albuminous matters, alkali, 

 and partially saponified oil, is technically called "mucilage." It is decomposed with 

 a gi'ight excess of acid, and the resulting dark-colored grease is heated to a tempera- 

 ture of 120 C. (=250F.) with concentrated sulphuric acid, which renders insoluble 

 the coloring matters, &c., while the impure fatty acids rise to the surface. On distil- 

 ling these with superheated steam, a mixture of fatty acids is obtained, which is sep- 

 arated into stearic and oleic acids by pressure. The " cotton-seed stearine" thus ob- 

 tained is employed for making soap and composite candles, as also for adulterating 

 tallow, &c. 



3 This method of treatment is economical, but causes the oil to acquire an unpleas- 

 ant taste and smell, which cannot be removed. 



