VOLATILE ACIDS OF BUTTER. 955 



other impurities are separated from it, and the pure oil rises to 

 the surface. It consists of margarine, oleine, butyrine, caprone, 

 and caprine. The three latter are in small quantity, but it is to 

 them, that the peculiar pleasant smell and taste of fresh butter 

 are owing. They are compounds of oxide of glyceryl (page 877) 

 with butyric, caproic and capric acids. 



Hircic acid, was discovered by Chevreul in the fat of the goat ; 

 its composition is unknown. 



Phocenic or delphinic acid, HO + C 10 H 7 O 3 (Chevreul) ; another 

 volatile acid contained in train oil or seal oil, and in the berries 

 of Viburnum opulus. Phocenic acid is a colourless liquid which 

 burns like a volatile oil; its taste is nauseous and ethereal, 

 its density 0.932 at 82.4, its boiling point above 212; it dis- 

 solves in 18 parts of water at 86. 



All these volatile acids are obtained in the same way. The fat 

 oil which they accompany is saponified by an alkali, and the soap 

 decomposed by an excess of tartaric acid, in which the volatile 

 acids are soluble, and may thus be separated from the fat insolu- 

 ble acids. The volatile acid is then converted into a salt of barytes 

 by adding barytes-water to it, and thus precipitated. The 

 barytic acid is again decomposed by phosphoric or sulphuric acid, 

 and the volatile acid thus set at liberty is rectified by the heat 

 of a water-bath ; it is then purified completely from water by 

 means of fused chloride of calcium. These volatile acids form 

 but a small proportion of the butter and oil in which they are 

 found. 



Cevadic acid exists in the fat extracted by ether from the 

 seeds of Veratrum sabadilla. It forms by distillation a sublimate 

 of white needles of a silky lustre, fusible at 68 (Pelletier and 

 Caventou.) It is named also sabadillic acid. 



Veratric acid (dried at 212) HO-j-C 18 H 9 O 7 , is obtained by 

 exhausting the seeds of cevadilla by alcohol and sulphuric acid, 

 and neutralising the alcoholic extract by hydrate of lime ; vera- 

 trine and other products precipitate, but veratric acid remains 

 in solution combined with lime, and is obtained by decomposing 

 its salt of lime with hydrochloric acid. Veratric acid forms 

 short thin quadrangular prisms, colourless and having a slightly 

 acid taste. Its solubility in cold water is small, but it is more 

 soluble in hot water, dissolves easily in hot alcohol and crystal- 

 lizes on cooling; it is insoluble in ether. The crystals lose 



