Gerhardt and Cahours on the JEthereal Oils. 189 



a product is also obtained which is probably tereben, but mixed 

 with a large quantity of colophen. Chloride of colophen is 

 cryslallizable. Formula is probably C 40 H 64 CI 8 . Colophen 

 also combines with hydrochloric acid, but the compound is 

 decomposed by treatment with carbonate of lime, &c. &c. — 

 {Annates de Chimie et de Phys., t. lxxv. p. 37.) 



On the JEthereal Oils. By Gerhardt and Cahours. 



iEthereal oils are mixtures of two substances, a hydrocarbon 

 and a peculiar oil containing oxygen. The hydrocarbon may 

 be driven off by distillation, but cannot thus be obtained pure; 

 this is only effected by means of fused potassa. By the action 

 of this substance on the oil, the hydrocarbon is separated, and 

 the peculiar oil, which was combined with the hydrocarbon, 

 is converted into an acid. By thus treating Roman caraway 

 oil {Cuminum Cyminum), cuminic acid is obtained; from oil of 

 valerian {Valeriana officinalis) and Roman oil of camomile 

 (Anthemis fiobilis), valerianic acid is obtained. The hydro- 

 carbons contained in these twolast-mentioned oils are different ; 

 that from oil of valerian is true camphogen, and oxidizes in 

 the air with great rapidity, forming camphor. The hydro- 

 carbon from caraway oil is called cymen ; the body, which is 

 changed into an acid by means of potassa, is cuminol. 



Cuminol may be obtained by distilling oil of caraway at a 

 temperature of 200° ; cymen mixed with cuminol passes over, 

 and cuminol remains behind, which may then be distilled in 

 an atmosphere of carbonic acid. Its formula is C 20 H 24 O 2 ; 

 sp. gr. of the vapour 5*24, according to calculation 5'094. It 

 is colourless, boils at 220°, absorbs oxygen and becomes acid ; 

 this change takes place more rapidly when a base is present to 

 saturate the so-formed acid. By means of bichromate of po- 

 tassa and sulphuric acid, it is also converted into cuminic acid. 

 Aqueous chlorine acts in the same manner, also strong nitric 

 acid. Cuminic acid is best obtained by dropping the oil into 

 fused potassa, the mass is then dissolved in water and preci- 

 pitated by nitric acid. Cuminic acid is white, crystallizable, 

 sublimes in beautiful needles, melts at 92°, boils at 250° ; for- 

 mula C 20 H 24 O 4 . By the action of potassa on cuminol, two 

 atoms of water are decomposed, hydrogen is set free, and two 

 atoms of oxygen taken up for the formation of cuminic acid ; 

 almost insoluble in cold water; somewhat soluble in dilute 

 acids; easily soluble in alcohol and aether. The silver salt 

 has the formula C 20 H 22 O 3 , Ag O. By heating this salt a 

 carburet of silver, Ag C, is obtained. Cuminic aether is ob- 

 tained by saturating an alcoholic solution of cuminic acid with 

 hydrochloric acid, heating and distilling over oxide of lead. 



