ACROLE1NE. !)6!> 



volume of cold water, and left at rest for twenty-four hours, the 

 sulpholeic and sulphomargaric acids being insoluble in dilute 

 sulphuric come in the form of a syrup to the surface of the 

 liquor, while the sulphate of glycerin remains in the strongly 

 acid liquid below. After the mixture of sulpholeic and sulpho- 

 margaric acids is washed with a little water, it is dissolved 

 entirely in a large quantity of water. The solution has an acid 

 and fatty taste, with a bitter after-taste, may be neutralised by 

 an alkali without decomposition, and the salt thus formed occa- 

 sions in metallic solutions precipitates insoluble in water, and 

 slightly soluble in alcohol. 



Left to itself, the mixture of sulpholeic and sulphomargaric 

 acid undergoes decomposition ; when the solution is made to 

 boil, the decomposition is instantaneous. The sulphuric acid then 

 separates from the elements of the oleic andmargaric acids, and 

 these last are themselves transformed into new acids; the marga- 

 ric acid yielding metamargaric acid and hydromargaritic acid, the 

 oleic acid, metoleic acid and hydroleic acid. A compound of 

 hydromargaritic and metamargaric acid, which has the properties 

 of a single acid, has been named hydromargaric acid, by Fremy. 

 These compounds are oily bodies insoluble in water, of which 

 those related to margaric acid are solid, and those related to 

 oleic acid liquid at ordinary temperatures. These acids have 

 been also examined by Varrentrapp and by Mr. Miller, but 

 their composition is still involved in considerable uncer- 

 tainty. 



When metoleic and hydroleic acids are distilled, they are 

 decomposed and resolved into two hydrocarbons of the olefiant 

 gas type ; elaene, C 18 H 18 , a white substance, boiling at 230, and 

 oleiine, C 12 H 12 , a colourless ethereal liquid. Elaene combines 

 with chlorine, with the evolution of hydrochloric acid, and 

 forms an oily compound (Fremy). 



ACROLEINE. 



Oils and fats boil at a high temperature, giving off carbonic 

 acid with a little inflammable gas, and a substance possessed of a 

 most pungent odour, which attacks the eyes most painfully, 

 and is named acroleine. The pure oily acids do not yield this 

 substance, but only their compounds with oxide of glyceryl, 



