ETHAL. 879 



consistence of a syrup in prismatic needles or colourless plates, 

 which are insoluble in alcohol and ether. The salt of lead has 

 a composition analogous to that of lime. The solutions of both 

 of these salts are decomposed by ebullition, and resolved into 

 insoluble sulphates and hydrated oxide of glyceryl. 



M. Liebig makes the remark that oxide of glyceryl probably 

 exists in nature combined with other acids besides those of the 

 fats. Thus a benzoate of oxide of glyceryl would possess the 

 same composition as picrotoxin ; mannite even might be an 

 oxide of glyceryl. (Traite, I. 602.) 



CHAPTER VIII. 



ETHAL, AND THE CETYL SERIES OF COMPOUNDS. 



Spermaceti differs from th6 other natural fats in affording a 

 peculiar substance, first observed by Chevreul, instead of 

 glycerin, when saponified by an alkali. This substance was 

 named ethal* by MM. Dumas and Peligot, who consider it the 

 alcohol of a new series of compounds, of which the radical is 

 cetyl 5 or ethal is the hydrate of oxide of cetyl. 



Formula of cetyl C 32 H 33 =Ct. Has not been isolated. 



Hydrate of oxide of cetyl, ethal ; C 32 H 33 O + HO. To liberate 

 ethal from spermaceti, the latter is digested with an equal 

 weight of hydrate of potash dissolved in 2 parts of water, at a 

 temperature not exceeding 200 for several days. The soap 

 thus formed which consists of oleate and margarate of potash 

 with ethal, is then decomposed by dilute sulphuric acid, which 

 gives a fatty mass, composed of the oily acids and ethal in a 

 state of mixture and not of combination ; it is washed well with 

 boiling water, and then boiled with barytes water in excess, 

 which forms insoluble soaps with the oleic and margaric acids;, 

 and ethal is dissolved out by means of cold alcohol, which is 

 afterwards distilled off. The ethal is dissolved in ether, to 

 separate a trace of adhering barytic salts. 



* A word formed of the first syllables of ether and alcohol. 



