FAT OF COCHINEAL INSECT. 141 



totally solidified at 110. 100 parts of boiling alcohol of the spe- 

 cific gravity 0-834 dissolve 2-9 parts of it. It is not so easily 

 saponified as the cetin of the macrocephalus, furnishes less ethal, 

 and a greater quantity of fatty acids. The ethal from this oil 

 melts at 1 16J, while that from the macrocephalus melts at 1 18 J. 

 The oil from which this cetin has been deposited is perfectly 

 liquid at 68, and at 59 resembles butter. Its specific gravity 

 is 0-924 ; 100 parts of alcohol of 0-820 dissolve 149.4 parts of 

 it before beginning to boil. By saponification, 100 parts of this 

 oil give 66 parts of margaric and oleic acids, along with which 

 are 14-3 of a fat not saponifiable, and similar to ethal, only more 

 fusible, and in fact composed of two fats, of which one melts at 

 80J , and the other at 95. They may be separated from the 

 fatty acids by the same means as those employed to isolate the 

 ethal. The saponification produces also 15 parts of glycerin, 

 and a considerable quantity of phocenic acid. 



12. FAT OF COCCUS CACTI OR COCHINEAL INSECT. 



In the year 1818, MM. Pelletier and Caventou made a set of 

 experiments on the fat of this insect* It was extracted by them 

 by means of ether, which forms with it a yellow solution ; the 

 ether being evaporated away, the fat remains. To obtain from 

 it a colourless stearin, we must dissolve it repeatedly in water, 

 and crystallize it. The crystals are white pearly plates. This 

 stearin melts at 104, and is but little soluble in cold alcohol. 

 When we distil off the alcohol, a little solid fat separates, and 

 there remains an elain, which continues liquid at 32, and which 

 is coloured yellowish-red by the colouring matter of the cochi- 

 neal insect. It still retains a small quantity of stearin in solu- 

 tion. This elain is easily saponified. It gives fatty acids, and a 

 volatile odorous]acid. The Coccus polonicus contains more fat than 

 the Coccus cacti Two specimens of it, the one moist and the 

 other dry, were examined by Berzelius, who found the acids 

 which they yielded similar to those in butter. f 



All these fatty or oily substances from animals, and many 

 others which have not hitherto been examined, are divisible into 

 two distinct substances, the one solid and called stearin, the other 

 liquid at the common temperature of the atmosphere, and called 



* Ann. de Chim. et de Phys. viii. 270. 

 f Traite de Chimie, vii. 551. 



