CHAP. VII.] THE CONNECTIVE TISSUES. 263 



Its melting-point varies, like that of stearin, according to its treat^ 

 ment ; the temperature at which it solidifies, after being melted, is 

 said to be 45 C. 



Margarin a From a mixture of stearin and palmitin, crystals 



mixture of often separate which consist of a mixture or perhaps of 

 stearin and a combination of stearin and palmitin, but which were 

 formerly supposed to be a special fat to which the 

 name of Margarin was given and which was supposed to be a glycerin 

 ether of margaric acid (C J7 H 34 2 ). 



The crystals which form not unfrequently in fat cells were 

 formerly supposed to consist of this compound. 



FIG. 51. CRYSTALS OF THE SO-CALLED MARGARIN. 



a. single needles. &. larger groups, c. crystals within fat cells, d. a fat cell con- 

 taining no crystals. (Funke.) 



Olein or Triolein. C S H 5 (0 . C 18 H 33 0) 3 . 



This neutral fat is obtained in a state of comparative purity from 

 the more liquid fats by exposing them to a temperature of C. and 

 then subjecting to pressure ; the liquid portion expressed consists of 

 olein. 



When pure, olein is a colourless oil which is fluid at ordinary tem- 

 peratures and which solidifies when the temperature falls below C. 

 When exposed to air olein absorbs oxygen, and in doing so it acquires 

 a faint yellow colour. 



It dissolves all the solid fats, especially at a temperature of 30 0. 

 Olein is easily soluble in cold absolute alcohol or in ether. 



Glycerin. C 3 H 6 (OH) 3 . 



Mode of As has been already stated, when the neutral fats 



froTSe 1011 are saponified, glycerin is set free. If the neutral 

 neutral fats. fats be boiled with litharge and water, the fatty acids are 

 all thrown down as insoluble lead soaps, and glycerin 

 dissolves in the water. By passing a stream of sulphuretted hydrogen, 

 it is freed from dissolved lead, and on filtering and evaporating the 



