PRODUCTS OF HYDROLYSIS. -17 



9'320 to 9'36"2 calories in three samples of butter, which appear 

 from the analytical results of Schweinitz and Emery to have 

 been of doubtful purity. 



The fat of milk is soluble in all hydrocarbons which are liquid 

 at the ordinary temperature, in their halogen derivatives, iu 

 ether, carbon bisulphide, nitro-benzene, and acetone. It is 

 slightly soluble in alcohol and to a considerable extent in amyl 

 alcohol when cold, but in all proportions when hot. CTlycerol, 

 when hot, dissolves it to a very small extent. It appears to mix 

 in all proportions with esters. Fatty acids have a limited solvent 

 effect, those of higher molecular weight dissolving more than 

 the lower homologues. Phenol also dissolves it to some extent. 

 On cooling a strong solution of the fat in any solvent, the portion 

 deposited has not the same composition as the original fat, but 

 is of the same nature as the solid portion obtained by slo\\' coolin;,' 

 of the melted fat. 



The molecular weight of the fat has been determined by (iaielli 

 and Carcano by Raoult's cryoscopic method in benzene solution 

 to be from 696 to 716. That calculated from the amount of alkali 

 necessary for saponification is 720 to 740. 



Products of Hydrolysis. 



Glycerol. — This is the simplest tri-hydiii- al<ohol and has 



CH.OH 



I 

 the constitution — CHOH . It was discovered by Sihcrlc ui 



I 

 CH.OH 



1779 in olive oil, and was first recognised in butter in 1784. 



The anhydrous product is a thick s\^rupy liquid, which can 

 be obtained in crystals by cooling to a low temperature ; the 

 melting point of the solid glycerol is given as 17' C. by Heuniger 

 and 2(J° C. by Nitsche. It boils at 290' C. under the ordinaiy 

 pressure, but undergoes slight decomposition ; it can be readOy 

 distilled without change under reduced pressure. It is not 

 volatile with steam. An aqueous solution containing less than 

 75 per cent, glycerol can be boiled without loss ; but fi'om solu- 

 tions coutaiuTng more than 75 per cent, glycerol it is somewhat 

 volatile (Hehner). Anhydrous glycerol volatilises slowly at 

 100° C. When heated above 150° C. it is inflammable. 



The density at ||^ is 1-2675; the refi-active index at the 



same temperature is 1-4748. 



When heated to its boiling point, especially if not pure, various 



