36 Memoir on the Nature of fat Substances. 



below zero, were treated as above ; and yielded : yellow oil 76 ; 

 very white suet 24. 



The above suet resembles the rest in its colour and con- 

 sistence ; but it is distinguished from them by its extreme fusibi- 

 lity ; for it melts at 5^ of Reaumur, and freezes again on the 

 temperature I)eing lowered. This suet, whicli is so fusible, is 

 transformed by the action of potash into oil, and into an adipo- 

 cire which melts at 45^ only ; which is very remarkable. The 

 oil of sweet almonds deprived of its suet resists the greatest cold 

 without losing its fluidity. 



Oil of Colsa. 

 By exposing this oil to the freezing temperature, and even 

 above it, a part of its solid matter is separated from it in the form 

 of round globules ; it is a mistake in Fourcroy to allege that it 

 is less capable of freezing than oil of sweet almonds, since the 

 latter require^ at least 7'' or S' below zero. At —3'^ R. the oil of 

 colsa goes into a mass much .*irmer than melted butter, and of 

 the yellow colour of wax. 100 parts of this substance, pressed 

 at the same temperature in gray paper, vielded : 



Oil of a fine yellow 54 



Suet, very white . • . 46 



100 

 This suet obtained after the first pressure had still a slight 

 yellowish tinge ; but when pressed a second time, after having 

 been melted, and then frozen at the temperature of 2° R. a bril- 

 liant white was obtained : it is inodorous, not very sapid, and af- 

 fects a spherical crystallization; it, is a little less fusible than the 

 suet of oil of sweet almonds, and melts at 6° R. Its chemical 

 characters seem to distinguish it from the other suets ; for, rn-- 

 stead of being converted into adipocire and oil by the action of 

 the acids, it only yields a thick and thready mass Hke turpentine: 

 time produces nearly the same effects as the acids on these oils. 

 The oil of colsa, deprived of its solid matter, is no longer sus- 

 ceptible of freezing : it merely jiossesscs the colour, smell, and 

 taste, which we recognise in the oil of colsa of commerce. 



The experiments just detailed on the fat principles, authorize 

 us to think that all the rest are similarlv composed of fluid oil 

 and a solid substance which we find even in the oils which have 

 the least disposition to freeze, as recent linseed oil, which depo- 

 sits during a cold niQ;ht very regular conical crvstals, as observed 

 by Professor Goettling. Most of the volatile oils also contain 

 concrete crystallizable substances, sometimes analogous to cani- 

 „phor : hence it would seem that camphor is to the volatile oils 

 what suet is to fat. Certain volatile oils, however, seem to con- 

 tain 



