SECT. XIII. OILS. 423 



and opaque, and assumes a white colour and a re- 

 semblance to fat. This is in consequence of the 

 absorption of oxygene ; but owing to the appearance 

 of a quantity of water, in oil that is exposed to the 

 action of the air, it has been thought that the oxy- 

 gene absorbed by it is not yet perhaps assimilated 

 to its substance. When exposed to cold it congeals 

 and crystallizes, or assumes a solid and granular 

 form ; but not till the thermometer has indicated 

 a degree considerably below the freezing point. 

 When exposed to the action of heat it is not vola- 

 tilized till it begins to boil, which is at 60O of 

 Fahrenheit. By distillation it is converted into 

 water, carbonic acid, and carburetted hydrogene 

 gas, and charcoal ; the product of its^combustion is 

 nearly the same ; and hence it is a compound of 

 carbon, oxygene, and hydrogene. 



Fixed oils are generally divided into two sorts Genera, 

 fat oils, and drying oils. The former are readily 

 inspissated by the action of the air, and converted 

 into a sort of fat. The latter are capable of being 

 dried by the action of the air, and converted into a 

 firm and transparent substance. 



The principal species of fat oils are the following : Fat oils, 

 1st, Olive oil, which is expressed from the, pulpy 

 part of the fruit of Olea europea or the Olive, a 

 shrub that grows naturally in the South of Europe. 

 The fruit is first broken in a mill, and reduced to a 

 sort of paste. It is then subjected to the action of 

 a press, and the oil which is now easily separated 



