264 POPULAR ECONOMIC BOTANY. 



factured. The imports in 1851 were 4902 tons, almost 

 the whole of which came from Manilla and Ceylon. 

 The fluid oils used in manufacturing processes are — 

 Olive Oil — expressed, or otherwise obtained, from the 

 fruit of the common Olive (Olea Europaa, Nat. Ord. Olea- 

 cea). (Plate IY. fig, 16.) 



The olive had already been described in the chapter on 

 fruits, therefore the oil now only remains to be described. 

 It is a fine thin fluid, varying in colour from a light green to 

 a pale straw-colour ; when exposed to a temperature but 

 little below the average in this country, its stearine sepa- 

 rates and falls down in white flocculent masses; and the 

 whole of it congeals at the freezing-point of water. It is 

 generally obtained by expression in a rude mill, consisting 

 of a large conical mass of stone with an axis of wood, to 

 which a horse is attached. The pressing stone revolves 

 upon a circular stone platform, around which is cut a small 

 groove ; as the olives are crushed, the oil runs into the groove, 

 from which it is conducted into vessels placed to receive it. 

 It varies very much in quality, from the fine Lucca Oil 

 used in salads, to the almost rancid Spanish kinds, which 

 are used for oiling machinery. The chief use of olive oil is 

 in dressing woollen cloths. We receive it in great quantities 



