446 OILS 



latter purposes. The oil is subjected to cold, when it principally solidifies ; the 

 portion, however, which still remains liquid is poured off from the solid portion. A 

 piece of sheet-lead, or some shot, are then placed in it, and it is exposed in a corked 

 phial to the action of sunshine. A white matter gradually separates, after which the 

 oil becomes clear and colourless, and is fit for use. Some oil prepared by this pro- 

 cess kept its consistence very well for four or five years while in a stoppered bottle, 

 but when exposed to the atmosphere it began to thicken, and did not answer so well 

 as was expected by the watchmaker who tried it, from its appearance before exposure 

 to the air. 



The principal object in the process appears to be to get as pure oleine as possible, 

 but the purer the oleine the more likely is it to become thick. According to 

 Kerwych, oleine of singular beauty may be obtained by mixing two parts of olive oil 

 with one part of caustic soda-lye, and macerating the mixture for twenty -four hours 

 with frequent agitation. Weak alcohol must then be poured into it, to dissolve the 

 margarine soap, whereby the oleine, which remains unsaponified, is separated, and 

 floats on the surface of the liquid. This being drawn off, a fresh quantity of spirit is 

 added, till the separation of the oleine be complete. 



It has a slightly yellowish tint, which may be removed by digesting with a little 

 animal charcoal in a warm place for twenty-four hours. By subsequent filtration, 

 the oleine is obtained limpid and colourless, and of such quality that it does not 

 thicken with the greatest cold, nor does it affect either iron or copper instruments 

 immersed in it. There are four different kinds of olive oil known in the districts 

 where it is prepared : 1. Virgin oil ; 2. Ordinary oil (huile ordinaire) ; 3, Oil of the 

 infernal regions (huile d'enfer) ; 4. Oil prepared by fermentation. 



1. Virgin oil. In the district Montpellier they apply the term virgin oil to that 

 which spontaneously separates from the paste of crushed olives. This oil is not met 

 with in commerce, being all used by the inhabitants of the district, either as an 

 emollient remedy, or for oiling the works of watches. In the district of Aix they 

 give the name virgin oil to that which is first obtained from the olives ground to a 

 paste in a mill, and submitted to a slight pressure two or three days after collecting 

 the fruit. Thus, there is no virgin oil brought from Montpellier, but a good deal of 

 it is brought from Aix. 



2. Ordinary oil. In the district of Montpellier, this oil is prepared by pressing the 

 olives, previously crushed and mixed with boiling water. At Aix, the ordinary oil is 

 made from the olives which have been used for obtaining the virgin oil. The paste, 

 which has been previously pressed, is broken up, a certain quantity of boiling water 

 is poured over it, and it is then again submitted to the press. By this second ex- 

 pression, in which more pressure is applied than in the previous one, an oil is ob- 

 tained somewhat inferior in quality to the_ virgin oil. The oil is separated from the 

 water in a few hours after the operation. 



3. Oil of the infernal regions (huile <? enfer). The water which has been employed 

 in the preceding operation is, in some districts, conducted into large reservoirs, 

 called the infernal regions, where it is left for many days. During this period, any 

 oil that might have remained mixed with the water separates, and collects on the 

 surface. This oil being very inferior in quality, is only fit for burning in lamps, for 

 which it answers very well. It is sometimes called lamp oil. 



4. Fermented oil (huile fermentee). This is obtained in the two above-named dis- 

 tricts, by leaving the fresh olives in heaps for some time, and pouring boiling water 

 over them before pressing the oil. But this method is very seldom put in practice, 

 for the olives during the fermentation lose their peculiar flavour, become much 

 heated, and acquire a musty taste, which is communicated to the oil. 



The fruity flavour of the oil depends upon the quality of the olives from which it 

 has been pressed, and not upon the method adopted in its preparation. 



When olive oil is mixed with nitrous acid or nitrate of mercury, it solidifies after 

 some time, and forms a solid fat, of a light yellow colour, which is called elaidine. It 

 is the oleine of the oil that is affected, and appears to undergo a molecular change, for 

 the elaidine is said to have the same ultimate composition as oleine itself. 



Olive oil is used as food and in salads, hence it is often called salad oil. 



Oil of Almonds. The tree (Amygdalus communis) which yields the almond is & 

 native of Syria and Barbary, but is now abundant throughout the south of Europe, 

 and grows even in England, though here the fruit seldom ripens. The oil is ob- 

 tained by expression from the bitter or sweet almonds, but most generally from the 

 former, from the fact of their being cheaper, and the residual cake being more 

 valuable, yielding by distillation with water the essential oil of almonds ; when the 

 presence of water is carefully avoided, the oil obtained from them is quite as good as 

 that obtained from the sweet almonds ; but when water is present with th almonds, 

 as would be the case if they were deprived cf their skins by maceration in water, the 



