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PROCESS TOR PURIFYING OILS AND GREASE. 
Galipoli, Spanish, Portugal, Sicily, and such like qualtities 
of olive oils. It is well known that these oils, when applied 
in their impure state to the working parts of machinery, 
quickly become glutinous, act injuriously upon the brass- 
work, and impede the proper working of the machine. This 
effect is produced by the action of the air upon the impu- 
rities contained in the oil, when the oil is exposed in small 
quantities. To remove this hurtful matter, the oil, when 
heated to about 90° or thereabouts, is treated with a strong 
solution of potash or soda, either in the state of a carbonate, 
or made caustic by lime. The use of the alkali, in a caustic 
state, is generally preferred, in consequence of its producing 
less effervescence in the oil, and the operation being more 
quickly finished than when the carbonates of either of the 
above alkalies are made use of. The specific gravity of the 
alkali solution may be 1.2, or even stronger. During the 
time that the alkali is being added, the oil is to be kept in 
a constant state of agitation to cause a thorough mixing. In 
order to ascertain when the operation is completed, and a 
sufficiency of the solution is added, the following test may 
be used: Put a small portion into a glass bottle, or any 
other convenient vessel, and add to it a solution of the alkali 
in excess. Shake it well, and then allow it to remain at 
rest for a quarter of an hour, or until the alkali has settled 
to the bottom of the vessel. Should the alkali settle quite 
clear, without causing a thick deposit to take place, the oil 
is sufficiently refined; if it does not remain clear, but carries 
down with it a thick soapy matter, more alkali is added to 
the oil under operation, until, on further trial, this effect 
takes place. The quantity of alkali required will depend 
entirely upon the quality of the olive oil operated upon. In 
practice it will be found that some qualities require as much 
as S per cent, of solution of specific gravity 1.2, while other 
qualities do not require more than 3k per cent. When the 
above operation is completed, the oil is allowed to remain 
at rest for twenty-four hours, or until such time as the thick 
