Few articles differ more in quality than olive oil; not that the
different kinds are produced from different fruit, but in the different
stages of the pressure of the olives. Thus, by means of gentle pressure,
the best or _virgin_ oil flows first; a second, and afterwards a
third quality of oil is obtained, by moistening the residuum, breaking
the kernels, &c. and increasing the pressure. When the fruit is not
sufficiently ripe, the recent oil has a bitterish taste; and when too
ripe it is fatty. After the oil has been drawn, it deposits a white,
fibrous, and albuminous matter; but when this deposition has taken
place, if it be put into clean flasks, it undergoes no further
alteration. The common oil cannot, however, be preserved in casks above
a year and a half or two years. The consumption of olive oil as food is
not surprising if we remember, that it is the lightest and most delicate
of all the fixed oils.
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