of perfumes and as a lubricating oil. Its high price, however, excludes it from any general use, except for special purposes. Its specific gravity at 15 degrees is .916, and it absorbs about 86 percent of its weight of iodin.
Olive Oil.—By far the most important of edible oils, both on account of its abundance and of its palatability, is olive oil. Olive oil has been used from the earliest historical times and probably was the first vegetable oil that was manufactured to any considerable extent in the early history of civilization. Its qualities have maintained for it a market among the nations of the world in spite of the fact that many other palatable and wholesome vegetable oils have been produced which, while not inferior in nutritive value to olive oil, are so very much cheaper that unless the olive oil possessed peculiar properties it would be forced out of the market. Its delicate flavor, extreme palatability, high nutritive power, and other general characteristics have maintained for it a market against the strongest competition.
Olive oil is procured from the fruit of the olive tree (Olea Europæa L.), and when it is to be used for edible purposes the method of extraction is by pressure. When olive oil is used for technical purposes, such as lubricating and the manufacture of soap, it is very commonly secured by extraction with a volatile solvent, such as petroleum. The olive is very rich in oil, the quantity varying from 40 to 60 percent. The quality of olive oil upon the market varies in a very great degree according to the country from which it comes, the degree of maturity of the olive from which the oil is extracted, the method of expression employed, and the character of the refining process to which the expressed oil has been subjected. Botanically, there are very many varieties of olive trees and thus nature would impart to the olive peculiarities due to the origin of the oil itself. The environment also has a great deal to do with the character of the olive and necessarily with the character of the oil produced. The olive tree flourishes best in semi-arid regions where the rainfall is not very abundant and the sunlight is not greatly obscured by clouds and the heat is reasonably high. The principal regions, at the present time, from which the commercial olive oils are obtained are Spain, Italy, Greece, southern France, and southern California.
Adulteration of Olive Oil.—By reason of its great value as an edible oil and its high price there is no one of the edible oils which has been subjected to such a systematic and extensive adulteration. By reason of the resemblance in general character of many of the edible vegetable oils to olive oil, adulterations of the most extensive character may be practiced without indicating to the eye any change in composition. Nearly all the edible vegetable oils have the light amber tint which is characteristic of many grades of olive oil, and the difference between the color of the olive oil and other edible oils is not greater than the difference between the tints of the various olive oils themselves. The connoisseur of extremely delicate taste is usually able to distinguish by the taste any
