THE OLIVE IN NICE. 633 



escapes through the texture of the bags and runs into a receptacle un- 

 derneath, it is this first pressure which produces that which is styled 

 44 virgin oil." Afterwards the bags of said paste are removed and soaked 

 in boiling water and placed a second time under the press. The same 

 operation is a third time renewed, when all the oil is extracted. The 

 second pressing yields the ordinary oil of commerce, and the third that 

 used for illuminating purposes, and generally consumed here in prefer- 

 enee to all other oils. It is styled " huile de colza.'' 



The farmers bring their oil to market in barrels of about 200 pounds 

 weight, or retain it in their cellars in earthen jars, glazed 'within, and 

 guarded from dust by wooden covers. Merchants keep it in large, 

 deep, cemented tanks, over which their warehouses are built, thus pro- 

 viding an even temperature. 



From these tanks the oil is drawn by pumps for the process of filtra- 

 tion and bottling for sale. The filter consists of a series of boxes, one 

 above the other, with perforated bottoms, and lined with layers, about 

 an inch in thickness, of white cotton-wool. 



Adulteration of oil. That the adulteration of the olive oil, notwith- 

 standing the severe penalties of the law therefor, is to some extent 

 practiced is undoubted, The fraud is accomplished by mixing with 

 the genuine the oil of the oleaginous seeds of cotton, sesamum, and 

 others. Immediate discovery of the imposition appears impossible, al- 

 though much study has been given to the matter. Densities, degree 

 of congelation, refraction, specific weight, and all other chemical prop- 

 erties must be taken into consideration, which is a labor of hours. 

 The following process of detection is generally used: In the trial tube 

 is placed 0.3086 grains of dried albumen, to which is added 30.864 

 grains of nitric acid, and an equal weight of oil. The tube is then 

 heated over an alcohol lamp and its contents mixed by ebullition. The 

 operation affords the following tests: (1) If the oil be genuine olive 

 the color will be of a yellow feebly greenish tint; (2) if the olive has 

 been mixed with 5 per cent, of seed-oil the color will be of an amber 

 yellow tint; (3) the tint of the mixture will deepen down to a deep or- 

 ange in proportion to the amount of the foreign oil. 



Insect pests. The special dangers to which the olive trees are ex- 

 posed are frost, wind, hail, and the ;< dacus." When a tree has been 

 caught by too low a temperature it seldom resists the frost. The loss in 

 Provence from this cause, in the year 1830, was ruinous to many pro- 

 prietors, and amounted to 4,000,000 francs. When the tree is but 

 partially frozen it can be saved by pruning, but when leaves and 

 branches are entirely frozen there is no remedy. A violent wind 

 brings down the fruit pell-mell, ripe or green, according to the season. 

 The hail cuts and bruises it as well as beats it from the branches. Such 

 fruit becomes mingled with the soil and more or less decayed, and pro- 

 duces an oil moldy in savor, disagreeable to the taste, and improper to 

 trade. The dacns, the chief enemy of the olive, appears in the mouth of 

 August, as soon as the fruit begins to ripen. The little insect destroys 



