This section is from the book "A Treatise On Beverages or The Complete Practical Bottler", by Charles Herman Sulz. Also available from Amazon: A Treatise On Beverages.
It is the aromatic principle of all wines. By repeated distillation of wine, after Liebig and Pelouze, a very small quantity of an intensely odorous oil is obtained, about one part of oil from 40,000 parts of wine. In larger quantities it is obtained by diluting lees of wine with some water, adding one pint of sulphuric acid to 100 pounds of lees, and distilling and introducing direct steam. A weak vinous liquid is received, upon which drops of black colored oil are distinguishable; the liquid furnishes by rectification another portion of oil. 2500 pounds of lees furnish about one pint of oil. By a repeated distillation the wine oil becomes colorless. It consists, after Liebig, Pelouze and others, of free oenanthic acid and ethylether; after Besanez, ether of cap-rylic acid. Its specific gravity is said to be 0.862. It has a vinous odor, sharp), disagreeable taste, easily soluble in ether, alcohol and very diluted alcohol.
Owing to the high price of this oil, it is most invariably adulterated. An admixture of alcohol is detected by the addition of some olive oil, when the alcohol will be separated.
From the grapes (berries, husk, stalk and kernels) an oil is obtained by distillation, that is frequently mistaken for wine or cognac oil, and even sold as such. The grape oil has a greenish color, but is colorless when rectified. It represents the perfume - the bouquet - of the respective grapes from which it was distilled. It is used in manufacturing artificial wines.
The most cognac oil of commerce is an artificial product. It is obtained by etherification of the volatile acids of the cocoanut oil. This artificial product is very similar to the real product, the difference being only that the artificial product has, in its undiluted state, a less penetrating and disagreeable odor, rather an aroma resembling that of pineapples.
Melted cocoa-nut oil is saponified with caustic soda, the resulting soap is decomposed by sulphuric acid, and by introducing steam vapor distilled - when principally capronic and caprylic acid will be received and separate as an oily mass on the surface of the water. The oil is separated from the water, and with alcohol and sulphuric acid etherificated - distilled when the ether will separate from the received distillate, like oil is separated - washed with water, then with a solution of carbonate of soda, and finally rectified by steam. A modified process on a small scale is said to be the following: Take oil of cocoanut melted, sixteen ounces; sulphuric acid, eight fluid ounces; mix; and when cool, add alcohol, sixteen fluid ounces. Then distil. This product does not compare with the one obtained by the former process.