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.
Oil of cloves is used quite extensively by some car-bonators as a flavoring agent, and is by some an ingredient in imparting a delicate "bouquet," noticeable in certain brands of ginger ale. The volatile oil is obtained from bruised cloves by distilling them with water; cohobation should be repeatedly resorted to and salt may be added to raise the boiling-point. Repeated distillation, three, four or more times, may be necessary to obtain the oil. At present the distillation is usually effected with super-heated steam. Oil of clove consists of two distinct oils, light and heavy. At first the light portion of the oil comes over and floats on the water; afterwards the heavy portion distils, and the two portions united constitute the commercial article, yielding about fifteen to twenty per cent. Clove-stalks are also used sometimes in the distillation of this oil. The clove-tree is found in the West Indies, Brazil, and India.
The fresh oil of cloves is somewhat thicker than most other volatile oils and has a pale-yellow color, but is obtained colorless by rectification, and becomes thicker, darker, and finally yellowish-brown. It has a strong odor of cloves, a burning aromatic taste, and. boils at 240° 0. (455° F.). According to the National Dispensatory its specific gravity varies between 1.034 and 1.056; oil of clove stalks though agreeing in odor has a density of about 1.009. Oil of cloves dissolves freely in alcohol. Vanillin may be obtained from this oil.
"The detecting of the boiling point and the specific gravity are sufficient for detecting most adulterations to which oil of cloves is sometimes subject; on treating the suspected oil with alcoholic solution of potassa, the odor of cloves disappears and the nature of the adulteration is established. For the detection of carbolic acid, Jacquemin (1875) recommended adding a trace of aniline, shaking with water, and adding a little chlorinated soda, when a blue color will be produced. Fluckiger (1870) proposed to shake one part of oil with fifty parts of hot water; concentrate the aqueous liquid by evaporation at a moderate heat, add a drop of ammonia and a little chlorinated lime; in the presence of carbolic acid a green color, passing into blue, will be produced". - N. D. "Hot water, on being agitated with oil of cloves, should not acquire an acid reaction, and after cooling the clear filtrate should not turn blue or green on the addition of a drop of solution of ferric chloride (carbolic acid), but it should become yellow with lime-water. The oil should yield a clear solution with an equal weight or a little more of alcohol, specific gravity 0.894 (oil of turpentine, copaiva, etc.)". - P. G.
If this be required, cut one ounce of the oil in the usual manner with eight ounces of alcohol and eight ounces of water.
One pound of bruised cloves, macerated in five pints of diluted alcohol; filter.