The oil gives with sulphuric acid a yellow-red turbid solution, which becomes clear and peach-blossom red by the addition of alcohol: _Eucalyptus oil_. 2. Laevorotatory oil. The oil showing an acid reaction becomes thick in the air and has a characteristic odor: _Mint oil_. The oil shows a neutral reaction and has a camphor-like odor: _Thyme oil_. IV. The oil does not dissolve iodine, does not heat with sulphuric acid, and does not react upon nitric acid. The odor is empyreumatic: _Petroleum_. B. _The oil is specifically heavier than water._ 1. The oil shows an acid reaction. It is soluble in 30 parts of water, boils at 356° F., and smells of bitter almonds: _Oil of bitter almonds_. The oil has an agreeable, sweet odor and boils at from 392° to 431.6° F.: _Wintergreen oil_. 2. The oil shows a neutral reaction. _a._ The oil is laevorotatory. It becomes blue by the addition of sulphuric acid: _Oil of cloves_. _b._ The oil is optically inactive. The thick oil gives with sulphuric acid a turbid, black-brown fluid; the odor is agreeable: _Cinnamon oil_. _c._ The oil is dextrorotatory. The thick oil has an agreeable odor: _Sassafras oil_. CHAPTER IV. THE VOLATILE OILS USED IN PERFUMERY. The volatile oils, as previously mentioned, may be divided into three groups, viz: the pure hydrocarbons, oxygenated oils, and sulphuretted oils. Chemically, this division is, however, of little value, since, among bodies which should be classed according to it in one of the groups, combinations are found which vary very much in a chemical respect, and belong partially in the groups of alcohols, indifferent bodies, acids, etc. It is, therefore, preferred not to attempt a classification of the volatile oils according to their chemical composition, but simply to enumerate them in alphabetical order. _Acacia, oil of_, commonly called _oil of cassie_. The flowers or buds of the _acacia Farnesiana_ yield a somewhat thickly-fluid, greenish-yellow oil of a very intense but delightful odor. The oil may be obtained either by extraction or absorption. The acacia is cultivated in special plantations along the _Riviera di Genova_. These plantations being controlled by a few perfumers, the oil is not allowed to reach the market, and does not form an article of commerce. The green-colored _extrait d'acacia_ is a solution of the oil in alcohol.