Pure oil of mirbane is pale yellow, the finest qualities being colorless and almost as clear as water. It has an agreeable odor resembling that of oil of bitter almonds, a specific gravity of 1.186 to 1.2 = 25° Bé., and congeals at 37.4° F. to a crystalline mass. It is scarcely soluble in water, sparingly so in alcohol and with difficulty in watery spirit of wine; it is miscible in all proportions with ether, benzine, volatile oils, and most fat oils.
Oil of mirbane is largely manufactured in England, but the German product is now generally preferred, it being purer and does not impart to soap perfumed with it a yellowish tinge. The finest oil of mirbane is prepared from pure crystallizable benzol, and again purified by washing with potassium bichromate and sulphuric acid, and by rectification with steam.
Pure nitrobenzol suffers no change by boiling with soda lye, while the poorly rectified product colors the lye yellow or brown.
Nitrobenzol is frequently adulterated with spirit of wine, which is recognized by shaking the oil with fat oil of almonds; in the presence of spirit of wine a turbid mixture is formed. By shaking nitrobenzol containing spirit of wine with an equal volume of water in a graduated cylinder, its volume decreases.
Oil of mirbane is much used for perfuming soaps, but even the finest quality of it cannot replace oil of bitter almonds for fine soaps and perfumery. Great care has to be exercised in storing, as well as in working, nitrobenzol, it igniting very readily, and it is also poisonous. Even the vapors, when inhaled for some time, may produce symptoms of poisoning, which consist in the skin acquiring a leaden color, and heavy feelings in the limbs with cold extremities, especially the hands and feet.
FRUIT ETHERS. At the London Exhibition, in 1851, various products called apple oil, pear oil, pine-apple oil, etc., were shown. They were examined by A. W. Hofmann, and found to consist of solutions of certain ethers in alcohol. Since then the manufacture has greatly increased and large quantities are now brought into commerce under the name of _fruit ethers_ or _fruit essences_.
Fruit ethers are fluids possessing an agreeable, refreshing odor closely resembling that of some fruits. For this reason they are used in confectionery, in the manufacture of liqueurs and also as a substitute for volatile oils, in the manufacture of perfumery. Chemically, fruit ethers are combinations of an organic acid--acetic, butyric, valerianic, etc.--with a so-called alcohol radicle, such as ethyl and amyl. The preparation of fruit ethers being connected with many difficulties, is seldom attempted by perfumers, especially as products of an excellent quality can at a low rate be procured from chemical laboratories making a specialty of their manufacture. However, for the sake of completeness, a brief description of the fabrication of the principal ethers used in their preparation shall here be given.