On account of its high price, ambergris is frequently adulterated, the commercial article being often nothing but an artificial mixture of benzoin, olibanum, wax, and flour, with other substances, perfumed with musk. Such adulterations are detected by the appearance, proportions of solubility, nature of the fracture and the content of ash. A small quantity of pure ambergris, exposed to heat, melts without forming bubbles or scum. It is easily punctured with a heated needle, which, when withdrawn, should come out clean and without anything adhering to it, and the characteristic odor of ambergris should be immediately evolved. The surface should be rugged, that with a smooth and uniform surface being generally factitious. In perfumery, ambergris is not so much used on account of its agreeable odor, but rather to make the perfumes more constant. CHAPTER VII. ARTIFICIAL PERFUME-MATERIALS. In speaking of the volatile oils used in perfumery, two artificial perfume-materials, artificial oils of bitter almonds and wintergreen have already been mentioned. There can be no doubt that when the chemical construction of volatile oils is better known, chemistry will succeed in preparing still more such combinations, valuable for perfumery, or in converting cheap volatile oils into more valuable ones, as has, for instance, been done by Bouchardat and Lafont, who have successfully converted oil of turpentine into oil of lemons. These chemists rectified French oil of turpentine at exactly 311° to 314.6° F., dissolved in the distillate, which amounted to 120 grammes, an equal quantity (120 grammes) of glacial acetic acid, cooled the mixture and then carefully added, so that the temperature never exceeded 104° F., 88 grammes of crystallized chromic acid dissolved in a sufficient quantity of acetic acid. Notwithstanding that the greater portion of the oil of turpentine remained unoxidized, a thorough reaction took place, and the product of decomposition proved to be a hydrocarbon, boiling at from 345.2° to 352.4° F., to which Bouchardat and Lafont have applied the term "terpilene." The properties of this hydrocarbon, especially its boiling point, corresponded with those of oil of lemons, its odor also resembling that of the latter, but it contained about one-sixth cymol which it was impossible to remove. Though thus far this artificial oil of lemons is of no importance for perfumery, it is of interest as showing the possibility of converting one volatile oil into another. The artificial musk, spoken of under "Musk," cannot be classed with the previously-mentioned artificial perfumed-materials. The odoriferous principle of the natural and artificial musk have nothing in common, the odor depending not on a common chemical combination.