Storax is the most fragrant of all the balsams. It is afforded by the styrax officinalis, a tree which grows in the Levant. It is sometimes in red tears. Common storax is in large cakes, and brittle and soft to the touch. This is more fragrant than the other sort, but is frequently adulterated with saw-dust. It is soluble in alcohol, and is said to yield some benzoic acid.
Styrax is a different substance; a semi-liquid juice obtained from the liquidambar styraciflua. Its odour is less agreeable than that of storax calamite. It is used in odoriferous fire, in pastes, in the composition for scented vases, and the like.
Sect. XVIII. Of Essential Oils.
Essential or volatile oils, as well as the raspings of red cedar, dried rosemary, and other fragrant plants, are all used in the preparation of odoriferous fire. In some preparations, the oil of roses is employed; in others, the essence of bergamot, of lemon, &c. which, being very volatile, evaporate in a moderate heat, and, being also inflammable, may assist in the combustion. In the case of the raspings of cedar in particular, it also communicates a peculiar appearance to the flame.
Oils, whether essential or fixed, when passed through ignited tubes, are decomposed, and furnish an inflammable gas called olefiant gas. Wax, tallow, &c. produce the same gas, the hydroguret of carbon. Messrs. Taylor and Martineau contrived an ingenious apparatus for generating gas from oil on the great scale, as a substitute for candles, lamps, and coal gas, it being much preferable for burning, as it contains no sulphur, and does not injure furniture, books, plate, paint, &c. Oil gas contains more hydroguret of carbon than coal gas, which is a great advantage, enabling one cubic foot of oil gas to go as far as four of coal gas. An elegant apparatus was erected by Taylor and Martineau at the Apothecaries' Hall, London, a drawing of which may be seen in the 15th number of the "Journal of Science and the Arts."
It is to be observed, that odoriferous fire-works are intended for exhibition in close apartments; so that the smell of certain gases, produced by the nitre, charcoal, and sulphur, according to the preparation used, will be more or less destroyed. Such preparations are, nevertheless, expensive, and for that reason seldom used.
Sect. XIX. Of Mastich.
This resin, obtained, from the pistacia lentiscus, by making transverse incisions in the tree, is first in a fluid state, and gradually concretes into yellowish semi-transparent brittle grains. In Turkey, great quantities of it are used for sweetening the breath, and strengthening the gums. It is from the use of the resin as a masticatory, that its name is said to be derived. It is not completely soluble in alcohol, a soft elastic substance separating from the solution. When exposed to heat, it melts, and exhales a fragrant odour: for which reason, principally, it enters into the composition of some fire-works, as the scented paste. In ordinary fumigations, mastich is commonly used.
Sect. XX. Of Copal.
Gum copal, by which name it is known, is a resin, obtained from a tree, called thus copallinum. It is often in the form of a beautiful white resin; but sometimes it is more or less coloured. It is frequently opaque. It may be dissolved in alcohol, spirit of turpentine, and oils, by a peculiar management, (by using camphor, previously melting it, and the like,) and then it forms the various copal varnishes, which are more or less perfect, as the copal is transparent, and the solution properly formed. When heated, it melts like other resins, and in this, and many other properties, it partakes of the character of resins in general. It is used in some of the formulæ for fire-works.