Sec. XV. Of Camphor.
Camphor is a resinous substance, although generally called a gum, which has a peculiar, and powerful smell. It is obtained principally from the Laurus Camphora. It is extracted from this, and other trees in the East Indies. We are informed, that, in Borneo and Sumatra, the larger pieces which contain the most camphor, are picked out with sharp instruments. The Chinese cut off the branches, chop them small, and place them in spring water. They are then boiled, and stirred with a stick. As soon as the camphor is observed to adhere to the stick, the fluid is strained. It is then poured into a basin, and the camphor separates, in Japan, the roots and the extremities of the branches are steamed. It is also obtained by sublimation. The roots, wood, and leaves are all boiled in large iron pots, and the camphor is collected on straw, placed in a tubular head.
With respect to the refining of crude camphor, in order to produce heads, as they are called, and to free it from impurities, the operation is nothing more than sublimation. Sublimers made of glass are used; and into each, the camphor, along with a small portion of lime, is introduced, and they are then placed in a sand bath. Heat is applied, and the pure camphor rises and attaches itself to the upper part of the vessel, forming the refined camphor.
The general properties of camphor are the following: It is not altered by the atmospheric air, but is volatilized during warm weather. It is insoluble in water; is soluble in alcohol, forming the spirit of camphor, and also in volatile and fixed oils. It is not acted upon by the alkalies. It is dissolved in acids without effervescence, and by some it is decomposed. Nitric acid converts it into a peculiar acid, called the camphoric. It melts between 300 and 400 degrees. It takes fire, and burns with a white flame, and, generally, while it presents the character of a resin, it shows, by its combustion, like other inflammable bodies, that it contains, in its composition, a large quantity of carbon and hydrogen.
There are several species of camphor, which have been examined by chemists and which differ in their properties. These are, common camphor, the camphor of volatile oils, and the artificial camphor, formed by treating oil of turpentine with muriatic acid.
The base of camphor forms a constituent part of some volatile oils, which are in a liquid state; and for its separation, it appears to require a combination with oxygen.
Camphor may be apparently set on fire by means of water, an experiment, which is nothing more than producing chemical action by it, in the following manner: Put a portion of nitrate of copper on some tin-foil, along with camphor; then by adding some water, and quickly wrapping the foil up, pressing the edges close, it will inflame, and sparks of fire be produced.
Camphor has been used in the manufacture of candles. For this purpose, it is dissolved in brandy, and the wick, composed of equal parts of cotton and linen, is dipped in. It is then dried, and covered, in the usual manner, with tallow or wax. The tallow, recommended as the best for candles, is a combination of equal parts of mutton and beef suet.
Camphor is very soluble in acetic acid, which is highly inflammable. This solution is decomposed by water. When combined with essential oils, it forms aromatic vinegar. Romieu has observed that small pieces of camphor floating on water have a rotary motion.
Camphor enters into a composition, which is used to determine, like a barometer, the state of the weather, and the changes it undergoes. According to the Journal de Pharmacie, 1815, some experiments were made in France on the fluid taken out of one of the English weather gauges. The liquid contained water and alcohol, was strong with camphor, and reddened litmus paper. The tube contained 31/2 ounces. On analysis, its contents were found to be, 24 grains of alum, 120 grains of camphor, and enough water to dissolve the former, and alcohol to dissolve the latter. A similar composition was made, and put into a tube, which, it seems, had the same effect. The tube is hermetically sealed. M. Cadet observes, that the prognosticator, made in Paris many years ago, was a similar preparation.