Myrrh is obtained from a plant, supposed to belong to the genus _mimosa_, which, as Bruce informs us, (_Travels, &c._) grows in Abyssinia and Arabia. It is in the form of tears, of a reddish-yellow colour; sometimes transparent, and at other times opaque. It possesses a peculiar odour, and a bitter and aromatic taste. It burns with difficulty, and does not melt when heated. With water, it forms a yellow opaque mixture. It dissolves in alcohol, and the solution is decomposed by the addition of water, the whole becoming opaque. According to Braconnot, myrrh is composed of 23 resin, and 77 gum, in the 100 parts. Pelletier, whose analysis differs from Braconnot's, observes, that, besides resin, it contains some volatile oil, to which, no doubt, its fragrance is owing. The gum, extracted from it, had the character common to all gums, with the exception, that, instead of forming the mucous or saclactic acid, by the action of nitric acid, it produced only oxalic acid. That myrrh burns with difficulty, is owing entirely to the presence of so much gum, and, comparatively speaking, the small quantity of resin, which enters into its composition. But, notwithstanding this property, as it partakes of a fragrant oil, it is used in some compositions for fire-works. The gummy part may retard, as is sometimes required in particular preparations, the rapidity of the combustion, and therefore have a two-fold effect when employed in fire-works. _Sect. XXII. Of Sugar._ Refined sugar is sometimes used in pyrotechno-mixtures. As it is a vegetable oxide, (composed of carbon, hydrogen, and oxygen), which is decomposed by heat, and has the property of decomposing nitric acid, and some of its combinations; its operation in such mixtures may be readily perceived. We have seen, when treating of chlorate of potassa, that, when this salt and sugar are mixed together, and sulphuric acid poured on the mixture, a rapid combustion ensues, which is owing as well to the decomposition of the sugar, as to that of the salt. The matches, likewise, which inflame by immersion in sulphuric acid, are covered with a similar mixture. That sugar, therefore, has the property of decomposing those salts, which are composed of acids, that have their oxygen but feebly combined, and thereby producing combustion, according to the temperature employed, or other agents made use of, is evident from a variety of experiments. By its action, then, in such cases, the products of combustion, arising from the elementary parts of the sugar alone, uniting with oxygen, must be carbonic acid and water. Sugar, submitted to destructive distillation, affords a variety of new substances; among which we may notice _caromel_, or that peculiar odour, which is recognised in the burning of sugar. Sugar may, therefore, besides assisting in part in the decomposition of saline bodies, and particularly nitre, and perhaps giving rise to new products, with which we are unacquainted, have another effect, that