According to Hager, myrrh consists in 100 parts of about 2.5 parts volatile oil (myrrhol), 25 to 35 parts resin (myrrhin), 55 to 65 parts gum soluble in water, 3 to 8 parts salts, impurities, and water. Water forms with myrrh an emulsion, and dissolves the gum. The resinous constituents are dissolved by spirit of wine.
The gum, which forms the portion of the myrrh soluble in water, but insoluble in alcohol, and amounts to from 57 to 59 per cent., is, according to Oscar Koehler, a hydrocarbon of the formula C_{ 6}H_{ 10}O_{ 5}. The portion soluble in alcohol is, according to the same chemist, a mixture of various resins, an indifferent soft resin of the formula C_{ 26}H_{ 34}O_{ 5}, soluble in alcohol and ether, forming the greater portion of it. There are further present two resin acids, one of which has to be considered a bibasic acid of composition C_{ 12}H_{ 16}O_{ 8}, and the other as a monobasic acid of the formula C_{ 26}H_{ 32}O_{ 9}. The principal constituent of the volatile oil of which, according to Koehler, 7 to 8 per cent. is present, while Ruickholdt formerly found only 2.18 per cent. corresponds to the formula C_{ 10}H_{ 14}O. The volatile oil is laevorotatory, and when diluted with bisulphide of carbon becomes, according to Flückiger, violet by the action of bromine. An extract of myrrh, prepared with bisulphide of carbon, gives the same reaction with bromine vapor. Hydrochloric or nitric acid also colors myrrh violet, which also applies to the volatile oil.
Petroleum-ether should, at the utmost, take up 6 per cent. of the myrrh, and the extract must be colorless.
Myrrh is frequently contaminated with bark, which forms either a film of cork as thick as paper or a crust of a fibrous and, at the same time, brittle nature. Sand or small pebbles are also frequently mixed with the myrrh. Other varieties of gum or gum-resin, which considerably decrease the value of the product, are often found in the commercial article, the inferior qualities especially being adulterated and mixed with dark pieces of Suakim gum, gum of the plum or cherry tree, bdellium, and similar substances, which are partially moistened with myrrh tincture, and scattered over with myrrh powder. Adulteration with gum-arabic, gum of the plum or cherry tree, which are coated with alcoholic myrrh solution, is recognized by the paler lustre, greater transparency, and mucilaginous taste. Pieces of resin melt on heating, while myrrh only swells up. Bdellium is detected by the dark or black-brown color, toughness, less bitter taste, and by crackling and spitting when held in the flame of a candle, as well as by the reaction of myrrh with nitric acid discovered by Bonastre. By mixing 5 cubic centimeters of alcoholic myrrh tincture with 5 to 10 drops of fuming nitric acid, a rose-color coloration passing into red results. Parker gives the following method for testing myrrh: Prepare a tincture of 1 part myrrh and 6 parts spirit of wine. Saturate with this tincture white filtering paper, allow it to drain off, and then wrap it around a glass rod moistened with nitric acid of 1.42 specific gravity. With genuine myrrh the paper immediately becomes deep yellow-brown and then black, while the edges of the paper strip appear dark purple-red. When a few drops of the tincture of myrrh are allowed to dry in, a transparent residue remains behind. The tinctures of spurious articles (with the exception of bissabol) give turbid residues.