Mix mustard (2 1/2 ounces) with 2 or 3 ounces of lukewarm water; mix the linseed meal with 6 to 8 ounces of boiling water; add the former to the latter and stir them together.

Oleum Sinapis, B.P.; Oleum Sinapis Volatile, U.S.P.

Oil of Mustard, B.P. - The oil distilled with water from the seeds of black mustard, Brassica nigra, after the expression of the fixed oil, B.P. A volatile oil obtained from black mustard by maceration with water, and subsequent distillation, U.S.P.

It is sulphocyanide of allyl (C3H5CNS).

Characters. - Colourless or pale yellow. Has an intensely pungent, acrid odour, and burning taste.

Solubility. - Soluble in alcohol and ether, slightly in water.

Action. - Applied to the skin, it produces almost instant vesication.

Preparations.

B.P

Linimentum Sinapis Compositum (vide p. 516).

U.S.P

Linimentum Sinapis Compositum (vide p. 517). 3 parts of the oil by weight in 100.

Action. - Locally applied to the skin or mucous membranes, mustard acts as a stimulant, causing warmth, redness, pain passing off if the application is short, but if the action is prolonged vesication is produced. Externally applied for a short time in the form of flying sinapisms, it is also a general stimulant, increasing the force of the circulation. Internally, it is a prompt direct emetic (a tablespoonful of mustard in a tumbler of hot water).

Uses. - Externally it is used as a counter-irritant in myalgia, lumbago, headache, in the form of poultice or paper to the back of the neck; in congestion of the brain, apoplexy, and opium-poisoning, in the form of poultices or leaves to the calves of the legs and other parts of the body. It is applied to the chest in catarrh, bronchitis, congestion of the lung, and catarrhal pneumonia. In phthisis, mustard-leaves applied to the chest are useful to check the spread of consolidation when the patient has taken cold. It is applied to the spine for the relief of pains in the loins, and loss of power in walking accompanying spinal irritation. For this purpose a very useful application is the linimentum sinapis compositum sprinkled on some spongiopiline. Mustard bathas to the feet are used in amenorrhoea (p. 453) and sleeplessness (p. 198).

When Rigollot's leaves are used, the pain they cause in persons with delicate skins renders them almost unbearable, and in such cases two or three layers of damped muslin should be placed next to the skin, to modify their action.

With the leaves of the B.P. it is advisable to use one layer of muslin to prevent the mustard coming off the leaf and sticking to the skin.

Internally, mustard is used as a condiment, to increase the appetite by stimulating the mucous membrane. One important use is that of an emetic in indigestion or narcotic poisoning (p. 864). In irritant poisoning - e.g. by croton oil - it is best given in linseed tea or thin gruel.