Emplastrum Sinapis. U. S. Mustard Plaster.
Emp. Sinap. [Charta Sinapis, U. S. VIII, Mustard Paper]
Related entries: Mustard
"A uniform mixture of powdered black mustard (deprived of its fixed oil), and a solution of rubber, spread on paper, cotton cloth or other fabric. Preserve it in tightly-closed containers. A square of 100 square centimeters contains not less than 2.5 Gm. of black mustard deprived of its fixed oil. When moistened thoroughly with tepid water and applied to the skin, the Plaster produces a decided warmth and reddening of the skin within five minutes. Before Mustard Plaster is applied, moisten it thoroughly with tepid water." U. S.
Sinapisme en feuille, Fr. Cod.; Papier Moutarde, Papier Sinapise, Fr.; Charta sinapisata, P. G.; Senf-papier, G; Carta senapata, It.; Papel sinapico, Charta sinapica. Sp.
"Black Mustard, in No. 60 powder, one hundred grammes [or 3 ounces av., 231 grains]; Rubber, ten grammes [or 154 grains]; Petroleum Benzin, Carbon Bisulphide, each, a sufficient quantity. Pack the Black Mustard in a conical percolator, and gradually pour Petroleum Benzin upon it until the percolate ceases to produce a permanent, greasy stain upon blotting paper. Remove the powder from the percolator, and dry it by exposure to the air. Having meanwhile dissolved the Rubber in a mixture of one hundred cubic centimeters [or 3 fluidounces, 183 minims], each, of Petroleum Benzin and Carbon Bisulphide, mix the purified Mustard with a sufficient quantity of the solution to produce a semi-liquid magma, and apply this, by means of a suitable brush, to one side of a piece of rather thick, well-sized paper, so as to cover it completely, and then allow the surface to dry. A surface of sixty square centimeters should contain about 4 Gm. of Black Mustard deprived of oil. Before it is applied to the skin, Mustard Paper should be dipped in warm water for about fifteen seconds." U. S. VIII.
"Black and White Mustard Seeds, equal proportions by weight; Benzol, Solution of India-rubber, of each, a sufficient quantity. Bruise the Mustard Seeds and extract the fixed oil by percolation with the Benzol. Dry the residue by exposure to the air in a warm closet, and reduce to No. 60 powder. Mix seventy-five grains (or five grammes) of the purified mustard with five fluid drachms (or eighteen cubic centimetres) of Solution of India-rubber, and spread by means of a suitable brush over about 30 square inches (or about two square decimetres) of one side of a piece of cartridge paper. Allow it to dry by exposure to the air." Br., 1898.
The name of this preparation was changed in the U. S. P. IX from mustard paper to mustard plaster; from a pharmaceutical point of view this was a mistake, for mustard leaves as they are often called are very different from. either mustard plasters or mustard poultices. The U. S. P. IX and the British Pharm. (1914) no longer .admit a process for making Charta Sinapis, the U. S. P. IX merely describing the preparation as found in commerce. The U. S. P. VIII and the Br. Pharm., 1898, processes are given above.
The formula for this preparation was greatly improved by the U. S. P. in 1890 and Br., 1898. The British preparation (1885) was at fault in not providing for the extraction of the fixed oil by previously percolating with petroleum benzin or carbon disulphide; otherwise the paper will be greasy, giving to the plaster an untidy appearance and soiling the linen of the patient. Solution of gutta-percha is unsuited for use in this preparation, on account of want of adhesiveness, and the tendency of the mixture, when dry, to crack and peel off. We have used instead a solution of 1 part of pure rubber in 30 of equal parts of carbon disulphide and petroleum benzin. On the large scale, by means of a plaster spreading apparatus a uniform coat of this solution may be applied to paper. As the latter passes out from under the apparatus, a sieve containing the powdered mustard is shaken over it; this is fixed by the adhesive coat and firmly retained after the evaporation of the volatile liquids in a warm place. The application of the powdered mustard must be properly regulated according to the speed with which the machine delivers the coated paper. The paper is cut into pieces of convenient size, and needs only to be wetted with tepid water to be ready for use. Owing to the fact that the large manufacturers can put mustard paper upon the market at such low rates that it pays the apothecary better to buy than to prepare it, Charta Sinapis, so far as we can learn, is rarely made in the retail stores.
Uses.—For the uses of the mustard plaster, see Sinapis.
Experience has shown that the ready-made mustard papers err rather from too much than from too little activity. Moreover, their action cannot be regulated with the same nicety as can that of the mustard poultice. Unless in the case of travellers, and of others who must wait upon themselves, the domestic application is preferable. The mustard leaves can rarely be borne for more than ten or fifteen minutes. Care should be observed to protect the leaves, as they are popularly called, from the action of moist air by keeping them in well closed containers.