Consists in the B.P. of mustard in powder, mixed with solution of gutta-percha, so as to make it stick to the paper upon which it is spread, and then dried. In the U.S.P. the fixed oil is removed from the mustard by percolation with benzin before it is spread on the paper. It is used as a substitute for a mustard poultice by immersing it for a few seconds in tepid water and then applying it to the skin. Rigollot's mustard-leaves are more frequently used than those of the Pharmacopoeia. They cause, as a rule, sharper pain than the ordinary mustard poultice, and can rarely be borne as long. They are, however, more convenient and readily applied, and in cases of narcotic poisoning the sharp pain they cause renders them preferable to the ordinary poultice.