Cantharis. Cantharides. The dried beetle Cantharis vesica-toria. About 3/4 to 1 inch long and a 1/4 inch broad, with two long wing-sheaths of a coppery-green colour; odour strong and disagreeable. The active principle is cantharidin, an acid anhydride, which is volatile; soluble slightly in water, less so in alcohol (1 in 1150) and in ether (1 in 700), more so in chloroform (1 in 65) and in acetone (1 in 40) and in glacial acetic acid; incompatible, with alkalies (forming salts which are active) and lead, silver, copper and mercuric salts in solution.

3Acetum Cantharidis. Vinegar of Cantharides. - 10; a mixture of Glacial Acetic Acid and Water in equal parts to 100.

1emplastrum Cantharidis

35; Yellow Beeswax, 20; Lard, 20; Resin, 20; Soap Plaster, 5.

2Emplastrum Calefaciens. Warming Plaster.- 4; Yellow Beeswax, 4; Resin, 4; Resin Plaster, 52; Soap Plaster, 32; Water, boiling, 20.

1Liquor Epispasticus. Blistering Liquid. - 50; Acetic Ether 100: by percolation.

1Collodium Vesicans. Blistering Collodium. - to 100; Pyroxylin, 2.5.

2Tinctura Cantharidi . Dose, if repeated, 2-5 min.; 0.1 - 0.3 c.c: for a single administration, 5 - 15 min.; 0.3 - 1 c.c. - 1.25. Alcohol, 100: by maceration.

1unguentum Cantharidis

10; Benzoated Lard 90.