Antidote to arsenious acid.

Preparation. - Mix the solution of tersulphate of iron 1,000 grs. (65.00 gm.) with twice its weight of water. Rub the magnesia, 150 grains (10.00 gm.) with water to a smooth and thin mixture; transfer this to a bottle capable of holding 32 fl. oz., or about 1 litre, and fill it up with water. When the preparation is wanted for use, mix the two liquids by adding the magnesia mixture gradually to the iron solution, and shake them together until a homogeneous mass results.

Note. - The diluted solution of tersulphate of iron and the mixture of magnesia with water should always be kept on hand, ready for immediate use.

Use. - As an antidote in poisoning by arsenic.