Contraction. - Ars.

Present name. - Arsenious Anhydride. As2O3. Arsenious Acid, White Arsenic. For. names: German, Weisser Arsenick; French, Oxide blanc d'Arsenic.

It may be obtained pure from the manufacturing chemists.

Characters and Tests. - A heavy white powder, octohedral crystals, or sublimed masses which usually present a stratified appearance, caused by the existence of separate layers differing from each other in degrees of opacity, of a slightly sweetish taste and no smell. Heated in a dry tube, it is entirely converted into vapour and is deposited on the cooler part of the tube as a white crystalline powder. Heated with charcoal, it emits a strong garlic odour. It dissolves in Hydrochloric Acid, and the solution gives the following precipitates. With Sulphuretted Hydrogen it gives a yellow precipitate, soluble in Caustic Ammonia. In neutral solutions Ammonio-Nitrate of Silver causes a yellow precipitate, easily soluble in weak acids and Ammonia.

Preparation. - Take 96 grains of Arsenic in powder, and put it into a flask capable of holding 30 fluid ounces; then add 20 fluid ounces of distilled water; mark the flask to denote the quantity, so that distilled water may be supplied from time to time to replace that which evaporates. Boil constantly until the whole of the Arsenic is taken up and the solution has been reduced to 15 fluid ounces, and when cold add sufficient rectified spirit to increase the bulk to 1 pint. If a stronger preparation than 1 is required, it should be made by trituration.

N.B. - There is a great difference in the solubility of different preparations of Arsenic; but the above solution of 1 in 100 will be found to be a good preparation for keeping, and from which the higher attenuations may be made. The 3X should be made with 20 O.P., and all above that with rectified spirit.

Reference to Horn. Proving. - Chr. Kr., v. R. A. M. L.,ii.

Proper forms for dispensing. - lx, Trituration only. 1, Solution only. 3X and upwards, Tincture, Pilules, or Globules.