PEROXYD OF HYDROGEN.
This most valuable bleaching agent is a contraction of hydrogen and oxygen, of the formula HO2, sp. grv. 1.45 (chemically given), or 94.12 per cent. oxygen with 5.88 per cent. hydrogen. It consists in a limpid, syrupous liquid, of characteristic color, and when heated to 15° C., is decomposed into water and oxygen, upon which property its great bleaching power is based. Experiments to reduce it to a solid form by refrigeration and pressure have thus far been unsuccessful. The commercial article is somewhat modified by the addition of water to prevent its ready decomposition under the influence of a warm temperature. For the same reason it is advisable to always keep it in a cool place.