Volume 2

The elements of experimental chemistry / by William Henry.

  • Henry, William, 1774-1836.
Date:
1815
Catalogue details

Licence: Public Domain Mark

Credit: The elements of experimental chemistry / by William Henry. Source: Wellcome Collection.

Provider: This material has been provided by King’s College London. The original may be consulted at King’s College London.

    172/586 (page 154)
    the property of giving a white stain to copper. Let a small bit of metallic arsenic, or a mixture of the white oxide with a little black Jinx, be put between two small plates of copper; bind these closely together with iron*wire; and heat them, barely to redness, in the fire. The inside of the copper plates will be stained white. VI. Arsenic, by exposure to the air, is tarnished, and becomes converted into a bulky blackish powder. In three months, Berzelius found that 100 parts acquired an increase of 8.475; and he is disposed to consider the product as an oxidule; but it is probably nothing more than a mixture of arsenic and arsenious acid, into both which, indeed, it is resolved by heat. Only two combinations of arsenic and oxygen have hitherto been clearly ascertained; and both are possessed of acid properties. The white oxide of arsenic has the following properties: 1. It has an acrid taste, and is highly poisonous. 2. It is soluble in water, which, at the ordinary tem- perature, takes up one eightieth. According to La Grange, it is soluble in one twenty-fourth of cold water, or one fifteenth of hot. Other statements have been given con- siderably diiFerjng from these; and Klaproth was, there- ■fore, induced to examine its degree of solubility with great attention. A thousand grains of cold water, left in con- tact with the white oxide during 24; hours, and frequently agitated, dissolved only 2-^ grains. But 1000 grains of boiling water took up 77^ grains; and, after being left three days to cool, and to deposit the crystals which sepa- rated, still retained in solution 30 grains. Bucholz has gince published results, which agree, very nearly, with those of Klaproth. The solution of the white oxide of arsenic has an acrid taste, and reddens vegetable blue colours. When slowly evaporated, the oxide crystallizes in regular tetrahedrons. The oxide is, also, soluble in 70 or 80 times its weight of •Icohol, and in oils. At 383° Fahrenheit it sublimes; or, if suddenly heated out of tho contact of air, runs into glass,