- ing 30 parts or a thirty-third of their weight.[1] Guibourt found a
difference between the transparent and opaque varieties; for a thousand parts of temperate water dissolved in thirty-six hours 9·6 of the transparent, 12·5 of the opaque variety; and the same quantity of boiling water dissolved of the transparent variety 97 parts, retaining 18 when cooled, but of the opaque variety took up 115 and retained on cooling 29.[2] More lately Mr. Alfred Taylor observed that temperate water, simply poured on the opaque oxide and left for seventy-two hours, contained one grain in a thousand, but if often agitated, 8·5 grains; that boiling water, occasionally agitated for the same period, contained 9·27 or 9·54 grains; that water, boiling gently for an hour dissolved 31·5, and on cooling and resting for three days retained 17; that with violent ebullition for an hour, it took up 46·3, and retained 24·7 grains on cooling and resting for three days; that a saturated boiling solution after six months contained 24 or 26 grains; and that a saturated boiling solution of the transparent oxide contained 46 or 47·5 grains, and on cooling and resting for two days retained 18·7 or 13·4 grains.[3] It is impossible to account for these discrepancies; for all the experimentalists conducted their investigations with care, and with a view to the medico-legal question stated above. Hahnemann farther remarked, that at the temperature of the blood a thousand parts of water dissolve ten parts with the aid of ten minutes' agitation;[4] and Navier, that boiling water kept for an hour on it, and decanted off in the way an infusion is usually made, dissolves 12·5 grains in every thousand.[5]
Its solubility is impaired by the presence of organic principles. When mixed with mucus or milk it dissolves, according to Hahnemann, with great difficulty; and I have found that a cup of tea, left beside the fire at a temperature of 200° for half an hour upon two grains of the oxide, does not take up entirely even that small quantity. An important consequence of the fact now mentioned is, that when swallowed in the solid state, little or no arsenic may be found in the fluid contents of the stomach. In a case which occurred to Scheele three grains of solid arsenic were found in the contents, but hardly a trace in solution.[6] It would be wrong, however, to suppose that it is never found in the fluid contents. For, not to mention the observations of others, I have myself often detected it in the fluid part of the stomach in persons poisoned by arsenic.
The solution of oxide of arsenic in boiling water yields minute crystals on cooling, which, when their form is defined, are octaedres. In this state, on account of its whiteness and brilliancy, it exceedingly resembles pounded sugar. By spontaneous evaporation I have procured in twelve months fine octaedres nearly as large as peas. These do not become opaque by keeping, like the sublimed masses.
