Page:Experimental researches in chemistry and.djvu/200

1826.] The heavier substance was a red crystalline solid, soft to the nail like a mixture of wax and oil. Its specific gravity was from 1.3 to 1.4, varying in different specimens; its taste sour, bitter, and somewhat metallic. When heated in a tube, it fused, forming, as before, a clear but deep red fluid. Further heat decomposed it, naphtha line, sulphurous acid, charcoal, &c. being produced. When heated in the air it burnt with much flame. Exposed to air it attracted moisture rapidly, became brown and damp upon the surface, and developed a coat of naphtha line. It dissolved entirely in alcohol, forming a brown solution. When rubbed in water a portion of naphtha line separated, amounting to 27 per cent., and a brown acid solution was obtained. This was found by experiments to contain a peculiar acid mixed with a little free sulphuric acid, and it may conveniently be called the impure acid.

The lighter substance was much harder than the former, and more distinctly crystalline. It was of a dull red colour, easily broken down in a mortar, the powder being nearly white, and adhesive like naphtha line. It was highly sapid, being acid, bitter, and astringent. When heated in a tube it melted, forming a clear red fluid, from which by a continued heat much colourless naphtha line sublimed, and a black acid substance was left, which at a high temperature gave sulphurous acid and charcoal. When healed in the air it took fire and burnt like naphtha line. Being rubbed in a mortar with water, a very large portion of it proved to be insoluble; this was naphtha line; and on filtration the solution contained the peculiar acid found to exist in the heavier substance, contaminated with very little sulphuric acid. More minute examination proved that this lighter substance in its fluid state was a solution of a small quantity of the dry peculiar acid in naphtha line; and that the heavier substance was a union of the peculiar acid in large quantity with water, free sulphuric acid, and naphtha line.

It was easy by diminishing the proportion of naphtha line to make the whole of it soluble, so that when water was added to the first result of the experiment, nothing separated; and the solution was found to contain sulphuric acid with the peculiar acid. But reversing the proportions, no excess of naphtha line was competent, at least in several hours, to cause the entire