Chromic acid and its salts, the chromates and bichromates, can be detected by the violet coloration which they give on addition of hydrogen peroxide to their dilute acid solution, or by the fact that on distillation with concentrated sulphuric acid and an alkaline chloride, the red vapours of chromium oxychloride are produced.
The sesquioxide, Cr 2 0 3, occurs native, and can be artificially obtained in several different ways, e.g., by igniting the corresponding hydroxide, or chromium trioxide, or ammonium bichromate, or by passing the vapours of chromium oxychloride through a red-hot tube, or by ignition of mercurous chromate.
Richard Head in his Life and Death of Mother Shipton (1684) says, "the body was of indifferent height, her head was long, with sharp fiery eyes, her nose of an incredible and unproportionate length, having many crooks and turnings, adorned with many strange pimples of divers colours, as red, blue and dirt, which like vapours of brimstone gave such a lustre to her affrighted spectators in the dead time of the night, that one of them confessed several times in my hearing that her nurse needed no other light to assist her in her duties" Allowing for the absurdity of this account, it certainly seems (if any reliance is to be placed on the so-called authorities) that the child was phenomenally plain and deformed.
They Are Removed By Passing The Vapours In Succession Through Concentrated Solutions Of The Caustic Alkalis, Concentrated Sulphuric Acid, And Triethyl Phosphine; The Residual Gas Is Then Purified By Liquefaction (W.
The graphite veins in the older crystalline rocks are probably akin to metalliferous veins and the material derived from deep-seated sources; the decomposition of metallic carbides by water and the reduction of hydrocarbon vapours have been suggested as possible modes of origin.