Page:Experimental researches in chemistry and.djvu/35

20 is converted into calomel in consequence of the action of the ammonia at high temperatures. Heated with potash, the ammonia is driven off, the chlorine is removed from the mercury, and red oxide results.

Some crystals of calomel were introduced into ammoniacal gas; they immediately blackened on the surface, and gas was absorbed. The action appeared to be exactly similar to that exerted when calomel is thrown into solution of ammonia. A black substance is produced, which though repeatedly washed in distilled water, gives off ammonia by heat, and calomel with a little mercury sublimes.

A piece of fused chloride of lead exerted but little action in a fortnight; a small quantity of gas was absorbed, and a very superficial combination had been formed.

Chloride of bismuth absorbed a small quantity of ammoniacal gas, which was again given out by heat; there was no remarkable change in appearance.

A small piece of chloride of nickel being placed in ammoniacal gas, absorbed it, and in twenty-four hours was converted into a bulky powder of a pale rose tint. The ammonia was separated by exposure to air, to water, or to heat.

Chloride of copper fused was powerfully acted upon by ammonia. It immediately burst open upon being placed in the gas, and absorbing great quantities fell into a blue powder. The compound placed in water was decomposed, and an ammoniacal solution of copper produced. Heated, it fused, boiled, the ammonia flew off, and the chloride remained.

The protochloride of iron introduced immediately after fusion into ammoniacal gas, exerted an instantaneous action; great quantities of gas were absorbed, and a very light adhesive white powder was formed. Exposed to the air, it immediately changed colour, became yellow, brown, then green, and ultimately black: this effect resulted from the presence of water in the atmosphere, and the separation of oxide by the ammonia; and the substance offers a test, if one should be wanted, for the presence of aqueous vapour. A portion of it thrown up into a small receiver of common air over mercury, immediately changed colour, and became brown. When the powder was heated out of the contact of air it gave off ammonia, and the chloride remained.