Fig. 2.
Fig. 3.
Commercial hydrochloric acid is usually of a yellow colour owing to its being contaminated with iron. It also very frequently contains sodium, arsenic, sulphuric and sulphurous acids, and free chlorine.
Pure aqueous solution of hydrochloric acid should leave no residue upon evaporation; it should give no precipitation of ferric oxide when saturated with ammonia, sulphuretted hydrogen should cause no turbidity in it; if diluted with three or four times its volume of water, and chloride of barium be added, no white cloud or precipitate should form in the mixture; nor should the acid, if pure, discolour a fluid made faintly blue with iodide of starch.
Hydrochloric acid is largely consumed in the manufacture of chlorine, sal ammoniac, chloride antimony, glue, phosphorus, in the preparation of carbonic acid for the manufacture of artificial mineral waters, in beet-root sugar works, hydro-metallurgy, and alone, or mixed with nitric acid, for dissolving various metals.[349] See Acids, Effects of Vegetation on, Chlorine.
[349] Wagner.
HYDROCHLORIC ETHER. (C2H5Cl.) Syn. Ethyl Chloride, Chloride of Ethyl. This ether may be obtained either by saturating alcohol with hydrochloric acid gas, and then distilling at a gentle heat, or by distilling a mixture of three parts of oil of vitriol, two of alcohol, and four of fused chloride of sodium; the retort is in either case connected with a tubulated receiver, surrounded by water at a temperature of about 68° Fahr., in which most of the alcohol and water which pass over during the operation become condensed, whilst the ether escapes in the form of vapour through a bent tube, which is inserted into the tubulure of the receiver, and passes to the bottom of a flask kept cool with ice. The liquid which is condensed in the flask must be rectified from calcic chloride.
Hydrochloric ether is a colourless liquid, having a specific gravity at 32° Fahr. of 0·921, and a boiling point of 51·9° Fahr. The specific gravity of its vapour is 2·219. It has an ethereal, penetrating, somewhat garlicky odour. It is sparingly soluble in water, but readily so in alcohol. These solutions fail to give a precipitate with argentic nitrate.