HYDROCHLORIC ACID
Forms.—Strong and the dilute acid. It is known as muriatic acid, or spirits of salts.
Characters.—Strong hydrochloric acid is either colourless or has a bright yellow tint, due to the presence of the perchloride of iron. It fumes in the air, and gives rise to dense white fumes when a glass rod moistened with ammonia is held over the surface of the acid. The dilute acid is colourless.
Symptoms.—Poisoning with muriatic acid is so rare that the symptoms have not been well studied, but they do not appear to differ much from those produced by the action of the other acids. It does not stain the skin, but may darken the mucous membranes. The fumes are apt to attack the air-passages.
Chemical Analysis.—The acid will have to be examined under the following heads: 1. Simple, concentrated acid. 2. Dilute acid. 3. Mixed with organic liquids, food, &c. 4. On the clothes of the person injured.
I. Concentrated Acid
1. Action on Organic Matter.—The strong acid tinges most organic tissues, when immersed in it, a yellow colour. The stains on black cloth are at first distinctly red, becoming reddish-brown after a few days.
2. Action on Metals.—This acid does not act on copper or mercury, even when boiled with them, and this distinguishes it from the other acids.
3. Hydrochloric acid, added to peroxide of manganese and then warmed, gives off chlorine gas, detected by its greenish-yellow colour and suffocating odour. The vapour thus produced bleaches litmus paper, and causes a blue coloration on starch paper moistened with iodide of potassium.
II. Dilute Acid