Treatment.—The same as for the other acids.
Table showing the Colour produced by
the Action of the Mineral Acids
on the Skin and on Cloth
| Skin. | Cloth. | |
|---|---|---|
| Sulphuric acid. | Brown colour. | Dirty-brown edges becoming |
| red after a few days from | ||
| absorption | ||
| Nitric acid. | Bright yellow, due to | Yellow, orange-red, or brown. |
| the formation of | ||
| picric acid. Colour | ||
| heightened by | ||
| alkalies. | ||
| Hydrochloric acid. | Greyish-white. | Bright red changing after some |
| days to reddish-brown. |
SULPHATE OF INDIGO
A dark blue liquid formed by dissolving indigo in strong sulphuric acid. Used as a dye. The symptoms are much the same as those detailed under sulphuric acid, with the additional bluing of the mouth and lips. It may be detected with the tests given under sulphuric acid, the blue colour being first discharged by boiling it with nitric acid.
CARBOLIC ACID
Phenol. Phenic Acid. Coal-tar Creosote. Oil of Tar
Carbolic acid is obtained in the dry distillation of coal, and forms the acid portion of coal-tar oil, from which it is subsequently extracted by shaking the crude coal-tar oil with a mixture of slaked lime and water. After allowing the mixture to stand for some time, the watery portion is separated from the undissolved oil, the former treated with hydrochloric acid, and the resulting oily fluid purified by careful distillation. Up to the year 1900 no restrictions were put upon the sale of carbolic acid, but owing to the large number of suicidal and accidental deaths from its use, it was by Act of Parliament scheduled as a poison, and all preparations containing more than 3 per cent. of it, cresylic acid, or their homologues, must be sold as poisons.
Pure carbolic acid forms long, colourless, prismatic needles, which melt at 35° C. into an oily liquid. It boils at 180° C., and greatly resembles creosote, for which it is very frequently substituted in commerce, but from which it differs in the following characters: It does not affect polarised light as creosote does; it forms a jelly-like mass with collodion, and is soluble in a solution of potash, whereas creosote is unaffected by collodion, and is insoluble in a solution of potash. It possesses a penetrating, characteristic odour; burning taste; is slightly soluble in water, but freely so in glycerine, ether, and alcohol; and gives no acid reaction to test paper. When undiluted, it attacks the skin, which it shrivels up.
Creosote is obtained from wood-tar, which imparts to it its caustic properties.