When the nails are stained or discoloured, a little lemon juice, or vinegar-and-water, is the best application. Occasionally, a little pumice-stone, in impalpable powder, or a little ‘putty powder,’ may be used along with water and a piece of soft leather or flannel for the same purpose. The frequent employment of these substances is, however, injurious to the healthy growth of the nail.
NANKEEN′. The coloured cotton cloth which bears this name was originally brought from Nankin, the ancient capital of China, and was prepared from a native cotton, of a brownish-yellow hue. It is now successfully imitated in England, and at the present time the English manufacturers supply the Canton market. In this country the colour is generally given to the cloth by successive baths of sulphate of iron and crude carbonate of soda or lime water.
NANKEEN DYE. The liquid sold under this name in the shops is a solution of annotta. It is employed to dye white calicoes of a nankeen colour; but chiefly to restore the colour of faded nankeen clothing.
NAPH′THA. Syn. Mineral naphtha; Naphtha, L. A name given to the limpid and purer varieties of PETROLEUM (which see), or ROCK OIL, which exudes from the surface of the earth in various parts of the world.
Prop. Naphtha possesses a penetrating odour and a yellow colour, but may be rendered colourless by distillation; it usually begins to boil at a temperature of about 180° Fahr., but, being a mixture of several different hydrocarbons, it has no fixed boiling-point; it is very inflammable; it does not mix with water, but imparts to that fluid its peculiar taste and smell; mixes with alcohol and oils, and dissolves sulphur, phosphorus, camphor, iodine, most of the resins, wax, fats, and spermaceti; and forms with caoutchouc a gelatinous varnish, which dries with very great difficulty.
Pur. Mineral naphtha is very frequently adulterated with oil of turpentine, a fraud which may be detected by—1. The addition of some oil of vitriol, which will, in that case, thicken and darken it.—2. Hydrochloric acid gas passed through the liquid for an hour, will occasion the formation of hydrochlorate of camphine, either at once or after a few hours’ repose, even if only 5% of oil of turpentine is present. (Dr Bolley.)—3. If a few grains of iodide of potassium and a little water are rubbed with the suspected sample, the colour of the water should continue unchanged; the presence of 1⁄300th part of oil turpentine will cause it to assume a red or orange colour. (Saladin.)
Uses. Naphtha is chiefly employed for the purposes of illumination, as a solvent for india rubber, and in the preparation of a very superior black pigment. It has been highly spoken
of as a remedy for cholera, by Dr Andreosky, a Russian physician. See Petroleum, and below.
Naphtha, Coal-tar. Syn. Naphtha, Coal n. A mixture of volatile hydrocarbons, obtained by distilling coal-tar. It is one of the first products which comes over, and flows from the still as crude coal naphtha. To obtain rectified coal naphtha, this crude liquid is distilled, and the product agitated with 10% of concentrated sulphuric acid; when cold, the mixture is treated with 5% of peroxide of manganese, and the upper portion is submitted to further distillation. The specific gravity of this purified product is ·850. It is extensively used as a solvent of caoutchouc, and other allied substances, also of resins for the preparation of varnishes. By repeated purification and fractional distillation, benzol, the chief and most important constituent of coal naphtha, is obtained. See Benzol.
Naphtha, Wood. See Pyroxylic spirit.