Latterly, however, it has been found possible to prepare, with aniline and methyl, colouring substances of a bluish-black shade, so intense and soluble in water that they can be used in the preparation of beautiful black writing-ink. One of these substances is an article of commerce under the name of soluble nigrosine. It dissolves in water with a slight residue, and, without thickening, furnishes a beautiful blue-black, which is purple in reflected light, and immediately becomes intense black on paper. It is, consequently, an ink that does not change, flows easily from the pen, does not turn brown, and when dry can be again rendered fluid with a little water. It does not possess the intensity of the black from gallnut, but a softer and more velvety tone. Although prepared with a soluble salt, it is not obliterated when dry, and not easily when moistened, unless it is too thick. On the other hand, the fibre of the paper does not completely absorb this colouring substance; the residue continues as a deposit on the surface, and can be removed. This imperfection may be remedied by diluting the black with water.

Acids change the characteristics into blue without destroying them, and, on account of the perfectly neutral reaction of nigrosine, this ink does not at all attack steel pens and render them unfit for use. (Tech-nologiste.) (d) Berzelius found that by treating an infusion of galls by a solution of vanadate of ammonia, in place of sulphate of iron, he could produce an ink of remarkably good quality. At the time of his discovery, in 1831, it was of no practical interest, because the vanadates were very costly. At the present time their cost has been so much reduced that his recipe can be employed for ordinary inks, which have the additional advantage of presenting great . resistance to most reagents and destructive materials. Gum-arabic can be dispensed with, and the chance of moulding or alteration thus reduced. (Chron. Indtistr.) (e) Peltz, in the 'Pharm. Zeitschr. fur Russland,' recommends: -

Parts

Extr. logwood ....

100

Lime-water ....

800

Carbolic acid....

3

Crude hydrochloric acid....

25

Distilled water....

600

Gum-arabic....

30

Bichromate of potash..

3

Distilled water to make up the weight to ...

1800

The ink should be made in a porcelain or enamelled iron vessel. The extract is first dissolved in the lime-water over a steam-bath with frequent stirring. To these are added the carbolic and hydrochloric acids, which change the solution from a red to a brownish-yellow colour. After half-an-hour's heating over the steam-bath, the mixture is set aside till cold, when it is strained or filtered. Lastly, the gum and the bichromate, each separately dissolved in a considerable quantity of distilled water, are added, and the remainder of the water to make up the necessary weight. This ink is of a fine red colour, which quickly turns black; it does not corrode steel pens; and if it dries, needs only the addition of water. (J) Joseph Ellis, of Brighton, stated to the Society of Arts that, by making a solution of shellac with borax in water and pure lampblack, an ink is producible which is indestructible by time or by chemical agents, and which, on drying, will present a polished surface, as with the ink found on the Egyptian papyri.

He made such an ink, and proved, if not its identity with that of ancient Egypt, yet the correctness of the formula.