Practical Magazine 16, 1876
(Chemistry applied to the Arts, Manufactures, &c.
Dyeing, Calico Printing, Bleaching, Tanning, and Allied Subjects.)
It is well known that aniline black, properly so called, is nearly insoluble in most chemical re-agents. It is applied to textile fabrics in a pounded state, or developed on the texture or paper by the re-action of a salt of copper on hydrochlorate of aniline. It thus furnishes an intense and indelible black. But a mixture of salt of copper and hydrochlorate of aniline is not long in the air without undergoing great changes. It soon turns to green, and deposits insoluble aniline black. This prevents the use of this black for flowing ink. Latterly, however, it has been found possible to prepare, with aniline and methyl, colouring substances of a blueish 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 residuum, 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 gall-nut, 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 residuum 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 re-action of nigrosine, this ink does not at all attack steel pens and render them unfit for use.
- Technologiste, Feb. 26, 1876.
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