Body Was Formerly Prepared From Indigo--in Spanish Anil Whence The

name; but is now produced on a larger scale from benzol, a coal-tar

product. As the source of mauve and magenta, aniline must be considered

the parent of coal-tar colours generally. Little was known of it at one

time except that on being mixed with a solution of chloride of lime

there was formed a splendid purple liquid, which immediately gave place

to a dingy reddish precipitate. From the investigation of this simple

fact, however, by Mr. W. Perkin, there was created a new and important

branch of chemical industry--the manufacture of coal-tar colours. The

violet mauve led the way, followed by the red magenta, the blue azuline,

the yellow phosphine, the green emeraldine, the orange aurine, by

purple, and brown, and black. Such were the hues, with many intermediate

tints and shades, which one reaction brought forth. The world rubbed its

eyes with astonishment; and truly it seemed almost as wonderful to

produce the colours of the rainbow from a lump of coal, as to extract

sunshine from cucumbers.

The history of these colours reads more like a romance than a sober

story, but to the artist it is of slight practical interest.

Sufficiently stable as dyes, though they be, coal-tar colours are not

adapted to the palette. Mauve, magenta, with a few others, hare been

introduced as pigments and fairly tried, but a want of permanence has

been fatal to their success. Mauve is more durable than magenta, and the

rest vary in stability, but none of them have proved really fitted for

artists' colours. Exposed to light and air, they all more or less fade,

especially in thin washes; and they have mostly the objection of

staining and permeating the paper or canvas on which they are employed.

Used in body, some may be found eligible in portfolio illuminations and

the like, where the brilliancy of their colours shows to advantage; but

in landscapes and pictures of life, coal-tar pigments are best avoided.

Cakes of red, blue, violet, and other hues, may be prepared for

painting, by combining the colours with a mixture of starch and alumina,

or with soap and alumina in a moist state--thus: 150 parts of white curd

soap, dissolved in 1000 parts of hot water, are mixed with an alcoholic

or a methylated spirit solution of six parts of the crystallized or

solid coal-tar colour. To this are added 250 parts by weight of washed

gelatinous alumina. The whole is then well stirred, collected on a

filter, drained, and dried. Several hues, tints, and shades may be

obtained by compounding: for instance, an orange is produced on

admixture of picric yellow with aniline red, or a green by adding the

same yellow to aniline blue.

Blue The Secondary Purple And Its Allies Crimson &c It Gives Some Body; By Which In Other Pigments Especially Those That Are facebooktwittergoogle_plusredditpinterestlinkedinmail