[This is taken from David N. Carvalho's Forty Centuries of Ink, originally published in 1904.]
SOME OBSERVATIONS ABOUT “ADDED” COLOR TO INK—INVENTION OF COAL TAR COLORS—CHRONOLOGICAL HISTORY OF THE “ANILINES” EMPLOYED AS INK—OTHER SUBSTANCES USED FOR THE SAME PURPOSE.
THE term “added color,” as applied to ink, is the popular phraseology for a multitude of materials which have been more or less utilized for a period of centuries, in adulterating and coloring ink. In olden times they were introduced into ink with an honest belief that it would also improve and ensure its lasting qualities, but latterly more often to cheapen the cost of its manufacture. Reference has been made to a large variety of these substances used for this purpose and the story told of the effect of the test of time upon them as indicative of their supposed value. Attention has also been directed to the discovery during the nineteenth century of the colors which owe their origin to by-products of coal tar.
Generically these colors are classified as “anilines.” They have worked a revolution in all the arts in which colors are used. Employed without a mordant, with few exceptions, they are measurably affected by both light, heat, moisture, or other changes and as made into inks are never permanent. Hence they should not be used for records, because if obliterated from any cause whatever, there are no known means to render them again legible.
The origin and history of the “anilines” are known. Viewed from an ink standpoint they are of vast interest. So extended in number are the “anilines” (they run into the thousands) that they include every shade of black and all possible tints or hues of the colors of the rainbow.
The chronological history of such of these artificial colors which appertain to ink or its manufacture is important as locating the dates of their invention and commercial use.
The first discovery of “aniline” is credited to Helot in 1750. In 1825 Faraday in rectifying naphtha discovered benzole, which by the action of strong nitric acid be converted into nitro-benzole; and this latter, when agitated with water, acetic acid and iron filings produced aniline. Unverdorben in 1826 discovered an analogous material in products obtained by the destructive distillation of indigo. Runge in 1834 claims to have detected it in coal tar and called it kyanol, which after oxidation became an insoluble black pigment and known as aniline black. It could not, however, be used as an ink. Zinan in 1840, experimenting along the same lines, produced another compound terming it benzidam. Fritsche in the same year by the distillation of indigo with caustic potash developed a product which he also called aniline, the name being derived from the Portuguese word anil, meaning indigo. Shortly afterwards A. W. Hoffman established the identity of these substances.
Aniline when pure is a colorless liquid, possessing a rather ammoniacal odor. It soon becomes yellow and yellow-brown under the influence of light and air. It does not affect litmus paper.
In 1856 Perkins accidentally discovered the violet dye called mauve, which acquired considerable commercial importance besides its utility for ink purposes.
Nicholson in 1862 succeeded in producing the first of the soluble blue anilines.
The discovery of induline, one of the modifications of aniline black, was made known in 1864.
Nigrosine, produced by the action of concentrated sulphuric acid on the insoluble indulines, was discovered in 1868.
The soluble indulines and nigrosines differentiate in appearance, the first a bronzy powder and the latter a black lustrous powder. When made into ink they possess about equal color values.
In 1870 the German chemists, Graebe and Liebermann, announced that they had succeeded in producing artificial alizarin,--the coloring matter of the madder root. Commercial value was not given to this discovery until it was put on the market in 1873, although it did not meet all the requirements.
Springmuhl in 1873 obtained an accessory product in the artificial manufacture of alizarin out of anthracene, from which a beautiful blue was made, superior in many respect to the aniline blues. It differed from aniline in having the same color in solution. Alkalis destroyed the color but acids restored it. The process was kept a secret for a long time. This product was originally sold as high as $1,500 for a single pound.
Caro, a German chemist, invented in 1874 the red color known as eosine, which was brought to this country in the following year and sold for $125 per pound. Its color is destroyed by acids.
Orchil or archil (the red color) was discovered in 1879. The commercial use of the so-called “orchil substitutes” (purples) began, however, in the years 1885 and 1887.
Artificial indigo, as the result of many years of experimenting, came into commercial use under the name of “indigo pure” only in 1897. It had previously been produced synthetically in a variety of ways, but the cost of the production was far above that of the natural product. Baeyer and Emmerling in 1870, Suida in 1878, Baeyer in 1878, Baeyer and Drewsen in 1882, and Heumann in 1890, can be said to have been the pioneers in the production of artificial indigo.
The intensity of some of the aniline colors may be indicated by the fact that a single grain of eosine in ten millions of water exhibits a definite rose-pink color.
It is asserted that in the last three years many improvements have been made in the permanent qualities of some of the soluble anilines, but no material which is soluble in plain water should ever be employed as an ink for record purposes.
Preceding the discovery of the “anilines,” as already related, other substances had been employed for “added” color in the admixture of ink, principally madder, Brazil wood, indigo, and logwood.
Only a casual reference has heretofore been made to Brazil wood and logwood.
Brazil wood, also called peach wood, is imported from Brazil. Its employment as a dyestuff is known to be of great antiquity, antedating considerably the discovery of South America. Bancroft states, “The name ‘Brazil’ was given to the country on account of the extensive forests of the already well-known ‘Brazil wood,’ which was found by its Portuguese discoverers. The dyestuff thus gave its name to the country from which it was afterwards principally obtained. The word ‘Brazil’ appears to have been originally used to designate a bright red or flame color. Thus in a contract between the cities of Bologna and Ferrara, in 1194, the dyestuff kermez is referred to as grana de Brazile and Brazil wood, both dyestuffs at that time being obtained from India.” For “added” color to ink and alone it was much used in the seventeenth and eighteenth centuries.
Logwood, employed more extensively for “added” color than any other color compound, was introduced into Europe by the Spaniards, A. D. 1502. In England it does not appear to have been much used until about 1575. In 1581 the Parliament prohibited its use “because the colours produced from it were of a fugacious character.” Its use was legalized in 1673 by an act, the preamble of which reads, “The ingenious industry of modern times hath taught the dyers of England the art of fixing, the colours made of logwood, alias blackwood, so as that, by experience, they are found as lasting as the colours made with any sort of dyeing wood whatever.” It is obtained principally from the Campeachy tree, which grows in the West Indies and South America.
The practical utility of logwood as the base for an ink was a discovery of Runge in 1848, who found that a dilute solution of its coloring matter, to which had been added a small quantity of neutral chromate of potassium, produced a deep black liquid which apparently remained clear and did not deposit any sediment. This composition became very popular on account of its cheapness and dark purple color. It is of a fugitive character, though, and has passed almost entirely out of commercial use.
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