第40章

INVESTIGATIONS BY STARK OF INK QUALITIES COVERINGA PERIOD OF TWENTY-THREE YEARS--ABSTRACT FROMHIS REPORT OF 1855--DR. CHILTON EXPERIMENTS INNEW YORK CITY 1856--ACTION OF THE PRUSSIAN GOVERNMENT IN 1859 AND EMPLOYMENT OF AN OFFICIALINK--WATTENBACH'S GERMAN TREATISE ON THE ARCHIVES OF THE MIDDLE AGES--WILLIAM INGLIS CLARK ATTEMPTS TO PLACE THE MANUFACTURE OF INKON A SCIENTIFIC BASIS--SUBMITS HIS VALUABLE RESEARCHES AND DEDUCTIONS TO THE ENINBURGH UNIVERSITY IN 1879--SCHLUTTIG AND NEUMANN IN 1890 ESTABLISH A STANDARD FORMULA FOR IRON AND GALL INK--NAMES OF SOME INK INVESTIGATORSOF THE NINETEENTH CENTURY.

DR. JAMES STARK, a famous chemist, submitted the results of twenty-three years of investigations of writing inks in a paper read by him in 1855 before the Society of Arts, in Edinburg, Scotland. The following is the abstract as printed by the London Artisan at the time:

"The author stated that in 1842 he commenced a series of experiments on writing inks, and up to this date (1855), had manufactured 229 different inks, and had tested the durability of writings made with these on all kinds of paper. As the result of his experiments be showed that the browning and fading of inks resulted from many causes, but in ordinary inks chiefly from the iron becoming peroxygenated and separating as a heavy precipitate. Many inks, therefore, when fresh made, yielded durable writings; but when the ink became old, the tanno-gallate of iron separated, and the durability of the ink was destroyed. From a numerous set of experiments the author showed that no salt of iron and no precipitate of iron equalled the common sulphate of iron--that is, the commercial copperas--for the purpose of ink-making; and that even the addition of any persalt, such as the nitrate or chloride of iron, though it improved the present color of the ink, deteriorated its durability. The author failed to procure a persistent black ink from manganese, or other metal or metallic salt. The author exhibited a series of eighteen inks which had either been made with metallic iron or with which metallic iron had been immersed, and directed attention to the fact that though the depth and body of color seemed to be deepened, yet in every case the durability of writings made with such inks was so impaired that they became brown and faded in a few months.

The most permanent ordinary inks were shown to be composed of the best blue gall nuts with copperas and gum, and the proportions found on experiment to yield the most persistent black were six parts of best blue galls to four parts of copperas.

Writings made with such an ink stood exposure to sun and air for twelve months without exhibiting any change of color, while those made with inks of every other proportion or composition had more or less of their color discharged when similarly tested. This ink, therefore, if kept from moulding and from depositing its tanno-gallate of iron, would afford writings perfectly durable. It was shown that no gall and logwood ink was equal to the pure gall ink in so far as durability in the writings was concerned. All such inks were exhibited which, though durable before the addition of logwood, faded rapidly after logwood was added to them. Sugar was shown to have an especially hurtful action on the durability of inks containing logwood--indeed, on all inks. Many other plain inks were exhibited, and their properties described --as gallo-sumach ink, myrabolams ink, Runge's ink, --inks in which the tanno-gallate of iron was kept in solution by nitric, muriatic, sulphuric, and other acids, or by oxalate of potash, chloride of lime, etc. The myrabolams was recommended as an ink of some promise for durability, and as the cheapest ink it was possible to manufacture. All ordinary inks, however, were shown to have certain drawbacks, and the author endeavored to ascertain by experiment whether other dark substances could be added to inks to impart greater durability to writings made with them, and at the same time prevent those chemical changes which were the cause of ordinary inks fading. After experimenting with various substances, and among others with Prussian blue and indigo dissolved in various ways, he found the sulphate of indigo to fulfil all the required conditions and, when added in the proper proportion to a tanno-gallate of iron ink, it yielded an ink which is agreeable to write with, which flows freely from the pen and does not clog it; which never moulds, which, when it dries on the paper, becomes of an intense pure black, and which does not fade or change its color however long kept. The author pointed out the proper proportions for securing those properties, and showed that the smallest quantity of the sulphate of indigo which could be used for this purpose was eight ounces for every gallon of ink. The author stated that the ink he preferred for his own use was composed of twelve ounces of gall, eight ounces of sulphate of indigo, eight ounces of copperas, a few cloves, and four or six ounces of gum arabic, for a gallon of ink.