INK USED BY US HAS NOTHING IN COMMON WITH THATOF THE ANCIENTS--MANUFACTURERS OF THE PRESENTTIME HAVE LARGELY UTILIZED FORMULAS EMPLOYED IN PAST CENTURIES--THE COMMON ACCEPTATION OF THE TERM INK--SEVEN DIFFERENT CLASSES OF INKSAND THEIR COMPOSITION BRIEFLY TOLD--FAILURE OFEFFORTS TO SECURE A REAL SAFETY INK.
THE inks used by us have nothing in common with those of the ancients except the color and gum, and mighty little of that.
Those of the "gall" class employed in the fourteenth, fifteenth, sixteenth, seventeenth and eighteenth centuries, some formulas of which are utilized by the manufacturers of ink in our own time, consisted generally in combination; infusions of nut-galls, sulphate of copper or iron, or both, and fish-glue or gum, slightly acidulated. The frequent introduction of the so-called "added" color into these inks, time has shown to have been a grave mistake.
The common acceptation of the term "ink" may be said to characterize an immense number of fluid compounds, the function of which in connection with a marking instrument is to delineate conventional signs, characters and letters as put together and commonly called writing, on paper or like substances.
To classify them would be impossible; but black writing ink, chemical writing fluid, colored writing ink, copying ink, India ink, secret or sympathetic ink, and indelible ink make seven classes; the others may be denominated under the head of miscellaneous inks, and of them all, there is no single ink answering every requirement and few answer at all times the same requirements.
Ink may be either a clear solution of any coloring matter or of coloring matter held in suspension.
It is a remarkable fact that although most inks are chemical compositions and many times made after the same formula, identical results cannot always be calculated or obtained. This is more particularly to be noted in the case of black writing inks otherwise known as the tanno-gallate of iron inks [gallic and gallotanic acid obtained from nut-galls, sulphate of iron, (green copperas) and some gummy vehicle].
The variations would appear to be largely due to the difference in quality of the gall-nuts, treatment, and temperature of the atmosphere; perhaps, however, not so much to-day as it was ten or twenty years ago, when to make ink of this character boiling processes were employed. Most of them as already stated are now "cold" made.
Inks of this class consist of a finely divided insoluble precipitate suspended in water by the use of gum and possessing a slight acidity.
The requisites of a good black writing ink or black writing fluid require it to flow readily from the pen, to indicate in a short time a black color and to penetrate the paper to an appreciable degree, and more important than all the rest, to be of great durability. When kept in a closed vessel no sediment of any account should be precipitated, although such will be the case in open ink-wells, and this the quicker the more the air is permitted to get to it. If it is to be used for record or documentary purposes it must not be altogether obliterated if brought into contact with water or alcohol, and should depend for permanency on its chemical and not on its pigmentary qualities.
The second class, called for distinction "chemical writing fluids," possesses the same essential ingredients to be found in class one, but much less in quantity and with some "added" colored substance which I shall term "loading," for its real purpose is to cheapen the cost of production and not altogether as some manufacturers state "simply to give them an agreeable color."Previous to the discovery of the soluble anilines, logwood, indigo, madder, orchil and other dyeing materials were used for a period of some eighty years and vanadium for some twenty years (very costly at that time), for this purpose, but since 1874, and with frequent changes as the newer aniline compounds were invented, these by-products of coal-tar, as well as logwood, etc., have been and are to-day employed for "loading," or as the manufacturer expresses, it "added color." The chemical writing fluids as now prepared, yield when first written a blue or green color with a tendency to change to black afterwards. They are not as permanent as those of the first class.
Another black ink not durable, however, is "logwood;"its extract is combined with a little chromate of potassium and boiled together in water. It possesses its own "gum" and contains some tannin. In combination with alum and water, it forms a dark purple ink.
