Part 15 (1/2)

In 1871 Professor Wattenbach of Ger the Middle Ages,” which has some valuable references to the color phenolis Clark in 1879 subh University a thesis entitled ”An Attempt to Place the Manufacture of Ink on a Scientific Basis,”

and which very justly received the commendation of the University authorities His researches and rational deductions are of the greatest possible value judged from a scientific standpoint The introduction of blue-black ink is a phase of the developth

The object of adding a dye in ive teo-paste is used, it has been assuallo-tannate in solution, whereas any virtue of this kind which indigo-paste possesses is more likely due to the sulphuric acid which it contains than to the indigo itself The essential part of the paste required is the sulpho-indiGodate of sodiuo-carmine He further remarks that the stability of an ink precipitate depends upon the amount of iron which it contains and which on no account should be less than eight per cent; he adds rightly, if gallic acid be preferably used in substitution for tannin, ”no precipitate is obtained under precisely similar conditions” This point followed up explains in a all infusion prepared with hot water is not suitable for a blue-black, while a cold water infusion is In the latter case a coalls, while much is extracted with hot water and the consequence is, on adding the indigo blue the color is not brought out as it should be Substantially the sa occurs with ink h the blue color remains for a time unimpaired in the tannin ink, apparently due to the fact that ferrous-tannate reduces indigo blue to indigo white, a change which the low reducing power of ferrous- gallate does little to effect The vegetable matter in common inks facilitates the destruction, or rather alteration and precipitation of the indigo, for the dye appears in the iron precipitate andwater

Dr Clark's investigations seek to deallic acid over infusions of the natural galls, and he undertakes to determine the correct ratio of tannin and sulphate of iron to be used as ink His experiments in this line show that:

1 The amount of precipitate increases as the proportion of iron to tannin is increased

2 The composition of the precipitate is so valuable as to preclude the possibility of its being a definite body Increase of iron in the solution has not at first any effect on the composition of the precipitate, but afterwards iron is found in it in greater but not proportional amount

3 At one point the proportions of iron in the precipitate and in solution are the same, and this is at between 6 and 10 parts of iron to 100 parts of tannin

4 The proportion of iron in the precipitate varies greatly with the length of time the ink has been exposed

At first the precipitate contains 10 per cent of iron, but by and by a new one having only 75 per cent is formed, and in from forty to seventy days we find one of 57 per cent Simultaneously iron increases in the ink (proportionate to the tannin)

5 The results show, and practice confirms, that 16 parts of iron (80 ferrous sulphate) and 100 parts of tannin are best for ink manufacture

The research now travelled in a direction which accuatory

Blue-black tannin ink lost color, and the reducing nature of the tannin tended to the forhly objectionable precipitate in the ink, whichbut a pleasure These two faults were doubtless linked together in soallic acid was used, for ink soexposure, it required no free acid to keep the precipitate in solution, and retained the indigo blue color for a long time; alkalis did not deco

Deterallic acid and ferrous-sulphate was the subject of prolonged experiments conducted on similar lines to those already detailed The conclusions as to precipitation were also similar Thirty parts of iron (150 of ferrous- sulphate) and 100 parts of gallic acid were found to be theIt is advisable, however, not to discard tannin altogether, owing to the slow blackening of the gallic acid ink, and a little tannin gives initial blackening and body, while it is absolutely necessary for copying ink

Initial blackness can also be ensured by oxidizing 21 per cent of the ferrous-sulphate without adding the extra acid necessary to the for portion of his research is devoted to the influence of sugar upon the permanence of ink, and the results of the experi sentences: ”It would be injurious to add 3 per cent of sugar to a tan in ink, while fro inks contain about 35 per cent of sugar-- not far froallic acid ar hardly varies the precipitate, but the importance of this point is soar is by noink Dextrin is a much superior substance to use Curiously this body rapidly precipitates a tannin ink; hence it is useless for copying ink, but for the gallic ink it is an excellent thickener”

Chen-Ki-Souen, ”Lencre de China,” by Maurice Jametel, appeared in Paris in 1882, but as the title indicates, it is the old ”Indian” or Chinese ink that is discussed

Schluttig and Neumann in 1890 issued their Edition Dresden on the subject of ”Iron and Gall inks” In this valuable work is to be found the forenerally adopted as the standard where one is used for tanno-gallate of iron ink

The investigations of other scientific men like Lepowitz, Booth, Desorer, Riffault, Precht, Nicholes, Runge, Gobert, Penny, Arnold, Thomson (Lord Kelvin), Davids, Kindt, Ure, Wislar and many more who have dealt with the che a considerable portion of the nineteenth century of the efforts ood ink

CHAPTER XIV

CLassIFICATIONS OF INK

INK USED BY US HAS NOTHING IN COMMON WITH THAT OF THE ANCIENTS--MANUFACTURERS OF THE PRESENT TIME HAVE LARGELY UTILIZED FORMULAS EMPLOYED IN PAST CENTURIES--THE COMMON ACCEPTATION OF THE TERM INK--SEVEN DIFFERENT CLassES OF INKS AND THEIR COMPOSITION BRIEFLY TOLD--FAILURE OF EFFORTS TO SECURE A REAL SAFETY INK

THE inks used by us have nothing in couall” class employed in the fourteenth, fifteenth, sixteenth, seventeenth and eighteenth centuries, some formulas of which are utilized by the enerally in coalls, sulphate of copper or iron, or both, and fish-glue or guhtly acidulated The frequent introduction of the so-called ”added” color into these inks, tirave mistake

The common acceptation of the term ”ink” may be said to characterize an immense number of fluid co instruns, characters and letters as put together and co, on paper or like substances

To classify the 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 le ink answering every requirement and feer at all times the same requirements