Home Correspondence: Mr. Underwood's Paper on Ink.

Journal of the Society of Arts 269, 15.1.1857

[---] I be permitted to make a few remarks on Mr. Underwood's paper on inks. Having had considerable [---] this manufacture, I am well acquainted [---] difficulties. From my numerous  [---] convinced that it is not from any  [---] that an advance and improvement in the manuvature of ink can be made. Logwood, and extract of logwood, has long been used, in all proportions, with gall nuts, metallic iron, and iron salts. The more logwood, the commoner and cheaper the ink, such as school in, &c. Now, how a patent can be claiemd for any such combiation in any proportion whatever, I cannot conceive. The princilap feature of Mr. Underwood's paper, viz., the use of "chromate of potassa," your correspondent Mr. B. Winstone has justly observed was invented by Professor Runge. The recipe, just as Mr. Winstone has queted it, was copied into all the cheap journals of the day, viz., some four or five years ago, and recommended as a very cheap ink for steel pens. A German got hold of it, and went about London among the stationers selling the recipe; many were victimised, as the product was worthless. I have some writing in my possession with this ink, carefully prepared, and it has quite faded, as might be expected. he also stated that he saturated copying paper with the chromate salt, and wrote with logwood solution. In the discussion which took place, Mr. May justly questioned the durability of any compound of logwood. Mr. Deputy Lott seemed to think if its indelible character could be proved, it would be valuable to the legal profession. No doubt an indelible ink would be, but certainly any logwood ink would be dangerous to rely upon. The only real scientific advance in this manufacture was made by the celebrated chemist Berzelius, from the rare metal "Vanadium;" this is, unfortunately, so scarce as to preclude its use for this purpose. It was stated to be indelible. The chemical action of chromate of potassa upon solutions of logwood, is an oxidising one. The colouring principle of this wood was first extracted and investigated by Chevreul, the French chemist; it is termed "Hematoxylin," and deposits in brownish-yellow prismatic crystals. By contact with air or oxidising agents, it is converted into "Hematin," which is granular and of a purplish black hue, and this is what is produced on the copying paper saturated with the chromate salt, when placed in contact with logwood ink. Very common inks are made with large proportions of logwood, or extract of logwood, from the fact of their being produced at about 4d. per gallon - very small quantities of iron salts being requisite. The chromate ink of Runge is still cheaper. I am now engaged with experiments on indelible ink, and trust some future day to lay the results before the Society, as the subject is one of some importance.

I am, &c.,
Robert Pinkley.

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