Art. LXXXV.—On a useful modification of common Writing Ink.

Transactions and Proceedings of the Royal Society of New Zealand, Volume 9, 1876, Page 557

Art. LXXXV.—On a useful modification of common Writing Ink. By William Skey, Analyist to the Geological Survey of New Zealand. [Read before the Wellington Philosophical Society, 24th February, 1877.] The subject of the improvement of our common Writing Ink (ferro-gallic ink) has lately been forced upon me by the proceedings here of a certain gentleman, a vendor of pens. These pens were alleged by him to be, at

least as to their exterior parts, of aluminium, and, in consequence of this, to be incorrodible by ink of this kind. Large numbers of them had been sold by him to various Governments and private persons under these representations; but, in an unpropitious hour, he was moved to attempt a sale of them to our Colonial Government, and under the same representations on their behalf as had been hitherto so successful. A sample of them was therefore handed for examination to the Department to which I belong, when their true character as steel pens was for the first time ascertained and publicly announced. The fact that there had been such a rush after pens supposed to be incorrodible, showed the great necessity there is for a cheap pen which is proof against the corrosive action of our common writing inks, or of a good cheap writing ink which will not corrode our steel pens; and I accordingly thought the matter over, when it occurred to me that the ink might at any rate be modified so as to afford us this great desideratum. The way in which such an ink should be modified for this purpose will at once suggest itself to you when the specific cause of its corrosive effect upon steel is considered. This is, as you are aware, the combination of oxygen with the iron of the pen, and a partial solution of the compound thus formed in the acids (gallic, tannic, carbonic acid, etc.) of which the ink in part consists, the rest of the compound combining with these acids to form adherent flocks or laminæ upon the pen. Now it is a well-known fact that all these processes—in short this corrosion, or indeed any corrosion of iron or steel—can only go on when the surrounding liquid is in an acid or possibly neutral condition; at least to speak guardedly and in mind of the easy superficial oxidizement of even the noble metals which I have before this shown to you, *Vol. VIII. “Trans. N.Z. Institute,” p. 332. it can but go on to a very limited, indeed an imperceptible extent as regards vision. It will therefore occur to you, as it occurred to me, that by alkalizing our common ink, a product would be obtained having no visible effect upon steel pens, the only question to determine being this—whether we can so radically change the character of the ink without rendering it useless? In regard to this question, I believe that I have, after several experiments, settled it quite favourably by using bi-carbonate of ammonia as the alkalizing agent. Any other bi-carbonate will do too, as also borax, or alkaline phosphates; but the first salt is on the whole the best, as any notable excess of it does not, on account of its volatility, long incommode one. Ammonia, or common soda, cannot safely be used for this purpose, as matters so caustic as these change the color of the ink to a weak pink or purple.

A lump of carbonate of ammonia the size of a walnut will generally be found sufficient to add to three or four ounces of ink, and, as soon as effervescence has ceased, the ink is ready for use. Ink of this description is slightly paler than that not thus modified, and, in drying, does not show quite so black. It is, besides, a little more liable to be washed off in part by water, but, to compensate for this, it neither corrodes nor clogs steel pens; it flows more readily, and is not so much affected by any greasy matter with which it may get in contact as in the unmodified variety. This kind of ink when dried in hot weather so as to be unusable, can be easily recovered by adding water thereto with or without carbonate of ammonia as may be required. Being an anti-corrosive ink, any pens which have been used with it may afterwards be left therein with very good effect.