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. It was shown that immersing iron wire or filings in these inks destroyed ordinary inks. He therefore recommended that all legal deeds or documents should be written with quill pens, as the contact of steel invariably destroys more or less the durability of every ink. The author concluded his paper with a few remarks on copying inks and indelible inks, showing that a good copying ink has yet to be sought for, and that indelible inks, which will resist the pencilings and washings of the chemist and the forger, need never be looked for." Professor Leonhardi, of Dresden, who had given much attention to the subject of inks, introduced in 1855 what he termed a NEW ink, and named it "alizarine ink," alizarin being a product obtained from the madder root, which he employed for "added" color in a tanno-gallate of iron solution. It possessed some merit due to its fluidity, and for a time was quite popular, but gradually gave place to the so-called chemical writing fluids; it is now obsolete. Champour and Malepeyre, Paris, 1856, issued a joint manual, "Fabrication des Encres," devoted almost exclusively to the manufacture of inks and compiles many old "gall" and other ink formulas. In 1856 Dr. Chilton of New York City published the results of ink experiments which he had made. The accompanying extracts are taken from the local press of the month of April of that year: