Scientific American 22, 24.11.1860
Treating Oils for Paint and Varnish. - Drying oils (such as linseed which is employed for painting) become semi-resinous by absorbing oxygen when exposed to the air. In order to render them quick-drying, however, they require to be boiled ofr a considerable period, and some oxydizing agent is incorporated with them. "Boiled oil" which is prepared for painting is very troublesome to manufacture, and the process i quite tedious. An improved mode of treating such oil for making varnishes and for painting has lately been patented by F. Walton, of Denton, England. He takes clear linseed oil, mixes it with about five per cent of acetate of lead, then puts it into a vessel where it is forced by a pump into a great number of small streams, like a shower; then it meets with a current of warm, dry air raised to the temperature of steam heat, when it rapidly absorbs oxygen and acquires the same drying quality of boiled oil, but is much clearer in color and superior for most purposes. Sometimes the air is heated as high as 550° Fah., in order to facilitate the operations.
Bank Paper and Ink for Writing. - A peculiar preparation of paper and ink has lately been patented by J. A. Ballande, of Paris. He introduces into paper pulp about 30 per cent of proto-chloride of mercury (calomel), and the paper is ready for use. An ink is now made with 1,000 grains of alum, 50 grains of salammoniac and 50 grains hyposulphite of soda, mixed with a little gum mucilage. This ink will not become black unless used with paper prepared in the above manner. A dark color is produced when the hyposulphite of soda combines with the calomel; but this would soon fade were it not for the alum and alkaline salt in the ink - these fix it. No chemical means known to M. Ballande can remove the writing produced in this manner, without altering the texture of the paper. It is the best means believed to be yet discovered for precenting the alteration of important signatures, &c., in bank bills and other valuable papers. Any white paper may be sponged on the surface with a dilute solution of calomel, then dried, and is ready for use with the above ink; but the most perfect way of preparing the paper is undoubtedly in the pulp.
New Material for Pencils. - Some black lead in powder mixed with india-rubber in solution, a small quantity of lampblack and some finely powdered charcoal, are incorporated together and subjected to great pressure. This forces out all the moisture and reduces the mixture to a hard block, which may be subdivided and cut out into suitable lengths for pencils. A patent has been taken out for this pencil composition by R. J. Cole, of London.
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