The gilding upon porcelain is in like manner fixed by heat and the use of borax, and this kind of ware, being neither transparent nor liable to soften, and thus to be injured in its form in a low red heat, is free from the risk and injury which the finer and more fusible kinds of glass are apt to sustain from such treatment. Porcelain and other wares may be platinized, silvered, tinned, or bronzed, in a similar manner. 16. GILDING THE EDGES OF PAPER The edges of the leaves of books and letter paper are gilded whilst in a horizontal position in the bookbinder's press or some arrangement of the same nature, by first applying a composition formed of four parts of Armenian-bole and one of candied sugar, ground together with water to a proper consistence, and laid on by a brush with the white of an egg. This coating, when nearly dry is smoothed by the burnisher, it is then slightly moistened by a sponge dipped in clean water and squeezed in the hand; the gold leaf is now taken up on a piece of cotton from the leathern cushion and applied on the moistened surface; when dry it is to be burnished by rubbing the burnisher over it repeatedly from end to end, taking care not to wound the surface by the point. 17. PROFESSOR WORTS' AMALGAM FOR SILVERING This is the only means yet discovered for silvering iron directly, yet it is not so lasting as some of the other processes. Take quicksilver and the metal potassium, equal parts by volume, put them together in a tumbler, and if both metals be good there will be a brisk ebullition, which continues until an amalgam of the two is formed, then add as much quicksilver as there is of the amalgam; let it work till thoroughly mixed, and it is ready for use. This amalgam you may apply with a cloth to any metal, even iron, though it be a rusty bar, and you have it neatly silvered over. 18. FOR COPPERING IRON