Transparent Paper.—A French paper contains the following recipe for making transparent sheets of paper: Saturate a sheet of suitable thickness in copal varnish; when dry, polish with pumice stone. It is then covered with a layer of water glass, and is rubbed with felt. It is said that the paper will then be as transparent and smooth as glass.

Zinc Plates in Lithography.—A litho printer writing to L'Imprimerie, gives the following recipe for the treatment of zinc plates:—Pour half a pint of hydrochloric acid into a porcelain vessel, slightly narrower and shorter than the plate, which will thus rest on the borders of the vessel. Allow the plate to remain for ten minutes, and on removal, the emanations from the acid will be found to have produced a uniform grain. A solution of potash should afterwards be used to remove all traces of acid from the pores of the zinc, and the plate should be finally rinsed in clear water. By this method the lithographers may procure a plate fit to receive a transfer or any other composition, the operation of rubbing being entirely obviated.

To Prevent Screws from Rusting.—It is well known that iron screws are very liable to rust, more especially when they are placed in damp positions. When employed to join parts of machinery they often become so tightly fixed that they can only be withdrawn with considerable trouble—a fracture sometimes resulting. In order to avoid this inconvenience screws are generally oiled before being put in their places, but this is found to be insufficient. According to the Moniteur Industrielle a mixture of oil and graphite (black lead) will effectually prevent screws becoming fixed, and, moreover, protect them for years against rust. The mixture facilitates tightening up, is an excellent lubricant, and reduces the friction of the screw in its socket.

To Emboss Cards.—Take a piece of six-ply card stock, with a smooth white surface, just the size of the card you wish to emboss, and sketch the shape of the panel you desire with a pencil, afterwards cutting out the design in one piece with a sharp knife: then trim the edge of the inside piece so that it will play freely through the outside piece. Paste the outside or female die firmly on the back of a wood letter large enough to hold it; and the inside, or male die, very lightly to the same letter; then lock up the letter and put it on the press; remove your rollers, make a good hard tympan, and after thoroughly pasting the surface of the inside die, take an impression, and hold the platen on the impression until the paste has had time to dry. On opening the press the under die will leave the wood letter on which it was lightly held, and adhere to the tympan, leaving the outside die attached to the letter on the bed of the press. Then set gauges and feed in your cards in the usual way, and proceed to emboss.