Printing. The plate is fixed by means of plaster of Paris to a lithographic stone, and printed by the aid of a lithographic press. The essential. You can dispense with it, and get along without infringing on any patent. On a flat marble slab in the press plaster is poured, and a plate glass of suitable size pressed on and allowed to set; on this plate glass the exposed plate is put on by capillary attraction with water; it is then ready to be inked and printed. As a sensitizer for the gelatin, I prefer the bichromate of ammonia, and I would strongly recommend one grain of salycilic acid to the ounce of solution, as a preventive of trouble when the weather is favorable to decomposition.

To strip negatives for lichtdruck purposes, etc., the glass must be carefully cleaned and polished with soapatone powder, or, still better, with a five - grain solution of pure wax in pure benzole. Polish with a Canton-flannel rag. After the negative is thoroughly washed, put it in a dish of clean water and soak a sheet of fine gelatin such as the dealers sell for printing borders for carbon prints, until it lays flat, but no longer; press on the negative under water, squeeze out the water and air-bubbles with a rubber squeegee, and lay it flat, face up, to dry in a place free from dust; whendry,it comes off the glass, taking the collodion film with it. - D.Bachrach, Jr.

359. After exosure, the sensitized plate is removed from the frame and placed at once to disgorge in a grooved tank filled with water, which is renewed, if possible, by a continuous current. The annexed figure will explain the kind generally used in France and Germany. -

Leon Vidal.