MANGANESE, PRINTING WITH : GANIC LACTATE PRINTING A novel printing process worked out by the Brothers Lumiere in 1895. For the sensitising solution, too grs. of potassium permanganate are dissolved in 2 oz. of water, the measure being placed in cold water so as to keep the solution as cool as possible ; drms. of lactic acid are then added, a drop or so at a time, and the solution swirled round after each addition ; these precautions will prevent the solution from becoming hot and frothing over. Allow to stand until all effervescence has ceased, and a thick brownish-black liquid results. Add a solution (cool) of r drm. of glucose or grape sugar in I oz. of hot water, and filter through cotton-wool. The paper should be gelatine coated, and fresh P.O.P., fixed and well washed, answers the purpose ; it is prepared by applying the solution with a broad camel-hair brush and, after half a minute, blotting off the excess and drying in the dark. The paper must be evenly
coated, and none of the solution allowed to reach the back. It yields a negative image from a negative, and, therefore, a good positive or lantern slide should be printed from ; print in daylight. Develop by immersing the print in a saturated solution of aniline sulphate in water, to obtain a green colour ; add a few drops of liquor ammonia' for a violet colour. By using orthotoluidine sulphate solution, rendered slightly acid with hydrochloric acid, a deep blue image results ; or, if the acid is replaced by liquor ammonia', a violet one. Paramido phenol develops an image something like an ordinary silver print. All the solutions used for developing should be as strong as possible. Development is complete in about thirty seconds, the prints being finished by washing in water.