=A Side Light=, particularly if direct sunlight, must be avoided, as any unevenness or grain of the paper will be exaggerated and rendered more apparent if lighted in such a manner. =Under Exposure=, if slight, is a fault much to be preferred to an error in the opposite direction. =New Transfer Paper for Photo-lithography.=—In the photographic office, Calcutta, a new method of preparing the photo-lithographic transfer paper with arrowroot has quite recently been introduced, which, as is said, has the advantage of being much cheaper than the method of coating with gelatine usually adopted, and of giving results quite as good, if not even better, than by the old proofs. Bank post paper is coated in the usual way with two coats of the following mixture:— Arrowroot 140 parts Bichromate of potash 70 ” Water 3,500 ” After exposure to light, the prints are coated with transfer ink in the press as usual, the transfer ink used being composed of— Hard re-transfer ink (plate to stone) 100 parts Lithographic chalk ink 100 ” Palm oil 7 ” After inking in the prints are washed off with hot water, hotter than is required for gelatine transfers. The arrowroot transfer prints are found to go down well on the zinc without sticking, and give clear, sharp transfers. =Gelatine Plates= have hitherto been considered almost useless for photo-lithography. Messrs. Mawson and Swan, however, have recently introduced a special make, known as the “Photo-mechanical” plate, which gives negatives of great density, and at the same time clearness in the shadows. The makers recommend the ammonia-pyro developer, with meta-bisulphite of potash. It will be found of considerable advantage if, before proceeding with the development, the plate be submitted for one minute to a bath of water 2 ounces, gallic acid 6 grains; this, without prolonging the development, will add considerably to the density of the resulting negative. CHAPTER XX. APPLICATION OF THE CARBON PROCESS TO PHOTO-LITHOGRAPHY. =An Ingenious Process=, capable of yielding satisfactory results, is one in which a carbon print is transferred to and developed upon the stone direct. Such operation will present no difficulty to those familiar with the details of the process. In the “Photographic Archives,” vol. 17, page 193, are to be found working details, and it is there shown that by this method it is possible to directly transfer to stone pen and ink sketches, impressions from woodcuts, or copper-plates, without the necessity of a photographic negative. This process may, therefore, be available in cases where anastatic[W] printing is not applicable.