_Succinate of Iron Developer_.--I have received a letter from M. Borlinetto, in which he states that he has been induced by the analogy which exists between oxalic and succinic acids to try whether succinate of iron can be substituted for oxalate of iron as a developer. To prove this he prepared some proto-succinate of iron from the succinate of potassium and proto-sulphate of iron, following the method given by Dr. Eder for the preparation of his ferrous oxalate developer. He carried out the development in the same way as is done by the oxalate, and he found that the succinate of iron is even more energetic than the oxalate. The plate develops regularly with much delicacy, and gives a peculiar tone. It is necessary to take some fresh solution at every operation, on account of the proto-succinate of iron being rapidly converted into per-succinate by contact with the air. _Method of Making Friable Hydro-Cellulose_.--At the meeting of the Photographic Society of France, M. Girard showed his method of preparing cellulose in a state of powder, specially adapted for the production of pyroxyline for making collodion. Carded cotton-wool is placed in water, acidulated with 3 per cent. of sulphuric or nitric acid, and is left there from five to fifteen seconds; it is then taken out and laid on a linen cloth, which is then wrung so as to extract most of the liquid. In this condition there still remains from 30 to 40 per cent. of acidulated water; the cotton is divided into parcels and allowed to dry in the open air until it feels dry to the touch, though in this condition it still contains 20 per cent. of water. It is next inclosed in a covered jar, which is heated to a temperature of 65° C.; the desiccation therefore takes place in the closed space, and the conversion of the material is completed in about two or three hours. In this way a very perfect hydro-cellulose is obtained, and in the best form for producing excellent pyroxyline.--_Corresp. Photo Mews_. * * * * * PHOTO TRACINGS IN BLACK AND COLOR. Two new processes for taking photo tracings in black and color have recently been published--"Nigrography" and "Anthrakotype"--both of which represent a real advance in photographic art. By these two processes we are enabled for the first time to accomplish the rapid production of positive copies in black of plans and other line drawings. Each of these new methods has its own sphere of action; both, therefore, should deserve equally descriptive notices.