Is not the use of sel d'or subject to the objection that the pictures with which it is used are liable to fade in time? DR. DIAMOND says that pictures produced by the use of amm. nit. of silver are not to be depended on for permanency. If this be so, it is very important it should be known, as the use of amm. nit. is at present generally recommended and adopted. C. E. F. _Mr. Lyte's New Process._--Although I presume it is none of your affair what is said or done in "another place," will you kindly ask MR. LYTE for me, if he will be so good as to explain the discrepancy which appears between his "new processes," as given in the Journal of the Photographic Society of Sept. 21, and "N. & Q." of Sept. 10? In the former he says, for sensitizing, take (amongst other things) iodide of ammonia 60 grains: in "N. & Q.," on the contrary, what would seem to be the same receipt, or intended as the same, gives the quantity of this salt one fourth less, 45 grains--a vast difference. Again, in the developing solution the quantity of formic acid is _double_ in your paper what it is in the journal. I should not have trespassed on your space, but would have written to MR. LYTE directly, except from the fear that some other unfortunate practitioner may have stumbled over the same impediment as I have done, and may not have had courage to make the inquiry. S. B. [Having forwarded this communication to MR. LYTE, we have received from that gentleman the following explanations of his process, &c.] The process which was published in the _Photographic Journal_ was, I am sorry to say, not quite correct in its proportions, on account of a mistake in inclosing the wrong letter to the Editor; but the mistake will, I trust, be rectified by another communication which I have now sent. The whole of the formulae, however, as given in "N. & Q.," are quite correct. Let me now, however, trespass on your pages by a few more answers to several other Querists, and which at the same time may be acceptable to some of your readers. 1. The developing agents which are made with iron are very applicable as baths to immerse the plate in; and the formic acid, from its powerful deoxidizing property, renders the iron salt more stable during long use and exposure to the air. 2. In coating paper with albumen, if the upper edge of the paper be sufficiently turned back, and the paper be forced down sufficiently on to the surface of the albumen, no bubbles will form; and {374} the operator will not be troubled with the streaks so often complained of. 3. No time can possibly be fixed for the exposure of the positive to the action of the hypo.; and to produce the best effects, the positive must be continually watched, both while printing and while in the hypo. 4. No hot iron should be applied to the positive after being printed, but the picture should be allowed to dry spontaneously.