It rests alone on the superior sensitive property the nitrate of silver possesses after being redissolved in ammonia, which every photographer must have experienced. And it has, I believe, in prospect, the dispensing with the crystals of nitrate of silver, and simply at last employing silver leaves, which will save a great expense to the operator. The first solution is, to the proportion of a wine-bottleful of water add three grains of pure tannin, well dissolved in filtered water. Upon this float every sheet of paper, taking care of bubbles when they are to be hung up to dry. Do a great number; they will be ready for the ultimate process. Make now a solution of nitrate of silver, twenty-six grains to the ounce: if three ounces are to be made, dissolve the nitrate in half an ounce of distilled water, and add liq. ammo. fortissimus till the precipitate is redissolved. Then fill up with two and a half ounces of distilled water. This is the formula of Mr. Alfred Taylor. With this solution pass over every sheet with a brush: it cannot be floated, as exposure to the air precipitates the silver. The iodizing solution is,-- Iodide of potassium 250 grs. Fluoride of potassium 20 grs. Cyanide of potassium 15 grs. Muriate of soda 30 grs. to a full half-pint of distilled water. The success of the operation depends upon this point, that the latter solution must be laid over the first, _before the first has entirely dried_, or at that point when all appearance of wet is absorbed. Three sheets of paper may be washed over at a time; and as the corner where the solution runs to is apt to remain wet longer than the rest of the paper, the drip may be assisted off with a bit of blotting-paper. Also, _before_ the second solution is dry, it is to be floated on water; but the same conditions must be strictly observed. When it has floated a short time, "it does not require so long a time as the acid process." It is, while wet, floated again upon a weak solution of free iodine for about half a minute; it may then be dried, and is ready for the sensitive solution. This last must be acid, and any of the approved formulæ will suit it; but the solution, whatever it is, must be allowed to dry before placing between the white glasses, nor on any account ought it to be touched with blotting-paper. The image is to be brought out with gallic acid and acetic acid, laid over with a brush, and requires no heat. It is of a very red colour generally, but that does not impair its effectiveness in taking the positive impression. WELD TAYLOR. 7. Conduit Street West, Bayswater. _Sir W. Newton's Process._--Will SIR W. NEWTON be kind enough, through the mediums of "N. & Q.," to give the _rationale_ of the _action_ of the _common soda_ and _powdered allum_ mentioned in his process published in Vol. vii., p. 140. and why the _soda_ is used for _negatives_ and the _allum_ for _positives_, both being produced on _iodized paper_?