The paper must not be allowed to remain upon the salting Bath much longer than the time specified, because the solution of Albumen being _alkaline_ (as is shown by the strong smell of Ammonia evolved on the addition of the Chloride of Ammonium) tends to remove the size from the paper and to sink in too deeply; thus losing its surface gloss. Albuminized paper will keep a long time in a dry place. Some have recommended to press it with a heated iron, in order to coagulate the layer of Albumen upon the surface; but this precaution is unnecessary, since the coagulation is perfectly effected by the Nitrate of Silver used in the sensitizing; and it is doubtful whether a layer of _dry_ Albumen would admit of coagulation by the simple application of a heated iron. _To render the paper sensitive._--This operation must be conducted by the light of a candle, or by yellow light. Take of Fused Nitrate of Silver 60 grains. Glacial Acetic Acid 1/3 minim. Distilled Water 1 ounce. Prepare a sufficient quantity of this solution, and lay the sheet upon it in the same manner as before. Three minutes' contact will be sufficient with the thin Negative paper, but if the Canson Positive paper be used, four or five minutes must be allowed for the decomposition. The papers are raised from the solution by a pair of bone forceps or common tweezers tipped with sealing-wax; or a pin may be used to lift up the corner, which is then taken by the finger and thumb and allowed _to drain a little_ before again putting in the pin, otherwise a white mark will be produced upon the paper, from decomposition of the Nitrate of Silver. When the sheet is hung up, a small strip of blotting-paper suspended from the lower edge of the paper will serve to drain off the last drop of liquid. A Bath prepared by the above formula is stronger than is really necessary. Forty grains of Nitrate to the ounce of water is abundantly sufficient if the sample be pure; but it must be borne in mind that the _strength_ of the Bath diminishes _rapidly_ by use, and hence, when the prints begin to be wanting in vigour, with pale shadows and perhaps a spotted appearance, an addition of Nitrate of Silver must be made. Fused Nitrate of Silver is recommended in preference to the crystallized Nitrate, on account of the latter being occasionally contaminated with an impurity alluded to at page 101. This when present will be likely to redden the pictures and to interfere with the rapidity of bronzing.