There are three principal varieties of sensitive paper in common use, viz. the Albuminized, the plain, and the Ammonio-Nitrate paper.
Formula I. Preparation of Albuminized Paper.—This includes the salting and albuminizing, and the sensitizing with Nitrate of Silver.
The Salting and Albuminizing.—Take of
| Chloride of Ammonium, or Pure Chloride of Sodium | [200] | grains. |
| Water | 10 | fluid ounces. |
| Albumen | 10 | fluid ounces. |
If distilled water cannot be procured, rain water or even common spring water[40] will answer the purpose. To obtain the Albumen, use new-laid eggs, and be careful that in opening the shell the yolk is not broken; each egg will yield about one fluid ounce of Albumen.
[40] If the water contained much Sulphate of Lime, it is likely that the sensitiveness of the paper would be impaired (?).
When the ingredients are mixed, take a bundle of quills or a fork, and beat the whole into a perfect froth. As the froth forms, it is to be skimmed off and placed in a flat dish to subside. The success of the operation depends entirely upon the manner in which this part of the process is conducted;—if the Albumen be not thoroughly beaten, flakes of animal membrane will be left in the liquid, and will cause streaks upon the paper. When the froth has partially subsided, transfer it to a tall and narrow jar, and allow to stand for several hours, that the membranous shreds may settle to the bottom. Then pour off the upper clear portion, which is fit for use. Albuminous liquids are too glutinous to run well through a paper filter, and are better cleared by subsidence.
A more simple plan than the above, and one equally efficacious, is to fill a bottle to about three parts with the salted mixture of Albumen and water, and to shake it well for ten minutes or a quarter of an hour until it loses its glutinosity and can be poured out smoothly from the neck of the bottle. It is then to be transferred to an open jar, and allowed to settle as before.
The solution prepared by the above directions will contain exactly ten grains of salt to the ounce, dissolved in an equal bulk of Albumen and water. Some operators employ the Albumen alone without an addition of water; but this commonly gives a highly varnished appearance, which is thought by most to be objectionable. Much however will depend upon the kind of paper which is employed, certain varieties taking more gloss than others; Papier Rive, for instance, often requires the Albumen to be nearly or quite undiluted.