[Sidenote: SALTING PAPER, ETC.] Take of Chloride of ammonium, or pure chloride of sodium 200 grains. Water 10 fluid oz. Albumen 10 fluid oz. If distilled water cannot be procured, rain water or even common spring water[L] will answer the purpose. To obtain the albumen, use new-laid eggs, and be careful that in opening the shell the yelk is not broken; each egg will yield about one fluid ounce of albumen. [Footnote L: 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 is 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. Pour off the upper clear portion, which is fit for use. Albumenous 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 the paper in that case has a very highly varnished appearance, which is thought by most to be objectionable. The principal difficulty in albumenizing paper is to avoid the occurrence of streaky lines, which, when the paper is rendered sensitive, bronze strongly under the influence of the light. The writer believes these to be caused by a commencing decomposition of the animal matter composing the cells in which the albumen is retained and the best remedy appears to be to use the eggs quite fresh; the same object may sometimes (but not invariably) be attained by allowing the albumen to stand for several weeks until it has become sour; after which it will be sufficiently limpid to run through a filter.