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Typo: A Monthly Newspaper and Literary Review, Volume 1

[trade wrinkles, part one]

Clear Shellac Varnish.—To get an absolutely clear solution of shellac has long been a desideratum, not only with microscopists, but with all others who have occasional need of the medium for cements, &c. It may be prepared (according to the National Druggist) by first making an alcoholic solution of shellac in the usual way; a little benzole is then added and the mixture well shaken. In the course of from twenty-four to forty-eight hours the fluid will have separated into two distinct layers, an upper alcoholic stratum, perfectly clear, and of a dark red color, while under it is a turbid mixture containing the impurities. The clear solution may be drawn off.

Mucilage of Acacia, or Gum Arabic.—It is usually stated that the preparation of this mucilage in the cold renders it less liable to become thick and muddy. This the Pharma. Zeitung, in a late issue, disputes upon the authority of H. Notfke, who recommends the hot treatment. The following is his plan. « By repeated experiments I have become convinced that the keeping qualities of mucilage gum arabic are improved by using hot water for solution. The water is first heated to boiling, then allowed to cool to about 80° C. (176° F.), and this is then poured upon the gum arabic, which had previously been carefully washed with cold distilled water. The whole is well covered, set aside in a cool place, and frequently stirred. Solution will take place rapidly. Any water lost by evaporation is replaced before straining. The straining must be done by passing the mucilage through a woollen strainer, previously washed repeatedly with distilled water. The strained mucilage should be filled into small bottles (2 to 8 oz.), which had previously been carefully dried in a drying oven, and must be still hot when filled. They should be filled to about three-fourths of the neck and at once corked, the cork, if possible, being pushed down so as to meet the surface of the mucilage. Mucilage thus prepared is clear and bright, and, if put up as here directed, keeps well, though it generally becomes faintly opalescent after a few days. But this happens also to mucilage prepared by the cold process. If the mucilage is heated in a steam bath, immediately after it has been strained, it will keep still better, but this second heating renders it quite opaque, which is not considered proper. »