Manufacturer and Builder 9, 1874
Take fine white sand, 9 parts; litharge, 25 parts; saltpeter and arsenic, 3 parts each; pulverize and mix well together, spread on the plates of glass, porcelain. or iron you wish to enamel. On a coat of this enamel one may write or draw as on paper, using for writing material a solution of some metallic salt, and in less than one minute it may be made indelible by simply heating the plate to the melting point of the enamel, (a low red heat.) For photographing, instead of collodion, the following compound must be used bichromate of potash, 3 parts; gum, 4 parts; honey, 1 part; water, 100 parts. This liquid is spread over the enamel, and after remaining in the dark some time, exposed in the camera or under the negative, it is developed by brushing over it a powder made of oxid of cobalt, 18 parts; black oxid of iron, 9 parts; red lead, 10 parts; sand, 30 parts. The bichromate is decomposed by immersion in a bath of water acidulated with five per cent. of hydrochloric acid; then Wash it clean in water, dry, and gradually expose to heat until the enamel vitrifies, then cool gradually and carefully. Photographs thus made are claimed to be everlasting; but we must confess that we never tried this process, and only give it on the authority of the statements made by its inventor.
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