Galvanoplastic manipulations : a practical guide for the gold and silver electroplater and the galvanoplastic operator / translated from the French of Alfred Roseleur by A.A. Fesquet.

  • Roseleur, Alfred, -1879.
Date:
1872
Catalogue details

Licence: Public Domain Mark

Credit: Galvanoplastic manipulations : a practical guide for the gold and silver electroplater and the galvanoplastic operator / translated from the French of Alfred Roseleur by A.A. Fesquet. Source: Wellcome Collection.

    35/536 (page 25)
    phuric acid pickle batli and bave been rinsed. They will remain there until the red coat of protoxide of copper lias entirely disappeared, leaving after rinsing a uniform metallic lustre. The dipping in old aqua fortis is not absolutely necessary, altliough we recommend it, for two reasons, the latter being the more important : First, it econo- mizes the cost of fresh acids ; second, as its action is slow, it prevents the too rapid corrosion of the cleansed copper dnring the time of the solution of the protoxide. If a few operators frequently com- plain of the burned, pitted, or pricked appearance of their pièces, it is due to the neglect of this operation and the direct dipping in stronger aqua fortis. I shall indicate further on the processes for utiliz- ing and extracting ail that can be saved from old aqua fortis and other dipping baths. Dipping in Aqua Fortis and Soot. After rinsing in fresh water, the absolute necessity of which has already been pointed out, the articles, well shaken and drained, are plunged into a batli composed of— Nitric acid at 36° Bauraé (yellow aqua fortis) . . . . 100 parts (volumes). Chloride of sodium (common sait) 1 “ “ Calcined soot 1 “ “ This mixture attacks the métal with the greatest energy, and the pièces should therefore not remain in it more than a few seconds. The volume of acid should be about thirty times as great as that of the articles to be cleaned, in order to prevent too great an élévation of température due to the Chemical re-