The Century, 1882
Bichromate of potash appears to be coming into use as a tanning material. The action of this chemical upon gelatine, under the influence of light, is well known, and is used in certain photo-printing processes. The leather prepared by the use of the new material is known as chrome leather, and from all accounts it appears to resist decay quite as well as leather prepared by the use of tannin obtained from oak bark. The chief gain of the process is a material shortening of the time - good leather, it is said, being obtained from raw hides in two weeks. No change in the process seems to be introduced. No intimation is given in the accounts of the new process whether the leather, while in the bath of bichromate, is exposed to light or not. The action of light upon the bichromate when combined with gelatine is to produce a hardening of the gelatine, which causes it to resist water (this being the basis of the photo-printing processes), and as the tanning is a hardening of the gelatine, it may be presumed that the new process is partly actinic.
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