Describing electro-etching in 1852 “If, for instance, plates of copper be covered on any part of their surface with a stratum of varnish, that part will be excluded from the line of action, while all else is being consumed. Advantage has been taken of this, by coating the plate with proper composition and then tracing through it any design, of which an etching is required. The plate in this condition is submitted to the action of nascent oxygen, and the surface is readily and effectively etched. There is some superiority to possessed by this method, over the ordinary etching by the use of nitric acid; for the operation can be conducted with considerable regularity; it can be rendered a slow or speedy process; and the results can be taken out from time to time, to be examined, and can be re-submitted in a moment.”
