The advance of photography : its history and modern applications (1911)

HISTORICAL SURVEY objects, these parts remained white, whilst the uncovered portions of the paper were blackened by the light ; and thus was produced a white outline, or " white silhouette/' of the superimposed objects upon a black ground (see figs. 1 and 2). Wedgwood produced in this manner copies of drawings upon glass, in white lines upon a black ground ; and this process became the basis of a mode of treatment which attained great importance, under the name of the lichtpaus process. Unfortunately these pictures were not durable. They Fig. i. had to be kept in the dark, and could only be exhibited in a subdued light. If they remained long exposed to the light, the white parts also became black ; and thus the picture disappeared. No means were then known to make the pictures durable— that is to say, to make them unalterable by light, or, as we now say, to fix them. But the first step towards the discovery of photography was made ; and the idea of producing pictures of objects without the help of the draughtsman became, after these first attempts, so extremely attractive that, from that time, both in England and in France, a large number of private persons occupied themselves with the subject with the greatest enthusiasm.