A Manual Of Photography

HELTOGEAPIIY. THE PROCESS OF M. NIEPCE. 15 adhere to the varnish. The plate is now to be dried with great care by a gentle evaporation: to preserve the picture, it is requisite to cover it up from the action of light and protect it from humidity. 5â protect it The varnish may be applied indifferently to metals, stone, or glass, but M. Niepce prefers copper plated with silver. To -à of engravings a small quantity of wax is dissolved described ° Iav.ender’ ^d added to the varnish already on the surfs b having, first varnished over the back, is placed exposed to n0 ° ?o prepared tablet, face towards it, and then exposure motion of the light. In the camera obscura an of Iio-10 i 10111 TX to, ??ght hours, varying with the intensity to ernå ^ed ; while from four to six hours is necessary a copy T, Waving. The picture, in the first Ze, ' !S ^presented by the contrast between the polished silver and the varnish coating. The discoverer afterwards adopted a plan of darkening the silver by iodine, which appears to have led the way to Daguerre’s beautiful process. To darken the tablet, it was placed in a box in which some iodine was strewed, and watched until the best effect was produced. The varnish was afterwards removed by spirit of wine. Of the use of glass plates M. Niepce thus speaks: — “ Two experiments in landscape upon glass, by means of the camera. $1? me results which, although imperfect, appear deserving of variety of application may be brought more easily to perfection, and in the end become a more interesting department of heliography. interesting varnkh0116 °f these the tight acted in such a way that the “proportion to the intensity with which gradation ' and the picture exhibited a more marked bindsr-mo n ,0^0 ; so that, viewed by transmitted light, the landscape produced, to a certain extent, the well-known effects of the diorama. 4 Known eiiecus in the second trial, on the contrary, the action of the ominous fluid having been more intense, the parts acted upon y the strongest lights, not having been attacked by the solvent remained transparent; the difference of tone resulted from the relative thickness of the coatings of varnish If this landscape is viewed by reflection in a mirror on ^“fe^at a certain angle, the effect™™™»^ shanS ^ |Ty tTmi “ed- ^ * " confused an'd shapeless : but, what is equally surprising, in this position the Mimic tracery seems to affect the local colour of the1objects” wenfSH eniCnt1Niepce was enabled to engrave by light t the round of the press : but this does not appear to have