ENAMELLED PHOTOGRAPHS. In the "Comptes Rendus" of June 11, 1855, various methods of producing enamelled photographs are described by M. A. Lafon de Camarsac. The following translation of this article is extracted from the Journal of the Photographic Society for September 21st, 1855 : " I select for grounds either metals or substances used for pottery ; .
I use vitrifiable compounds for tracing the image on them ; and I operate both on the images obtained by the use of metallic salts and those furnished by the resins.
" With pictures produced by the aid of collodion, albumen, gela tine, and by the ordinary processes of the salts of silver, I develop the image by nitrate of silver until the half tints are overdone and obscured, and the deep shades are covered with a thick deposit presenting the appearance of a bas-relief. The proof is then placed in an enamel ler's muffle ; the organic matters vanish under the action of a suitable temperature. The fire cleans the image and restores all its delicacy.
" I operate on white grounds, or black, or coloured grounds. On tinted porcelain, coloured glass, or on brown or black enamel, the whites of the image are formed by the deposit of reduced metal, which acquires great brilliancy in the furnace. On white porcelain, or enamel, or on transparent glass, the blacks of the image will be formed by the metallic deposit, which I then treat with solutions of salts of tin, salts of gold, or salts of chromium. In the latter case I obtain various colours, very vigorous when removed from the muffle, pre senting a peculiar semi-metallic brilliancy. A very thin layer of an appropriate and very fusible flux fixes the image on the ground, as in the case of applying gold or silver to porcelain. On enamel, the fusion of the matrix itself fulfils the same office.
" With regard to images obtained by the action of light upon salts of chromium,—as soon as the image is cleaned by distilled water I expose it in a muffle to temperature which destroys the gelatine ; the metallic deposit remains alone upon the ground. Salts of silver and of lead laid on this give yellow tints after baking; salts of tin and of gold produce violets and purples. These colours are developed under a layer of flux which here covers the metallic deposit. The
image presents the appearance of a painting on porcelain.
" The pictures furnished by resins are treated differently. I com pound a coating capable of receiving application of a negative, and of being easily rendered sticky after the exposure to light. Solution of bitumen of Judrea in essence of turpentine, with the addition of resin, fulfils this requirement. The exposure to light being finished and the solvent having performed its office, I proceed to the substitu tion of ceramic colours for this varnish, which must be destroyed by the fire. Metallic oxides and their fluxes, ground very fine and dried, are deposited on the surface of the image, while a gentle and gra duated heat restores to the coating the adhesive property it had lost in drying. These enamel powders, carried over the entire surface of the picture, follow with great delicacy all the inequalities of the sub ject, which they partially penetrate, and translate faithfully all its depths and delic,acies. The piece is then ready for the fire ; the organic matters are destroyed, and the image, formed of indestructible substances, remains fixed by vitrification.
" One of the remarkable characters of these images is the aspect of under-enamel (nut-email) which they present, which cannot be fur nished in the same degree of perfection by any other kind of painting.
" The heliographic image thus treated may receive any kind of colouring : it may be transformed into gold or silver as well as into blue or purple ; it may even be burnt into porcelain with the furnace/ colours.
" Observing that, in the same image, the light, in tracing the bright parts, left a faithful image of the shadows, and that the entire negative cliche might be transformed into a positive clich4-1 was led to com bine two opposite and successive impressions of the aame image. By taking from one of these impressions all the light tints and from the other all the dark ones, I obtained the image of the lights (defined) by the shades, and of the shades (defined) by the lights, with the infinite variety of tints resulting from the combination."