| Show hydrogen peroxide many blany years ago it was discovered that hydrogen peroxide slowly dissolves out of the reduced silver and the gelatin substratum ot of a photographic plate and thus leaves a relief image with the denser portions sunk and the parts least affected photographically to raised the process has been quickened so as to be compi completed etea in a few minutes by adding a little acetic acid to the peroxide bath or using a dilute solution containing hydrochloric dro add acid and barium dioxide seeking to improve the process further belan and drouilland Dro illand have brought out in france a bath in which nitric acid copper sulphate and potassium bromide are added to the hydrogen peroxide A positive image Is obtained it if the negative has not previously fixed in and the variations of shade are represented by varying of silver this positive image Is given any desired tint by being myde to absorb aniline colors the thick parts of the image take up considerable sid erable color and the thin parts proportionately less prints may be obtained from simple contact with the colored positive while damp one soaking in the color bath yielding twe two or three impressions |
