| 摘要 |
1, 008, 694. Preparing photographic emulsions. GEVAERT PHOTO-PRODUCTEN N.V. May 8, 1962 [May 8, 1961], No. 17712/62. Heading G2E. Gelatino silver halide emulsions are prepared by reacting silver nitrate with an alkali metal halide in an aqueous solution containing gelatin thus precipitating the silver halide in gelatin, the amount of gelatin being not more than 2% by weight of water and the ratio of gelatin to silver nitrate being between 2:100 and 25:100 by weight, physically ripening the silver halide, co-precipitating the gelatin and silver halide by adding an aqueous solution of ammonium sulphate or a mixture of ammonium sulphate and sulphuric acid so that the pull is kept above 7, removing the supernatant liquid, hardening the gelatin and removing residual silver nitrate by washing. Preferably between 5 and 20% by weight of ammonium sulphate is used and more ammonium sulphate is added to harden the gelatin. Specification 655,082 is referred to. |
