Abstract: The invention relates to a novel process for the chemical sensitization of silver halide photographic emulsions.The process according to the invention comprises adding as additional sensitizing agents a 40-260 .mu. moles/mole of a cyclic polyether containing 1 nitrogen and 5 oxygen atoms, or 2 nitrogen and 4 oxygen atoms, or 3 nitrogen and 3 oxygen atoms, or 4 nitrogen and 2 oxygen atoms as well as 12 carbon atoms and/or their complexes formed with gold and/or palladium and optionally 40-260 .mu. moles/mole of silver halide) of gold (I) or gold (III) sulfide to the sulfur-sensitized emulsion, and employing the cyclic polyether in relation to the noble metal salt in a molar ratio of 0.5:1-5:1 for the complex formation.

Abstract: The invention relates to a process for removing nucleic acids and purine bases from gelatine by(a) adding cyclodextrin bead polymer having a particle size of 20 to 600 .mu., a cyclodextrin content of 30 to 70% and a polyvinyl alcohol content of 0.3 to 0.5% to the gelatin solution in a weight ratio of 1:1 to 10:1 calculated on the amount of the gelatin then filtering off the cyclodextrin polymer or(b) passing the gelatin solution through a cyclodextrin bead polymer column, whereby the amount of the gelatin is 5 to 50% of the weight of the column charge, then eluting the nucleic acids and the purine bases from the cyclodextrin bead polymer.