Abstract: Method and apparatus of determining the dynamic surface potential of a solution, wherein a steady stream of the solution is formed, and the surface potential at a free surface of the stream of solution is measured by means of a rotary electrode that rotates in close vicinity of, but separated from, the free surface of the solution, and is mounted within an electrically grounded chamber.

Abstract: Light-sensitive photographic silver halide material comprising a hydrophilic colloid layer containing in dispersed state a light-absorbing merostyryl dye that corresponds to the following general formula: ##STR1## in which: R.sup.1 is hydrogen, alkyl, substituted alkyl, aryl, substituted aryl, aralkyl or substituted aralkyl,R.sup.2 is carboxy, alkoxycarbonyl, aryloxycarbonyl, carbamoyl, ureido, sulphamoyl or one of the groups represented by R.sup.1 ;at least one of R.sup.1 and R.sup.2 being or containing carboxy or carbamoyl,R.sup.3 is hydrogen, C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy, and when R.sup.3 is alkyl or alkoxy it stands in ortho or para in respect of the hydroxy group, which itself is in ortho or para in respect of the methine group,said merostyryl dye containing no group that renders the dye soluble in the hydrophilic colloid layer.

Abstract: Fluorine-containing surfactants according to formula (Rf--X).sub.n --A--L--Z wherein Rf is a short-chain fluorine-containing group derived from hexafluoropropylene or trifluorochloroethylene, X is --O--, --S--, or --SO.sub.2 --, n is at least 2, the Rf groups being same or different, L is a monovalent bond or a bivalent bridging group such as --COO--alkylene, --CONR.sup.1 --alkylene, or --SO.sub.2 NR.sup.1 --alkylene, wherein R.sup.1 is hydrogen or C.sub.1 -C.sub.5 alkyl, and Z represents a hydrophilic polyoxyethylene group or a hydrophilic group such as ##STR1## wherein M is hydrogen, an alkali metal, ammonium, or organic ammonium, and R.sup.3 is alkyl; A is an aliphatic, aromatic, or aliphatic-aromatic group. These surfactants can be used in hydrophilic colloid layers, which may form part of light-sensitive silver halide materials.