Process for pulsed flow, balanced double jet precipitation

Claim 1

In a process for double jet precipitation of silver halide particles in which a silver salt solution and a halide salt solution are each separately introduced into and diluted by a gelatin solution disposed in both a primary and a secondary mixing zone defined within a reaction vessel by a rotating mixing element, the gelatin solution being initially devoid of silver halide particles, the axis of rotation of the mixing element being coincident with the central axis of the reaction vessel, comprising the steps of: (a) introducing a predetermined volume of one of the silver salt solution or the halide salt solution into the gelatin solution at a predetermined point spaced from the mixing member and substantially along its axis of rotation in the primary mixing zone; (b) pausing a first predetermined time interval to allow the first salt solution to enter a predetermined distance into the gelatin solution; (c) thereafter introducing a predetermined volume of the other of the salt solutions into the gelatin solution at substantially the same predetermined point in the primary mixing zone; (d) pausing a second predetermined time interval to allow the second salt solution to enter a predetermined distance into the gelatin solution; and (e) repeating steps (a) through (d).