Apparatus for making silver halide grains

Apparatus for producing silver halide grains by a process which comprises introducing a water soluble silver salt solution and a water soluble halide solution for purposes of reaction to form silver halide grains into a vertically disposed mixing chamber whose interior is filled with an aqueous colloid solution, which mixing chamber is within a reaction vessel which is also filled with said aqueous colloid solution, comprising:

• the mixing chamber comprising a polygonal-pillar casing, the upper and lower ends of which are open, and which is provided with
• (i) first agitator means in the lower portion thereof to achieve a first agitation which quickly mixes and reacts both reactant liquids;
• and
• (ii) second agitator means in the upper interior portion thereof to achieve a second agitation which quickly expels the silver halide grains formed upwardly into the aqueous colloid solution in the reaction vessel outside said mixing chamber;
• and
• (iii) means for controlling the rate of revolution of said first agitator means and said second agitator means independently of each other.