I'm not sure if this has been discussed - What advantages or disadvantages are there to having the nozzles hear or far when making a double run emulsions. I suspect it's best to have them apart, giving the halide time to disperse into the emulsion before the silver is introduced. If they are really close, then I can imagine you can get irregular mixing as the stream of silver ions mixed with the halide ions. And I'm sure it doesn't take much distance, especially if rather slow addition rates are used. But any thought, observations, or speculation?