using particleEmitter Simulate

How do I control a particleEmitter with particleEmitter.Simulate(dt); I have a particleEmitter on a gameObject called Light Snow. I want to be able to control time of the simulation so it advances at t at 1 frame per second instead of the usual rate or freezes the particles in the scene like a pause.

lightsnow=GameObject.Find("Light Snow").GetComponent(ParticleEmitter).Simulate(t); putting in different values for t does not seem to change the particles.

Just as a test I set t=0 in the update loop but the particleEmitter seems to keep moving at it's regular pace.

Is there a way to control the particles by frame?

Does it work on iphone?