Apple Motion 4 - Manual (Page 660)

This results in the following image:
4 To make the particles generated by each different cell mingle together, select the
Interleave Particles checkbox in the Emitter tab of the Inspector.
5 Select the Flare01 cell in the Layers tab, then set the Scale slider in the Particle Cell tab
of the Inspector to 15%.
Doing this reduces the size of the particles generated by this cell.
6 Select the Spark12 cell in the Layers tab, then set the Scale slider in the Inspector to 45%.
The resulting image should look approximately like this:
Note: If necessary, disable the original Spark12 source layer.
7 Next, change the color of the particles generated by the Spark12 cell by doing the
following:
a Choose Colorize from the Color Mode pop-up menu.
b Click the color well in the Color section of the Inspector and choose a light red color
in the Colors window.
c Close the Colors window.
660 Chapter 11 Working with Particles