1 : a gelatinous or mucinous substance found in tissues in disease (as in the thyroid) or normally
2 a : a substance that consists of particles dispersed throughout another substance which are too small for resolution with an ordinary light microscope but are incapable of passing through a semipermeable membrane b : a mixture consisting of a colloid together with the medium in which it is dispersed

Platinum and Van Dyke and cyanotype solutions do not contain particles- they are dissolved organic and metal salts in an aqueous solution that WILL pass through a semi-permeable membrane - I know because that is how I filter them when I make them up.

I'm finished on this subject. I know quite enough to know I am right on the definition of an emulsion.