Lampblack was used as a filler, applied by way of a special machine. After exposure, the plate was processed to reversal in an acid dichromate type process. The final photograph has a beautiful look with wide tonal gradation and if you could see an original well preserved Autochrome today, you would be amazed at the extrodinary way they age, and can in fact appear as though they were processed only yesterday. The image below is an original Autochrome, photographer unknown. I'm always interested in discussion, scientific or otherwise.
Pitch is the sap or crude turpentine that exudes from the bark of pines.
Elutriation is a method to separate the light and heavy particles by washing. My research into this method, while it does work, causes the grains to puff up, clump, and generally turn into a real mess, in addition to becoming charged with static electricity. Today we would separate the sizes by filtering in an air cyclone prior to dying. It was a purple dye made from a sea creature, now extinct.