What exactly have I got here?

[interneg]

Thanks for the info, I'm interested in experimenting triple color-filtered BW glass plate negative, I'll start with those wrattens you point. This is not separating colors from film, but from scene, but it should work close.

Shouldn't make any difference between in camera or darkroom separations. A lot of colour work was done in this manner on single-shot cameras with the filtration done by pellicle beam-splitters inside the camera. Check out the work of Madame Yevonde to see what could be done with those cameras in the pre-Kodachrome era.

Good luck!