The first color process (which, by its nature, had to have at least some red sensitivity) was patented in, IIRC, 1869. Dry gelatin plates had some red sensitivity unless care was taken to prevent it; even a pure silver chloride emulsion has a little (very little) response to red light. The products available in the 1890s weren't what we'd now call panchromatic, but there was enough red response to record images that would read as full color to the eye.