I remember this from my own researches into the history of photography, and
I may even have the info around somewhere. Basically, early materials were
sensitive to blue light but no other color--so the 'black' dresses
Victorian woman always appear to be wearing might well have been red. This
is also why clouds and sky tones were hardly ever captured--the blue sky
washed out completely. The color sensitivity was increased to include more
of the spectrum with the 'ortho' emulsions, but panchromatic emulsions did
not appear until (I think) the early 20th century. 

Blue-sensitive and ortho materials could be developed in a darkroom with a
safelight, just as black and white printing is still done today. 

Sign me, Ca n'est pas Daguerre