Dear APUG Members, I recently bought a box of color transparency's, which were advertised as being from the 1930s/1940s, but i am not quite sure what kind they are. Maybe the APUG community would be so kind to help me with this? There are 2 kinds of transparency's in the box: - (1) Good color and sharpness with a silverish emulsion on the back. When you look at the back and turn it a bit sideways it looks like a negative, but when you look at it from the glossy front it looks normal. Image size (not counting the black borders of the transparency): 5.9 by 5.6cm and a bit under 6 by 9cm - (2) Less/washed out color and a bit less sharp. Glossy on both sides (no silverish emulsion). These have a 7 digit number at the side and about 5 of them are dated 1949. Image size (not counting the black borders of the transparency): 5.9 by 5.6cm Could number 1 be Kodachrome sheet film and number 2 be Ektachrome sheet film? Or were there any other color films availible in the 1930s/1940s in these sizes? I really hope someone could help me identify these. Please also see the pictures in the attachment (either numbered 1 or 2) Thank you.