Thanks for your reply. I read that article a few years ago when I realised how much Uranium glass I had collected (without knowing it) and was a bit worried that it might be a health hazard. I found it informative, very re-assuring and would recommend it to anyone wanting a guide to Uranium glass.
I'm equally lost when it comes to the science of photography or the science of Uranium glass. But that is the point I'm trying to make, a simple, practical test for Uranium glass which is science-free and relies solely on the images produced by my (basic) camera.
It doesn't matter if the colour changes from the eye to camera, or from camera to lap-top. The question is whether the camera accurately reproduces the intensity of the glow or not.
My photos of the Bagley and 113 bowl accurately show what I see, including that the 113 bowl's glow is weaker than that of the Bagley. I would also point out that those photos were taken with the same set-up as the photos of the Walther "Rosen" bowl (in another thread) which was accepted as Uranium glass.
My photos of the Davidson and Inwald pieces are inaccurate (whether or not they pick up some of the glow through proximity to the pieces next to them) because although they appear in the photos to glow very weakly, (hardly at all in the case of the Davidson bowl) to the eye the glow is stronger, is clearly visible to the extent that for some time I thought the Inwald bowl was blue Uranium glass.
The photos show two entirely different reactions to the same UV light-bulb and I have very little doubt that the Rosen, Bagley and 113 bowls all contain Uranium. Whereas the other two pieces do not.