[sphere and ash]

This is almost certainly a silver gelatin print. Silver is the element that reacts to light and actually holds or contains the image; gelatin is the binding agent that binds the silver to the paper. This is definitely not an albument print.

It is not worth having the photograph "authenticated" unless your authenticator can test for the presence of brightening agents in the paper, which would indicate that the paper is later (1950s). Put another way, there is no way to know if the print dates from 1915 or 1935. I do not believe there is any other scientific means for dating a silver gelatin print.

I hope this helps.