Hypothesis on why Becquerel development works

[jphil]

I have the following hypothesis on to why Becquerel development works. I have not found anything regarding the science of this development process. If anyone has better information, I would appreciate it. I think Becquerel development may work because red light may have just enough energy to develop the silver particle that was effected by light, analogous to how film developers grow the grain size in the gelatin emulsion. I think that the red light may have enough energy to develop the effected grains, but not enough to split up the silver halide unaffected by light. It stands to reason that you cannot use Becquerel development with AgBr because AgBr needs less energy (light) to reduce the silver. Which is also why when you fume with bromine, the exposure time is much less. Anyways, thats my thought in a nutshell. Any comments are most welcome.

[porkkala]

Edmond Becquerel himself explains this phenomenon and his findings in the 1842 publication “Mémoire sur le rayonnement chimique qui accompagne la lumière solaire et la lumière électrique”. He said the important fact discovered by him was that certain rays, which are incapable of carrying out a primary action on paper, are very suitable for continuing this action.

The Becquerel effect works also with silver bromide on paper; Becquerel actually did most of his tests with silver bromide. He announced that he had succeeded with papers impregnated with bromide or chloride of silver, and with plates of iodized silver.

http://gallica.bnf.fr/ark:/12148/bpt6k90370t/f2.image

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