Pixophrenic
Member
So you are not opposed to the idea that this ingredient could be both a hardener and a developing agent. Or such that it becomes a hardener during the development reaction. It has been assumed without reason that Harvey's developer uses one or more of the better known developing compounds, while it was overlooked that he made hundreds of tests, in his own words, to come up with an original compound. "The formula for the Harvey developer will not be disclosed. Great skill is required to manufacture it. The reducing agent is original and not obtainable in the market anywhere." Sounds like there was a capable friend who could synthesize it. Or was it all a smokescreen?Mees & James, 3rd ed p371 notes the temperature coefficient T is the ratio of the rate of development at a particular temperature to the rate at a temperature 10 degrees lower on the Centigrade scale.
It is particularly high for developers containing ppd. Among other things, T for a soft emulsion is substantially higher than that for a hard emulsion. Maybe Harveys contains an ingredient to harden the emulsion.