Quote Originally Posted by DREW WILEY View Post
About all I know is that once I forgot to add the pinch of sulfite first and the metol wouldn't dissolve at
all! Packaged D76 contains a sequestering agent.
Metol will dissolve in plain water the solubility is 50g/l according to the MSDS.

Some one noticed that oxygen in the water caused a discoloration. True, but the amount of oxidation is insignificant in the case of developers. But since then people have been adding a pinch of sulfite for none other than cosmetic purposes.

The sequestering agent is to prevent calcium sulfite from precipitating when tap water is used.