Quote Originally Posted by Kirk Keyes View Post
Have you collected some and done some spot tests to see what it is? Does it burn after drying? What's the pH if you dissolve it in some more water? If you can dissolve some in water, does it form a precipitate with calcium ions?

There are 3 simple tests to get you headed in the right direction for identifying the precipitate.
It does dissolve when I add more water.
My tap water is eminently suited for drinking because of its good taste and calcium content. It forms a precipitate in most developers that contain carbonate. I don't see that with this version of Metolal, but I have been using demineralized water. If I were to substitute an equimolar amount of p-aminophenol and reduce KOH accordingly, I would see no lingering precipitate. I can try that as soon as my shipment of p-aminophenol arrives.
I hate to try filtering the K2SO4 out of the precipitated metol freebase, but if everything else dissolved, that should tell me something. At the moment, I'm also fresh out of Metol.