Finally I have a real question. Given what you have said, what would the difference in the pH be of (say) your P-C-Borax developer above using an unlikely but possible scenario that one had a box of pentahydrate versus a box of pure decahydrate and made the developer from one or the other?
Approximately 20g /litre would show a difference of how much pH?
My suspicion is that the single decimal place pH meter wouldn't help one distinguish the one from the other. Yes/no?

Quote Originally Posted by gainer View Post
My Borax Project
Borax has 2 possible states of hydration, decahydrate and pentahydrate. If a 100 gram sample of pure borax has pentahydrate and decahydrate mixed, the assay will show a greater weight than 100 grams. If 5 grams of a 100 gram sample are the pentahydrate and the rest the decahydrate, no matter how purely the saple is composed only of sodium tetraborate and water of hydration, the assay will show 101.5 grams of the decahydrate. There is no way you can tell at time of collecting a sample from a large batch of pure mixture how much of each hydrate you are getting.separated from the solid at a low temperature, it will have a constant weight of borax per unit weight of solution at any (reasonable) higher temperature. The weight per unit volume will stay constant enough for most