Clearly the idea that 100g in 100ml of water constitutes a 100% solution is not correct. There was a raging debate on the B&S forum about a year ago about this, with the people who have never taken chemistry insistent that this would indeed be a 100% solution. Nevertheless, the formula as printed in unblinkingeye.com IS correct in the amounts it calls for. Keep in mind that the catechol is the main developing agent, not the phenidone. All I can say is that this developer blows the socks off of any other staining developer in terms of sharpness, low b+f, and predictability.