Yes, meth is very soluble in water. It's insoluble in acetone, but the acetone you're going to be buying has enough H2O in it to suck out some of your meth along with the acetone. You can use baked epsom salts to draw some of the H2O out beforehand, but it'll still have some. Google it if you want to pursue this, it's trivial really.... I don't think your idea would work. Chemistry is not my thing though, so I can't really tell you why. For one thing though, in the real world and not the ideal situations that are so useful for learning, things are really messy. Like really, really messy. There's probably a dozen different things in random amounts that will always change from one order to the next, so you can't really count on that. Also, I don't see how you're going to measure with the kind of accuracy you'd need to make this feasible.I'm always open to being told I'm just plain fucking wrong though, so speak up if somebody knows I am.