Its allowed, definitly, and i've made chemistry references before in my riddles (no one got it).
As for WHAT the answer is, saturation of a string...well, most of us know what saturation is, but in crystalisation, it is definitly not the string is saturated. The solution is saturated (works better if its heated too), not the string. So I honestly cannot think of any chemistry experiment (and i've done a few) that fits this description. The thing that hits me here is "rightfully gain copper". This could indeed refer to the pretty blue copper sulphate, but you dont gain copper - you gain a copper salt. A possible alternative is that it refers to a piece of copper equipment, and the crystals might be some of the many strange articles seen in the game which may be crystals.
