As their arms brushed, and she settled in next to him, Peter looked over at Sadie with a bit of a frown as he took in the look of the girl only a few years younger than him. In one instance he saw her as a potential student, and that bothered him, the way he looked at her and the way she looked to him; yet, on the other hand, he looked at her as a peer. Someone he was close to in age, someone who probably shared more interests than one of his much older colleagues.
Sighing a second, he shook his head clear of the thoughts and turned back towards the parchment they were looking at, "Boiling is a combination of too much of a particular substance, and thickening of another. There're different elements that go into potion making, but always two guarantees; there's one meant to be a base, it 'thickens' it, gives it substance. It's where the power exists for the potion; then there's another that heats it up, causes the 'steam', it's what allows it to absorb and get into the body to create the magic effect. They require a particular balance or one becomes too powerful, or the power becomes negated and can't be absorbed."