Harry didn't know whether to be comforted or not by the fact that Ron had taken the bottle without arguing anymore. It meant that Ron was still unwilling to run any of his plans by him or Hermione, which still indicated that he was doing things they probably wouldn't approve of. Harry hadn't been able to do anything about that, though, and neither had Hermione, no matter how many times they'd tried.
"I don't know exactly," he said. "I think how much you take affects how long it lasts, though, not as much how well it works. Hermione probably knows exactly how it works."