Professor Snape was forcing them to research antidotes. They took this one seriously, as he had hinted that he might be poisoning one of them before Christmas to see if their antidote worked.
J. K. RowlingThere was a horrible smell in the kitchen the next morning when Harry went in for breakfast. It seemed to be coming from a large metal tub in the sink. He went to have a look. The tub was full of what looked like dirty rags swimming in gray water. "What's this?" he asked Aunt Petunia. "Your new school uniform," she said. Harry looked in the bowl again. "Oh," he said, "I didn't realize it had to be so wet.
J. K. Rowling