Things didn't improve for the Gryffindors as the Potions lesson continued. Snape put them all into pairs and set them to mixing up a simple potion to cure boils. He swept around in his long black cloak, watching them weigh dried nettles and crush snake fangs, criticizing almost everyone except Malfoy, whom he seemed to like. He was just telling everyone to look at the perfect way Malfoy had stewed his horned slugs when clouds of acid green smoke and a loud hissing filled the dungeon. Neville had somehow managed to melt Seamus's cauldron into a twisted blob, and their potion was seeping across the stone floor, burning holes in people's shoes. Within seconds, the whole class was standing on their stools while Neville, who had been drenched in the potion when the cauldron collapsed, moaned in pain as angry red boils sprang up all over his arms and legs.

　　"Idiot boy!" snarled Snape, clearing the spilled potion away with one wave of his wand. "I suppose you added the porcupine quills before taking the cauldron off the fire?"

　　Neville whimpered as boils started to pop up all over his nose.

　　"Take him up to the hospital wing," Snape spat at Seamus. Then he rounded on Harry and Ron, who had been working next to Neville.

　　"You -- Potter -- why didn't you tell him not to add the quills? Thought he'd make you look good if he got it wrong, did you? That's another point you've lost for Gryffindor."

　　This was so unfair that Harry opened his mouth to argue, but Ron kicked him behind their cauldron.

　　"Doi* push it," he muttered, "I've heard Snape can turn very nasty."

　　As they climbed the steps out of the dungeon an hour later, Harry's mind was racing and his spirits were low. He'd lost two points for Gryffindor in his very first week -- why did Snape hate him so much? "Cheer up," said Ron, "Snape's always taking points off Fred and George. Can I come and meet Hagrid with you?"

之后的几节药学深里，情况一点好转的迹象都没有。史纲皮让同学们分成两人一组，教他们如何混合几种简单的药草来治疗烫伤。他穿着他那件宽大的黑斗篷在地牢里走来走去，看他们怎样称那些干等麻和磨碎了的蛇牙。几乎每一个人都挨了骂，只有马尔夫幸免于难。看来史纳皮有点喜欢马尔夫，他告诉大家，要好好地看看马尔夫是怎么做的。当酸性的绿雾从炖着的蛞蝓角上冒起，发出一阵阵嘶嘶的时候，马尔夫他处理得多么好啊！尼维尔却不知道鼓捣了些什么，他居然把谢默斯的大汽锅烧穿了，他们偎着的药汁顺着地势到处流，在同学们的鞋子上烫出一个又一个小洞洞。不到一会儿，整个班的学生都站到他们的桌子上去了。只有尼维尔没来得及跳上桌子，结果，被彻底烧坏的大汽锅倒了下来，药汁溅得他全身都是。他的手臂和腿都被烫红了，尼维尔忍不住呜呜地哭了起来。

　　"傻瓜！"史纲皮咆哮着，用他的魔杖一挥就把地上乱溅的药汁弄干净了。

　　"把汽锅从火上提起来之前，你是不是把豪猪尖刺扔进去了？"尼维尔鼻子上的小疮一个个红得发亮，好像马上就会爆开。现在他哭得更起劲了。

　　"带他到医务室去。"史纳皮吩咐谢默斯。接着，他盯着坐在尼维尔旁边的哈利和罗思，低声说："你——波特——你为什么不告诉尼维尔炖这种药时是不能加入豪猪尖刺的？你是想着，他要是做错了，你就有好戏看了，对不对？我要再扣掉你一分！"这是不公平的！哈利张大嘴正要反驳，罗恩从他们的汽锅下踢了他一脚，暗示他别干傻事。

　　一个小时之后，他们走出了地牢。哈利的心情低落到了极点。

　　入学才一周他就已经被扣掉了两分！为什么史纳皮这么讨厌他？

"嘿，哈利！你得振作起来！"罗恩说，"史纳皮也经常扣弗雷德和乔治的分啦，他不会是针对你的。对了，我能够和你一起去拜访哈格力吗？"