"The Laboratory" isn't about the kind of science we usually think about. There are no white coats or controlled experiments or anything like that. Still, the poem does take place in a laboratory of some kind. Even though they wouldn't have used the same words or methods, guys like the poison-maker in this poem are doing a kind of science. Good for them! Oh wait—Browning is telling a story about love and revenge, but he's definitely in love with the details of the laboratory. He spends a lot of time talking about vials and mortars and gums and mixing and pounding, inviting us to see this world of science through the enamored eyes of his speaker.
The speaker's interest in the laboratory lets us know that she's not just some mean and crazy so-and-so. No! She's also a curious, clever, and sharp-eyed so-and-so as well.
Beware! "The Laboratory" takes a dark view of the possibilities of science, showing us its dangerous, devilish side and its power to do evil.