‘The Laboratory’ references both Robert Browning’s eponymous poem and the life of the 17th century murderer Marie Madeleine Marguerite D'Aubray who inspired it.
The poem opens with this verse:
‘Now that I, tying thy glass mask tightly,
May gaze thro' these faint smokes curling whitely,
As thou pliest thy trade in this devil's-smithy--
Which is the poison to poison her, prithee?’