The subtitle to Robert Browning's poem “The Laboratory”, “Ancien Regime”, tells us that it is set in France before the revolution, when the old regime of the monarchy was still in place. The poem is a dramatic monologue. The narrator appears to be a woman, a fact which is not apparent in the opening stanza, but becomes so as the poem develops.
In the first stanza, the narrator addresses another person using the terms 'thou' and 'thy', which are the old-fashioned familiar forms of 'you' and 'your'. She is putting on a mask and watching the person in the laboratory through a haze of smoke: 'thro' these faint smokes curling whitely'. The narrator refers to the laboratory as 'this devil's-smithy', which is the first sign that something sinister is going on. The final line of this stanza leaves us in no doubt of this, as the woman asks, 'Which is the poison to poison her, prithee?' The repetition of 'poison' emphasises its importance.
The opening phrase of the second stanza, 'He is with her,' suggests that the narrator has asked for poison to be concocted because she is jealous. It would seem that her lover has deserted her for another woman. She says that they think she is crying and has gone to pray in 'the drear / Empty church'. The couple, meanwhile, are making fun of her, stressed by the repetition of 'laugh' in line 7. The stanza closes with the brief phrase 'I am here', emphasising the setting of the laboratory which is in such sharp contrast to the church.
The phrase 'Grind away' at the start of the third stanza shows the woman's eagerness for the chemist to make the poison. Browning brings the description alive by using alliteration in the phrases 'moisten and mash' and 'Pound at thy powder'. The narrator is not in a hurry and says she would rather watch the concocting of the poison than be dancing at the King's court.
In the fourth stanza the narrator comments on the ingredients of the poison. The chemist is mixing it with a pestle and mortar, and the woman describes the gum from a tree as 'gold oozings', giving the impression that it is both beautiful and valuable. She then looks at a blue liquid in a 'soft phial', finding the colour 'exquisite'. She imagines that it will taste sweet because of its beautiful appearance and is surprised that it is a poison.
Stanza five begins with the narrator wishing she possessed all the ingredients, which she refers to as 'treasures'. Browning uses personification to describe them as 'a wild crowd', and the woman considers them as 'pleasures', a sinister attitude to poisonous substances. The use of the adjective 'invisible' means that just a tiny amount would be required. The narrator delights in the thought of being able to carry 'pure death' in any one of a list of small accessories, such as an earring or a fan-mount.
In the sixth stanza the narrator turns her thoughts to how easy it will be at court to give 'a mere lozenge', like a sweet, that will kill a woman in just half an hour. She names two women in this stanza, Pauline and Elise, and it is not clear if one of them is the current target of her jealousy and desire to murder. She delights at the thought of Elise dying, and Browning uses enjambment to create the list 'her head / And her breast and her arms and her hands', perhaps because she is jealous of Elise's beauty.
The seventh stanza opens with the sudden exclamation 'Quick!' and the narrator is now excited as the poison is ready. She then reveals her disappointment, however, as its colour is 'grim', unlike the blue liquid in the phial. She hoped that it would make her intended victim's drink look so appetising that she would be encouraged to drink it. In the eighth stanza she is concerned about how tiny the amount of poison is: 'What a drop!' She says that the other woman is considerably bigger than her, and thinks that she 'ensnared' or caught the man in her trap because of her size. The narrator is not convinced that the drop of poison will be fatal: 'this never will free / The soul from those masculine eyes'. It will not be enough to stop the victim's pulse, which the narrator describes as 'magnificent'.
In the ninth stanza the narrator recounts, in lines using enjambment, how she had gazed at the other woman the previous evening when her ex-lover was with whispering to her. She had hoped that by staring at her she 'would fall shrivelled'. This obviously did not happen, but the narrator knows that the poison will do its work. Stanza ten has slightly shorter lines than the others, and the narrator addresses the chemist directly. She knows that the poison will act quickly, but she does not want her victim to have an easy death: 'Not that I bid you spare her the pain'. Browning uses alliteration in a cluster of three to describe how the narrator wants the other woman to suffer the effects of the poison, in the phrase 'Brand, burn up, bite'. The stanza ends with the narrator commenting that her ex-lover will always have the memory of the pain on the dying woman's face, and she appears to relish this thought.
The narrator asks the chemist if the poison is ready at the start of the eleventh stanza. She asks him to remove her mask and not to be 'morose', or gloomy. The poison will be lethal for her victim, and she does not want the mask to stop her having a good look at it. She describes it with the alliterative phrase 'a delicate droplet', and alliteration appears again as she comments 'my whole fortune's fee!' meaning that it has cost her everything she owns. In the closing line of the stanza, she wonders if she herself can be harmed by the poison, considering the effect it will have on her victim.
The twelfth and final stanza begins with the narrator once again showing how much the poison is costing her. She tells the chemist 'Now take all my jewels, gorge gold to your fill', and the alliteration in the phrase 'gorge gold' adds emphasis. She shows her gratitude by telling the chemist, whom she addresses as 'old man', that he may kiss her on her lips if he would like to. She asks him, however, to 'brush this dust off' her, referring to traces of poison, as she is afraid it will harm her too: 'lest horror it brings'. The poem ends as she proclaims that she will 'dance at the King's!' a triumphant announcement. Whether or not her victim dies from ingesting the poison, we do not know, but she shows no remorse and is obviously determined to go through with her murderous plan.
Browning has used an anapaestic metre in “The Laboratory”, in other words two stressed syllables followed by one unstressed one. This gives the lines of poetry an upbeat, fast-paced rhythm that convey the woman's excitement at the idea of poisoning her victim. Browning has created a character who is totally ruthless and eaten up by jealousy, determined to carry out an act of revenge that will prove fatal to another woman.
In his book “Revise the English and English Literature Anthology,” Tony Childs states that the narrator of “The Laboratory” is based on an imaginary incident in the life of Marie Madeleine Marguerite D'Aubray Brinvilliers (1630-76). In reality, she killed her father and two brothers by poisoning them and also planned to poison her husband. Although her victims were all male, Browning has adapted the character into a dangerously jealous woman targeting her ex-lover's new female interests. His portrait of her is utterly convincing.