Final answer:
Sinclair's use of 'alchemists' is a metaphor for the way workers at Durham's meatpacking plant transformed base or poor-quality products into marketable meat, reflecting the deceptive and unsanitary practices in the industry.
Step-by-step explanation:
When Sinclair writes, “They were regular alchemists at Durham’s,” he is employing a metaphor to criticize the practices at Durham’s meatpacking plant. The term “alchemist” refers historically to someone who tries to change base metals into gold. In the context of Upton Sinclair’s novel “The Jungle,” this statement suggests that the workers at Durham’s were skilled at transforming worthless or unappetizing parts of animals into saleable meat products, much like alchemists attempting to transform lead into gold. This is part of Sinclair’s broader critique on how the meatpacking industry operated, filled with unsanitary conditions and deception. In this sense, the word “alchemist” is used to denote a form of deceitful wizardry in manipulating substances, contributing to the muckraking aspect of Sinclair’s work.