What does sinclair mean when he says “they were regular alchemists at durham’s” (lines 25-26)

In "The Jungle" when Sinclair refers to "regular alchemists at Durham's" means that they were creating meats from a variety of sources, later in the text you found this comment “They advertised "potted chicken,"--and it was like the boardinghouse soup of the comic papers, through which a chicken had walked with rubbers on. Perhaps they had a secret process for making chickens chemically--who knows?” here you can infer that the chicken announced actually does not look like chicken.

you need to include the text. we have no idea what you are referring to

lol

today at the bank, an old lady asked me to check her balance. so i pushed her over.