In chapter 9, What went into the mixture for “potted chicken”?

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? said Jurgis' friend; the things that went into the mixture were tripe, and the fat of pork, and beef suet, and hearts of beef, and finally the waste ends of veal, when they had any.