Complex sentence: Mr. Knox set up the business when he watch his wife, rose making homemade gelatin in her kitchen, and thought there would be a good business in producing it, thus he moved to Johnstown and set up his business.
Split into simpler sentences: Mr. Knox set up the business after he watched his wife, Rose, making homemade gelatin in her kitchen. He thought there would be a good business opportunity in commercially producing gelatin, thus he moved his family to Johnstown and set up his business.