How does Jeeves prevent Mr. Trotter from leaving Brinkley in Chapter 21?

Mr. Trotter plans to leave to see a doctor due to stomach problems he has been experiencing at Brinkley. Dahlia is concerned because Trotter has not yet committed to buying her newspaper. To prevent Trotter from leaving, Jeeves offers to make him one of his special drinks, which is likely to soothe Trotter's stomach.