 What is Hilary's tone described as "dark" when he remarks that there will be people interested in using his before-shave lotion?
They manufacture simple compositions like polishing waxes and sell them from door-to-door. Some groups have built up tidy little bank accounts which are available for later educational expenses." Marjorie put back her head and laughed, and I was forced to join her, for we both recognize that my understanding and "feel" for commercial matters—if I may use that expression—is almost nonexistent. "Well, sure, I suppose we want to," said Hilary. "No, they're formulations—you know, mixtures. "Some," said Hilary, "and I've got a home laboratory."
 He senses that Donald is underestimating the potential of his good idea
 He senses that Donald is going to dismiss the idea because it is too costly  He senses that Donald is scheming to patent the idea for his own profiteering  He senses that Donald is beginning to understand his malicious intent for the before-shave lotion  He senses that Donald is underestimating the potential of his good idea