 What is Hilary's tone described as "dark" when he remarks that there will be people interested in using his before-shave lotion?
"Some," said Hilary, "and I've got a home laboratory." He thought there should be two colors in the same bottle—orange for morning and blue for night, the blue ones designed to leave the mouth alkaline at bed time. Hilary, reluctantly forsaking his ideas on detergents, suggested we make black plastic discs, like poker chips but thinner and as cheap as possible, to scatter on a snowy sidewalk where they would pick up extra heat from the sun and melt the snow more rapidly. These latter ideas had made unknowing use of some basic physics, and I'm afraid I relapsed for a few minutes into the role of teacher and told them a little bit about the laws of radiation and absorption of heat.
 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