“‘While I think of it,’ he said, looking up suddenly, ‘is there any particular colour you would like me to make?’
“‘Rose pink,’ grunted someone, and he nodded.
“‘Certainly,’ he answered. ‘That will necessitate the addition of a somewhat rare strontium salt—making forty in all.’
“He beamed at us and then he commenced. To say that we watched him closely would hardly convey our attitude: we watched him without movement, without speech, almost without breathing. He weighed his salts, and he mixed them—and that part of the process took an hour at least.
“Then he took up the bowl and we examined that. It was obviously some form of metal, but that was as far as we could get. And it was empty.
“‘Without that retort, gentlemen,’ he remarked, ‘the process would be impossible. There is no secret
