H.M. opened his eyes. "The surgery window? Then it was actually broken outside, accordin' to you? But, here! As Antrim himself pointed out, why does an outsider choose that window when it'd be much simpler to crack the French one?"
Here was a point which (to my simple mind, in any case) seemed to have been too much muddled with mere words. I said:
"Because he was an outsider. Because he didn't know anything about the house. How should he know anything about the house, or what windows were apt to stick? He walked round the house: and there was a window. He opened the catch from outside with a knife and broke the catch. As for the scratches on the window-sill, which everybody seems to think were made from inside — why shouldn't they have been made from inside? Why shouldn't they have been made when the burglar climbed out?
"Right you are, then. He climbs in. He's looking for a poison, any poison. He finds strychnine neatly labelled. I don't suppose Bowers is a chemist, but anybody knows what strychnine is. He notes that it's the same white powdery stuff as the bromide. So he conceives the idea of substituting it for the stuff Hogenauer has taken away, and pretending it came from here. There's Antrim's bromide container on the shelf in front of Bowers, with a quarter of an ounce gone. So he fills it up with a quarter of an ounce of?'
"Ahhh! Of what? If he didn't come prepared, with what?"
"What about ammonium bromide? Same crystals, and there's bound to be a bottle of it in here. What about common table salt, even? I've got an idea," said the Compleat Detective, "that an analysis of that container would have interesting results."
"Rubbish!" said Evelyn.
All the same, she looked impressed. H.M. continued to tap his pencil on the head of the skull, with a steady ticking which was beginning to get on my nerves. I know it must have been getting on Serpos's nerves. Since Stone had begun to read those papers, Serpos had not said a word. The whisky was wearing off; his nerves were as raw as the blue stubble on his chin; his long collarless neck gave him the look of a clerical dinosaur; and his eyes had begun to water. From the second I had spoken I knew he had recognized me, and he was watching.
Tap, tap, tap went H.M.'s pencil sleepily, tap, tap, tap.
The rain was slackening, and you could hear it distinctly. "Next case," said H.M.