It was mere chance, mere luck, as to when the exact moment of death came to him.

There had been six pills in that box--there were five left.

So Collishaw picked out the poisoned pill--first! It might have been delayed till the sixth dose, you see--but he was doomed." Mitchington showed a desire to speak, and Bryce paused.
"What about what Ransford said before the Coroner ?" asked Mitchington.
"He demanded certain information about the post-mortem, you know, which, he said, ought to have shown that there was nothing poisonous in those pills." "Pooh!" exclaimed Bryce contemptuously.

"Mere bluff! Of such a pill as that I've described there'd be no trace but the sugar coating--and the poison.

I tell you, I haven't the least doubt that that was how the poison was administered.