“Here's the stuff,” he explained, holding it out to the Chief Constable. “That's the hydrobromide, of course—a salt of the alkaloid itself. This is the compound that's used in medicine.”
Now that he had got it, Sir Clinton seemed to have little interest in the substance. He handed it across to Flamborough who, after looking at it with would-be sagacity, returned it to Markfield.
“There's just one other point that occurs to me,” the Chief Constable explained, as Markfield returned the poison-bottle to its original place. “Have you, by any chance, got an old notebook belonging to young Hassendean on the premises? Anything of the sort would do.”
The Inspector could make nothing of this demand and his face betrayed his perplexity as he considered it. Markfield thought for a few moments before replying, evidently trying to recall the existence of any article which would suit Sir Clinton's purpose.
“I think I've got a rough notebook of his somewhere in my room,” he said at last. “But it's only a record of weighings and things like that. Would it do?”
“The very thing,” Sir Clinton declared, gratefully. “I'd be much obliged if you could lay your hands on it for me now. I hope it isn't troubling you too much.”
It was evident from Markfield's expression that he was as much puzzled as the Inspector; and his curiosity seemed to quicken his steps on the way back to his room. After a few minutes’ hunting, he unearthed the notebook of which he was in search and laid it on the table before Sir Clinton. Flamborough, familiar with young Hassendean's writing, had no difficulty in seeing that the notes were in the dead man's hand.
Sir Clinton turned over the leaves idly, examining an entry here and there. The last one seemed to satisfy him, and he put an end to his inspection. Flamborough bent over the table and was mystified to find only the following entry on the exposed leaf:
| Weight of potash bulb | = | 50.7789 | grs. |
| Weight of potash bulb + CO₂ | = | 50.9825 | grs. |
| ─────────── | |||
| Weight of CO₂ | = | 0.2046 | grs. |
“By the way,” said Sir Clinton casually, “do you happen to have one of your own notebooks at hand—something with the same sort of thing in them?”