inted time, call and collect you."

"That is assuming a good deal," I objected. "It is assuming, for
instance, that she lives within a moderate distance of Sloane Square.
Otherwise it would have been impossible."

"Exactly. That is why I assume it. You don't suppose that she goes about
habitually with lumps of prepared sugar in her pocket. And if not, then
she must have got that lump from somewhere. Then the beads suggest a
carefully prepared plan, and, as I said just now, she can hardly have
been made-up when she met us in Kennington Lane. From all of which it
seems likely that her present abode is not very far from Sloane Square."

"At any rate," said I, "it was taking a considerable risk. I might have
left the theatre before she came back."

"Yes," Thorndyke agreed. "But it is like a woman to take chances. A man
would probably have stuck to you when once he had got you off your
guard. But she was ready to take chances. She chanced the railway, and
it came off; she chanced your remaining in the theatre, and that came
off too. She calculated on the probability of your getting tea when you
came out, and she hit it off again. And then she took one chance too
many; she assumed that you probably took sugar in your tea, and she was
wrong."

"We are taking it for granted that the sugar was prepared," I remarked.

"Yes. Our explanation is entirely hypothetical and may be entirely
wrong. But it all hangs together, and if we find any poisonous matter in
the sugar, it will be reasonable to assume that we are right. The sugar
is the Experimentum Crucis. If you will hand it over to me, we will go
up to the laboratory and make a preliminary test or two."

I took the lump of sugar from my pocket and gave it to him, and he
carried it to the gas-burner, by the light of which he examined it with
a lens.

"I don't see any foreign crystals on the surface," said he; "but we had
better make a solution and go to work systematically. If it contains any
poison we may assume that it will be some alkaloid, though I will test
for arsenic too. But a man of Weiss's type would almost certainly use an
alkaloid, on account of its smaller bulk and more ready solubility. You
ought not to have carried this loose in your pocket. For legal purposes
that would seriously interfere with its value as evidence. Bodies that
are suspected of containing poison should be carefully isolated and
preserved from contact with anything that might lead to doubt i