Clever actor or innocent intruder, Zendt betrayed neither interest nor disappointment. He simply nodded and went out.
Roger considered his position.
He reasoned: if Zendt was blameless, some one else was watching. From seeing Zendt emerge the unknown would be sure that Roger was still all right. But if he left, all possibility of detecting who was the culprit might be gone.
Still, he had no chemicals in assortments that would enable him to detect the possible introduction of some fume through a hole in the walls, or some other move. Besides, he was open to bodily attack.
He must not be there. No one must see him leave.
He remembered that there were chemicals that he would need, and inasmuch as he was known to be all right, he could easily get them.
He emerged, seeing Doctor Ryder busy with his arrival of white rats, with Toby helping him put them into the glass pen through the trapdoor in the top that prevented them from escaping.
“Got to force-up some underexposed negatives,” he remarked as he passed them. To the stock-room he went, and procured the ingredients he needed; but not for an intensifier for under-exposed film! Returning, he noticed Zendt, watching the rats also.
Once more in the dark-room Roger proceeded methodically and carefully to produce a very businesslike detonating torpedo with crystals of gritty hard iron oxide-rust! to take the place of the gravel usually packed in a commercial torpedo of the sort formerly sold for exploding by contact with the sidewalk.
The other ingredients he mixed with care as to method, as well as formula, knowing that certain chemicals must be combined in a certain sequence. Wrapped in a fairly good paper taken from a packet of printing paper, he had his torpedo ready at last.