Alleyn took the dead arms and moved them across the table. ‘You see, they follow the marks exactly. Here on the floor are the things he knocked off. Modeller’s tools. A plate—smashed in four pieces. Two dishes that were probably intended for use as etching baths. There’s almost as much dust under them as there is on the rest of the floor, so they haven’t been there more than a day or two. They themselves are not very dusty—he brushed them with his sleeves. Agreed that there’s a strong likelihood he swept them off?’

‘Certainly,’ said Fox.

‘All right. Now look again at the table. This bottle which held the nitric acid and this cup into which it was poured—these two objects we find bang in the middle of the area he swept with his arms in the violent spasm that followed the moment when he drank. Why were they not hurled to the floor with the plate and the modeller’s tools?’

‘By God, because they were put there afterwards,’ said Curtis.

‘Yes, and why was that cup which he held with his left hand put down on the right of the table with the print on the far side? To put the cup down where we found it he must have stood where I am now—or here—or perhaps here. Well, say he drank the stuff while he was in such a position. After taking it he put the cup at this end of the table and the bottle, which has a left-hand print, beside it. He then moved to the chair, swept away the other stuff in his death throes, but replaced the bottle and the cup.’

‘Which is absurd,’ said Thompson solemnly.

‘Ugh,’ said Bailey.

‘I think it is,’ said Alleyn. He glanced at Curtis. ‘What would happen when he drank nitric acid?’

‘Undiluted?’

‘I think so.’

‘Very quick and remarkably horrible.’ Curtis gave a rapid description of what would happen. ‘He wouldn’t perform any intelligent action. The initial shock would be terrific, and intense spasms would follow immediately. It’s quite beyond the bounds of possibility that he would replace the cup, seat himself, or do anything but make some uncontrolled and violent movement such as you’ve described in reference to the arms. But I cannot believe, Alleyn, that anybody in his senses could ever take nitric acid without knowing what he was doing.’

‘If he was not in his senses, but half doped with opium, and very thirsty? If he asked for a drink and it was put beside him?’

‘That’s more likely, certainly, but still—’

‘If he was asleep in his chair with his mouth open, and it was poured into his mouth,’ said Alleyn. ‘What about that?’

‘Well then—of course’—Curtis shrugged—‘that would explain everything.’