At his place he takes off his waistcoat and hangs it up and in the pocket, just separated from the explosive by the lining of the waistcoat, he places, secretly, the tube.

The tube has now four hours of life and the workman three and a half hours of work.

When the whistle goes to knock off for luncheon, the workman leaves his waist coat still hanging up on the peg and goes out in the stream.

But half an hour afterwards, half-way through the hour of luncheon, the acid reaches the explosive.

There is a tiny explosion in that empty hall, not enough to make a great noise, but quite enough to start a big fire; and when the workmen return, the building is ablaze.
No lives are lost, but the factory is burnt down." Hillyard sat for a little while in thought.
"Perhaps you can tell me," he said at length.