However, the steward, during our sleep, had cleared the table.

I breathed with difficulty.

The heavy air seemed to oppress my lungs.

Although the cell was large, we had evidently consumed a great part of the oxygen that it contained.

Indeed, each man consumes, in one hour, the oxygen contained in more than 176 pints of air, and this air, charged (as then) with a nearly equal quantity of carbonic acid, becomes unbreathable.
It became necessary to renew the atmosphere of our prison, and no doubt the whole in the submarine boat.