It had completely saturated the atmosphere.

A few minutes more and it would have killed the travellers, not like carbonic acid, by smothering them, but by burning them up, as a strong draught burns up the coals in a stove.
[Illustration: "THE OXYGEN!" HE CRIED.] It took nearly an hour for the air to become pure enough to allow the lungs their natural play.

Slowly and by degrees, the travellers recovered from their intoxication; they had actually to sleep off the fumes of the oxygen as a drunkard has to sleep off the effects of his brandy.

When Ardan learned that he was responsible for the whole trouble, do you think the information disconcerted him?
Not a bit of it.
On the contrary, he was rather proud of having done something startling, to break the monotony of the journey; and to put a little life, as he said, into old Barbican and the grim Captain, so as to get a little fun out of such grave philosophers.
After laughing heartily at the comical figure cut by his two friends capering like crazy students at the _Closerie des Lilas_, he went on moralizing on the incident: "For my part, I'm not a bit sorry for having partaken of this fuddling gas.

It gives me an idea, dear boys.