[CHAPTER XXV.]
OXYGEN.
"We were saying that oxygen——" cried Miss Miette, with a smile, that evening, after dinner, seeing that Monsieur Roger had completely forgotten his promise.
"Yes," Monsieur Dalize hastened to add, as he wished to distract his friend from sad thoughts; "yes, my dear Roger, we were saying that oxygen——"
"Is a gas," continued Monsieur Roger, good-humoredly. "Yes, it is a gas; and Miette, I suppose, will want to ask me, 'What is gas?'"
"Certainly," said Miette.
"Well, it is only recently that we have found out, although the old scientists, who called themselves alchemists, had remarked that besides those things that come within reach of our senses there also exists something invisible, impalpable; and, as their scientific methods did not enable them to detect this thing, they had considered it a portion of the spirit land; and indeed some of the names which they adopted under this idea still remain in common use. Don't we often call alcohol 'spirits of wine'? As these ancients did not see the air which surrounded them, it was difficult for them to know that men live in an ocean of gas, in the same way as fish live in water; and they could not imagine that air is a matter just as much as water is. You remember that universal gravitation was discovered through——"
"The fall of an apple," said Miette.