The Question and Answer section for Around the World in 80 Days is a great resource to ask questions, find answers, and discuss the novel.
From the text:
Just as the train was whirling through Sydenham, Passepartout suddenly uttered a cry of despair.
"What's the matter?" asked Mr. Fogg.
"Alas! In my hurry—I—I forgot—"
"To turn off the gas in my room!"
I suppose Mr. Fogg is a mysteriously wealthy Englishmen with a knack for gambling, and is generally seen as a confident, inspiring sort of man. Sounds like this might be something he would like to do.
This depends on what chapter you are referring to.