Combeferre finds Enjolras's earnest attempts at questions (which are intelligent, but also betray his utter ignorance) highly endearing, of course. Still, he grows animated, gesticulating wildly with both hands as he explains the chemical reactions involved.

When the lull comes, he hesitates, and notes Enjolras's silence. He lets a hand come to rest on Enjolras's shoulder. "Is Valjean still at Milliways, or has he left?"

It's as good an opening question as any, Combeferre feels.