Which gas did Jacques Charles discover could be used as the source of hot air for a hot air balloon's envelope?

Dec 15, 2016

$F e \left(s\right) + {H}_{2} S {O}_{4} \left(a q\right) \rightarrow {H}_{2} \left(g\right) + F e S {O}_{4} \left(a q\right)$.