Read it through once

The walls of the ditch were brilliant with yellow banks of sulphur and with lava and pumice-stone of many colors. No fire was visible any where, but gusts of sulphurous steam issued silently and invisibly from a thousand little cracks and fissures in the crater, and were wafted to our noses with every breeze. But so long as we kept our nostrils buried in our handkerchiefs, there was small danger of suffocation.