Hydrogen sulfide is a particularly foul-smelling gas, common to sewers and rotting eggs.

It had not one source, but many, far underground or beyond the hills, and then it spread out to become a marsh from which issued bubbles of foul-smelling gas.

The magnetic lock was demolished by a blast from a thermo-beamer and the door swung open in a cloud of foul-smelling gas.

He said the firefighters' job was complicated because of the design of the system, which included fans that would normally suck foul-smelling gases into the carbon filters.

Llongctik lacked a single great mountain worthy of the name and foul-smelling gases heaved from the crust into the murky seas and astonishingly mucky atmosphere.

The alleyways were filled with decaying and decomposing carcasses - sheep and goats, even cattle, their swollen I' bodies releasing foul-smelling gas into the foetid air.

A bubble of foul-smelling gas followed the probe to the surface.

Bubbles of foul-smelling sulphurous gas churned around the sides of the hull.

Acids react with it to rapidly produce hydrogen sulfide, which is a toxic and foul-smelling gas.

In a normal swamp it would have been a bubble of foul-smelling gas bursting to leave ripples and a flag of mud in the water.