In the world of greenery, no good deed goes unpunished

Bright yellow though it be, sulphur is, from one point of view, a pretty green product as well. Its principal source, providing more than 80% of the total made, is compounds derived from refining oil and gas, which would otherwise go to waste. Left in situ, these would gum up catalysts and also burn to form sulphur dioxide, a notorious pollutant that causes acid rain. Instead, their sulphurous contents are used in the vulcanisation of rubber, to make preservatives for foods and as ingredients of soap. They are also turned into sulphuric acid, a chemical of great industrial importance that is used, among other things, in the manufacture of fertiliser.