The gas is easily produced using readily available ingredients. The usual method employed is to add a concentrated acid to an inorganic sulfide. For example adding concentrated hydrochloric acid to calcium sulfide leads to the rapid production of the gas.
2HCl + CaS 4 H2 S + CaCl
The sulfide used in the early spate of Japanese suicides was reported as ‘bath sulphur’ a product used as a supplement added to bath water for therapeutic use. In western countries where there is little interest in sulphur baths, the commonest source of sulfides is the readily available ‘Lime Sulphur’ used as a common fungicide and insecticide by home gardeners. The major ingredient is calcium polysulfide (CaSx
) in aqueous
solution. The addition of a strong acid to Lime Sulphur liquid in a plastic bucket results in the copious production of hydrogen sulfide gas. Common acids that release the gas include hydrochloric acid (HCl) available from hardware stores, and used as a paving, brick or toilet bowl cleaner, or as a swimming pool chemical, where it is used to lower the pH of the pool. An alternative acid that can be used in sulphuric acid (H2
is used in vehicle lead acid batteries. SO4 ) (See Chapter 6) which