In 1984, a teacher was successfully prosecuted by the Health and Safety Executive. The case centred around chemically prepared hydrogen that was dried by bubbling it through concentrated sulfuric(VI) acid and then passed over hot copper(II) oxide. The procedure was often carried out quantitatively to find the mass of copper in a sample of copper(II) oxide and the hydrogen acted as an inert atmosphere to avoid any re-oxidation of the copper. However, if the demonstrator tried to ignite the excess hydrogen before all the air was flushed out then the apparatus exploded. In this case, the bottles of concentrated sulfuric(VI) acid exploded, showering the watching pupils (not wearing eye protection) with acid. To avoid this, microscale techniques can assist chemists to carry out some experiments which on a large scale would be quite hazardous. Hydrogen-oxygen explosions, reducing metal oxides with hydrogen and working with toxic gases can all be carried out very quickly and safely once the techniques have been assimilated and practised. (Contains 13 figures, 1 table, 5 boxes, and 3 online resources.)