The Romance of Modern Chemistry

SMALL CAUSES; GREAT EFFECTS sulphur trioxide, which need only be dissolved in water to produce sulphuric acid. This sounds all very simple, and, in fact, this way of making sulphuric acid was discovered long ago. It could not, however, be employed on the manufacturing scale, as the platinum turned out to be very sensitive to impurities in the sulphur dioxide, and gradually be- came ineffective. Ways and means, however, have now been discovered for thoroughly removing the impurities and keeping the platinum in good condition, so that what for long was merely a laboratory experiment has now become the basis of a very important manufacturing operation. The “ contact ” process is rapidly coming to the front, and bids fair to oust the old and cumbrous method of manufacture, the prominent feature of which is the use of huge leaden chambers. In recent years platinum has been prepared in another condition in which it exhibits remarkable catalytic act- ivity, namely in solution in water. It may seem to the reader rather absurd to speak of dissolving a metal in water, as if it were so much sugar or salt, but it is indeed a fact that, by the help of the electric current, platinum has been got into water in such a state that it closely resembles a dissolved substance. If two pieces of stout platinum wire are immersed in water so that their points are very close together, and an electric discharge is passed across the intervening space, the water gradually assumes a deep brown colour, and is found then to contain platinum in solution. At least it seems to be in solution, for the liquid may be filtered through a piece of blotting-paper without leaving any particles behind, and it may be kept for a long time without depositing any sediment. On grounds, however, into which we cannot go here, the 332