The Romance of Modern Chemistry

NATURES BUILDING MATERIAL elements are simply modifications of one original parent substance. This plausible suggestion was made long ago, and has been revived at occasional intervals, but the evid- ence of experiment has so far been against its acceptance. In the earlier part of this chapter the elements have been frequently referred to as existing in a state of com- bination, in the form of compound substances. Now a compound of two elements is something quite different from a mere mixture. The two elements which combine do so in a very thorough and intimate fashion, with the result that each, as it were, loses its own individuality, and an entirely new individual, with other characteristics, is pro- duced. The two differently coloured bricks, which we may suppose to represent the two elements, are not merely laid side by side so that we could lift the one away from the other without any trouble, but they are fused and coalesced in some mysterious manner into one new brick, different in shape and colour from each of the two original ones. The only statement we can make with certainty about the new brick is that its weight is equal to the sum of the weights of the two component bricks. It is very interesting to observe that in some cases we can start with two elements and make either a mixture or a compound of them. Two such elements are iron and sulphur. If the iron is taken in the form of fine filings, which are grey in colour, and if these are inti- mately mixed by grinding with sulphur, which is yellow, a powder is obtained which is intermediate in colour between grey and yellow. And in this mechanical mixture each component retains its own characteristics just as if the other were not there. The particles of iron can be drawn out of the mixture with a magnet; the 83 c