The Romance of Modern Chemistry

SMALL CAUSES; GREAT EFFECTS The reader is probably familiar with the experiment in which a lighted taper is brought to the mouth of a soda- water bottle containing a mixture of hydrogen and oxygen. A vigorous action, marked by a violent explosion, takes place between the gases, and water is produced. The striking liberation of energy which accompanies the chemical action between hydrogen and oxygen is evidence of the extreme eagerness of the two elements to “ go for ” each other. Yet, if care is taken to remove all traces of moisture from the original gases, this lust of battle has apparently gone. A tube containing a mixture of per- fectly dry hydrogen and perfectly dry oxygen may be strongly heated without the contents exploding—a really astounding result. It has been put on record that in twelve successive experiments on pairs of tubes, one of each pair containing perfectly dried hydrogen and oxygen, the other containing the imperfectly dried gases, the result of heating the tubes to redness in a Bunsen burner was invariably the same; there was an explosion in the tube containing the im- perfectly dried gases, but no explosion in the other. It is true that in order to secure this result the gases in the latter tube had been very carefully dried for ten days, but this does not detract from the striking character of the experiments. “ Dried for ten days ! ” the reader may exclaim ; “ how is that done ? ” He must, of course, dismiss from his mind the idea of using any ordinary methods of drying wet objects. A gas can be dried only by letting it come in contact with some material which has an intense fond- ness for water, and which will readily absorb it when- ever it gets the chance. Such substances are quicklime, sulphuric acid, and phosphoric oxide. 327