256 SCIENCE FROM AN EASY CHAIR 



stituents may have some action on those who drink or 

 bathe in the water. Ever since the time of the Romans 

 natural mineral waters have been sought, and the springs 

 which discharge them have been frequented, not because 

 their chemical composition was known, but because ex- 

 perience seemed to show that they produced a beneficial 

 result. It can hardly be doubted that the baths and 

 springs frequented at the present day are not so much 

 themselves the cause of the benefit to the cure-seekers 

 as are the change of scene and diet, and the repose and 

 regular life willingly accepted by those who travel so far 

 to reach these springs. 



With regard to ozone, there remains something more 

 to be said, namely, in regard to its application, in a far 

 less diluted form than is possible when it is taken into 

 the lungs, to the destruction of putrefying organic matter 

 and putrefactive and disease-producing bacteria. It is 

 now some five or six years since air containing a high 

 percentage of ozone produced by the action of the 

 electric discharge was used for the purification of the 

 water-supply of large towns. It is a fact that river water 

 into which such ozone containing air is pumped becomes 

 pure in the highest degree, in consequence of the destruc- 

 tion by the ozone's oxydising action, both of the bacterial 

 germs always present in vast numbers in river water and 

 of the organic matter on which the bacteria depend. 

 This application of ozone is in use in several large towns 

 for the purification of drinking-water, for which purpose it 

 has very great advantages. It has also been successfully 

 used by Dr. Allen, the director of the Plymouth Marine 

 Laboratory, for keeping the water of the marine aquarium 

 there in a state of purity and well charged with oxygen 

 gas. A similar use has been made of oxygen containing 

 a considerable percentage of ozone by enterprising surgeons 

 for the cleansing of ulcer and abscess. It is clear that such 



