METEOROLOGY AND OTHER SCIENCES 739 



pretation of meteorological phenomena (up to now we have no other 

 means whereby to arrive at such knowledge), it is evident that meteor- 

 ology may secure most important explanations from a study of the 

 phenomena of the earth's magnetism. 



The chemical properties of the constituents of the atmosphere 

 have hitherto received at the hands of meteorologists relatively 

 little consideration. And yet, this phase of the subject is of the very 

 greatest importance to us. The disintegration of the earth's crust 

 and the production of plant-life upon it stand therewith in intjmate 

 connection. Here again, carbonic acid gas and water-vapor play the 

 principal role. An increase in the carbonic acid gas content of the air 

 would promote in the highest degree the luxuriousness of plant-life. 

 And consequently, more oxygen would be produced. Probably, as 

 first suggested by Koene, all the oxygen of the atmosphere is a pro- 

 duct of plant-life, which has reduced he carbonic acid gas coming 

 from volcanoes to oxygen. The amount of coal present in the earth's 

 crust corresponds tolerably well with the amount of oxygen in the 

 atmosphere. In addition to the carbonic acid gas referred to above, 

 that which is stored in the carbonates - - particularly in limestone - 

 must have been gradually removed from the earth's interior through 

 volcanic action. 



From the foregoing, we perceive how extraordinarily powerful 

 have been the chemical processes at the boundary surface between 

 the atmosphere and the solid crust of the earth. Moreover, the appear- 

 ance of oxygen in the atmosphere, which is so vastly important in 

 animal as well as in human life, is explained. One might have ex- 

 pected that this constituent of the atmosphere, so chemically active, 

 would long ago, through disintegration processes, have been con- 

 sumed. In this domain, meteorology and plant physiology work 

 together. 



The other constituents of the atmosphere, nitrogen, argon, and the 

 numerous rare gases recently discovered by Ramsay, are remarkable 

 by virtue of their chemical inertness. It is, therefore, not astonishing 

 that they have remained in the atmosphere. It is much more sur- 

 prising that one of these gases, namely, helium, is not more met with 

 in the atmosphere, since it has been pointed out that many sources 

 furnish helium to the atmosphere from the interior of the earth. 



In order to explain this difficulty, Johnstone Stoney assumes that 

 the lightest gases, hydrogen and helium, have such active molecular 

 motions that the earth's gravitational force is not sufficiently strong 

 to hold them to our planet. Against this view, the objection has been 

 made that the helium would escape from the higher layers of the 

 atmosphere, and that there, on account of the existing low tempera- 

 ture, the molecular motions of the gas are extremely much reduced. 

 Without wishing to dispute that the Johnstone Stoney view has to 



