718 ABOUT THE ATMOSPHERE AND ITS PHENOMENA. 



ammoma, ozone, vai^or of water and ti-aces of other substancoa which Lave? 

 80 far eladed the formulfo of the chemist. The presence of these substances, 

 so easily managed as to make them common objects in the laboratory, de- 

 monstrates that they are introduced into the atmosphere, or mixed with it^ 

 from the earth. And the life of plants and animals — their processes of life 

 evidence that from the immense quantities thrown oft", or utilized, thev 

 must be re-absorbed into the circulation of the globe, or life would become 

 extinct by their abundance overcharging the atmosphere witii their noxious 

 properties. For we must remember the nature of its chief components is to 

 resist combination — their office is to diffuse, not absorb and change. 



Then we come to the other phenomena, which are apparent to the senses 

 only in their ultra manifestations — in stonns, clouds, rain, thunder, light- 

 nings. That these are impossible without direct connection, is so patent 

 to the sense that they hardly need extended notice. The cloud discharges 

 itself upon the earth, the earth responds to the cloud, and when intensely 

 excited even earthquakes answer in sympathy, and declare the universal 

 kinship of matter. 



That the same currents of circulation pervade both, the response of the 

 magnet to the splendors of the aurora attest, and even man by invoking 

 this kinship can talk from mountain top to mountain toj), as has been done, 

 by simply asking the air to bear his messages — showing that the life cur- 

 rents of matter equally pervade the atmosphere with the more palpable 

 elements of the solid globe. 



That there is this intimate and constant relation between the earth and 

 air — an absorption and e7nanation, so to speak — is better illustrated by the 

 elements forming the smaller components of the atmosphere. And why 

 should it not be so, when before our senses every day is shown that beyond 

 all absorbents and disinfectants is mother earth, and beyond all diffusant 

 mediums is the sustaining air. Take for example carbonic acid. If the 

 supply is too small, life languishes, if over-abundant, death intervenes. That 

 the supply is not everywhere and at all times the same, we see in the con- 

 ditions of health in cities, and in marshy districts, and at certain periods ; 

 in the sometimes rank display of vegetation, and in places where no plant 

 can live froni. its excess. It is exhaled into the air b}^ animal respiration, 

 by combustion of fuel, from decay of organic matter, from volcanoes, from 

 thermal Avaters. It goes back through the leaves and by the roots of plants 

 — but this is only one of the methsd-s — it is stoi-ed in the coal measures, and 

 the peat beds show that the process of storing it beyond the normal wants 

 of life is keeping pace with the ages. That the atmosphere contained once 

 immensely more than now, the saurian age, when only cold blooded animals 

 could live on the earth, attests. Eestore the carbonic acid of that period, 

 and mammal life would become at once extinct. 



Next is the vapor of water — its nature proolainis it an emanation and in 

 constant flow from the earth. Then, we find ammonia, so intensely diff'u- 

 sive, and bo strong in affinity for other substances, that its presence in the 



