432 



Sir James Dewar 



[Jan. 28, 



radiation affected — from 8 J/* to 14/x — all the other constituents in 

 the atmosphere appear very transparent. The functions of the ozone 

 in our atmosphere would thus seem to be very extensive. 



The carbonic acid absorption for long waves was also determined 

 by the Smithsonian experimenters (loc. cit.), who were able to identify 

 an absorptive region beyond a wave length of 13 /x. Carbonic acjd 

 being present in the atmosphere in smaller proportion than water 

 vapour, its absorption is less important. Since the atmosphere 

 weighs approximately one kg. per sq. cm. the solid layer of carbonic 

 acid snow (4/10,000 by volume, or 6*1/10,000 by weight) would be 

 ■6/lOfchs of a gramme per sq. cm., or only about 4 mm. thick all 

 over the earth's surface. 



The distribution of the principal constituents of the atmosphere 

 has been studied by Cailletet, Muntz and Schloesing, who obtained 

 and analysed samples from a height of 15 J km. They found no 

 variation of the proportions up to that height. An adaptation of 

 the high efficiency rockets devised by Goddard * would, however, 

 make it possible to secure samples from much greater heights. 

 Table IV. is a list of the substances present in the air. The final 

 absorptive effect as estimated by Fowle and Aldrich (loc. cit.) is such 

 that only 20 per cent, of the earth's radiation escapes into space. 



Table IV. — Substances found in the Air. 



Mol. Weight 



Hydrogen and helium ...... 



Water, marsh gas, ammonia, neon 

 Nitrogen, oxygen, carbonic oxide, hydrogen peroxide 

 Argon, carbonic acid, ozone, nitrous and nitric acids 

 Sulphurous acid ....... 



Krypton and xenon ...... 



Radium emanation ...... 



Inorganic dust (factories and volcanoes) 



Organic effusions (natural and industrial) 



Spores and microbes ...... 



Meteoric dust, etc. ...... 



2 and 4 



16 to 20 



28 „ 34 



40 ,, 53 



64 



88 and 128 



222 



Cloud Radiation. 



The earliest charcoal thermoscope was actuated by a beam whose 

 radiation was sifted from most of the long wave lengths by passing 

 through the glass bulb at liquid air temperature. When the present 

 thermoscope therefore is exposed to luminous clouds higher readings 



Smithsonian Coll., 1920. 



