86 Prof. Tyndall on the Absorption and Radiation 



Table III.— Nitrous Oxide. 







Absorption in 





Absorption in 



Thickness of 



hundredths 



Thickness of 



hundredths 



gas 



. 



of the total 

 radiation. 



gas. 



of the total 

 radiation. 



0-01 of 



an inch 



1-48 



0*4 of an inch 



10-20 



002 



)) 



233 



0-5 



11-00 



0-03 



a 



3-80 



0-6 „ 



11-70 



0-04 



ii 



4-00 



0-8 „ 



12-17 



0-05 



}} 



4-20 



1-0 „ 



12-80 



01 



» 



6-00 



1-5 „ 



14-20 



02 



}} 



7-77 



20 „ 



15-7 







Table IV.— defiant Gas. 





0-01 of 



an inch 



1-80 



0'5 of an inch 



23-30 



0-02 



}> 



3-08 



10 „ 



26-33 



0-05 



)> 



5-37 



2-0 „ 



32-80 



0-1 



a 



9-14 







We here find that a layer of olefiant gas only 2 inches in thick- 

 ness intercepts nearly 33 per cent, of the radiation from our 

 source. Supposing our globe to be encircled by a shell of olefiant 

 gas only 2 inches in thickness, this shell would offer a scarcely 

 sensible obstacle to the passage of the solar rays earthward, but 

 it would cut off at least 33 per cent, of the terrestrial radiation 

 and in great part return it. Under such a canopy, trifling as it 

 may appear, the surface of the earth would be kept at a stifling 

 temperature. The possible influence of an atmospheric envelope 

 on the temperature of a planet is here forcibly illustrated. 



The only vapour which I have examined with the piston appa- 

 ratus is that of sulphuric ether. Glass fragments were placed 

 in a U tube and wetted with the ether. Through this tube dry 

 air was gently forced, whence it passed, vapour-laden, into the 

 space between the rock-salt plates S S\ The following Table 

 contains the results. 



Table V. — Air saturated with the Vapour of Sulphuric Ether. 



Absorption in 



hundredths 



of the total 



radiation. 



207 



Thickness of 

 vapour. 



005 of an inch 



O'l 



0-2 



0-4 



4-6 



8-7 



14-3 



Thickness of 

 vapour. 



0*8 of an inch 



1-5 



20 



Absorption in 



hundredths 



of the total 



radiation. 



21-0 

 34-6 

 35-1 



Comparing these results with those obtained with olefiant gas, 

 we find for thicknesses of 0'05 of an inch and 2 inches respect- 

 ively the following absorptions : — 



