THE 

 LCWDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



-*- 



[FOURTH SERIES.] 



OCTOBER 1866. 



XXXI. On the Absorption of Radiant Heat by Dry and by Moist 

 Air. By H. Wild*. 



THE results of the beautiful researches made, almost simul- 

 taneously, by Professor Magnus of Berlin and Professor 

 Tyndall of London t, on the absorption of radiant heat by different 

 gases, agree on the whole as closely as could be expected, consi- 

 dering the delicacy of the measurements. Hence it is the more 

 striking that these investigators differ so widely in their state- 

 ments concerning the absorption by dry and by moist atmo- 

 spheric air. 



Whilst Professor Magnus maintains, in the most recent pub- 

 lication known to me, that the moisture which, under ordinary 

 circumstances, is mixed with air has only a very trifling, if any, 

 influence on the absorptive power of the latter, Professor Tyndall 

 infers from his old, as well as from his recent experiments, that 

 the absorption is sensibly increased when dry air is mixed with 

 aqueous vapour. 



The decision of this disputed point has manifestly a consider- 

 able interest for meteorology ; hence, on occupying myself during 

 the past winter with the new phenomena of radiant heat, and 

 after arranging an apparatus by means of which it was possible 

 to demonstrate satisfactorily, according to a slightly modified 

 form of TyndalPs method, the most important facts connected 

 with the absorptive power of gases (even in my lectures on experi- 

 mental physics), I felt myself induced to enter more closely into 

 an examination of the point in question. The following de- 



* Translated from a separate impression communicated by the Author, 

 having been read to the Scientific Society, Berne, June 9, 1866. 



t [For an account of the order of sequence of these investigations see 

 Phil. Mag. for April 1862, p. 252.— Eds.] 



Phil. Mag. S. 4. Vol. 32. No. 216. Oct. 1866. R 



