Prof. Magnus on the Propagation of Heat in Gases. 103 

 Transmission of the Heat of a Gas-flame (continued) . 



Blackened tube. 



Unblackened tube. 



No. 



Position 

 of equi- 

 librium 

 of the 

 needle. 



Mean. 



Ob- 

 served 

 deflec- 

 tion. 



Differ- 

 ence. 



No. 



Position 

 of equi- 

 librium Mean, 

 of the 

 needle. 



Ob- 

 served 

 deflec- 

 tion. 



Differ- 

 ence. 



Ammonia under 1 atm. pressure. 



XIa 



o- 



+0-5 

 07 

 0-7 

 07 



+0-25 

 06 

 0-7 

 07 



o 



117 

 120 

 12-2 

 12-2 



11-45 

 11-4 

 11-5 

 11-5 



XIa 



+0-5 

 07 

 07 

 07 

 0-7 



+0-6 

 0-7 

 07 

 0-7 



56-5 

 567 

 56-5 

 56-7 



55-9 

 56-0 

 55-8 

 56-0 



Mean 11-5 



Corresponding to ... 11-5 

 XI: XI a = 19-3: 11-5 = 100: 5958 



Mean 55-9 



Corresponding to ... 224-0 

 XI :XIa=265: 224 = 100: 8452 



The relation of the radiation through the various gases is 

 therefore the following : — 









Blackened 



Unblackened 









tube. 



tube. 



Atmospheric air under 1 atm. . 



. 100 



100 







4 millims. 



. 102-6 



117-21 







6 millims. 



. 102-3 









8 millims. 





117-37 



Oxygen 



under 



1 atm. . 



. 100 



100 



Hydrogen 



)> 



)> 



98-85 



98-26 



Carbonic acic 







94-11 



91-59 



Carbonic oxide „ 





94-15 



84-52 



Protoxide of nitrogen 



» 



9005 



88-57 



Marsh-gas 







98-27 



89-87 



defiant gas 

 Ammonia* 



» 



yy 



T65-71 



\6703 



59-58 



70-33 

 71-55 

 84-52 



Since oxygen gave the same values as atmospheric air, it ap- 

 peared superfluous to investigate nitrogen. 



The great difference between the radiation in rarefied space, 

 according as it is investigated in the blackened or in the un- 

 blackened tube, led me to determine it once more. This was 

 done with the unblackened tube in such a manner that the de- 

 flections were smaller than before, which was effected by remo- 



* As tbe tube had to be filled with ammonia without using the air-pump, 

 it is not improbable that small quantities of atmospheric air may have been 

 left ; for in passing the gas through a tube 35 millims. wide, it is very dif- 

 ficult to expel the air completely. For this reason I have not examined 

 cyanogen. 



