of Heat by Gaseous and Liquid Matter. 



85 



the gas substituted for it. If the layer of gas possessed any- 

 sensible absorbing power, the equilibrium of the two sources of 

 heat would be destroyed; the source C would triumph, and 

 from the deflection due to its preponderance the exact amount 

 of heat intercepted by the gas could be calculated. 



When oxygen, hydrogen, or nitrogen was substituted for 

 atmospheric air, no change in the position of the galvanometer- 

 needle occurred ; but when any one of the compound gases was 

 allowed to occupy the space between the plates, a measurable 

 deflection ensued. The plates of rock-salt were not so smooth, 

 nor was their parallelism so perfect as entirely to exclude the 

 gas when they were in contact. The contact was but partial, 

 and hence a stratum of gas sufficient to effect a sensible absorp- 

 tion could find its way between the plates even when they touched 

 each other. On this account the first thickness in the following 

 Tables was really a little more than 0*01 of an inch. The first 

 column in each contains the thickness of the gaseous layer, while 

 the second column contains the absorption expressed in hun- 

 dredths of the total radiation. The first layer of carbonic oxide, 

 for example, absorbed 0*2, and the second layer 0*5 per cent, of 

 the entire heat. 



Table I. — Carbonic Oxide. 







Absorption 



in 







Absorption in 



Thickness of 



hundredths 



of 



Thickness of 



hundredths 



gas. 





the total 

 radiation. 





gas. 





of the total 

 radiation. 



O'Ol of 



an inch 02 





0*4 of an inch 3'5 



002 



a 



0-5 





0-5 



n 



3-8 



0-03 



a 



07 





0-6 



jj 



4-0 



004 



)> 



0-9 





1-0 



)) 



5-1 



0-06 



a 



1-4 





1-5 



)i 



6-1 



0-1 



)) 



1-6 





2-0 



>) 



6-8 



0-3 



t> 



3-0 

 Table II.- 



-c 



arbonic Acid 







0-01 of 



an inch 0*86 





0-4 of 



m inch 5-3 



002 



)) 



1-2 





0-5 



y> 



5-7 



0-03 



>> 



1-5 





0-6 



)) 



5-9 



0-04 



>) 



1-9 





0-7 



)) 



6-0 



005 



>i 



2-1 





0-8 



)) 



61 



006 



)) 



23 





0-9 



)) 



6-2 



01 



» 



3-3 





1-0 



)) 



6-3 



0-2 



» 



41 





1-5 



)j 



7-0 



0-3 



» 



4-8 





20 



}} 



76 



