510 Prof. TyndalPs Contributions to Molecular Physics. 



With the same spiral, brought still nearer to its point of 

 fusion, the following results were obtained with four of the 

 vapours : — 



Table XIV. — Radiation through Vapours. Source, platinum 

 spiral at an intense white heat. 



Name of vapour. Deflection. Absorption. 



o 



Bisulphide of carbon . . 14*5 2*5 1 



Bisulphide of carbon . . 14*5 2*5 J 



Chloroform 23'0 391 



Chloroform 23-0 3*9 J 



Formic ether 60*4 21*31 



Formic ether ..... 60-5 21*3 J 



Sulphuric ether .... 62-3 23'6 \ 



Sulphuric ether .... 62*5 23'8 J 



Total heat 82'7 100-0 



In the experiments recorded in the foregoing Table, a total 

 heat of 82°'7, or 588 units, was employed; and to test whether 

 the absorption calculated from this high total agreed with the 

 absorptions calculated from a low total, a portion of the current 

 was diverted, the branch passing through the galvanometer pro- 

 ducing a deflection of 49°*4. This corresponds to 77 units. 

 The source, it will be observed, is here quite unchanged ; the 

 rays are of the same quality, and pass through the tube in the 

 same quantity as before ; but in the one case the absorption is 

 calculated from the deflection among the high degrees, and in 

 the other case it is calculated from deflections among the low 

 degrees of the galvanometer. 



The experiments were limited to formic and sulphuric ether, 

 with the following results : — 



Deflection. Absorption. Absorption from 

 l Table XIV. 



Formic ether . .17*7 23 21*3 



Sulphuric ether . . 19-1 24*8 23-7 



The agreement is such as to prove that no material error can 

 have crept into the calibration. 



Placing the results obtained with the respective sources side 

 by side, the influence of temperature on the transmission comes 

 out in a very decided manner. 



