Prof. TyndalPs Contributions to Molecular Physics. 513 



When the absorptions were calculated from these deflections, 

 the absorption of formic ether was found to be 6'3 per cent, in 

 advance of that of sulphuric. 



But in both Tables XVI. and XVII. we notice another case of 

 reversal. In all the experiments with the platinum spiral 

 recorded in Table XV., chloroform showed itself less energetic 

 as an absorber than iodide of methyle ; but in Tables XVI. and 

 XVII. chloroform shows itself to be decidedly the more powerful 

 of the two. Cases of this kind have, in my estimation, a pecu- 

 liar significance, and I therefore take care to verify them. The 

 experiments with all the vapours were therefore repeated, with 

 the following results : — 



Table XVIII.— Radiation throu 



gh Vapours. 



Source, Leslie's 



cube at 21 



2° Fahr. 





Niim of vapour. 



Defl ection. 



Absorption. 



Bisulphide of carbon . 



15-0 



6-6 



Iodide of methyle 



, , 



38-3 



18-8 



Chloroform . . , 



. 



40-7 



21-6 



Iodide of ethyle 



, 



46-2 



29-0 



Benzole . . . 





50-0 



345 



Amylene . . . 





57-8 



47-1 



Sulphuric ether 



, 



60-3 



54-1 



Formic ether . , 



, 



62-1 



60-4 



Acetic ether . , 



, 



64-3 



699 



Total heat . . . 



, 



71-4 



100/0 



The absorption by formic ether is here also 6*3 per cent, in excess 

 of that effected by sulphuric ether; while, as in the last two 

 Tables, chloroform excels iodide of methyle. 



Preserving the quality of the heat unchanged, but reducing 

 its quantity from 71°'4= 227 units to 52°'3 = 86'5 units, the 

 following results were obtained : — 



Table XIX. 





Name of vapour. 



Deflection. 



Absorption 



Iodide of methyle . 



16-5 



18-3 



Chloroform . . . 



18-5 



20-6 



Iodide of ethyle 



, 24-4 



271 



Benzole .... 



300 



33-3 



Amylene . . . 



38-6 



48-6 



Sulphuric ether . . 



40-3 



53-2 



Formic ether . . , 



42-8 



60-0 



