511 Prof. Tyndall's Contributions to Molecular Physics. 



Placing the figures of Tables XVL, XVIII., and XIX. side 

 by side, we have an opportunity of seeing how results obtained 

 on different days check each other. 



Table XX. — Source, blackened cube of boiling water. 



Absorptions from 



Name of vapour. Table XVL Table XVIII. Table XIX. 



Bisulphide of carbon . . 6*4 



Iodide of methyle . . . 18'4 



Chloroform 19-5 



Iodide of ethyle .... 



Benzole 



Amylene 



Sulphuric ether .... 54'8 



Formic ether . . . . . 60*9 



Acetic ether 



6-6 





18-8 



18-3 



21-6 



20-6 



29-0 



27-1 



345 



333 



47-1 



48-6 



54-1 



53-2 



60-4 



60-0 



69-9 





Were it essential to my purpose, I should certainly be able to 

 make even the small differences which here show themselves to 

 disappear. But the agreement is such as to place the reliability 

 of the experiments beyond doubt. It will be seen that, contrary 

 to the results obtained with a white-hot spiral, in all three cases, 

 where a blackened cube of boiling water was the source, chloroform 

 exceeds iodide of methyle, and formic ether exceeds sulphuric in 

 absorbent power. To confirm the demonstration, I once more 

 resorted to the white-hot spiral, and obtained the following 

 results : — 



£1. — Radiation through Vapours. 



Source, white- 



platinum spiral. 





Name of vapour. 



Deflection. 



Absorption. 



Chloroform . . 



. . 9-8 



4-5 



Chloroform . 



. 95 



4*5 



Iodide of methyle 



. 16-0 



7-3 



Iodide of methyle 



. 15-8 



73 



Formic ether . 



. 42-1 



24-2 



Formic ether . 



. 42-3 



24-5 



Sulphuric ether 



. 43-6 



26-3 



Sulphuric ether 



. 435 



26-2 



Total heat . . . 



. 70-9 



100-0 



Here chloroform retreats once more behind iodide of methyle, 

 and formic ether behind sulphuric. 



The positions of sulphuric and formic ether are reversed within 

 the range of the experiments made with the platinum spiral, but 

 this is not the case with the chloroform and the iodide of methyle. 



