516 Prof. Tyndall's Contributions to Molecular Physics. 



version : the experiments prove that there is a greater synchro- 

 nism between the vibrating periods of chloroform and lampblack 

 than between those of chloroform and platinum raised to the 

 temperature of the lampblack. It will be seen, however, that as 

 the temperature of the platinum falls, the opacity of the chloro- 

 form increases more quickly than that of the iodide : with an 

 intensely white-hot spiral, as shown in Table XXL, the absorp- 

 tion of chloroform is to that of the iodide as 100 : 162, while, 

 with the spiral heated to a temperature of 212° Fahr., the ratio 

 of the absorptions is as 100 : 105. 



§ IX. Radiation from gas-flames through vapours. — Reversals of 



position. 



We have hitherto occupied ourselves with the radiation from 

 heated solids : I will now pass on to the examination of the 

 radiation from flames. The first experiments were made with a 

 steady jet of gas issuing from a small circular burner, the flame 

 being long and tapering. The top and bottom of the flame were 

 excluded, and its most brilliant portion was chosen as the source. 

 The following results were obtained : — 



Table XXIV. — Radiation of heat through Vapours. Source, a 

 highly luminous jet of gas. 



Name of vapour. Deflection. Absorption. White-hot 



spiral. 



Bisulphide of carbon . . 8-9 9-8 2*9 



Chloroform 10-9 12*0 56 



Iodide of methyle . . . 15-4 16-5 7 '8 



Iodide of ethyle .... 17-7 19-5 12-8 



Benzole 20'0 22-0 16-5 



Amylene 27'5 30«2 22'7 



Formic ether 31'5 346 25'1 



Sulphuric ether .... 32'5 35-7 25'9 



Acetic ether 34*2 38-7 27'2 



Total heat 53*8 lOO'O 



It is interesting to compare the heat emitted by the white-hot 

 carbon with that emitted by the white-hot platinum ; and to 

 facilitate the comparison, I have placed beside the results in the 

 last Table those recorded in Table XIII. The emission from 

 the flame is thus proved to be far more powerfully absorbed than 

 the emission from the spiral. Doubtless, however, the carbon, 

 in reaching incandescence, passes through lower stages of tem- 

 perature, and in those stages emits heat more in accord with the 



