Radiant Heat, and it? Conversion thereby into Sound. 461 

 Table II. 



Polished tube. Blackened tube. 



Spiral Spiral Spiral 



dull. bright. duU. 



Bisulphide of carbon . 3°-() 2°*4 3°0 



Chloroform .... 7-0 4*6 5'0 



Benzol 9-4 7'5 10-0 



Iodide of ethyl . . . 13-6 S'6 12-3 



Iodide of methyl . . .15-6 10-7 13-8 



Amylene 206 14-3 17*5 



Sulphuric ether . . . 27'0 21'0 23"8 



Acetic ether .... 33-0 23-0 29-0 



Formic ether .... 33-0 23"0 3O0 



The vapour-pressures here are the same as those employed 

 in Table I. The order of absorption is the same in both tables; 

 but its amount is diminished. This was to be expected, from 

 the difference in the quality of the heat. We are dealing with 

 transparent vapours — in other words, rapours pervious to the 

 luminous rays; and the greater the proportion of these rays in 

 the calorific beam, the less will be the absorption. This is 

 well illustrated by the second column in the table, which shows 

 the fall of the absorption when the spiral is raised from a dull 

 red to almost a white heat. The polished tube was used in 

 both these cases. 



The third column of figures in Table II. shows the results 

 obtained when the experimental tube was coated within with 

 lampblack. The absorptions are in the same order, and almost 

 of the same amount as those of the first column. The case is 

 representative, and might be multiplied to any extent. It is 

 incompatible with the notion that my results were due to films 

 collected on the polished interior surface of my experimental 

 tube. 



Placing the substances recently experimented on in the 

 order of their absorption, and also in the order which they 

 exhibited in 1864, we have the following two columns: — 

 1880. 1864. 



Bisulphide of carbon. Bisulphide of carbon. 



Chloroform. Chloroform. 



Benzol. Iodide of methyl. 



Iodide of ethyl. Iodide of ethyl. 



Iodide of methyl. Benzol. 



Amylene. Amylene. 



Sulphuric ether. Sulphuric ether. 



Acetic ether. Acetic ether. 



Formic ether. Formic ether. 



Phil Mag. S. 5. Vol. 13. No. 83. June 1882. 2M 



