396 FKAGMENTS OF SCIENCE. 



being 10 per cent., that of iodide of methyl is 16; with 

 the blackened cube as source, the absorption by chloro- 

 form is 22 per cent., .while that by the iodide of methyl 

 is only 19. This inversion is not the result of tem- 

 perature merely; for when a platinum wire, heated to 

 the temperature of boiling water, is employed as a 

 source, the iodide continues to be the most powerful 

 absorber. All the experiments hitherto made go to 

 prove that from heated lampblack an emission takes 

 place which synchronises in an especial manner with 

 chloroform. For the cube at 100 C., coated with 

 lampblack, the absorption by chloroform is more than 

 three times that by sulphide of carbon; for the radia- 

 tion from the most luminous portion of a gas-flame the 

 absorption by chloroform is also considerably in excess 

 of that by bisulphide of carbon; while, for the flame 

 of a Bunsen's burner, from which the incandescent 

 carbon particles are removed by the free admixture of 

 air, the absorption by bisulphide of carbon is nearly 

 twice that of chloroform. The removal of the carbon 

 particles more than doubles the relative transparency of 

 the chloroform. Testing, moreover, the radiation from 

 various parts of the same flame, it was found that for 

 the blue base of the flame the bisulphide of carbon was 

 most opaque, while for all other parts of the flame 

 the chloroform was most opaque. For the radiation 

 from a very small gas flame, consisting of a blue base 

 and a small white tip, the bisulphide was also most 

 opaque, and its opacity very decidedly exceeded that 

 of the chloroform when the source of heat was the 

 flame of bisulphide of carbon. Comparing the radia- 

 tion from a Leslie's cube coated with isinglass with 

 that from a similar cube coated with lampblack, at the 

 common temperature of 100 C., it was found that, 

 out of eleven vapours, all but one absorbed the radia- 



