388 FRAGMENTS OF SCIENCE. 



hot platinum spiral to pass through it; benzol absorbs 

 43 and transmits 57 per cent, of the same radiation; 

 alcohol absorbs 67 and transmits 33 per cent., and alco- 

 hol, as an absorber of radiant heat, stands at the head 

 of all liquids except one. The exception is water. A 

 layer of this substance, of the thickness above given, 

 absorbs 81 per cent., and permits only 19 per cent, of 

 the radiation to pass through it. Had no single experi- 

 ment ever been made upon the vapour of water, its 

 vigorous action upon radiant heat might be inferred 

 from the deportment of the liquid. 



The relation of absorption and radiation to the 

 chemical constitution of the radiating and absorbing 

 substances was next briefly considered. For the first 

 six substances in the list of liquids examined, the radi- 

 ant and absorbent powers augment as the number of 

 atoms in the compound molecule augments. Thus, 

 bisulphide of carbon has 3 atoms, chloroform 5, iodide 

 of ethyl 8, benzol 12, and amylene 15 atoms in their 

 respective molecules. The order of their power as radi- 

 ants and absorbents is that here indicated, bisulphide 

 of carbon being the feeblest, and amylene the strongest 

 of the six. Alcohol, however, excels benzol as an ab- 

 sorber, though it has but 9 atoms in its molecule; but, 

 on the other hand, its molecule is rendered more com- 

 plex by the introduction of a new element. Benzol 

 contains carbon and hydrogen, while alcohol contains 

 carbon, hydrogen and oxygen. Thus, not only does 

 atomic multitude come into play in absorption and 

 radiation atomic complexity must also be taken into 

 account. I would recommend to the particular atten- 

 tion of chemists the molecule of water; the deportment 

 of this substance towards radiant heat being perfectly 

 anomalous, if the chemical formula at present ascribed 

 to it be correct. 



