198 FRAGMENTS OF SCIENCE. 



13. Liquids and their Vapors in relation to Radiant 

 Heat. 



The deportment here assigned to atmospheric vapor has 

 been established by direct experiments on air taken from 

 the streets and parks of London, from the downs of Epsorn, 

 from the hills and sea-beach of the Isle of Wight, and also 

 by experiments on air in the first instance dried, and after- 

 ward rendered artificially humid by pure distilled water. 

 It has also been established in the following way : Ten 

 volatile liquids were taken at random and the power of 

 these liquids, at a common thickness, to intercept the waves 

 of heat was carefully determined. The vapors of the liquids 

 were next taken, in quantities proportional to the quantities 

 of liquid, and the power of the vapors to intercept the waves 

 of heat was also determined. Commencing with the sub- 

 stance which exerted the least absorptive power, and pro- 

 ceeding upward to the most energetic, the following order 

 of absorption was observed : 



Liquids. Vapors. 



Bisulphide of carbon. Bisulphide of carbon. 



Chloroform. Chloroform. 



Iodide of methyl. Iodide of methyl. 



Iodide of ethyl. Iodide of ethyl. 



Benzol. Benzol. 



Amylene. Amylene. 



Sulphuric ether. Sulphuric ether. 



Acetic ether. Acetic ether. 



Formic ether. Formic ether. 



Alcohol. Alcohol. ' 

 Water. 



We here find the order of absorption in both cases to 

 be the same. We have liberated the molecules from the 

 bonds which trammel them more or less in a liquid condi- 

 tion ; but this change in their state of aggregation does not 



