194 Absorption and Radiation of Heat by Gases and Vapours. 



in the former being three-tenths, and in the latter five-tenths of 

 an inch. 



Table XVIII. 



Absorption. 



Bright tube, Blackened tube, Absorption with 

 Vapour. 0-5 tension. - 3 tension. bright tube pro- 



portional to 

 Bisulphide of Carbon . . 5'0 21 23 



Iodide of Metbyle ... 15-8 60 71 



Benzole ...... 175 78 79 



Chloroform 175 89 79 



Iodide of Ethyle ... 21*5 94 97 



Wood-spirit 265 123 120 



Methylic Alcohol . . . 29'0 133 131 



Chloride of Amyle . . . 300 137 135 



Amylene 31 -8 157 143 



The order of absorption is here shown to be the same in both 

 tubes, and the quantity absorbed in the bright tube is, in 

 general, about 4-§- times that absorbed in the black one. In the 

 third column, indeed, I have placed the products of the numbers 

 contained in the first column by 4-5. These results completely 

 dissipate the suspicion that the effects observed with the bright 

 tube could be due to a change of the reflecting power of its 

 inner surface by the contact of the vapours. 



With the blackened tube the order of absorption of the fol- 

 lowing substances, commencing with the lowest, stood thus : — 

 Alcohol, 

 Sulphuric ether, 

 Formic ether, 

 Propionate of ethyle ; 

 whereas with the bright tube they stood thus : — 

 Formic ether, 

 Alcohol, 



Propionate of ethyle, 



Sulphuric ether. 



As already stated, these differences would in all probability 



disappear, or be accounted for on re-examination. Indeed very 



slight differences in the purity of the specimens used would be 



more than sufficient to produce the observed differences of ab- 



" ' [To be continued.] 



* In illustration of this I may state, that of two specimens of methylic 

 alcohol with which I was furnished by two of my chemical friends, one gave 

 an absorption of 84 and the other of 203. The former specimen had been 

 purified with great care, but the latter was not pure. Both specimens, 

 however, went under the common name of methylic alcohol. I have had 

 a special apparatus constructed with a view to examine the influence of 

 ozone on the interior of the experimental tube. 



