Intelligence and Miscellaneous Articles. 483 



and in consequence a more attenuated rarefaction of the interstellar 

 gaseous matter. — Comptes Eendus de I'Academie des Sciences, Oct. 30, 

 1882, p. 769. 



ON A PROPERTY OF THE COEFFICIENT OF ABSORPTION. 

 BY EILHABD WIEDEMANN. 



Bunsen represents the absorption-coefficient a. at a temperature 

 / by the formula 



a=a — bt+cf, 



in which a and b = a constant. 

 Instead of this, we can write 



c=a \l--t+ c -f } 

 [ a a J 



In the following Table I have set down, together with the values 

 of a, b . 10 8 , and c . 10 7 , the values of b / a and c I a for a series of 

 and water : — 



Hydrogen 



Nitrogen 



Air 



Diethyl 



Carbonic oxide 



Osygen 



Marsh-gas 



Dimethyl 



Hydride of ethyl 



Ethylene 



Propylene 



Nitrous oxide 



Carbonic acid 



Sulphurettedhydrogen. . 



Sulphurous acid 



Chlorine : 



0-0193 

 0-0203 

 00247 

 0-0315 

 0-0329 

 0-0412 

 0-0545 

 0-0871 

 0-0946 

 0-2563 

 0-4465 

 1-3052 

 1-7967 

 4-3706 

 79-789 

 3-0361 



654 



1045 



816 



1089 



1180 



3324 



3532 



9136 



22075 



45362 



77610 



83687 



2607700 



46196 







112 



135 



251 



164 



226 



103 



603 



628 



1881 



5388 



6483 



16424 



5213 



263490 



1107 





 002648 

 0-026487 



0-033198 



0-0243 

 1 0-02648 

 i 002166 

 j 0-03816 

 | 0-03735 



0-03564 

 ! 004943 

 • 003475 

 ! 0-04320 



0-01914 

 1 0-03268 







0-000548 

 0-000548 

 0-000796 

 0000499 

 0-000548 

 0-000188 

 0-0O0692 

 0-000663 

 0-000(354 

 0-000206 

 0-000496 

 0-000914 

 0-000119 

 0-000367 



It will be remarked that the values of b/a in this Table vary only 

 from 0-02 to O05, while a itself ascends from 0-02 to 79-789, *. e. 

 up to 4000 times the former value. But the values of b/a indicate 

 how large a fraction of the gas absorbed at 0° escapes on the tem- 

 perature being raised 1° ; and from the above it follows that that 

 fraction varies within very narrow limits for all gases. 



In order to further test this proposition, it would be necessary 

 to institute experiments for larger intervals of temperature. 



A comparison of the absorptions in alcohol gave similar results. 

 — Wiedemann's Anncden, vol. xvii. p. 349 (1882). 



