742 Dispersion of Carbon Dioxide in the Infra-red Region. 

 The diagram below is drawn using the numbers in Table II. 



n -i =0000 



600 

 550 

 500 

 4-50 

 400 

 350 

 300 

 250 

 200 





f wltftttifo iFP 



'■ "",: " 







Jt ~iT T "t. : : n ~nrr: 



iS2?ls 









3^ 



; ?--^^k£ 







JifmiLUiji iihtttttt 



»234-5676&<0Ulia 14-*->s.in|4 



i3 44-^A.inji 



I repeated the observations for X=l, 2, and 3 //, respec- 

 tively in conditions of greater sensitiveness. As the heat- 

 energy was great m this region I was able to make use of a 

 metallic mirror M'" of radius 3 metres instead of M". 

 M"' B was 3148*7 mm., so that Ad was magnified more than 

 three times. Table III. gives the new values obtained. 



Table III. 



X in /z. 



&d in mm. 



Ap' in mm. 

 of Hg. 



1423 8 



t°G. 



w -l. 



n —l 



reduced to 



absolute value. 



0-5894 Na 



9-9499 



14°-20 



0'000443 7 



| 0-0004508 





9-8786 



1406-6 



14°-20 



445 9 



10 



9-720 



1409-0 



14° 65 



438 3 



1 445 7 





9-8J0 



1421-6 



14°75 



440 5 



2-0 



9-544 



14090 



l4°-65 



430 7 



} 437 4 





9-629 



1421-6 



14°-75 



432 4 



30 



9-274 



1409-0 



14° 65 



418 6 



} 424 





9-283 



1421-6 



14°-75 



416 8 



Analysis of the curve shows the existence of an absorption 

 band at 4*270 fi and a tendency towards another one at about 



14*7 fi. 



Now it is known that carbon dioxide shows anomalous dis- 

 persion at 2*7 15 (i*, 4*270 //,*, and 14*7 fif. I could not detect 

 the presence of a band between 3 and 4 /ju. It may be supposed 

 that, owing to these bands being very near one another, the 

 very marked band at 4*270 fi completely obscured the other. 



* K. Angstrom, Phys. Rev. i. p. 606 (1892). 



t Bubens and Aselikinass, fVied. Ann. lxiv. p. 600 (1898). 



