642 On Light Absorption and Fluorescence. 



Values of O-l)10 8 . 



X. 



Calculated. 



Observed. 



Differences. 



6708 



29302 



29306 



-4 



6438 



29346 



29344 



+2 



5790 



29470 



29468 



+2 



5770 



29474 



29474 







5461 



29550 



29550 







5209 



29626 



29622 



+4 



5086 



29667 



29666 



+ 1 



4800 



29774 



29776 



_o 



Nitrous Oxide. 

 \ (infra-red band) = 4*47 /**, whence v 9 = 0-67114 x 10 14 . 



V* 



In this case the value of — = 50, and the following formula 

 was used : v v 



*-* = lmfxrxv where n261 * io2, = (5 °^ )2 - 





Values of 



0,-1)10*. 





X. 



Calculated. 



Observed. 



Differences. 



6708 



50534 



50544 



-10 



6438 



50614 



50616 



—2 



5790 



50848 



50848 







5770 



50857 



50857 







5461 



51002 



51000 



+2 



5209 



51143 



51145 



—2 



5086 



51216 



51208 



+8 



4800 



51419 



51415 



+4 



The agreement between the calculated values of the 

 refractivities and those actually measured by Mr. and 

 Mrs. Cuthbertson is exceedingly close in all the above six 

 substances. The agreement is indeed as good as Mr. and 

 Mrs. Cuthbertson themselves obtained using Sellmeyer's 

 formula, the constants of which they calculated from the^r 

 observed refractivities in each case by the method of least 

 squares. The oscillation frequencies thus found for the 

 ultra-violet absorption bands are therefore only theoretical, 

 as they have not actually been observed and measured. The 

 values given in the tables above have the materially important 

 advantage that they have been calculated from an absorption 

 band that has been measured. 



* Warburg and Leithauser, loc. cit. 



