Ultra-violet Absorption of Sulphur Dioxide. 509' 



shows clearly that the true optical centre lies at X = 2961 or 

 l/\ = 3378. According to Baly's theory this number, 3378, 

 should be an even multiple o£ a fundamental band in the 

 short-wave infra-red region. The absorption of sulphur 

 dioxide between 3/jl and 11/j, has been observed by Coblentz, 

 and the most pronounced band lies at \ = 7'4/it or l/\ = 135*1. 

 Now 135*1 x 25 = 3377*5_, which is exceedingly near to the 

 observed ultra-violet wave-number 3378, which entirely 

 supports Baly's contention. Moreover, Baly further postu- 

 lates that the constant differences in the wave-numbers in 

 the ultra-violet are compounded from certain basis constants 

 which are characteristic of the molecule, and that these basis 

 constants also determine the infra-red absorption of the 

 molecule. 



Now, the wave-numbers of the six infra-red absorption 

 bands of sulphur dioxide observed by Coblentz * can be 

 expressed as multiples of 96*32, as shown in Table IV. 



Table IV. 

 Infra-red Absorption of Sulphur Dioxide. 



Factors. 



Wave 

 Numbers. 



Wave-lengths 

 Calc. 



Wave-lengths 

 Obs. 



Differences 

 Obs. -Calc. 



9-632x10 



96-32 



10-38 a 



10-37 n 



-o-oi 



9632x12 



115-6 



865 



8-7 



+005 



9-632x14 



134-8 



7-42 



74 



-002 



9-632x18 



173-3 



5-77 



5-6S 



-0-09 



9-632x26 



250-4 



3-99 



3-97 



-002 



9-632x32 



308-0 



3-23 



3-18 



-0-05 



We therefore have three numbers which appear to be 

 characteristic of the absorption of sulphur dioxide, namely, 

 22*4, 34*4, and 9*632, and if Baly's contention is valid 

 these must be derived from certain basis constants charac- 

 teristic of the oxygen and sulphur atoms. Now 



22*4 = *2x4x 2*8x10 



34*4 = *2x 4x4*3x10 



9-632 = *2x4x2*8x4*3; 



and therefore it would seem that there are four basis 



* Publications of the Carnegie Institution, Washington, 1905, No. 35, 

 p. 52. 



