290 JONES AND ANDERSON— ABSORPTION SPECTRA OF [April 25, 



to the aqueous solution diminish in intensity and reach about half 

 value in the 8 per cent, aqueous solution, while those belonging to the 

 alcoholic solution increase in intensity, as the amount of water 

 is decreased. 



The band in the red near A 6800 shows the change very well 

 indeed, the " water " band having the position A 6800, while that 

 pertaining to the alcoholic solution is situated at A 6860, and hence 

 the two are well separated. Here the point of equal intensity 

 appears to be reached in the solution containing io| per cent, of 

 water, but this is due to the fact that the alcoholic band has a 

 considerably greater intensity than that due to the aqueous solu- 

 tion, conditions as to concentration and depth of layer being the 

 same. Taking this into account it is seen that this band obeys 

 substantially the same rule as the others. 



The change in the band at A 7325 is more difficult to follow, on 

 account of the small intensity of the photographic action on the 

 less refragible side of this position. The band belonging to the 

 aqueous solution may be seen very clearly even in the strip corre- 

 sponding to the 2§ per cent, water solution, but is of course en- 

 tirely absent in the alcoholic solution. Its intensity in the 2f per 

 cent, solution, however, seems a little greater than we should ex- 

 pect from the behavior of the other bands, but this is perhaps due 

 to the rather weak photographic action in this part of the spectrum, 

 combined with the great intrinsic intensity of the band. The alco- 

 holic solution transmits light as far as A 7355 where its spectrum 

 ends abruptly in a band. 



Throughout this description we have laid great stress on the 

 fact that on plate 4 the two sets of bands coexist; the bands due to 

 the aqueous solution decreasing, while those belonging to the alco- 

 holic solution increase in intensity with decrease in the percent- 

 age of water. We have also called attention to the fact that the 

 two sets of bands have about one-half their full intensity in a solu- 

 tion containing about 8 per cent, of water. This was for a 0.5 

 normal solution. 



