42 



STUDY OF ABSORPTION SPECTRA 



nearly identical. The solution whose percentage transmissions are 

 given in table 14, along with those of the solvent, is not nearly so 

 strongly alcoholated as it would be hydrated at the same concentration 

 if water was used as the solvent. Neither the work on magnesium 

 nitrate in acetone, nor in absolute alcohol, presents any evidence that 

 the salt has any absorption for the wave-lengths of light in question. 

 Jones and Anderson 1 and Jones and Strong, 2 in mapping and studying 

 the absorption spectra of solutions, found abundant evidence for the 

 existence of "solvent bands." In mixtures of certain solvents, say 

 alcohol and water, neodymium salts showed simultaneously upon the 

 plate two separate and distinct sets of absorption bands, where only 



TABLE 14. Magnesium nitrate in alcohol. 



one would appear in each solvent. They ascribed the one band 

 to the hydrate formed with the neodymium salt and water, and the 

 other to the alcoholate formed by the neodymium salt. The "water" 

 band and the "alcohol" band appeared to be of equal intensity when 

 7 or 8 per cent of water was present in the alcohol. 



A large number of other solvents were used, and "solvent" bands 

 were found for each of them. They could even distinguish between 

 a given alcohol and its isomer, by means of the absorption spectra of 

 a neodymium salt dissolved in them. This was regarded as good 



Carnegie lust. Wash. Pub. No. 110. 



Ibid., Pubs. Nos. 130 and 160. 



