CHAPTER V. 



THE ACTION OF SALTS WITH WATER OF HYDRATION AND WITHOUT 

 WATER OF HYDRATION ON THE VELOCITY OF SAPONIFICATION 

 OF ESTERS. 



BY J. E. L. HOLMES. 



Jones and Anderson, 1 in their work on the absorption spectra of 

 solutions, studied the absorption spectra of neodymium chloride in 

 water, in methyl alcohol, and in mixtures of these two solvents. They 

 found two sets of absorption spectra corresponding, the one to the 

 aqueous solution, the other to the alcoholic. In the mixture of these 

 solvents, both of these spectra were obtained when the water was 

 present in smaller quantities than 15 per cent. With decrease in the 

 percentage of water, the alcoholic spectrum increased in intensity. 

 The water spectrum and the alcohol spectrum were found to be quite 

 different from one another, and do not change over into each other 

 when the composition of the mixed solvent changes. 



Similar results were obtained with neodymium nitrate and praseo- 

 dymium chloride. These results showed that the solvent played an 

 important part in the absorption of light by solutions. Jones and 

 Anderson explained this fact on the basis of the solvate theory of 

 solution proposed by Jones in 1900, that a part of the solvent combines 

 with the dissolved substance and that the solvated parts have different 

 resonance from the unsolvated. 



The work of Jones and Anderson was continued by Jones and Strong, 2 

 who studied a large number of salts in various solvents, to see if the 

 solvent in general played a role in the absorption of light by solution. 

 Most of their work was done with salts of neodymium and uranium, 

 since these substances had sharp absorption lines and bands. That the 

 solvent has much to do with the absorbing power of the solution can be 

 seen from table 53, which contains the wave-lengths of the absorption 

 lines of uranyl chloride in various solvents. 



TABLE 53. 



'Carnegie Inst. Wash. Pub. No. 110 (1909); Amer. Chcm. Journ, 41, 163 (1909). 



2 Carnegie Inst, Wash. Pubs. Nos. 130 (1910) and 160 (1911); Amer. Chem. Journ., 43, 37, 

 224 (1910); 45, 1 (1910); 47,27 (1912); Phys. Zeit., 10, 449 (1909); Phil. Mag., April 1910; 

 Journ. Chim. Phys., 8, 131 (1910). 



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