CHEMISTRY. 355 



covered by Jones and Strong. These results have been recorded in 

 Pubhcations 130 and 160 of the Carnegie Institution of Washington. 

 They were able to distinguish, for example, between the absorption 

 spectrum of a salt dissolved in an alcohol and in its isomer. 



The existence of "solvent bands" was explained in terms of the 

 solvate theory of solution as proposed bj^ Jones. The combined 

 solvent had different resonants, and, therefore, different power to 

 absorb light from the free or uncombined solvent. 



Jones and Guy (Publication 190 of the Carnegie Institution of Wash- 

 ington), from a quantitative study of the intensities of the absorption 

 lines and bands by means of the radiomicrometer already referred to, 

 found that solutions of slightly hydrated salts absorbed to just about 

 the same extent as pure water; while solutions of strongly hydrated salt, 

 such as calcium and magnesium chlorides, were as much as 30 per cent 

 more transparent than pure water. This showed that combined water 

 had less resonance and, therefore, less power to absorb light than free 

 water. 



Shaeffer and Paulus repeated these investigations, and obtained the 

 same general results that had been earlier found b}^ Jones and Guy. 

 They showed that solutions of certain very strongly hydrated salts were 

 as much as 40 per cent more transparent than pure water, thus estab- 

 lishing a marked physical difference between free and combined water as 

 illustrated by their action on light. These results have appeared in 

 Publication 210 of the Carnegie Institution of Washington. 



Having found this physical difference between free and combined 

 water, the question arose, is there any difference in the chemical 

 activity of free water and of water of hydration? To test this, Dr. J. 

 E. L. Holmes took up the study of a reaction effected by water alone, 

 the saponification or hydrolysis of an ester, breaking it down into the 

 free acid and the free alcohol. The rate of decomposition as effected 

 by pure water alone was first measured. The rate of decomposition 

 in the presence of slightly hydrated salts, such as potassium chloride 

 and nitrate, was determined; and finall}^ the rate of decomposition of 

 the ester in the presence of such strongly hydrated salts as calcium 

 chloride, magnesium chloride, etc., was measured. 



The action of a fairly large number of both of these classes of salts, 

 on the decomposition of methyl formate and methyl acetate, was 

 studied. The results indicate that the cheixdcal activity of combined 

 water, as determined by means of the saponification of an ester, is 

 greater than that of free water. 



Mr. Connolly studied the hydration of acetic anhydride by water 

 alone, also in the presence of only slightly hydrated salts, and finally, 

 in the presence of strongly hydrated salts. This work has not pro- 

 ceeded far enough to justify us in drawing any final conclusion. 



