IN THE PRESENCE OF STRONGLY HYDRATED SALTS. 57 



Strong, 1 and Guy and Jones, 2 when the absorption of salts as affected by the 

 water present was studied. It was found that rise in temperature and 

 increase in the concentration of the solution both tended to shift the ab- 

 sorption of the salt towards the longer wave-lengths. The effect of rise in 

 temperature and the increase in the concentration of the solution tended to 

 simplify the hydrates in combination with the particles of the salt. The 

 resonator within this simplified system seems to vibrate so as to shift the 

 absorption bands towards the red. 



The effect of the salt on the absorption of the water is the same as that of 

 rise of temperature and increase of concentration on the absorption of the 

 dissolved substance. We would naturally look for a similar explanation of 

 the two sets of phenomena. It has been suggested by Dr. Guy, that the 

 effect of the salt on the absorption of light by water may be due to the 

 breaking down of the associated molecules of water by the dissolved sub- 

 stance. This would be in keeping with the fact established by Jones and 

 Murray, 3 that one associated substance when dissolved in another associated 

 substance diminishes its association. 



In terms of this explanation, however, it is a little difficult to see why non- 

 hydrated salts, such as were used in this work, do not also diminish the asso- 

 ciation of water and cause a shifting of its absorption bands towards the 

 longer wave-lengths. It may be that the effect of the dissolved substance 

 in breaking down the association of the water is pronounced only in the case 

 of water of hydration or the water that is combined with the dissolved sub- 

 stance, and that the explanation offered above is fundamentally correct. 



70- 



60-- 



50- 



40- 



30 



20 



10 



CaCI 2 ,5.38N 

 Depth 1cm. 



1.15 12 1.3 1.4 1.5 



1 Cam. Inst. Wash. Pubs. 130 and 160. 3 Amer. Chem. Journ., 30, 193 (1903). 



2 Amcr. Chem. Journ., 49, 1 (1913). 



