i86 re;ports o^ investigations and proje;cts. 



work was to test the applicability of the law of mass action to the problem 

 of hydration. 



(3) The study of the absorption spectra of solutions as throwing light 

 directly upon the hydration of the dissolved salt, and upon the change in 

 hydration produced by the presence of a second salt. The absorption spectra 

 of solutions of salts in such non-aqueous solvents as methyl alcohol, ethyl 

 alcohol and acetone, on the addition of varying amounts of water, show 

 clearly the formation of hydrates and the change in their composition. 



The dissociation of 10 salts and 3 acids has been measured by the freezing- 

 point and by the conductivity methods. Hydration, or combination with the 

 solvent, should afifect the freezing-point method to a greater extent than 

 the conductivity method. This will be seen at once, if we consider that 

 freezing-point lowering is directly proportional to the number of molecules 

 of water present acting as solvent. If a part of the water is in combination, 

 this would affect the freezing-point lowering proportionally, while the con- 

 ductivity would be affected to a much smaller extent. 



The dissociation of solutions of concentrations varying from normal to 

 one one-hundredth normal, of the following substances, was measured by 

 both the freezing-point and the conductivity methods : Sodium bromide, 

 barium nitrate, barium bromide, barium iodide, calcium chloride, cobalt 

 nitrate, nickel nitrate, copper chloride, copper nitrate, aluminium chloride, 

 hydrochloric acid, nitric acid, and sulphuric acid. 



The results show that the dissociation of the salts as measured by the 

 freezing-point method is uniformly greater than as measured by conduc- 

 tivity, just as would be expected from the hydrate theory. 



The effect of one salt on the hydrating power of another salt has been 

 studied fairly extensively — the following pairs of compounds having been 

 brought within the scope of this investigation: Potassium chloride and 

 calcium chloride ; calcium chloride and magnesium chloride ; calcium chloride 

 and strontium chloride ; potassium chloride and ammonium chloride ; ferric 

 chloride and aluminium chloride; lithium bromide and sodium bromide; cal- 

 cium nitrate and magnesium nitrate ; magnesium nitrate and strontium 

 nitrate ; and calcium nitrate and calcium chloride. 



The dilutions used ranged from two-thousandths to 3.5 normal. 



The freezing-point lowerings and the conductivities of all of the solutions 

 of the above substances, separately and when mixed, were measured, and the 

 results obtained under these widely different conditions compared with one 

 another. 



Careful quantitative measurements showed that the effect of one salt with 

 a given hydrating power, on the hydrating power of a second salt, was in 

 accord with the law of mass action. 



The effect of one salt on the dissociation of another salt with a common 

 ion was investigated, using such pairs of compounds as potassium chloride 



