Aqueous Solutions of Hydrogen Chloride, &c. 

 Table IV. 



317 



water in its ordinary condition, then potassium chloride no longer 

 forms an exception, and the differences increase with the molecular 

 weights of the salts ; the increase, however, does not bear any apparent 

 relation to the increase in the molecular weights. 



The differences for the normal solutions, calculated in both ways, 

 are slightly less than double those for the semi-normal. 



The object of these experiments was the determination of the 

 refractive indices and densities of normal and semi-normal aqueous solu- 

 tions of hydrogen chloride and the chlorides of the alkalis at a uniform 

 temperature ; the results obtained at 18 are set forth in Table I, the 

 indices being given to six places of decimals and the densities to 

 five places. 



In Table II the results corrected for small errors in the strengths of 

 the solutions are given. The table shows that both the densities and 

 the refractive indices increase with the molecular weight of the sub- 

 -stance in solution, except in the case of the refractive index of potas- 

 sium chloride, which is slightly lower than that of sodium chloride. 



Table III gives the weight of water contained in 1000 c.c. of each of 

 the solutions, and Table IV the differences between the refractive 

 indices of the solutions, and the refractive index of water under 

 ordinary conditions, and also the differences between the refractive 

 indices of the solutions and the calculated indices of the water con- 

 tained in the solutions. 



[Note. From the data given in Table I, it is not possible to draw 

 any satisfactory conclusions as to the sensitiveness of the different 

 solutions. The values for the indices at temperatures other than 18, 

 rest on single sets of observations, and in some cases there was not 

 sufficient difference between the temperature at which these observa- 

 tions were made and 18, to enable the rate of change of the index to 

 be determined at all accurately. 



I have, therefore, made some further observations with the same 

 solutions of hydrogen chloride and the chlorides of lithium, ^sodium, 



