AQUEOUS SOLUTIONS. McKAY. 351 



Distilled water was used in making up all the solutions. In 

 'the case of the very dilute solutions, the conductivity of the 

 water used was subtracted from the measured conductivity of 

 the solution. The greatest value of this correction was 0.2 per 

 cent. 



The combined error in 'the determination of the conductivity 

 and concentration of a double salt solution might be for solutions 

 of concentration 0.4 gr.-eq. per litre, 0.3 per cent., for 0.8 solu- 

 tions, 0.4 per cent., and for the very dilute solutions, from 

 0.02 downwards, 0.8 per cent. The errors in the case of the 

 stronger simple solutions mi^ht be 0.2 per cent, greater. The 

 error in plotting results and calculating from them by Professor 

 MacGregor's graphical process might be 0.2 per cent. 



Kohlrausch's values of the molecular conductivity at infinite 

 dilution, were used in the calculations. They are, for potassium 

 sulphate 1270, for magnesium sulphate 1080, expressed in terms 

 of 10~ 8 times the conductivity of mercury at 0C. 



The following table gives the results of the measurements of 

 simple solutions, made to secure data for the subsequent calcula- 

 tions. The concentrations are given in gramme-equivalents 

 per litre at 18C. The conductivities are for the temperature 

 18C., and are expressed in terms of the conductivity of mercury 

 at 0C. multiplied by 10-* : 



