252 



solutions were prepared by dissolving each of the following number of 

 grams of salt in 200 ce. of distilled water: 7.82 g., 15.04 g., 31.28 g., 46.92 g., 

 62.56 g., 72 g. (saturated solution). 



Six solutions each of copper sulphate and sugar were prepared in the 

 same way as in the case of sodium chloride, and each solution was tested 

 for the number of grams to separate the liquid films. 



The results for the eighteen different solutions are tabulated as fol- 

 lows : 



First. — The number of grains to separate the disk from the solutions 

 when 7.82 g. of each of the three materials were dissolved in 200 cc. of 

 water. 



Trial. 



Sodium 

 Chloride. 



Copper 

 Sulphate. 



Sugar. 



1 

 2 

 3 



42.45 

 42.50 

 42.50 



48 . 40 

 48.45 

 48.47 



48.50 

 48.52 



48.48 



Mean. 



42.48 



48.44 



48.50 



Second. — The number of grams to separate the disk from the solution 

 when 15.64 g. of each of the three materials were dissolved in 200 cc. of 

 water. 



T . . Sodium 

 Chloride. 



Copper 

 Sulphate. 



Sugar. 



1 42 . 1 5 



2 42.00 



3 41.95 



49.20 

 49.30 

 49.35 



50.50 

 50.52 

 50.51 



Mean. 



42.03 



49.28 



50.51 



Third. — The nuaiber of grams to separate the disk from the solutions 

 when 31.2S g. of each of the three materials were dissolved in 200 cc. of 

 water. 



„ . . Sodium 

 TnaL Chloride. 



Copper 

 Sulphate. 



Sugar. 



1 46.39 



2 46.30 



3 J 



50.35 

 50.37 

 50.35 



51.50 

 57.49 

 51 .51 









Mean. 46.345 



50.356 



51.50 



