Mr. T. Graham on Liquid Diffusion applied to Analysis, 217 



Table VI. — Diffusion of a mixture of 5 per cent, of Chloride of 

 Potassium and 5 per cent, of Chloride of Sodium, for seven 

 days, at 12° to 13°. 



Number of 



Chloride of 



Chloride of 



Total diffu- 



stratum. 



Potassium. 



sodium. 



sate. 



1 



•018 



•014 



•032 



2 



•025 



•015 



•040 



3 



•044 



•014 



•058 



4 



•075 



•017 



•092 



5 



■101 



•034 



•135 



6 



•141 



•063 



•204 



7 



•185 



•104 



•289 



8 



•252 



•151 



•403 



9 



•330 



•212 



•542 



10 



•349 



•351 



•700 



11 



•418 



•458 



•876 



12 



•511 



•559 



1-070 



13 



•552 



•684 



1-236 



14 



•615 



•772 



1-387 



15 aud 16 



1-385 



1-551 



2-936 





5-001 



4-999 



10-000 



In the upper part of the Table chloride of potassium always 

 appears in excess, but not in so large a proportion in the first 

 three strata as in the fourth. This inequality may be partly 

 owing to mechanical dispersion of the mixed solution, but is to 

 be referred chiefly, I believe, to errors of analysis from a loss of 

 the chloride of potassium difficult to avoid in the determination 

 of minute proportions of that salt by means of chloride of platinum. 

 Of 92 milligrammes of salt found in the fourth stratum, 75 mil- 

 ligrammes, or 81*5 per cent., are chloride of potassium. The 

 first six strata contain together 561 milligrammes, of which 404 

 milligrammes, or 72 per cent., that is nearly three-fourths, are 

 chloride of potassium. We have to descend to the tenth stratum 

 before the salts are found in equal proportions. The progression 

 is then inverted, and chloride of sodium comes to preponderate 

 in the lower strata. 



It is evident that the preceding experiment might be so con- 

 ducted as to diffuse away the chloride of potassium and leave 

 below a mixture containing chloride of sodium in relative excess, 

 to as great an extent as the chloride of potassium is found above, 

 in the last experiment. 



Further, the mixture in which chloride of potassium was con- 

 centrated in the experiment described, so as to form 72 per cent, 

 of the whole mixture, might be subjected again to diffusion in 

 the same manner. In an experiment upon a mixture of 7*5 

 grammes of chloride of potassium and 2*5 grammes of chloride 

 of sodium, the six upper strata gave 640 milligrammes of salt, 



