212 



EEPOET 1886. 



Experiment VTI. 



In discussing these experiments it is to be noted that when the t-wo 

 salts were potasrdc and sodic chlorides, the water was divided as nearly 

 as possible equally between them, a little being, however, left in its small 

 tube. The first weighing was not made until all the water seemed to be 

 invaporated by the salts. When the two salts were sodic and lithic 

 chlorides, the greater part of the water was given to the latter before en- 

 closing in the large tube. Experiments I., II., and III. were made to- 

 discover the efiect produced by increasing the relative quantity of water 

 (an accident spoiled the experiment coming between II. and III.). It is 

 evident from these experiments that sodic chloride invaporates water more 

 powerfully than potassic chloride, for, as all the experiments show, the 

 sodic solution increases in weight at the expense of the potassic. A 

 preliminary experiment made this very apparent. The three tubes were 

 enclosed without dividing the water between the salts : after 24 hours 

 the sodic chloride had begun to deliquesce, while the potassic chloride was 

 quite dry ; after 25 days about one-half of the water was invaporated, 

 and, while the potassic chloride was only slightly moist, the sodic 

 chloride was dissolved to a considerable extent. In repeating and 

 extending our experiments this method (as above indicated) will be 

 followed. Our c/«ie/ object, so far, has been to determine how the water 

 is divided between the two salts when a condition of equilibrium is 

 reached. As might be expected, when the relative quantity of water is 

 increased, the process is retarded, as the weaker solutions invaporate 

 more slowly. But even with 32 molecules of water to 1 of each of the 

 salts, the sodic chloride goes on steadily stealing water from the potassic 

 (III.), although, after 15\ days, it has succeeded in abstracting only 5 

 per cent, of the whole quantity of water. 



Experiment I., with the greatest relative quantity of salts, is not yefc 

 completed. The sodic chloride has, after 172 days, 86 per cent, of the 

 water, and is still invaporating. In experiment II., which has lasted 290 

 days, the process of invaporation is apparently nearly complete, and the 

 result is somewhat surprising. There are 100 molecules of water to 12-5 



