EXPANSION OF SALINE SOLUTIONS. 213 



■of each of tlie salts. The sodic chloride has nearly 93 per cent, of the 

 water. It is possible that in course of time all the water may be 

 attracted by the sodium salt ; in which case we should conclude that the 

 force in operation is different from chemical affinity. 



Experiment IV. was made to ascertain the effect of increasing the 

 Telative quantity of sodic chloride. The effect is to hasten the invapora- 

 tion of water by this salt. After 144 days it has over 99 per cent, of the 

 water. Now, it is known that even a saturated solution of sodic chloride 

 gives off water- vapour to a dry atmosphere, so that in this final condition 

 -of experiment IV. the potassic chloride is in the presence of water- vapour. 

 If the force of invaporation (which is probably intimately connected with 

 the force of solution) were of the nature of chemism, it would cause com- 

 bination of the potassic chloride with the water, and the condition of 

 •equilibrium would be one in which the relative quantities of water held 

 by the two salts would be a measure of their affinities for water. The 

 discussion of this point will, however, be better postponed until our ex- 

 periments have been further extended. 



In experiments V., VI., VII., sodic chloride is pitted against the 

 highly deliquescent lithic chloride. In V., with the same number of 

 molecules as in I., the lithic chloride takes all but about one-third per 

 cent, of the water; VI. and VII. show the effect of increasing the relative 

 quantity of water. (Owing to the rapid deliquescence of the lithic 

 chloride, the water is sometimes in slight excess of the theoretical 

 quantity.) VI. shows that when the relative quantity of water is 

 doubled, the lithic chloride still takes nearly all after 42 days, and quite 

 all after 173 days. In this case 12*5 molecules of the salt have in- 

 vaporated 100 molecules of water. When the relative quantity of water 

 is again doubled, as in VII., an unexpected result is obtained. As in V. 

 and VI., the greater part of the water was given to the lithic chloride 

 before enclosure. After 177 days, we find that the sodic chloride is gain- 

 ing water, and this continues until in 129 days it has gained about 6 per 

 cent, of the whole quantity. The condition of equilibrium is not yet 

 reached, but there is clearly a limit to the quantity of water which the 

 lithic chloride can hold against the attraction of the sodic chloride. 



There is a wide field of research opening up in the direction indicated 

 by these few experiments. We shall extend the investigations to other 

 salts, particularly chlorides, with a view to testing more fully the effect 

 of increasing the relative quantities of water and of one of the salts ; and 

 shall also attempt to determine the influence, if any, of temperature. 

 With large proportions of water, experiments conducted at the tempera- 

 tures at which cryohydrates are formed may yield interesting results. 



Report (Provisional) of the Committee, consisting of Professors 

 McLeod and W. Ramsay and Messrs. J. T. Cundall and W. A. 

 Shenstone (Secretary), appointed to investigate the Influence 

 of the Silent Discharge of Electricity on Oxygen and other 

 'Gases. 



The Preparation and Storage of Oxygen Gas in a Pure State. 

 By W. A. Shenstone aiid J. T. Ctjndall. 



Tor the purposes of this investigation it is necessary to provide oxygen 

 and other gases in as pure a state as possible, in considerable quantities, 



