

Displacement in their own Mother-liquor 211 



caesium bromide; and, similarly, next to potassium chloride, 

 in molecular weight and in solubility, we have potassium 

 bromide. In the latter case the solubility increases with the 

 molecular weight, while in the former it decreases with it. 

 But, if Table III be referred to, it will be observed that, 

 as regards molecular weight, KC1 and Csl occupy singular 

 positions in the ennead. On the other hand, KBr (119-1) and 

 RbCl (121) have almost identical molecular weights, as have 

 also CsBr (213) and Rbl (212-5). yet the solubilities in each 

 pair respectively are very different. The lowest solubilities are 

 on the diagonal KCl-CsI and the highest solubilities on the 

 diagonal KI-CsCl. RbBr, which occupies the middle place on 

 both these diagonals, is also in the middle of the middle column 

 and of the middle line, and is the centre of the ennead. It^ 

 solubility, besides being nearly the average of the group, has 



mmetrical position with respect to those of the other salt- 

 < >n one diagonal the solubility of its neighbours is lower, on 

 the other higher than its own. In its column the solubility of 

 it- neighbours is higher, in its line it is lower than its own. 



In compartment (b) of Table V we have the values of S, 

 the specific gravity of the mother-liquor at T, referred to that 

 of distilled water of the same temperature as unity. These 

 numt>< r- ' i mint, as they stand, be compared with each otlu r 

 becan^ thrv refer to solutions of such different concentrations. 

 Tin \ (nable us, however, to arrive at the average apparent 



hicement of one gram-molecule of salt in the saturated 

 which contains 1000 grammes of water at T. Thus, 

 .u.iin < ar-inm chloride as an example, we have for the 

 weight of salt dissolved in 1000 grammes of water 



w = m. CsCl = 2048-34 gr;ur.: 



A'Min- loco grammes to thU wr hav. for the weight of tin- 

 solution 



W == looo + w - 3048-34 grammes. 



The specific gravity (S) being 1-9101, \\v <li^ placement of the 







W 



I - -=- 1595*92 grammes of w . 



' I* 



