208 Specific Gravity of Soluble Salts by 



latter is the fundamental attribute of a substance, on which all 

 its properties depend. The molecular weights of the salts 

 which occur in one column differ by the amount of the difference 

 of the atomic weights of the metalloids which they contain, 

 that is, by 44-5 or 47. Similarly, contiguous salts in one line 

 have molecular weights which differ by 46-4 or 47-5. If we 

 consider the two diagonal triads in the ennead, we see that 

 they are characterised by the fact that both the elements in 

 each unit are different from those in either of the other units. 

 Further, along the diagonal KCl-CsI the molecular weights 

 of the units differ as much as possible from each other, while 

 the atomic weights of the components of each unit are as 

 nearly as possible identical, being close neighbours in the 

 atomic series. On the other diagonal, KI-CsCl, the molecular 

 weights of the units agree with each other as nearly as possible, 

 while the atomic weights of the constituents of the units differ 

 from each other as much as possible. 



The Crystal. Table IV contains four compartments. In 

 the first (a) we have the values of T, the temperature at which 

 the crystals and mother-liquor of each salt were in equilibrium, 

 and that at which the various displacements were observed. 



Under the experimental conditions, which have been 

 minutely described above, it is impossible to fix in advance 

 the exact temperature of equilibrium of the crystallising 

 liquid. This is given by the meteorological conditions, modified 

 by the structural features of the laboratory and of the apart- 

 ment or enclosure where crystallisation takes place. 



In the second compartment (b) we have the values of D, 

 or the specific gravity of the salt in crystal at T, referred to 

 that of distilled water of the same temperature as unity. The 

 data in this compartment are in most cases for different, but 

 always neighbouring temperatures. The differences of the 

 values of T are however so small and those of D are so great 

 that we may discuss the specific gravities as if they had been 

 made at one common temperature. 



On examining the values of D, we see that they increase 

 with those of MR in Table III; but the increase is not con- 

 tinuous, it is remittent. It takes place triad-wise; and this 



