106 



MR J. Y. BUCHANAN ON THE 



and the second triad those having the general formula MRO3. Each triad is entered 

 in the ascending order of the molecular weights of the salts which compose it, and each 

 group of three triads forms the ennead MR or MRO3 respectively. 



Salt ill Solution. 



Molecular 

 Weight of Salt. 



Weight of 



1/16 grm.-mol. 



Salt. 



to. 



Specific Gravity of Solution 



of 1/16 grm.-mol. Salt in 



1000 grams Water. 



S. 



Increment of Displacement 

 produced by the Dis- 

 solution of w grams Salt 

 in 1000 grams Water. 



V. 



KCl 



74-6 



4-6625 



1002973 



1-684 



KBr 



119-1 



7-4437 



1-005279 



2-153 



KI 



1661 



10-3812 



1-007588 



2-772 



KCIO3 



122-6 



7-6625 



1-004863 



2-785 



KBrOg 



167-1 



10-4443 



1 007662 



2-761 



KIO3 



214-1 



13-3812 



1-011169 



2-189 



RbCl 



121-0 



7-5625 



1-005531 



2-020 



RbBr 



165-5 



10-3437 



1-007868 



2-456 



Rbl 



212-5 



13-2812 



1-010046 



3-203 



RbClOj 



169-0 



10-5593 



1-007354 



3-183 



RbBrOg 



213-5 



13-3412 



1-010253 



3-057 



RblOg 



260-5 



16-2812 



1-013673 



2-576 



CsCl 



168-5 



10-5312 



1-008036 



2-475 



CsBr 



213-0 



13-3125 



1-010409 



2-873 



Csl 



260-0 



16-2500 



1-012529 



3-675 



CsClOg 



216-5 



13-5312 



1-009825 



3-669 



CsBrOg 



261-0 



16-3125 



1-012756 



3-511 



CSIO3 



308-0 



19-2500 



1-016299 



2-903 



If we consider the increments of displacement, v, produced by the dissolution of 

 1/16 gram-molecule of each of these salts in 1000 grams of water, we see that, for the 

 salts of the same metal, the values increase from the chloride to the bromide, and from 

 the bromide to the iodide ; and that for the chlorates the values of v are almost identical 

 with those for the iodides ; they diminish from the chlorates to the bromates, and suffer 

 a considerable fall from the bromates to the iodates. There is also a decided fall in the 

 value of V from that of the iodate of potassium or rubidium to that of the chloride 

 of rubidium or caesium respectively. 



The following diagram, illustrative of the above table, shows graphically, by the 

 heights of the columns, the different increments of displacement produced by the 

 dissolution in 1000 grams of water at 19*5° C. of 1/16 gram-molecule of each salt 

 of the double ennead (MR, MRO3). The columns representing the increment of 

 displacement produced by salts of the ennead MRO3 are shaded. It shows in a very 

 striking manner the regular periodic variation of values of v from ennead to ennead. 

 It is unfortunate that a complete series of solutions of higher concentration of all the 

 salts of the double ennead cannot be obtained, on account of the sparing solubility of 

 the oxyhalides, especially those of rubidium and caesium. 



