proportions for its own type. In each table, the first column 

 shov/s the twenty-one solution numbers, the next three columns 

 present the volume-molecular proportions of the three salts used, 

 and the remaining three columns give the actual volume-molecular 

 partial concentrations of the three salts — the latter always stated 

 for a mixture having a total osmotic value of 1.00 atmosphere. 

 The reader should be warned that the relative partial concen- 

 trations cannot be read vertically ; for example, in table I it can- 

 not be said that the volume-molecular partial concentration of 

 KH-PO^ is the same in all solutions of row 1, etc., although the 

 relative proportional values for this salt are all set down as unity 

 for these solutions. The data of the last three columns of the 

 table show how this comes about ; the unit used in reckoning the 

 relative proportions steadily becomes smaller as we proceed 

 along the row from left to right (on the triangular diagram). 

 This reduction is necessary on account of the phenomena of ioni- 

 zation, etc. (as evidenced when the complete solutions are sub- 

 jected to the freezing-point determination), and on account of 

 the desideratum that all solutions should have approximately the 

 same osmotic value (1.00 atm.) . But the relative salt proportions 

 for each individual solution are stated correctly if simply read 

 from left to right in the table; thus, for IRISI, KH^PO*: 

 Ca ( NO - : MgSO^ : : 1 : 1 : 6, etc. It will be noted that the proportions 

 of elements and ions may be read in a similar way, note being 

 taken of the number of atoms or ions in each molecule considered. 

 Thus, K:Ca:Mg :: 1 :1:6 ; but PO^: NO^: SO^:: 1:2:6, andH:N: 

 S: : 2:2:6. The proportions of the three kations K, Ca, and Mg 

 are read directly from the position of the solution on the triangu- 

 lar diagram for types I, III, V and VI, since none of the mole- 

 cules used for these types gives more than a single one of these 

 ions. For the other two types it must be remembered that there 

 are two K ions in each molecule of K-SO^. (In this last considera- 

 tion is will be noted that the term "ionic proportions" refers to 

 atoms or atomic groups — Ca, POs etc. — as ions, without regard 

 to the actual degree of dissociation of the corresponding mole- 

 cules. When we say that the ionic proportions of a solution 

 are: — PO*: SO^: NO'': : 1 :2:6, we merely signify that these 

 atomic groups were placed in the solution in these proportions, 

 not implying at all that the ionized portion alone shows such 

 proportions.) 



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