A NEW THREE-SALT NUTRIENT SOLUTION 
343 
various points brought out in Shive's paper), it appears that our 
solution R8C1 is physiologically the best balanced for young wheat 
plants of all the nutrient solutions so far noted in the literature, but 
this matter assuredly requires still further study. 
Of course the proportions of the various atoms and atomic groups 
(constituting the essential ions) are, in our solutions, very markedly 
different from the corresponding proportions in Shive's series, and 
table 3 is here appended to emphasize this aspect of the general prob- 
lem of the salt nutrition of plants and to put the comparative data thus 
far available in convenient form for future reference. In this table 
the solutions are each indicated by the proper Roman numeral (re- 
ferring to the foregoing scheme of six logically possible series of three- 
salt solutions) and by the symbol showing the position of the particular 
set of salt proportions considered, on the triangular diagram employed 
by Shive. This will furnish a convenient method for future reference 
to the large number (216) of different solutions that will require atten- 
tion in this field. All three solutions here considered have approxi- 
mately the same osmotic value (or total concentration), this value 
being that employed by Shive for his optimum series (1.75 atm.). 
The index of total concentration should be most conveniently expressed 
in terms of the lowering of the freezing-point (the familiar A of physical 
chemistry), but the requisite determinations for a statement of these 
magnitudes are not yet available. In table 3, solution IR5C2 is 
Shive's optimal R5C2, while solutions IIIR6C1 and IIIR8C1 are the 
two new well-balanced solutions brought forward in the present paper. 
The first column of table 3 shows the various atoms or atomic 
groups (ions, whether still in their molecules or free i,n the solution) 
with which a physiological discussion of these solutions will eventually 
have to deal. The third column shows the absolute values of the 
respective partial concentrations, on the basis of solution volume. 
These may be called the partial volume-ionic or volume-atomic con- 
centrations, but a new term will be required when the dissociated ions 
are to be considered separately from those still held in the molecules. 
To illustrate the significance of these values, the quantity 0.0180 in 
this column (referring to K) denotes that solution IR5C2 contains 18 
thousandths of a gram-atom of potassium in a liter of solution. The 
same quantity occurs below with reference to H2PO4 and also to PO4, 
which means that the solution in question contains 18 thousandths 
of a gram-ion of H2PO4 and of PO4 per liter of solution, the term gram- 
