326 Journal of Agricultural Research voi. xxiv, No. 4 
the left is shown the results of mixing the three added substances at 
their five maximum concentrations with the untreated soil and also 
with the carbonate soil (fig. 7, tumblers i, ii, and 15). The center chart 
represents tumblers 2, 3, 7, 10, 12, and 14 (fig. 7). These contain sodium 
carbonate and a binary mixture with one of the added substances dis¬ 
tinctly predominating. On the right are given the results for tumblers 
4, 5, b, 8, 9, and 13 (fig. 7). These contain the carbonate and both binary 
and ternary mixtures in which the concentrations are more nearly equal. 
It should be emphasized that the fractions occurring in the legends to 
0/?£r£A/^/ll£ LO/9M 
describe mixtures refer to a proportionate part of the maximum con¬ 
centration of the unmixed substance and not to the total amount of the 
mixture. For example, in figure 8, in the second triangle, the maximum 
quantities of sulphuric acid, potassium sulphate, and sodium sulphate 
are 4,000, 3,000, and 3,000 parts per million, respectively. Then the 
mixture one-fourth sulphuric acid, one-half potassium sulphate, and one- 
forth sodium sulphate in this grouping contmns 1,000 parts per million 
sulphuric acid, 1,500 parts per million potassium sulphate, and 750 parts 
per million sulphate, or a total of 3,250 parts per million, and it is this 
total which is plotted in the curves for this mixture. 
