29 



The concentrations are stated, as in preceding tables, both in parts 

 of salt to 100,000 of solution and in fractions of a normal solution. 



In the following tables of the effects of mixtures each of the more 

 soluble alkali salts (excepting sodium bicarbonate) is taken up in 

 succession in the order of its toxicity in pure solution. The neutral- 

 izing effect is expressed in terms of the gi-eatest concentration of the 

 more toxic salt endurable in the presence of the less toxic one. As 

 the determination of the value of a less injurious salt in neutralizing 

 a more toxic one was the objective of all experiments with mixtures, 

 it follows that the number of added salts decreases successively from 

 table to table. For comparison, the limit of endurance for the more 

 toxic salt in pure solution is stated at the head of the table. The 

 details of neutralizing effect upon each salt are taken up in connec- 

 tion ^ith its respective table, while a discussion of the general sig- 

 nificance of the whole series of experiments with mixtures of two 

 solutions is appended. 



The results embodied in Tables III to IX were obtained from experi- 

 ments with Lupinus alhus onlj*. In Table X, however, the limits 

 are given for both Lupinus cdbus and Medicago sativa (alfalfa) in 

 solutions of each readilj' soluble salt (excepting calcium chloride) in 

 the presence of an excess of calcium sulphate and calcium carbonate 

 together. 



MAGNESIUM SULPHATE IN MIXTURES. 



The following table shows the results of experiments with Lupinus 

 in solutions of magnesium sulphate with other salts added : 



Table III. — Limits for magnesium sulphate in mixtures. 



Name of salt added. 



Greatest endurable 

 concentration o f 

 magnesium s u 1 - 

 phate. 



Concentration of the 

 salts added. 



In f rac 



tions of a 



normal 



solution. 



In parts In fractions In parts per 

 per 100,000 of a normal 100,000 of 

 of solution.' solution. solution. 



None 



Magnesium chloride 



Sodium carbonate 



Sodium sulphate 



Sodium chloride *. 



Calcium chloride 



Magnesium carbonate 



Calcium carbonate 



Calcium sulphate 



Calcium sulphate and calcium carbonate 



0.00125 



> 



.000625 



3.5 



.00125 





.00375 



21 



.0075 



42 



.2 



1,120 



.01 



56 



.02 



112 



.6 



3,360 



' A 



2,240 



0.0025 

 .00^ 

 .01 

 .015 

 .2 



Saturated. 



Saturated. 



Saturated. 



Saturated. 



12 

 13 

 80 

 87 

 1,101 



Saturated. 



Saturated. 



Saturated. 



Saturated. 



In the light of figures given above, the enormous discrepancy between 

 the results obtained by experiments with this salt in i)ure solution and 

 the limit determined by field survey is completel}' obliterated. For 

 in alkali lands magnesium sulphate is rareh', if ever, found in any 

 quantity except in the presence of calcium sulphate; and it is com- 

 monly accompanied by both sodium and calcium sulphate (the Billings, 



