RESULTS WITH MIXED SOLUTIONS. 



17 



Table IX. — Critical concentrations for Lupinus albus in sodium chlorid plus different 

 amounts of calcium sulphate. 



Amount of calcium, sulphate present. 



Critical concentrations 

 of sodium chlorid. 



Degree of saturation. 



Grams per 

 liter in the 

 mixed so- 

 lution. 



Grams per 

 liter in the 

 mixed so- 

 lution. 



Fractions 

 of a nor- 

 mal solu- 

 tion. 



Saturated in the XaCl solution 



One-half saturated in H 2 



One-fourth saturated in H 2 0. . . 

 One-eighth saturated in HoO. . . 

 One-sixteenth saturated in H 2 

 None 



3.69 

 *1.062 



.531 

 .265 

 .132 



None. 



11.7 

 12.3 

 12.5 

 10 

 7.5 

 1.17 



0.2 

 .21 

 .21 

 .17 

 .13 

 .02 



* Cameron (The solubility of gypsum in aqueous solutions of sodium chlorid. Journal Phys. Chem., 

 5:55ti. 1901) has shown that'calciiim sulphate dissolves in -water at a temperature of 26° C. at the rate 

 of about 1 part per 470 of water; hence at the rate of about 2.125 grams per liter. Marignac and 

 Goldammer obtaiued similar results. 



We see from these results that the maximum neutralizing effect of 

 calcium sulphate upon sodium chlorid in raising the critical concentra- 

 tion of the latter for white lupine seedlings is reached when the mixed 

 solution contains 0.5 gram of the calcium salt, and that the endurable 

 concentration of sodium chlorid can be raised no further although the 

 amount of calcium sulphate present be increased more than seven 

 times. At concentrations below 0.5 gram per liter the effect of the 

 calcium salt gradually diminishes. It would be interesting to ascertain 

 the minimum amount of calcium sulphate that can perceptibly diminish 

 the toxic effect of sodium chlorid. 



EESULTS WITH ANDROPOGOX SORGHUM. 



In this series of experiments a saturated solution of calcium sulphate 

 in water was prepared and was then diluted with distilled water to the 

 desired concentrations. Normal solutions of sodium chlorid, sodium 

 carbonate, and magnesium chlorid were obtained and then brought 

 to the concentration that is critical in the presence of an excess 

 of calcium sulphate by diluting with the different concentrations 

 of the calcium sulphate solution that were used. a The object of this 

 series of experiments was to ascertain the minimum amount of calcium 

 sulphate which would have as complete neutralizing effect upon the 

 more toxic salts as could be obtained by saturation with the calcium 

 salt. 



a Since the normal solutions contained no calcium sulphate it was necessary to 

 correct for this in determining the amounts of calcium sulphate present in the total 

 volume of the mixed solutions. 



113 



