68 



WORK OF J. N. PEARCE. 



solution are, in general, higher than the amounts combined with calcium nitrate. 

 This is just what we should expect when we consider that calcium chloride crystal- 

 lizes with 6 molecules of water, while calcium nitrate crystallizes with 4. 



STRONTIUM NITRATE. 



The strontium was precipitated and weighed as the carbonate. Unlike the other 

 salts thus far studied, the freezing-point lowerings show no minimum within the 

 range of concentrations used, the molecular lowering constantly decreasing in value. 

 A minimum was, however, obtained by Jones and Bassett 1 at a concentration of about 

 1.5 normal. The data are given in table 50. 



The values for the combined water show a minimum at 0.075 normal, just as cal- 

 cium nitrate does. The hydration per ion and the molecule also shows no tendency 

 to become constant. The curves are plotted in figs. 24 and 25. 



MAGNESIUM NITRATE. 



The nitrate of magnesium, like the chloride, shows a much greater power to com- 

 bine with water, throughout the range of concentration studied, than do the nitrates 

 of the alkali earth metals. (Table 51.) 



Table 51. Magnesium Nitrate Data for Freezing-point and Conductivity Measurements, 



Specific Gravity, and Hydrates. 



Freezing-point. 



m 



0.02 

 0.05 

 0.10 

 0.15 

 0.20 

 0.50 

 1.00 



Ajm 



0.1078 5.3903 

 0.249684.9938 

 0.490854.9085 

 0.744864.9671 

 0.998754.9937 

 2.742805.4856 

 6.5145 J6.5145 



2.8980 



6848 

 6390 

 6705 

 6848 

 9492 



a 



94.90 

 84.24 

 81.95 

 83.52 



3.5024 



Hydrates. 



m 



Ajm 



M 



0.05 



0.10 



0.15 



0.20 



0.50 



1.00 



1.274 



78.80 

 74.78 

 71.40 

 69.25 

 60.07 

 49.43 

 44.46 



2.157 



2.817 



4.759 



5.819 



13.260 



22.672 



29.006 



// 



43.14 

 28.17 

 31.73 

 29.09 

 26.52 

 22.67 

 22.76 



Conductivity. ^0=! 19.90. 



50 

 20 

 10 



6.666 



5 



2 



1 



M* 



102.06 

 94.48 

 89.66 

 85.61 

 83.04 

 72.03 

 59.27 



85.12 



78.80 

 74.78 

 71.40 

 69.25 

 60.07 

 49.43 



Specific gravity. 



m 



0.02 

 0.05 

 0.10 

 0.15 

 0.20 

 0.50 

 1.00 

 1.274 



>Sp. gr. 



sol 



1.00224 

 1.00563 

 1.01112 

 1.01656 

 1.02203 

 1.05480 

 1 . 10786 

 1 . 13661 



1002.224 

 1005.626 

 1011.118 

 1016.557 

 1022.026 

 1054.804 

 1107.865 

 1136.615 



II" 



idt 



2.968 



7.422 



14.844 



22.266 



29.688 



74.220 



148.440 



189.112 



Wmo 



999.255 

 998.204 

 996.274 

 994.291 

 992.338 

 980.584 

 959.425 

 947.502 



Correction, 

 per cent. 



0.074 

 0.179 

 0.372 

 0.571 

 0.766 

 1.941 

 4.057 

 5.249 



The amount of water decreases with increase in concentration in the dilute solu- 

 tions, reaches a minimum at 0.05 to 0.075 normal, and then increases regularly with 

 increase in concentration. The values of H do not approach a constant until normal 

 concentration is reached. It is very probable that the relatively low values of H for 

 0.05 and 0.1 normal are due to errors in measuring the freezing-points of those solu- 

 tions. The curves for magnesium nitrate are given in figs. 24 and 25. 



Amer. Chem. Journ., 34, 305 (1905). 



