78 



ABSORPTION SPECTRA OP A NUMBER <>F SALTS 



The results recorded in these curves are in agreement with previous photo- 

 graphic results. The minimum in transmission, which in each case is about 

 30 per cent, occurs near X5900. The total deviation from Beer's law over 

 the dilution studied is not over 3 per cent, which is well within the experi- 

 mental error in this portion of the spectrum. 



PRASEODYMIUM NITRATE. 

 Corresponding results for solutions of praseodymium nitrate are given in 

 table 17. The concentrations of the solutions, beginning on the left and 

 reading towards the right, were 1.282, 0.641, 0.320, and 0.160 normal, respec- 

 tively, the corresponding depths of absorbing layer being 2.5, 5, 10, and 

 20 mm., respectively. 



Table 17. Percentage Transmission of Praseodymium Nitrate Solutions. 



100, 



o 



z 



< 



< 



50 





25 



Cell Depth 2 5mm 

 Concentration I 282 N 



Cell Depth 5mm. 

 Concentration 0.641 N 



Cell Depth 10 mm. 

 Concentration 320N 



Cell Depth 20mm. 

 Concentration I60N 



0.55^ 



0.6/.' 0.55a 



0.6a 0.55a 



Fig. 35. 



0.6/i 0.55a 



0.6a 



The results are plotted in fig. 35. Reading from left to right, there is 

 shown the effect of increased dilution on solutions of praseodymium nitrate 

 and such concentrations and depths of absorbing layers as were mentioned 

 above, the most concentrated solution being nearest the left of the figure. 



