Radiometric Measurements of Constants of Indicators. 



67 



The percentage transmissions for these solutions are given in table 

 39. The concentrations of the two tautomeric forms, and the hydroly- 

 sis and ionization constants calculated from table 39 are recorded in 

 table 40. 



TABLE 40. 



The series of solutions the results of which are recorded in table 41 

 were prepared from another solution of phenolphthlaein. Its concen- 

 tration was 4.603 X 10" 5 gram-molecules per liter. The concentrations 

 of the ammonium hydroxide and ammonium chloride solutions were the 

 same as for the previous series. It will be noticed that 1 c.c. of a solu- 

 tion of ammonium hydroxide was used instead of 2 c.c. as in the former 

 case. 



SOLUTIONS. 



I. 75 c.c. phenolphthalein, 1 c.c. NH 4 OH, 0.5 c.c. NH 4 C1, diluted to 100 c.c. 

 II. 75 c.c. phenolphthalein, 1 c.c. NH 4 OH, 1 c.c. NH 4 C1, diluted to 100 c.c. 



III. 75 c.c. phenolphthalein, 1 c.c. HN 4 OH, 2 c.c. NH 4 C1, diluted to 100 c.c. 



IV. 75 c.c. phenolphthalein, 1 c.c. NH 4 OH, 2.5 c.c. NH 4 C1, diluted to 100 c.c. 

 V. 75 c.c. phenolphthalein, 0.8 c.c. N NaOH, diluted to 100 c.c. 



TABLE 41. 



[I/Io for depth of solution =20 mm. Temperature =20.] 



