Ein Beitrag zur Gültigkeit des Massenwirkungsgesetzes. II

Radioactive Indicators in Analytical Chemistry.

“…The validity of the mass action law at great dilutions The sensitivity of radiometric procedures is admirably illustrated by recent tests of the validity of the mass action law as applied to the insoluble compound radium sulfate. O. Erbacher and B. Nikitin (5,18), and more recently B. Nikitin and P. Tolmatscheff (19), have found that the activity product of radium sulfate remains constant in sodium sulfate and sulfuric acid concentrations as high as 0.1 N. Table 6 illustrates some of the findings from the latter paper.…”

Isotopes as indicators

“…With radioelements it has been possible to test a number of fundamental laws down to very small concentrations, Thus the mass action law, applied to the solubility of radium sulfate (9) in sodium sulfate solutions, was found to hold in 0.1 N solutions of the latter; and the validity of the Nernst electromotive force equation ( 10) was demonstrated down to 10 ~12 N with bismuth using thorium C as indicator. In view of the great sensitivity of detection of radioelements, it is not surprising that adsorption and coprecipitation studies have been made at exceedingly low concentrations (U).…”

Electrostatic radionuclide separation: A new version of Rutherford's "thorium cow"

“…For instance, in 1930 O. Erbacher and B. Nikitin (7) found a value of 1.40 • 10_4g/100 ml H20 at 20°C for the solubility of RaS04. Two years later B. Nikitin and P. Tolmatscheff (8) found this value to be too low and, by correction for adsorption on glass surfaces, arrived at 2.1 • lCD4g/100 ml H20 at 20°C-a much higher value.…”

“…For this reason, a Pt electrode which has been exposed for sufficient time, and is then left off the "thorium cow" for approx. 8 hr may be used for identification of the 212Pb. After this time, the (8 activity of the deposit, which may be measured in a Geiger counter, is proportional to the 212Pb amount present.…”