The rates of deposition of silver and cadmium on a metallic foil, and powdered zinc have been investigated and it has been found that the concentration drops of the solution at an initial stage of a reaction depend on the surface area of a zinc foil or the mean particle size of zinc powders. Hence the concentration drops caused by (1) a definite quantity of zinc powder and (2) a known surface area of a zinc foil present the method of determination of the mean particle size of zinc powder. If one uses radioactive tracer metal ions such as Ag
110 or Cd115, a rapid measurement of mean particle size of zinc powder for zinc refining the electrolytes is possible by some dipping type G. M. counter.
The experimental relationship to calculate the mean particle diameter 2γ is expressed by:
γ=(
C/C0-C)·γ
C0m,
where
C and
C0 are the molar concentration of a noble metal ion at a given instant and at a start respectively,
m the amount of zinc powder used in mol/litre, and α constant which has the value 1.5×10
2 for silver ion and 0.75×10
2 for cadmium ion.
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