The trangient wear in various loads was observed by using the radioactive specimens (pure copper, Sn-Sb-Cu alloys, and chromium plated steel), using the spindle oil No. 60 as lubricating oil.
The specific activity of the specimen was 0.1-1.5mc/g which required irradiation for 2-5 days in the thermal neutron flux of approximately 3×10¹¹n·cm^-2·sec^-1.
A NaI scintillation crystal (13/4″×1″) with a conventional photomultiplier tube was used as a detector.
The result obtained are summarized as follows:
1) The minimum detectable wear was 10^-5-10^-6g.
2) In the radioactive copper specimen, as shown in Fig. 3, the initial wear during the first 50 minutes was 75% of total wear during 200 minutes run at 1000rpm under 5kgs of load.
3) The initial wear during the first 10 minutes of radioactive Sn-Sb-Cu alloy specimen, as shown in Fig. 5, was 50% of the total wear during 50 minutes run at 1000rpm under 5kgs of load.

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Reducing agents, such as sodium thiosulfate, sodium hypophosphite, hydroxylamine and hydrazine sulfate were added to the W-Co alloy plating bath, and the hydrazine sulfate showed the best result. On addition of the hydrazine sulfate to the W-Co alloy plating bath, though the contents of W in the deposits was decreased slightly, the cathode current efficiency was increased markedly compared with the ordinary bath, and the bright deposits were obtained through a long time operation.
Addition of hydrazine sulfate to the W-Fe alloy plating bath was as effective as in the case of W-Co alloy plating, but in the case of W-Ni alloy plating W content in the deposits was less than those in the cases of W-Co and W-Fe alloy plating.

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It is essential to decrease the time of analysis for simplifying the control of plating bath. Because, according to the result of analysis, a suitable chemical should be added in proportion to the variation of solution composition, which is caused by three main factors, chemical, electrochemical and mechanical factors. The mechanical factor depends mainly on drawing of plating solution.
From the result of the investigation of mechanism of drawing of barrel plating solution, the following empirical formula for drag out of barrel plating solution was obtained:
D=D_B+S_S⋅D_S
where D is the total drawing amount of barrel plating solution, D_B is the drawing amount from barrel only that changes depending on the porosity of barrel, D_S is the drawing amount per surface area that changes depending on the ratio of total apparent volume of plating solution to the barrel volume and S_S is the total surface area of plating solution.

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