Vacuum fusion gas extraction techniques using platinum-nickel bath at 1800°C and platinum baths at various temperatures from 1900°C to 2050°C were examined to determine microgases in molybdenum and the maximum permissible molybdenum content in fluid platinum for effective gas extraction. And microscopic examination was also carried out in order to see the graphite precipitated from bath alloys.
Gases were extracted out of electrolytically polished one-gram samples cut off from a sintered, swaged molybdenum rod used in the previously described nickel bath technique and others, in which gaseous impurities might be distributed homogeneously. And, in the 2050°C platinum bath technique, two- or four-gram samples from arc-melted molybdenum ingots were also used to determine the maximum permissible molybdenum content in platinum bath at this temperature. Extracted gases were analyzed by means of the fractional freezing under low pressure, and the sensitivity of measurement was, in these experiments too, O.5 micron-liter for both oxygen (as carbon monoxide) and hydrogen analyses, and 0.05 micron-liter for nitrogen.
The allawance for reproducibility of analysis of experimental one-gram samples was +1 part per million by weight for both oxygen and nitrogen below about 30 ppm. and 10 ppm. respectively and ± 0.1 ppm. for hydrogen below about 1.0 ppm., same as the experiments described in the paper I. And the following results were found : (1) Oxygen analyses by using the platinum bath technique gave the results which were by about 10 ppm. (about 11 micron liters of carbon monoxide evolved from one gram sample) greater than about 18 ppm. obtained by using the platinum-nickel, nickel, and nickel-tin baths, these facts suggesting the sorption of evolved carbon monoxide on the film or vapor of nickel evaporated from baths ; (2) Each result of nitrogen and hydrogen analyses by using the platinum bath technique agreed with that by the solid extraction technique mentioned before, within errors of 1 ppm. and 0.1 ppm. respectively ; (3) The maximum permissible molybdenum contents in a fluid platinum bath for extracting gases were about 70 per cent by weight at 2050°C, about 20 per cent at 2000 °C, and about 10 per cent at 1950°C ; (4) Accordiding to the microscopic examination of bath alloys, graphite flakes precipitated from fluid platinum-carbon or platinum-molybdenum-carbon alloy were so much less than those from fluid nickel-carbon or nickel-molybdenum-carbon alloy, that the control of carbon content in platinum bath by addition of pure platinum was unnecessary, in contrast with the case of nickel or iron bath.
From these experiments following the previous ones, it can be concluded that the vacuum fusion gas extraction technique by platinum bath at 2050°C is the most reliable and useful one for micro-gas analysis of molybdenum.

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