A temperature sensor 42 is provided in a furnace 11, measuring {TAIL ~ temperature} above a molten liquid 24 put in {HEAD ~ a crucible} 12 to check proceedings of evaporation of oxygen vaporized from a free surface 44 of the molten liquid 24 
A temperature sensor 42 is provided in a furnace 11 , measuring { TAIL ~ temperature } above a molten liquid 24 put in { HEAD ~ a crucible } 12 to check proceedings of evaporation of oxygen vaporized from a free surface 44 of the molten liquid 24
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH