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