A paper of Rosenthal published in 1941 shows that the heat conducted to the electrode from the molten tip is 0.20 of the total arc heat V1, and so the heat delivered to the base metal is 0.65, 0.15 being the loss due to the radiation and convection of arc column. According to Rosenthal the above calculated result coincides well with the experimental data reported in 1938. It is evident from the paper that the heat part 0.20 is not radiated from the electrode surface, and that as the temperature rise does not exist in a remote part beyond about 1cm (1″/4) from the elec-trode tip, there is no heat flow and consequently no heat loss due to conduction can be observedni such a part. The heat conducted from the tip as far as 1cm is absorbed usefully to preheat the electrode metal before the metal reaches the arc surface. In other words, the heat energy conducted from the molten tip by the thermodynamic motions of metal molecules is transported back to the electrode tip as the metal part which absorbed the energy moves to the tip with the melting speed of the electrode. So the loss is only 0.15 instead of 0.35. In the experiment of 1938, the input arc power is calculated as V1, V and 1 being the effective values of arc voltage and current of a. c. respectively. But the wave from of arc voltage being nearly rectangular, so the power is 0.90 V1 and therefore the experimental data 0.65 becomes 0.72. The figure may get somewhat greater if the reduction of true power due to the instantenuous short circuits caused by irregular motions of molten tip metal is tanken into consideration, or if the input power is measured by a wattmeter or a watthourmeter. It is also remarkable that the base metal energy might be more incresed owing to the convection from the arc column, if the breadth of the base metal were greaterr than 12 mm and the protecting plate (forthermocouples) were uncovered as may be the case of practical welding.
The author prepared many ingots of manganese-chromium steels which have an austenitic structure or consist of an austenitic and ferritic structure. Then he worked them at high and room temperature and in this way trially manufactured core-rods, and made coated electrodes. Subsequently he welded one kind of alloy steel with these electrodes, and observed the appearances and the sections of welded specimens, and measured hardnesses of weld metals. The following results were obtained by these experiments. (1) If Mn-Cr steel rods, which contain above 30% or so Mn and have a stable austenitic structure, are used, cracks are apt to occur in the weld metal or in the heat-affected zone. (2) If Mn-Cr steel rods, which contain under 30% or so Mn and have a stable austenitic structure, are used, cracks do not occur in the weld metal, but the occurrence of cracks in the heat-affected zone isxnot prevented, (3) If Mn-Cr Steel rods, which containl5.25 % Cr and under about 12% Mn and consist of a ferritic and austenitic structure, are used, the occurrence of cracks in the heat-affected zone is prevented, but cracks are apt to occur in the weld metal. (4)If coated electrodes made of Mn-Cr steel rods, which contain about 15% Cr and 13-20% Mn, and suitable coating, are used, the results of such welding show a tendency that cracks are prevented both in the weld metal and heat-affected zone. And the author considered about such results from many points of view.
The yield of gaseous impuritis in acetylene generated by a "water to carbide" generator is affected by the temperature of water used. The results of the experiment are as follows; (1) yield of acetylene decreases sharply at a water temperature of 50°C; (2) yield of hydrogen phosphide is almost independent of temperature; (3) yield of hydrogen sulphide has a maximum point at about 30°C because of less solubility of SH2 in warm water and the formation or Ca(SH)2 (highly soluble in water) from CaS at higher temperatures. But the temperature of water in an acetylene generator should be held as low as possible in practice. In fhis analysis hydrogen sulphide was measured as BaSO4 and hydrogen phosphide as Mg2P2O7.