386 GOODWIN ELECTROLYTIC CALCIUM. [Nov. 4. 



couple of minutes without the least trouble by drawing an arc 

 between the iron cathode and graphite anode at the surface of the 

 solid calcium chloride which immediately melts, allowing the iron 

 end to be immersed and moved slowly to the centre of the furnace 

 as the zone of fusion widens until it soon extends to the graphite on 

 all sides. The sticks of calcium obtained were of irregular shape 

 and covered with chloride. The bright metal showed the follow- 

 ing composition, found by an analysis of the piece used in the 

 tension and conductivity tests : 



Si 0.03% 



Fe 0.02 " 



Al 0.03 '« 



Ca 98.00" 



Mg o. 1 1 ** 



CI 0.90 " 



O (by difference) 0.91 ** 



100.00 «' 



The product of run No. 5 is shown in Fig. 6. This piece was 

 56 cm. (22") long, .8 cm. {-^") least and 3.2 cm. (i^") greatest 

 diameter, weighed 295 grams and represented a current efficiency 

 of over 40%. Some of the other pieces were of larger diameter. 

 The difficulty experienced until recently in making metallic calcium 

 was probably due to the small scale on which the operation was 

 tried. The simple and satisfactory operation of this furnace would 

 lead one to believe that, technically, the process would be still more 

 efficient and easily controlled. A furnace five times as large, using 

 about 1200 amperes, would require about 8 volts, and the screw 

 mechanism could be electrically controlled, keeping the current 

 constant and the product perfectly uniform, as the rotary furnaces of 

 the Union Carbide Co. are controlled. A water-cooled shield 

 might be necessary to cool the large calcium cathode as it was 

 drawn from the bath. The two essential conditions of operation 

 are — 



1. Rapid withdrawal of the metal formed to increase the yield 

 and minimize recombination. 



2. Narrow temperature limits. The bath must be hot enough to 

 deposit the metal molten, not spongy, and cool enough to let it 

 congeal upon the cathode and be raised without breaking off". 



To clean the metal most of the chloride was broken off" with a 



