1904.] 



GOODWIN ELECTROLYTIC CALCIUM. 



383 



and retain the molten calcium, like the nickel gauze in the Castner 

 sodium furnace, but the long continued action of 225 amp. would 

 not fill this gauze with calcium because it presented a large surface 

 for the rapid recombination of the calcium: Ca -f CaCL := 

 2 CaCl.^ The formation of calcium and chlorine almost ceases and 

 active reaction and circulation are seen to take place in the molten 

 electrolyte. 



In the satisfactory furnace (Fig. 3) the bottom of solid calcium 

 chloride was maintained by the cooling effect of a copper coil (E, 

 Fig. 3 and Fig. 4) through which water was circulated. This coil 

 was insulated from the graphite by asbestos, 

 but a Weston milliammeter indicated that it 

 was carrying .17 amp. of the anode current 

 (190 amp.); therefore, to prevent contami- 

 nation of the bath by copper, a gravity cell 

 (B, Fig. 5) was connected between the cop- 

 per and the graphite and the milliammeter 

 indicated .04 amp. flowing the other way. 

 This very simple and efficient cooling coil 

 was made by annealing four feet of y^g-inch 

 seamless copper tube in a Bunsen flame, 

 filling it with sand, plugging the ends and 

 bending it easily into shape by hand. 



The new form of cathode was a ^-inch 

 iron rod (K, Fig. 3), dipping into the bath 

 from above and capable of being raised or 

 owered by the screw mechanism O. As the calcium was deposited 

 on the end of this iron rod it solidified, due to the cooling effect of 

 the cold upper part, the whale was gradually raised, the calcium 

 itself conducted the current away and formed the cathode, continu- 

 ing to grow in the shape of an irregular cylinder J. This is sim- 

 plicity itself because it accomplishes at once — 



I. A method of making cylinders of calcium up to 4 cm. diam- 

 eter and of any length desired with this small furnace. (When the 

 limit of the screw is reached the clamp M can be loosened, lowered 

 and a new hold taken.) 



' 2. Quick removal of the calcium from the molten calcium chlo- 

 ride, which is essential to maintain a fair current efficiency. 



Figure 4. 



1 Borchers, Elektto-Metalliirgie, 1896, p. 78. 



