1904.] 



GOODWIN ELECTROLYTIC CALCIUM. 385 



resistance was supplied by a barrel of soda solution H, having two 

 ten-inch square cast iron furnace doors for electrodes and capable 

 of carrying 75 amp., two pairs of two wire resistance frames R of 

 75 amp. capacity and i ohm resistance per pair in series, two wire 

 resistance frames T of 10 amp. capacity and 8 ohm resistance each. 

 A Siemens 320 amp. ammeter is indicated at A and a 150 volt 

 Weston voltmeter at V. F is the calcium furnace and B the 

 gravity battery to keep the copper coil from carrying any of the 

 anode current. The anode was turned in a lathe from a six-inch 

 length of Acheson graphite electrode six inches in diameter. 

 Being pure and able to withstand the high temperature and 

 chlorine without disintegration made this material by far the most 

 suitable for constructing the furnace. 



In operation tlie volts and amperes vary when the cathode is 

 raised, but the following rough furnace record will give a pretty 

 close average of the working conditions : 



Date T' 7. ^ . Lj Grams Current 



^"''- 190!^. ^''^''- ^'"^- ^'''''' Calnum. Efficiency, 



I July 12 20 105 40 



2 " 14 15 160 4 200 41.9 



3 " 15 H 175 8 225 21.5 



4 »' 16 22 125 6 150 268 



5 " 18 19 160 6 295 41.2 



6 "21 18 180 5 150 22.3 



7 "22 19 185 4 125 22.6 



Total 1 183 



Taking account of the different length of runs and averaging we 

 get for runs 2 to 7 — 



Average volts ... :r= 17.7 

 '< amp. ... = 163. 

 " efficiency =: 29.1% 



On finally weighing the total yield of clean calcium there 

 remained 1050 grams. Adding 35 grams for loss by oxidation, 

 analysis and samples (= 1085 grams), the efficiency becomes 



1085 . .^ 



If covered by an inverted graphite crucible the furnace can be 

 left cold for more than forty-two hours, and then started again in a 



