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FOOD FROM THE AIR 



outside diameter, lined with very refractory material, leaving a cylindrical 

 space in the center. Air is supplied by any convenient blower, and the prod- 

 ucts pass out by special openings to the condensing or absorbing vessels. The 

 electrodes are U-shaped copper tubes, the curve being tipped with the poles. 

 Water circulates constantly through the tubes. The points of the electrodes 

 are within a strong magnetic field by the action of which the arc is spread out 

 in the form of a fan on each electrode. In an apparatus of the dimensions 

 noted above the arc will be about six feet in diameter. Interesting electric 

 phenomena are noted during the running of the furnace, but these do not re- 

 quire discussion here. The operation of the furnace involves severe action on 

 the materials with which it is lined, and renewals have to be made frequently. 



Arc of the Birkeland-Eyde furnace. From Trans. Far. Soc, 1906, 2, 98. 



A plant operating on the general principle of the Birkeland-Eyde appa- 

 ratus was installed by Bradley and Lovejoy, near Niagara Falls, deriving elec- 

 tric power from that point, but it was apparently not commercially success- 

 ful, as it was discontinued in 1904. In normal conditions, heretofore, the 

 abundance of sodium nitrate and the ease with which it may be imported into 

 the United States have rendered methods of nitrogen-fixation unprofitable, 

 but conditions in these respects threaten to change very much and it behooves 

 Americans to give earnest attention to the application and development of 

 such procedures. 



Another form of nitrogen-oxidizing furnace is that devised by Schoenherr. 

 It is essentially a long tube into which an iron rod enters at the lower end, con- 



