st>Mi: ci>.\ 1 1 Mfi'K.iio tin .ixu-.s i.\ rilVSICS VI l.io 



liiii', is for thf arc a (iDwnw.iril-slaiilinK rur\i' (l-'i^;- •">). Such a curvt' 

 is ralli'tl a ilianuliristic, ami tin- arr is said lo liaw a ncn'iUvc cliaractrr- 

 istic. Ii>iiixatii)ii gm-s on roiilimialK witliiii the positive column, 

 ami ions of l)olh si^ns can Ik; drawn out i)y a crosswise field; hut 

 recombination of ions, a proccs,>? which we have not considered, also 

 goes on i-onlimiaily and maintains an cfiuilibrium. Presumably it 



Fig. 6 — Voltage-current curves or "characteristics," for arc discharges (lielow) and 

 glow discharges (above) in air, between gold electrodes. The different curves corre- 

 s|K)nd to different anofle-cathcKlc distances. (Ives, Journal of the Franklin In^lilute) 



is the effect of the field strength on this equilibrium which causes 

 the current-voltage curve to slant in what most people instinctively 

 feel is the wrong wa>'; but the theory of the eciuilibriuiii is not yet 

 far advanced. 



Langmuir and Schottky, working independenth' in Schenectady 

 and in dermany, [)erformcd some very pretty experiments by thrust- 



