546      Mr.  H.  E.  Hurst :  Genesis  of  Ions  by  Collision  and 
Nitrogen  prepared  by  second  method. 
V 
(with  light). 
Spark 
p. 
d, 
yd. 
Xd. 
potential 
without  light. 
4 
•72 
2-88 
502 
507 
512 
4 
•708 
2-832 
504 
504 
4 
•6 
24 
460 
464 
2 
•58 
116 
332 
334 
2 
•65 
1-30 
339 
343 
2 
•665 
1-33 
349 
344 
346 
2 
•85 
1-70 
382 
384 
2 
•67 
1-34 
329 
345 
1 
•4 
•4 
330 
336 
1 
•5 
•5 
310 
314 
1 
•58 
•58 
304 
300 
304 
1 
•601 
•601 
298 
303 
1 
•868 
•868 
300 
306 
1 
1-0 
1-0 
310 
314 
Mixtt 
ire  of  Nitrogen  and  1*1  pe 
r  cent,  of  Oxygen. 
4 
•72 
2-88 
516 
518 
4 
•708 
2-832 
514 
520 
4 
•6 
2-4 
472 
476 
2 
•58 
116 
335 
343 
2 
•65 
1-30 
342 
350 
2 
•85 
1-70 
392 
398 
2 
•665 
1-330 
341 
349 
1 
•601 
•601 
302 
Mi 
xture  of  Nitrogen  and  5  p 
sr  cent.  Oxygen. 
i 
•4 
•4 
369 
371 
•5 
•5 
334 
338 
•58 
•58 
320 
324 
•601 
•601 
320 
•65 
•65 
316 
320 
•70 
•70 
312 
316 
•8 
•80 
316 
320 
•868 
•868 
320 
324 
1-0 
10 
324 
332 
The  sparking-potentials  for  nitrogen  do  not  agree  with  those 
obtained  by  Strutt  (Phil.  Trans.  193,  p.  377,  1900).  He 
found  that  the  sparking-potential  of  nitrogen  varied  con- 
siderably with  different  samples  of  gas,  although  prepared 
by  the  same  method.     This  he  attributed  to  the  presence  of 
