Various  Gases  by  the  a,  Particles  of  Radium.  625 
Again  RI  =  2-95x  104-4, 
=  308,  uncorrected. 
Correcting  for  want  of  saturation, 
ri=308xSS' 
=  321. 
On  the  same  day  and  under  the  same  conditions  RI  for 
air  =  231.  The  leakage  correction  is  found  to  be  the  same 
for  both,  and  need  not  be  applied.  Now,  as  far  as  con- 
sumption of  energy  is  concerned,  *23  molecules  of  air  are 
equivalent  to  '23/3"59  molecules  of  pentane,  =*065.  Hence 
if  all  the  energy  had  been  spent  as  pentane  molecules,  the 
value  for  RI  would  have  been 
1-065  x321--065x  231, 
=  342-15, 
Finally  =32T* 
Total  ionization  in  pentane      327 
Total  ionization  in  air  231 
It  is  quite  possible  that  the  low  density  of  the  mixture 
(2*22  instead  of  the  2*5  of  pure  pentane)  is  due  to  an 
admixture  of  lighter  and  more  volatile  hydrocarbons.  If  it 
were  so,  the  result  as  to  the  value  of  RI  would  not  be  affected 
in  any  essential  way. 
Determination  of  Stopping -power  and  RI  of 
Acetylene  (C2H2). 
Same    conditions    as    previous    experiment.       Apparatus 
charged  to  atmospheric  pressure  with  gas  ;  when  tested,  gas 
was   found  to   contain  less   than  2  per  cent,   of  impurities. 
Temperature  of  apparatus  =  37°-5  C.     Barometer  =  763  mm. 
1-41. 
'istance  from  Ra  to  middle 
Leak  in 
of  ionization  chamber. 
ten  seconds. 
4-2 
1430 
4-3 
1276 
4-4 
1024 
4-5 
818 
4-6 
698 
4-7 
688 
4-8 
701 
4-9 
698 
Cu  over 
Ra. 
46 
At  5-2  : 
for  300  volts  net  leak 
=  688 
and 
»   600     „       „      „ 
-706 
