Conductivity  of  Metallic  Oxides. 
521 
Electrolysis  was  more  easily  detected  with  this  oxide  than 
with  plumbic  oxide,  a  small  polarization  current  being- 
obtained  even  at  200°  (J. 
Cupric  Oxide. 
Some  pure  oxide  of  copper  was  melted  up  by  means  of  the 
oxy-hydrogen  flame,  and  the  melted  mass  ground  into  shape 
on  a  carborundum  wheel.  Its  dimensions  were  : — 1*006  cm. 
X  *991  cm.  and  2'179  mms.  thick.  Two  series  of  experiments 
were  made  with  this  specimen,  the  first  up  to  400°  0.  and  the 
second  to  over  1000°  C.  The  results  obtained  in  both  series 
are  given  in  the  following  table  : — 
Temperature 
Centigrade. 
Resistance  in 
ohms. 
Conductivity  in 
mhos. 
12-2 
462,400 
4-71  XlO-7 
59 
91,560 
2-38  X10-6 
66 
74,560 
2-92  Xl0~6 
134 
12,360 
1-76  X10~5 
157 
5,930 
3-67  X 10  ~5 
268 
556-5 
3-91  x  10~4 
303 
300-8 
7-24X10-4 
385 
96-2 
2-26  xlO-3 
463 
36-3 
6-00  Xl0~3 
12 
645,100 
3-38  Xl0~7 
487 
27-8 
•00784 
564 
11-13 
•02424 
618 
5-87 
•03711 
691 
2-34 
•0931 
733 
1-455 
•1497 
786 
•845 
•258 
873 
•347 
<628 
944 
•196 
1-111 
974 
•121 
1-80 
1038 
•021 
1037 
The  resistance  of  copper  oxide  at  high  temperatures  is  so 
small,  that  it  was  necessary  to  subtract  from  the  measured 
resistance  the  resistance  of  the  platinum  leads.  The  resistance 
of  these  at  various  temperatures  was  found  by  a  preliminary 
experiment  in  which  the  two  electrodes  were  placed  in  contact 
Phil.  Mag.  S.  6.  Vol.  11.  No.  64.  April  1906.       2  M 
