Conductivity  of  Metallic  Oxides. 
515 
used,  being  over  100  megohms.  The  values  of  the  resistance 
at  higher  temperatures  and  also  of  the  conductivity  calculated 
from  the  resistance  and  dimensions  of  the  slab  are  given  in 
the  following  table. 
Temperature 
Centigrade. 
Resistance  in 
ohms. 
Conductivity  in 
mhos. 
471             | 
35,000.000 
3-69  XlO"9 
564 
3,000,000 
4-34  xlO"8 
630 
800,000 
1-61  Xl0-7 
743 
215,000 
6-00  xlO~7 
S28 
88,000 
1-46X10"6 
933 
31,000 
4-16xl0~6 
970 
22,300 
5-79  xlO"6 
1055 
12,450 
104xl0-5 
1191 
4,900 
263  x  10- 5 
1204 
6,800 
1-90  xlO-0 
1280 
12.900 
100x10"° 
1341 
290,000 
4-45x10"' 
Diagram  III . — Showing-  increase  of  conductivity  of  MgO 
with  temperature. 
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In    diagram    III.  the   values  of   the   conductivity    given 
in  the   above   table  are   plotted   against  the  corresponding 
