522 
Dr.  F.  Horton  on  the  Electrical 
and  heated  up  just  as  in  the  experiment  proper.  The  values 
of  the  conductivity  are  plotted  against  the  temperatures  in 
diagram  VII. 
Diagram  VII. — Showing  increase  of  conductivity  of  Cupric  Oxide 
with  temperature. 
1 
\ 
1 
1 
$> 
1 
$ 
J 
\\ 
I 
< 
: 
/ 
"^1 
i 
V  1 
1 
( 
> 
I 
1 
J 
I 
/ 
J 
f 
/ 
J 
1 
/ 
f 
/ 
X 
&<^ 
*f 
100         200        300        400         500 
600 
70Q 
800       900 
1000 
No  sign  of  electrolysis  could  be  found  when  a  current  was 
sent  through  this  oxide  at  the  ordinary  laboratory  temperature. 
A  current  of  1*625  x  10~8  ampere  was  sent  through  the  oxide. 
This  slowly  decreased  to  1*528  X  10~s  ampere  in  10  minutes, 
but  on  cutting  out  the  battery  no  trace  of  polarization  current 
could  be  observed.  The  decrease  of  current  was  not  due  to 
decomposition  such  as  had  been  observed  in  the  case  of  lime  ; 
for  on  reversing  the  direction  of  the  current  through  the 
copper  oxide  a  steady  and  equal  deflexion  of  the  galvanometer 
in  the  opposite  direction  was  obtained.  Thus  we  may  conclude 
that  the  passage  of  a  current  of  electricity  through  copper 
oxide  at  the  ordinary  laboratory  temperature  is  not  accom- 
panied   by    electrolysis.       At    higher    temperatures    it   was 
