70       Royal  Society : — Mr.  G.  Gore  on  the  Thermo-electric 
to  the  line  F  with  the  same  mixture  ;  the  dish  A  was  then  filled  with 
the  weaker  mixture  up  to  the  same  level  and  the  bung  slowly  with- 
drawn. The  two  copper  dishes,  previously  connected  with  the 
galvanometer,  were  next  simultaneously  immersed  in  the  mixtures 
and  the  effect  noted.  The  following  are  the  results  obtained  by  this 
method : — 
Nitric  Acid. 
Experiment  I . — In  A,  1  volume  of  acid  diluted  to  80  volumes. 
In  B,  1  volume  diluted  to  40.  Copper  in  A  was  positive  tempo- 
rarily, value  *0270;  and  permanently,  value  '0198. 
Experiment  2. — In  A,  1  volume  of  acid  diluted  to  40  volumes. 
In  B,  1  volume  of  acid  diluted  to  20  volumes.  The  copper  plate  in 
A  was  first  positive  temporarily,  value  of  deflection  *0064  ;  and  then 
that  in  B  permanently,  value  *2850. 
Experiment  3. — In  A,  1  volume  of  acid  diluted  to  40  volumes. 
In  B,  1  volume  diluted  to  10  volumes.  Copper  plate  in  B  was  po- 
sitive temporarily,  value  #4863 j  and  permanently,  value  -0819. 
Hydrochloric  Acid. 
Experiment  1 . — In  A,  1  volume  of  acid  diluted  to  40  volumes. 
In  B,  1  volume  diluted  to  20  volumes.  The  copper  in  B  was  positive 
temporarily,  value  *9608  ;  and  permanently,  value  *1087. 
Experiment  2. — In  A,  1  volume  of  acid  diluted  to  40  volumes. 
In  B,  1  volume  diluted  to  2666  volumes.  The  copper  in  B  was  po- 
sitive temporarily,  value  *3479  ;  and  permanently,  value  -0702. 
Chloric  Acid. 
In  A,  1  volume  of  acid  diluted  to  80  volumes.  In  B,  1  volume 
diluted  to  40  volumes.  The  copper  in  B  was  positive  temporarily, 
value  "0036  ;  and  permanently,  value  *0009. 
Sulphuric  Acid. 
In  A,  1  volume  of  acid  diluted  to  80  volumes.  In  B,  1  volume 
diluted  to  40  volumes.  The  copper  in  B  was  positive  temporarily, 
value  '0467;  and  permanently,  value  '0330. 
On  examining  these  results,  it  will  be  perceived,  1st,  that  only 
in  one  half  the  number  of  the  experiments  did  increased  strength 
of  liquid  produce  electrical  currents  similar  in  direction  to  those  pro- 
duced by  increased  temperature ;  and  therefore  the  heat  does  not 
act  simply  by  causing  a  greater  number  of  molecules  of  each  indi- 
vidual substance  to  touch  the  hot  plate ;  and,  2nd,  that  only  in  one 
of  the  experiments  was  the  copper  in  the  weaker  liquid  both  tempo- 
rarily and  permanently  positive  to  that  in  the  stronger ;  whilst  in 
five  of  the  experiments  the  copper  in  the  stronger  liquid  was  tem- 
porarily and  permanently  positive  to  that  in  the  weaker.  Increase 
of  strength  of  the  liquid  therefore  made  the  copper  positive  in  five 
cases  out  of  six. 
