72       Royal  Society : — Mr.  G.  Gore  on  the  Thermo-electric 
a  tin  box,  B.  The  box  is  water-tight,  and  has  in  its  lower  surface  a 
long  semicircular  cavity  (shown  by  dotted  lines)  to  receive  the  upper 
ends  of  the  twelve  tubes.  To  the  back  of  the  box  is  fixed  a  short 
cylinder  of  tin,  C,  closed  at  its  outer  end.  When  the  apparatus  is  in 
action,  the  box  is  filled  with  hot  water,  and  the  water  kept  boiling 
by  means  of  a  lamp  placed  beneath  the  tube  C.  The  twelve  tubes 
were  kept  in  position  by  divisions  of  wood  fixed  to  the  back  of  the 
stand,  as  shown  in  the  figure. 
The  tubes  1,  3,  5,  7,  9,  and  11  were  filled  with  a  previously  boiled 
and  cooled  mixture  of  j  of  an  ounce  of  sulphuric  acid,  and  19 
ounces  of  distilled  water;  and  the  others,  viz.  2,  4,  6,  8,  10,  and 
12,  with  a  similarly  prepared  solution  of  110  grains  of  hydrate  of 
potassium  dissolved  in  1 9  ounces  of  distilled  water. 
The  platinum  wires  were  connected,  in  the  order  shown  in  the 
sketch,  by  means  of  small  binding-screws  not  represented  in  the 
figure. 
On  connecting  the  terminals  with  a  galvanometer  containing  about 
180  turns  of  moderately  coarse  copper  wire,  and  applying  heat  to 
the  upper  electrodes  and  ends  of  tubes  by  means  of  the  boiling  water, 
no  deflection  of  the  needles  took  place ;  but  on  substituting  a  Thom- 
son's reflecting  galvanometer,  which  offered  a  resistance  of  30407 
B.A.  units  (=77872-32/  miles  of  copper  wire  TV  of  an  inch  thick), 
a  deflection  of  40  degrees  was  readily  obtained,  the  hot  platinum  wire 
in  the  dilute  acid  being  negative,  and  that  in  the  alkali  positive,  as 
shown  by  the  direction  of  the  arrows  in  the  sketch. 
From  these  results  it  is  evident  the  quantity  of  the  electric  current 
produced  was  exceedingly  small,  and  its  intensity  considerable.  By 
employing  electrodes  of  larger  surface,  such  as  spirals  of  platinum 
wire  and  more  concentrated  liquids,  the  quantity  of  the  current 
would  be  very  largely  increased.  (See  Phil.  Mag.  1857,  vol.  xiii. 
p.  1.) 
Fig.  9  represents  a  simpler  arrangement  of  this  apparatus,  in  which 
only  one  kind  of  liquid,  either  acid  or  alkaline,  is  employed.     The 
Fig.  9. 
electrodes  in  this  arrangement  must  be  disposed  in  the  order  repre- 
sented by  the  figure. 
