376 
DE.  A.  MATTHIESSEN  ON  THE  THEEMO-ELECTEIC  SEEIES. 
as  shown  in  fig.  1 ; and  lastly,  the  long  end  of  the  glass  was  melted  off  at  c,  and  the 
superfiuous  platinum  wire  cut  oif.  During  the  experiments  the  tube  was  so  placed  that 
the  one  end  found  itself  in  the  middle  of  the  one,  and  the  other  in  the  middle  of  the 
other  box ; that  filled  with  warm  water  was  placed  higher  than  the  other,  in  order  that 
the  tube  might  remain  in  an  inclined  position,  preventing  thereby  the  warming  of  the 
other  end  through  currents  which  would  otherwise  have  arisen  in  the  oil.  The  con- 
nexion was  now  formed  by  soldering  on  the  silver  or  other  wdi’es  to  the  platinum  ones. 
To  ascertain  whether  this  arrangement  would  give  correct  results,  a silver-palladium 
element  was  compared  with  two  composed  of  silver-copper ; in  the  one  case  the  palla- 
dium wire  was  fastened  in  the  wire-holders  as  above  described,  in  the  other  it  was 
soldered  directly  to  the  silver.  The  ratio  of  the  electromotive  power  of  the  two 
elements  was  found,  when  the  wrre-holders  were  used,  in  four  obseiwations,  1‘779, 1'776. 
1‘767,  1'777,  the  mean  of  which  is  1'775,  agreeing  very  well  '^'ith  1‘780,  the  mean  ol 
the  results  obtained  when  the  wires  were  soldered  together. 
The  above-described  boxes  could  only  be  used  with  metals  in  form  of  wire,  or  rods  ot 
a considerable  length  (at  least  8 inches) ; for  experimenting  with  other  metals  two  smaller 
boxes  were  employed,  of  which  fig.  3 is  a sketch.  A and  B are  two  copper  boxes  of 
Eig.  3. 
about  4 inches  in  height,  4 in  width,  and  5 long.  B consists  of  two  halves,  a and  b. 
insulated  from  each  other  by  a piece  of  india-rubber.  A was  filled  with  warm,  B with 
cold  oil. 
If  two  pieces  of  different  metals,  c and  d,  are  placed  between  the  two  boxes,  which 
are  pressed  against  each  other  by  screws,  and  if  the  two  wries  e and/’  soldered  to  the  ‘ 
two  halves  of  B,  be  connected,  a cnrrent  is  formed  in  the  circuit  whose  electromotive  , 
power  is  equal  to  that  of  a thermo-element  constructed  with  the  metals  c and  d,  whose  J 
extremities  have  the  temperature  of  the  oil  in  the  boxes.  To  determine  this  electro-  | 
motive  power,  a circuit  was  formed  Avith  the  Avires  of  the  multiplier  used  for  the  [ 
former  experiments,  the  two  wires  e and  /’  and  the  Avries  of  one  or  more  thermo- 
elements made  of  wires  Avhose  soldering-points  dipped  alternately  in  the  oil  of  each  box. 
The  tAvo  commutators  were  again  brought  into  the  circuit,  and  ansAvered  the  same  pur- 
