DE.  A.  MATTHIESSEN  ON  THE  THEEMO-ELECTEIC  SEEIES. 
377 
Fig.  4. 
pose  as  before.  Where  two  or  more  thermo-elements  were  used,  as  was  generally  the 
case,  they  were  fixed  in  a piece  of  wood,  as 
fig.  4 shows,  and  which  needs  no  explanation. 
With  the  same  apparatus  the  difference  in  the 
thermo-electric  behaviour  of  the  cleavage  planes 
of  bismuth  and  antimony  crystals  was  studied. 
The  bismuth  crystals  had  about  8 millims.  the 
sides ; two  cleavage  planes  were  made  pei'pen- 
dicular  to  the  principal  axis,  and  two  parallel 
to  it.  As  antimony  crystals  could  not  be  ob- 
tained large  enough  for  these  experiments, 
pieces  were  cut  out  of  commercial  antimony, 
as  Feaxz  did  for  his  research  on  the  same  sub- 
ject*. These  were  so  experimented  with,  that  in  one  case  the  planes  perpendicular  to 
the  principal  axis,  in  the  other  those  parallel  to  it,  were  pressed  between  the  sides  of 
the  boxes.  The  position  of  the  crystals,  where  the  current  passes  in  the  direction  of 
the  principal  axis,  is  called  the  axial,  the  other  the  equatorial.  The  results  of  the 
observations  with  the  crystals  do  not  agree  very  well  with  each  other,  owing  probably 
to  the  cleavage  planes  not  being  exactly  ground  at  the  proper  angles,  and  also  to  their 
being  placed  in  a rather  oblique  position  between  the  boxes.  Table  III.  gives  the 
results  obtained  with  the  copper  boxes. 
Table  III. 
7 Copper,  Argentine — Argentine,  Bismuth  (pure  cast). 
o o Mean. 
t,=2b-b  f,=47-0  i;=I-5031 
^,=25-8  ??2=40-4  v=I-609ll-505 
f,=25-5  72=38-7  v=l-604:} 
Silver,  Cohalt  (No.  I) — Silver,  Argentine. 
f,  = I8-7  72=43-7  v=l-722^ 
7,  = 18-7  72=40-0  i;=I-7I0ll-7I3 
7,  = 19-3  72=36-8  ^;=I-708j 
Silver,  Argentine — Silver,  Nickel. 
7,  = 20-5  72=56-0  i;=I-0401 
7,  = 20-6  72=50-2  ?;=l-048ll-044 
7, =21-0  72=44-6  t;=l-044j 
Silver,  Argentine — Silver,  Cobalt  (No.  2). 
7,  = 21-2  72=60-0  ?;=l-389'j 
C = 21-4  72=53-0  ^;=l-409il-398 
7.=21-7  72=47-7  ^=1-395) 
* PoGaENDOEPF’s  Annalen,  vol.  Ixxxiii.  p.  374. 
3 E 2 
