64      Royal  Society: — Mr.  G.  Gore  on  the  Thermo-electric 
Acetate  oj 
*  Sodium. 
Grains  diluted 
Value  of 
To. 
to  20  OZ8. 
Deflection. 
1. 
50 
.... 
•0016^ 
2. 
....       100 
. . .  • 
•0070 
3. 
4. 
5. 
....       200 
....       400 
....       800 
.... 
•0198 
•0594 
•1328 
Hot  plate  positi 
>Solution   alkaline 
6. 
....     1600 
•2202 
test-paper. 
7. 
....     2000 
.... 
•2850 
8. 
....     2727 
.... 
•2997^ 
Acetate 
of  Zinc. 
Grains  dilated 
Value  of 
To. 
to  20  ozs. 
Deflection. 
1. 
50 
«... 
•ooor 
2. 
....       100 
.... 
•0006 
3. 
....       200 
.... 
•0016 
4. 
....       400 
.... 
•0025 
5. 
....       500 
.... 
•0020 
>Hot  plate  positive. 
6. 
....       800 
.... 
•0020 
7. 
....     1000 
.... 
•0012 
8. 
....     1600 
.... 
•0004 
9. 
....     2000 
.... 
•0001 
to 
Crystallized  Tartaric  Acid. 
The  hot  plate  was  negative.      Eight  different  solutions,  varying  in 
strength  from  50  to  3200  grains  in  20  ounces  by  measure  of  the  so- 
lution, were  tried ;  but  very  feeble  currents  were  obtained,  and  the 
plates  were  not  tarnished. 
Crystallized  Citric  Acid. 
The  hot  plate  was  negative.  With  a  series  of  seven  solutions, 
varying  in  strength  from  50  to  3200  grains  in  20  ounces  of  liquid, 
more  feeble  results,  even,  than  those  with  tartaric  acid  were  obtained, 
and  the  plates  were  net  tarnished.  Probably,  with  this  substance 
and  with  others  where  the  resulting  currents  were  very  feeble,  more 
distinct  effects  would  be  obtained  by  employing  a  galvanometer  of 
much  greater  electrical  resistance. 
Several  experiments  similar  to  those  already  described  were  made 
with  the  apparatus  shown  in  fig.  3.  The  apparatus  consists  of  a 
glass  beaker  containing  the  liquid,  and  two  platinum  electrodes — A 
being  a  disk  of  platinum  rivetted  to  a  platinum  wire  enclosed  by  a 
glass  tube,  B,  and  C  a  platinum  crucible  (for  receiving  the  boiling 
water)  with  a  platinum  wire  rivetted  to  it. 
Experiment  1. — With  a  solution  of  100  grains  of  citric  acid  in  2 
ounces  of  distilled  water,  the  hot  platinum  cup  was  negative,  the  value 
of  the  temporary  deflection  being  -0007. 
Experiment  2. — With  100  grains  of  tartaric  acid  in  2  ounces  of 
water,  the  hot  cup  was  negative,  value  of  deflection  -0001. 
Experiment  3. — With  100  grains  of  racemic  acid  in  2  ounces  of 
water  the  hot  cup  was  negative,  value  of  deflection  *00005. 
