Action  of  Metals  and  Liquids. 
71 
In  the  fourth  experiment  with  hydrochloric  acid  with  difference 
of  temperature,  and  in  the  second  one  with  difference  of  strength,  the 
mixture  in  each  case  consisting  of  1  volume  of  acid  diluted  to  40  vo- 
lumes with  water,  an  increase  of  temperature  from  16°  to  about 
98°  C.  produced  a  deflection  of  the  value  '28o4,  whilst  an  increase 
of  strength  to  1  volume  in  26'66  gave  a  deflection  in  the  same 
direction  of  the  value  *34/9.  An  increase  of  temperature  of  about 
82°  C.  was  not  quite  equal  in  electrical  effect  to  an  increase  of  50 
per  cent,  in  the  number  of  molecules  of  the  acid  which  touched  the 
plates. 
In  the  third  experiment  with  chloric  acid  with  difference  of  tem- 
perature, and  in  the  single  one  made  with  difference  of  strength,  the 
mixture  in  each  instance  consisting  of  1  volume  of  the  acid  diluted 
to  80  volumes  with  water,  an  increase  of  temperature  of  about  82°  C. 
produced  an  electrical  effect  of  '0040  ;  whilst  an  increase  of  100  per 
cent,  in  the  number  of  molecules  of  the  acid  which  touched  the 
plates  produced  an  opposite  electrical  effect  of  *0036. 
In  the  third  experiment  with  sulphuric  acid  with  difference  of 
temperature,  and  in  the  single  one  made  with  difference  of  strength, 
each  being  with  a  mixture  of  1  measure  of  acid  in  80  of  water,  an 
increase  of  temperature  of  about  82°  C.  caused  an  electrical  effect  of 
•0418,  and  au  increase  of  100  per  cent,  in  the  number  of  molecules 
of  acid  which  touched  the  plates  caused  an  opposite  electrical  effect 
of -0467. 
A  liquid  thermo-electric  battery. 
Acting  upon  the  general  results  thus  obtained  in  this  subject,  I 
constructed  a  liquid   thermo-electric    battery    consisting  of  twelve 
glass  tubes,  f  of  an  inch  in  diameter  and 
10  inches  long, 
closed  at 
one  end  (and  containing  a  platinum  wire  hermetically  sealed  in  that 
Fig-  7. 
Fig.  8. 
\ n 
1 
end),  and  bent  to  the  form  shown  in  fig.  7,  each  tube  being  filled 
with  a  conducting  liquid,  and  its  outer  end  closed  by  a  cork,  in  winch 
was  fixed  a  second  platinum  wire  to  dip  into  the  liquid. 
Fig.  8  represents  the  apparatus  ;  A  A  is  a  wooden  stand  supporting 
