188  ME.  G.  GOEE  ON  THE  PEOPEETIES  OF  ELECTEO-DEPOSITED  ANTBIONT. 
tartar-emetic  and  dilute  hydrochloric  acid.  The  first  hquid  exhibited  no  material 
irregularity  in  its  rate  of  cooling,  indicative  of  molecular  change,  between  220°  and 
100°Fahr.  By  previously  evaporating  the  same  solution  to  one-half  its  oiiginal  bulk, 
its  tendency  to  yield  a grey  deposit  by  heat  was  considerably  reduced ; and  by  diluting 
it  either  with  pyroxylic  spirit,  dilute  hydrochloric  acid,  or  solution  of  table-sEdt,  its 
aptitude  to  give  grey  metal  at  ordinary  temperatures  was  increased  and  its  depositing 
quality  injured. 
12.  Upon  examining  the  electric  relations  of  the  depositing  hquids  uith  platinum 
plates  in  the  apparatus  described  at  page  1 of  the  Philosophical  Magazine,  Januaiy 
1857,  hot  platinum  was  found  to  be  increasingly  electro-negative  to  cold  platinum  up 
to  210°Fahr.  in  the  tartaric  acid  solution,  in  accordance  with  the  general  rule  there 
stated;  but  with  the  first  liquid  an  unusual  variation  occurred,  hot  platinum  being 
increasingly  negative  to  cold  platinum  up  to  110°Fahr.,  then  decreasingly  to  145°Fahe., 
and  above  that  temperature  increasingly  positive  to  210°Fahr.  Similar  effects  were 
obtained  with  small  square  columns  of  Duboscq’s  carbon  (made  by  him  for  electric  light 
apparatus)  immersed  in  those  liquids  in  V-tubes.  In  each  case  the  solution  was  pre- 
viously boiled,  and  repeated  experiments  gave  uniform  results. 
13.  By  separating  the  first  and  second  solutions  from  each  other  by  means  of  a porous 
diaphragm,  and  immersing  two  perfectly  similar  pieces,  either  of  platinum  or  of 
Duboscq’s  carbon,  one  in  each  liquid,  and  connecting  them  with  a galvanometer,  that 
in  the  chloride  solution  was  in  each  case  found  to  be  rather  strongly  electro-positive  to 
that  in  the  tartaric  acid  liquid. 
14.  In  depositing  from  either  of  the  solutions  which  yield  the  amorphous  metal, 
especially  ordinary  chloride  of  antimony  nearly  saturated  with  antimony  by  the  battery 
process,  there  is  a great  tendency  in  the  deposit  to  extend  itself  in  the  form  of  a thin 
sheet  of  grey  metal  upon  the  surface  of  the  liquid ; this  lateral  spread  of  the  metal  is 
unique,  and  increases  rapidly,  and  like  the  grey  excrescences  formed  upon  other  parts 
of  an  amorphous  deposit,  its  speed  of  increase  is  much  greater  than  that  of  the  dark 
metal  near  it  (see  10.) ; the  reason  of  this  appears  to  be  that  crystalline  antimony  is 
more  electro-negative  than  the  amorphous  variety,  and  therefore  receives  the  electric 
current  with  greater  facility.  I have  found  with  perfect  specimens  of  grey  and  dark 
antimony  deposited  upon  perfectly  similar  copper  wires,  that  the  amorphous  variety  was 
electro-positive  to  the  crystalline  in  the  following  liquids : — dilute  phosphoric,  sulphimc, 
hydrochloric,  and  nitric  acids ; in  aqueous  solutions  of  ammonia,  potash,  and  carbonate  of 
soda ; also  in  the  first-mentioned  chloride  solution.  This  difference  of  electric  condition 
was  in  some  instances  of  deposition  so  great  as  to  generate  a separate  electric  current, 
and  completely  redissolve  some  of  the  dark  portions.  The  phenomenon  of  lateral  sur- 
face deposit  did  not  occur  in  the  tartaric  acid  solution.  Antimony  trees,  consisting  of 
branches  of  amorphous  and  crystalline  nodules,  were  easily  formed  by  suspending  a hori- 
zontal copper  wire  as  a cathode  upon  the  surface  of  the  terchloride  solution. 
15.  Heat  was  perceptibly  evolved  in  the  first-named  hquid  during  deposition;  on  one 
