ME.  G.  GOEE  ON  THE  PEOPEETIES  OF  ELECTEO-DEPOSITED  ANTIMONY.  187 
or  better  for  one  week,  the  edges  of  the  deposit  assume  a j)artly  nodular  form.  The 
cleaning  of  the  anode  in  this  case  may  be  of  less  frequency,  and  with  water  alone. 
7.  A speed  of  deposition,  varying  from  0*75  to  3'0  grains  per  square  inch  of  receiving 
surface  per  hour,  has  repeatedly  yielded  a good  bright  deposit  with  the  first-named 
solution;  and  from  0'25  to  2’25  grains  per  square  inch  per  hour  has  often' given  a good 
crystalline  deposit  with  the  second  liquid.  By  keeping  the  cathodes  in  constant  motion, 
much  more  rapid  action  may  be  successfully  ventured. 
8.  By  similar  means  to  those  described,  and  without  the  aid  of  motion,  a solid  bar  of 
dark  bright  antimony,  upwards  of  1 inch  in  diameter  and  3 inches  long,  was  formed 
upon  a piece  of  copper  wire  i^th  of  an  inch  thick  and  2 inches  long,  in  a period  of  twenty- 
eight  days,  and  with  the  aid  of  motion  in  about  half  that  time. 
9.  In  depositing  antimony  from  these  solutions  a variety  of  circumstances  occur,  a 
knowledge  of  which  will  greatly  assist  in  obtaining  perfect  specimens  of  the  two  varieties. 
In  using  the  ordinary  chloride,  after  the  process  has  been  progressing  one  or  two  days 
with  continuous  bright  deposit,  warty  excrescences  of  the  grey  variety  will  nearly  always 
occur  upon  portions  of  the  recemng  surface,  the  localities  of  their  appearance  differing 
according  to  the  shape  of  the  cathode  and  its  depth  of  immersion ; if  it  be  mthin  half 
an  mch  of  the  surface  of  the  liquid,  rough  grey  metal  will  appear  upon  its  upper  parts. 
The  presence  of  these  excrescences  appears  in  nearly  all  cases  to  depend  upon  accumu- 
lations of  partly  exhausted  solution  at  the  upper  part  of  the  liquid,  and  at  different 
parts  of  the  recemng  surface.  The  solution,  partly  deprived  of  its  metal  by  the  action, 
and  thus  rendered  specifically  lighter,  ascends  in  a layer  against  the  cathode,  and  accumu- 
lates at  its  over-hanging  parts  and  at  the  surface  of  the  liquid,  and  yields  in  those 
exhausted  or  acid  portions  only  the  grey  deposit ; similar  effects,  but  in  a much  less 
degree,  occur  in  the  solution  of  chloride  of  antimony  and  tartar-emetic.  To  obviate  these 
effects,  the  solution  should  be  frequently  stirred;  and  to  entirely  prevent  them,  the 
cathode  should  be  immersed  at  least  I inch  below  the  surface  of  the  liquid,  and  be 
kept  in  a constant  state  of  gentle  swinging  motion  by  attachment  to  the  moving  pallets 
of  an  ordinary  clock.  Roughness  or  want  of  cleanhness  of  the  receiving  surface  also 
seems  to  favour  the  production  of  those  excrescences. 
10.  On  every  occasion  -with  the  first  liquid,  when  the  battery  power  became  nearly 
exhausted  grey  nodules  appeared,  and  when  once  commenced  there  was  a strong  tendency 
in  them  to  continue ; but  by  increased  electric  power,  stirring  the  liquid,  and  persistent 
action,  they  became  covered  with  amorphous  deposit. 
11.  If  during  the  process  of  deposition  the  temperature  of  the  first  solution  was 
gradually  raised,  the  deposited  metal  suddenly  changed  from  amorphous  to  crystalline 
at  about  205°Fahr.,  and  less  suddenly  resumed  its  amorphous  character  on  cooling  at 
about  79°Fahr.  ; on  interposing  a galvanometer  the  conductivity  of  the  circuit  was 
found  to  be  gradually  increased  during  the  rise  of  temperature,  and  gradually  decreased 
during  the  fall.  These  phenomena  were  repeatedly  produced  by  reheating  the  same 
portion  of  liquid ; and  similar  effects  were  obtained  with  the  solution  composed  of 
2 c 2 
