ME.  G.  GOEE  ON  THE  PEOPEETIES  OF  ELECTEO-DEPO  SITED  ANTIMONY.  191 
28.  The  production  of  the  change  and  the  rapidity  of  its  action  are  considerably 
dependent  upon  the  temperature  of  the  mass ; pieces  which  would  easily  fracture  without 
further  change  .in  cold  water  would  not  break  without  change  in  the  air  at  60°  Fahr.  ; 
the  certainty  and  quickness  of  the  action  were  also  manifestly  greater  when  the  metal 
had  been  previously  warmed. 
29.  Immersing  the  metal  in  water  and  gradually  heating  it  to  212°  Fahr.  did  not 
cause  the  change,  destroy  the  property,  or  have  any  material  elfect  upon  the  rate  of 
heating  of  the  liquid.  N or  did  sudden  immersion  in  boiling  water,  or  partial  dissolving 
of  the  metal  by  warm  aqua-regia,  cause  it,  or  destroy  the  property ; but  slight  percussion 
on  removing  it  from  the  hot  water  caused  it  powerfully. 
30.  At  the  suggestion  of  Mr.  Faraday,  and  with  the  kind  assistance  of  him  and 
Dr.  Tyndall,  I have  been  enabled  to  reduce  pieces  of  the  metal  of  moderate  thickness 
(i^th  of  an  inch)  to  a state  of  fine  division  without  exciting  the  change  or  destroying 
the  thermic  property,  by  carefully  tritm’ating  them  in  a mixture  of  broken  ice  and  salt. 
Pieces  of  the  thickness  of  an  address  card  were  reduced  to  powder  without  the  change 
occurring  by  careful  pulverization  in  water  at  60°  Fahr.  ; the  most  ready  plan  adopted 
was  by  gently  pressing  the  pieces  in  small  quantity,  under  water,  in  a mortar  with  a 
rolling  motion  of  the  pestle  (not  by  blows  or  rubbing)  until  they  attained  the  size  of  a 
pin’s  head,  listening  all  the  time  to  detect  molecular  changes,  then  reducing  the  particles 
to  complete  powder  by  gentle  rubbing. 
31.  By  placing  small  quantities  of  the  dried  active  powder  upon  thin  sheets  of  metal 
and  gradually  applying  heat  until  the  change  occurred,  sufiicient  heat  was  evolved  by 
the  molecular  force  to  commence  oxidation,  which  spread  at  a much  lower  speed 
throughout  the  mass,  producing  true  combustion,  and  raising  it  to  a temperature  of  dull 
redness  visible  in  daylight.  The  molecular  change  in  the  powder  is  attended  by  a 
\isible  commotion  amongst  the  particles,  Portions  of  the  grey  variety  reduced  to 
powder  and  treated  similarly,  exhibited  the  same  combustion. 
32.  It  would  appear  from  these  experiments  that  amorphous  antimony  is  susceptible 
of  three  different,  distinct,  and  independent  changes : — 1st,  the  cohesive  change  of  its 
mass,  consisting  of  extensive  fractures  and  bending ; 2nd,  the  peculiar  change,  attended 
by  evolution  of  heat ; and  3rd,  a chemical  change,  consisting  of  oxidation  and  true  com- 
bustion ; whilst  the  crystalline  variety  is  susceptible  of  only  two  of  these  changes.  Anti- 
mony, deposited  in  the  state  of  a black  powder  upon  a small  cathode,  by  rapid  action 
in  the  solution  of  tartar-emetic  and  chloride  of  antimony,  exhibited  no  perceptible 
change  of  the  second  kind,  but  manifested  rapid  combustion  by  application  of  heat ; 
and  similarly  with  antimony  powder,  deposited  from  a solution  of  antimonic  oxide  in 
pyrophosphate  of  soda.  Deposits  of  metal,  obtained  from  solutions  of  tersulphide  of 
antimony  in  caustic  potash,  exhibited  the  phenomenon  of  unequal  cohesion,  but  not  the 
peculiar  change.  Fused  terchloride  of  antimony,  free  from  water,  with  an  anode  of 
antimony  and  cathode  of  copper,  did  not  conduct,  even  in  a small  degree,  the  electric 
current  from  five  pairs  of  zinc  and  silver  batteries.  By  rotating  a horizontal  silvered 
