:396 
Chemical  Notes. 
f  Am.  Jour.  Pharni, 
(    August,  lii82. 
Processes  for  Direct  Coppering  of  Castings  of  Iron  and  Steel. — F. 
Weil  gives  an  account  of  tlie  processes  devised  by  liim  for  the  direct 
cop})ering  of  castings  of  iron  and  steel,  witlioiit  the  use  of  any  inter- 
mediate coating  of  plumbago  or  other  material  upon  the  surface  of  the 
casting. 
The  deposit  of  copper  by  this  method  is  so  homogeneous,  and  so 
faithfully  reproduces  the  most  delicate  details  of  ornamentation,  as  to 
give  to  articles  so  coppered  the  artistic  value  of  bronze,  and  at  the 
same  time  is  so  firmly  adherent  that  castings  coppered  by  this  process 
have  remained  exposed  to  the  weather  for  ten  years  without  requiring 
any  retouching.  The  alkaline  organic  baths  used  in  the  process  pre- 
sent several  advantages  over  the  ordinary  alkaline  baths  used  in  elec- 
trotyping.  The  cyanides,  which  are  both  injurious  to  the  health  of 
the  workmen  and  expensive,  are  replaced  by  organic  acids,  or  by  gly- 
cerin, both  of  which  are  cheap  and  have  the  advantage  of  not  l)eing 
decomposed  in  the  operation.  Thus  the  baths  require  no  renewal  of 
organic  material,  and  act  continuously,  provided  the  necessary  amount 
of  oxide  of  copper  is  added  from  time  to  time.  Finally  the  well- 
known  property  of  alkaline  organic  solutions  of  dissolving  oxide  of 
iron  easily  and  rapidly,  without  attacking  the  metal  itself,  always  ren- 
ders the  cleansing  of  the  castings  perfect,  as  the  bath  finishes  the 
cleansing  of  articles  before  coppering  them. 
The  process  is  carried  on  in  three  different  w^ays,  according  to  local 
conditions  and  the  different  applications  of  the  articles  to  be  co2)pered. 
The  first  method  consists  in  plunging  the  articles  in  the  bath  in  con- 
tact with  strij)s  of  zinc.  The  coppering  begins  immediately,  and 
according  to  the  alkalinity  of  the  bath  and  the  destination  of  the 
articles  to  be  coppered,  requires  a  variable  time,  from  a  few  minutes  to 
several  hours. 
The  second  process,  which  has  been  employed  with  great  success  for 
coppering  the  street  lamps  of  a  large  city,  consists  in  placing  in  the 
vessel  containing  the  bath  and  the  objects  to  be  plated  poious  jars, 
filled  with  a  strong  solution  of  caustic  soda,  in  which  are  placed  plates 
of  zinc,  connected  with  the  articles  in  the  bath  by  a  coarse  coi)per  Avire. 
The  time  required  for  depositing  a  moderately-thick  coating  of  coi)per, 
such  as  required  by  candelabra,  etc.,  is  very  short. 
The  third  process  consists  in  the  use  of  the  same  baths  as  in  the  first 
^nd  second  processes,  in  conjunction  with  a  dynamo-electrical  machine. 
The  baths,  as  has  been  said,  only  require  the  addition  of  a  certain 
