416 
A  NEW  METHOD  FOR  GILDING  COPPER  WIRE. 
time  would  be  necessary,  as  many  as  three  to  four  weeks  in 
some  cases.  To  avoid  the  tediousness  of  this  operation,  the  im- 
mersion in  the  alkaline  bath  is  only  continued  for  12  to  18  hours, 
but  after  washing  in  warm  water  the  coated  objects  are  then 
placed  for  12  or  24  hours  in  an  ordinary  solution  of  blue  vitriol, 
which  will  increase  the  deposit  quite  as  uniformly,  but  much 
more  rapidly.  In  this  manner  a  coating  up  to  one-fifth  milli- 
metre in  depth  may  be  formed,  which  is  sufficient  for  out-door 
work,  and  even  exposure  to  water. — KulmJieim,  Druggists'  Cir- 
cular;  Aug.,  1868,  from  Dingier  s  Journal,  vol.  188,  p.  286. 
A  NEW  METHOD  FOR  GILDING  COPPER  WIRE 
Has  been  invented  by  Mr.  Helouis  (36  rue  Meslay,  Paris)  by^ 
which  the  blackening  so  common  with  ordinary  gilding  is  pre-* 
vented.  It  is  partly  the  same  plan  as  that  by  which  platinum 
or  gold-wire  of  extreme  tenuity  has  been  made,  i.  e.,  by  enclos- 
ing these  metals  within  a  cylinder  of  silver  or  copper,  and  draw- 
ing them  out  together  to  a  fine  degree  of  fineness,  when  on  treat- 
ment of  the  wire  with  dilute  nitric  acid,  the  outer  coating  is  dis- 
solved, leaving  a  continuous  thread  of  the  metal  not  affected  by 
the  acid.  In  the  present  case,  however,  the  purpose  is  to  coat 
the  copper-wire  with  a  thin  film  of  platinum,  upon  which  gold 
may  then  be  deposited  without  danger  of  its  subsequent  black- 
ening, as  generally  happens  when  deposited  upon  copper  or 
even  silver,  and  the  object  is  accomplished  by  enclosing  the  cy- 
linder of  copper  in  a  heated  ring  of  platinum,  which  latter,  on 
cooling,  contracts  and  firmly  attaches  itself  to  the  inner  cone ; 
then  the  drawing-out  process  proceeds  as  usual,  the  resulting 
copper-wire  being  coated  uniformly  with  a  thin  layer  of  plati- 
num, upon  which  the  gold  may  be  readily  and  permanently  de- 
posited. This  process  is  also  more  profitable,  because  the  scraps, 
etc.,  of  wire,  which  accumulate  in  working  it,  are  valuable  enough 
to  be  collected  for  the  purpose  of  recovering  the  precious  metals. 
Druggists  Circular,  Aug.,  1868,  from  Dingier  s  Journal,  June, 
1868. 
