ON  ELECTRO-PLATING. 
319 
lye  of  specific  gravity  1,200,  is  made  and  filtered,  whilst  hot, 
through  an  excess  of  oxide  of  tungsten.  The  solution,  when  cold, 
is  then  placed  in  a  Woulfe's  apparatus,  and  saturated  with  hydro- 
cyanic gas  ;  when  the  solution  has  acquired  a  dark  brown  color, 
the  operation  is  finished.  The  Woulfe's  apparatus  is  then  allowed 
to  cool,  after  which,  the  double  cyanide  thus  obtained  is  poured 
into  a  lye  of  carbonate  of  soda,  of  specific  gravity  1,043,  in  which 
75  parts  of  cyanide  of  potassium  has  previously  been  dissolved  in 
each  1,000  parts  of  the  concentrated  solution  of  the  double 
cyanide.  The  whole  is  then  boiled  for  one  hour,  ami  twice  care- 
fully filtered.  In  this  condition  the  bath  contains  about  15  parts 
of  metal  in  each  1,000  parts  of  the  solution. 
Molybdenum. — M.  Junot  has  obtained  some  very  excellent  de- 
posits of  molybdenum  in  solutions  of  phosphate,  tartrate  and  sul- 
phite of  soda,  also  in  cyanide  of  potassium,  by  employing  the  red 
oxide  of  molybdenum,  precipitated  by  yellow  prussiate  of  potash; 
but  he  finds  the  same  kind  of  bath  as  that  used  for  tungsten  to 
answer  quite  as  well. 
Titanium. — M.  Junot  effects  a  deposition  of  titanium  by  dis- 
solving titanate  of  potash  in  boiling  sulphuric  acid,  evaporating 
the  solution  to  a  pasty  consistence,  and  dissolving  the  mass  in  a 
solution  of  sulphate  of  soda  of  specific  gravity  1,051  to  1,059. 
The  titanium  thus  obtained  is  white,  very  brilliant,  having  a  slight 
golden  cast  when  viewed  in  a  certain  position. 
Silicium. — After  having  drained  in  a  filter  the  silicious  jelly  ob- 
tained by  precipitation  from  a  solution  of  soluble  glass  by  means 
of  hydrochloric  acid,  a  concentrated  solution  is  made  of  it  in  car- 
bonate of  soda  lye  of  specific  gravity  1,200.  The  boiling  is  con- 
tinued for  some  time, until  there  remains  an  excess  of  silica,  which 
will  not  dissolve;  the  solution  is  then  filtered  whilst  hot,  and 
allowed  to  stand  for  two  days.  The  clear  solution  is  then  drawn 
off  irora  the  crystals  of  soda  which  are  formed  at  the  bottom  of 
the  vessel,  diluted  with  five  times  its  volume  of  distilled  water,  in 
which  25  parts  of  cyanide  of  potassium  for  every  1000  have  pre- 
viously been  dissolved  ;  the  whole  is  then  well  boiled  and  care- 
fully filtered.  After  several  days'  rest,  this  bath  works  perfectly 
if  a  current  of  electricity  be  passed  through  it  for  one  day.  The 
deposit  of  silicum  obtained  by  the  use  of  this  bath  is  of  a  buff 
color,  slightly  rainbow  tinted,  and  its  resisting  power  is  so  great 
