NEW  PROCESS  FOR  SILVERING  GLASS. 
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been  no  further  development  of  the  goldfields,  and  trade  is 
rather  dull.  The  most  expansive  part  of  the  trade  just  now  is 
the  development  of  the  coalfields.  Many  new  mines  have  been 
opened,  and  the  competition  has  led  to  a  reduction  in  price,  as 
well  as  to  an  improvement  in  quality. — Journ.  of  the  Soc.  of 
Arts,  Nov.  20,  1863. 
NEW  PROCESS  FOR  SILVERING  GLASS. 
By  M.  A.  Martin. 
Among  the  large  number  of  processes  for  silvering,  Dray- 
ton's  process  is  the  best  adapted  for  telescope  glasses ;  but,  as 
this  process  requires  great  skill  on  the  part  of  the  operator,  I 
have  endeavored  to  find  some  method,  which,  by  its  simplicity 
and  sureness,  might  become  general.  After  carefully  studying 
and  experimenting  on  all  the  known  processes  (aldehyde,  sugar 
of  milk,  glucosate  of  lime,  &c),  I  have  arrived  at  one,  which, 
from  its  simplicity  and  the  firm  adherence  of  the  layer  of 
silver  deposited,  seems  to  fulfil  all  the  necessary  conditions. 
I  begin  by  preparing  : — 1.  A  solution  of  10  grammes  of 
nitrate  of  silver  in  100  grammes  of  distilled  water.  2.  An 
aqueous  solution  of  pure  ammonia,  marking  13  degrees  on 
Carter's  areometer.  3.  A  solution  of  20  grammes  of  pure 
caustic  soda  in  500  grammes  of  distilled  water.  4.  A  solution 
of  25  grammes  of  ordinary  white  sugar  in  200  grammes  of 
distilled  water.  Into  this  pour  1  centimetre  cube  of  nitric 
acid  at  36  degrees,  boil  for  twenty  minutes,  to  produce  the 
interversion  of  the  sugar,  and  then  make  up  the  volume  of  500 
centimetres  cube  with  distilled  water,  and  50  centimetres  of 
alcohol  at  36  degrees.  This  done,  I  prepare  an  argentiferous 
liquid  by  pouring  into  a  flask  12  cubic  centimetres  of  the 
solution  of  nitrate  of  silver  (1),  then  8  cubic  centimetres  of 
ammonia  at  13  degrees  (2),  then  20  centimetres  of  the  solution 
of  soda  (3)  ;  and  lastly,  make  up  a  volume  of  100  centimetres 
by  60  centimetres  of  distilled  water.  If  the  proportions  have 
been  properly  observed,  the  liquid  will  remain  limpid,  and  a 
drop  of  solution  of  nitrate  of  silver  will  produce  a  permanent 
precipitate  ;  then  after  being  left  quiet  for  twenty-four  hours 
