34 
PREPARATION  OF  MARKING  INKS  FOR  LINEN. 
and  of  such  a  consistence  that  it  will  flow  readily  from  a  pen. 
This  ink,  and  the  one  prepared  according  to  the  second  formula, 
form  no  precipitates,  and  thicken  by  boiling,  whereby  their  colors 
become  darker,  and  their  ammoniacal  odor  weaker. 
5  parts. 
12  « 
5  « 
7  « 
10  « 
Formula  No.  2. 
Nitrate  of  silver 
Distilled  water 
Powdered  gum  arabic 
Carbonate  of  soda 
Liquor  of  ammonia  . 
These  ingredients  are  to  be  treated  in  the  manner  above 
described,  and  the  resulting  mixture  heated  in  a  flask  until  it 
has  become  of  a  very  dark  color,  which  is  generally  the  case 
when  its  volume  has  diminished,  about  five  per  cent,  by  evapora- 
tion. By  continuing  the  evaporation  too  long,  a  precipitate  is 
produced,  in  consequence  of  the  loss  of  ammonia. 
The  ink  prepared  in  this  manner  is  distinguished  by  producing 
very  black  characters  on  linen,  and  is  very  suitable  for  marking 
with  stamps. 
Formula  No.  3. 
Nitrate  of  silver 
Distilled  water 
Powdered  gum  arabic 
Carbonate  of  soda  . 
Liquor  of  ammonia 
Sulphate  of  copper 
17  parts. 
85  « 
20  « 
22  « 
42  « 
33  « 
The  twenty-two  parts  of  carbonate  of  soda  are  to  be  dissolved 
in  twenty  five  parts  of  distilled  water,  and  the  seventeen  parts  of 
nitrate  of  silver  in  the  forty-two  parts  of  ammonia.  The  twenty 
parts  of  gum  are  to  be  dissolved  in  the  remaining  sixty  parts  of 
water,  and  mixed  with  the  soda  solution,  and  afterwards  with  the 
silver  solution.  At  last,  the  thirty-three  parts  of  sulphate  of 
copper  are  to  be  added. 
The  large  quantity  of  ammonia  in  this  formula  is  explained 
by  the  presence  of  the  copper  salt.  The  sulphate  of  copper 
could  be  replaced  by  nitrate  of  silver ;  but  to  do  so,  requires  a 
much  larger  quantity  of  nitrate  of  silver,  to  render  the  ink  as 
