Am.  Jour.  Pharm.  ) 
Sept,  1,  la72.  j 
Our  Writing  Fluids. 
413 
The  learned  doctor  has  here  taken  advantage  of  a  fact  well  known 
to  chemists — viz.,  that  tannic  acid  is  more  soluble  in  cold  than  in  hot 
water — hence  the  cold  maceration  is  prescribed,  which  I  believe  is 
pretty  generally  employed  by  first-class  ink  manufacturers. 
The  celebrated  blue-black  ink,  prepared  by  Messrs.  Duncan,  Flock- 
hart  &  Co.,  of  Edinburgh,  is  said  to  be  prepared  by  the  process  of 
cold  maceration.  A  formula,  said  to  be  that  of  Messrs.  Duncan, 
Flockhart  &  Co.,  was  printed  and  circulated  some  years  ago  by  an 
Edinburgh  gentleman,  of  which  the  following  is  a  copy,  and  which 
explains  the  process  more  fully  : — 
RECEIPT  FOR  PREPARING  BLUE-BLACK  WRITING  INK 
{Which  also  serves  well  for  copying  ink). 
Blue  Aleppo  galls  (free  from  insect  perforation)  4J  ounces. 
Bruised  cloves,        .        .        .        .        .1  drachm. 
Cold  water,        ......    40  ounces. 
Purified  sulphate  of  iron,  ....         1J  " 
Purified  sulphuric  acid  (by  measure)     .       .    35  minims. 
Sulphate  of  indigo  (in  the  form  of  a  thinnish 
paste,  and  which  should  be  neutral  or  nearly  so)  ounce. 
Place  the  galls,  when  bruised,  with  the  cloves,  in  a  fifty-ounce  bot- 
tle, pour  upon  them  the  water,  and  digest,  often  daily  shaking  for  a 
fortnight.  Then  filter  through  paper  in  another  fifty-ounce  bottle. 
Get  out,  also,  the  refuse  of  the  galls,  and  wring  out  of  it  the  remain- 
ing liquor  through  a  strong  clean  linen  or  cotton  cloth  into  the  filter, 
in  order  that  as  little  as  possible  be  lost.  Next  put  in  the  iron,  dis- 
solve completely,  and  filter  through  paper.  Then  the  acid,  and  agi- 
tate briskly.  Lastly  the  indigo,  and  thoroughly  mix  by  shaking. 
Pass  the  whole  through  paper.  Just  filter  out  of  one  bottle  into  the 
other  till  the  operation  has  been  completed. 
On  a  large  scale,  this  fine  ink  may  be  made  by  percolation,  as  Dun- 
can, Flockhart  and  Company,  and  others  in  Edinburgh,  do  it,  the 
above  being  said  to  be  their  recipe. 
The  weights  used  are  avoirdupois,  and  the  measures  used  are  apo- 
thecaries' measures. 
Note. — No  gum  or  sugar  is  proper,  and  on  no  account  must  the 
acid  be  omitted.  When  intended  for  copying,  5J  ounces  galls  are  the 
quantity. 
You  will  observe  that  there  are  several  peculiarities  about  this  writ- 
