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PREPARATION  OF  A  WRITING-INK  IN  CAKES. 
of  organic  remains  in  the  heart  of  the  natural  product  excludes 
the  probability  of  its  igneous  formation  ;  and  it  would  also  be 
difficult  to  understand  how,  if  a  fusion  of  the  mass  really  took 
place,  the  chloride  of  magnesium  was  not  decomposed.  As  to 
the  phenomenon  of  decrepitation,  since  it  is  observed  to  a  certain 
extent  in  rock-salt  as  well  as  in  that  which  has  been  crystallized 
in  the  humid  way,  it  cannot  serve  as  a  character  in  support  of 
the  hypothesis  of  igneous  formation. — Chern.  Gaz.9  March,  1857, 
from  Comptes  Bendus,  Feb.  1857. 
ON  THE  PREPARATION  OF  A  WRITING-INK  IN  CAKES. 
By  A.  Leonhardi. 
After  the  author  had  discovered  the  mode  of  preparation  of 
the  so-called  alizarine-ink,  which  is  particularly  useful,  he  was 
anxious  to  prepare  it  in  a  form  which  would  allow  it  to  be  sent 
to  a  great  distance,  and  at  any  time  of  the  year  render  its  tran- 
sport convenient,  and  diminish  its  cost  considerably,  but  at  the 
same  time  fulfil  all  the  requirements  of  an  excellent  article.  This 
is  attained  by  the  dry  alizarine-ink  in  cakes.  The  "  ink  powders" 
hitherto  found  in  commerce  are  not  to  be  compared  with  it,  for 
they  not  only  possess  a  different  composition,  but  never  dissolve 
completely  to  form  a  clear  solution  in  water,  and  their  employ- 
ment is  attended  with  so  many  inconveniences  and  disadvantages, 
that  they  have  been  given  up.  Common  black  ink  may  indeed 
be  evaporated  to  dryness,  but  it  leaves  a  residue  which  does  not 
again  dissolve  completely  in  water,  and  never  furnishes  a  useful 
ink  by  this  solution.  The  recipe  for  the  preparation  of  this 
cake-ink  is  as  follows  : — 
42  parts  of  Aleppo  galls  and  3  parts  of  Dutch  madder  are  ex- 
tracted with  a  sufficient  quantity  of  hot  water ;  the  fluid  is  then 
filtered,  b\  parts  of  sulphate  of  iron  are  dissolved  in  it,  and  2 
parts  of  a  solution  of  iron  in  wood- vinegar,  with  lj-  part  of 
solution  of  indigo,  are  added  to  it.  The  mixture  is  evaporated 
to  dryness  at  a  moderate  heat,  and  formed  into  cakes  of  a  proper 
size  (for  instance  5  inches  long,  3J  inches  broad,  and  f  inch 
thick). 
1  part  of  this  cake-ink  dissolved  in  6  parts  of  hot  water,  fur- 
