PREPARATION  OF  ARTIFICIAL  COLORING  MATTERS,  ETC.  253 
mann  and  the  process  of  MM.  Renard  and  bVane  is  evident. 
If,  as  appears  from  the  fourth  addition  to  their  patent,  fuchsine 
may  be  prepared  by  boiling  sesquichloride  of  carbon  with  ani- 
line, it  is  quite  clear  that  Dr.  Hofmann  had  fuchsine  in  his 
hand,  and  that  it  is  identical  with  the  substance  which  gave  a 
magnificent  crimson  solution.  It  is  right,  however,  to  add, 
that  if  Dr.  Hofmann  was  the  first  who  obtained  fuchsine  as  a 
secondary  product  in  his  theoretical  experiments,  M.  Verguin 
has  certainly  the  merit  of  having  modified  the  process,  so  as  to 
make  it  capable  of  industrial  application. 
In  October,  1859,  M.  Gerber-Keller  patented  in  France  the 
preparation  of  a  red  coloring  matter,  which  he  called  Azaleine, 
«^by  means  of  aniline  treated  under  the  influence  of  heat,  and 
in  proper  proportions  with  several  salts  which  are  formed  by 
the  oxyacids  of  nitrogen,  sulphur,  chlorine,  bromine,  and  iodine 
with  metallic  oxides."  We  shall  complete  this  too  concise  and 
consequently  obscure  description  of  the  process  by  adding  what 
is  known  respecting  the  preparation.  The  salts  preferred  by 
the  author  are  the  mercurous  and  mercuric  nitrates.  Aniline 
is  carefully  heated  to  about  150*^  C,  and  nitrate  of  mercury  in 
powder  is  then  dropped  in,  a  small  quantity  at  a  time.  A 
higher  temperature  than  150^  must  be  avoided,  or  the  action  be- 
comes too  violent,  and  the  coloring  matter  destroyed.  At  every 
addition  of  the  mercury  salt  a  sort  of  ebullition  is  produced,  the 
consequence  of  the  reaction  which  takes  place  ;  metallic  mercury 
is  deposited  at  the  bottom  of  the  vessel,  and  the  liquor  gradually 
acquires  a  deep  crimson  color.  After  being  decanted,  the  whole 
is  allowed  to  cool,  and  the  coloring  matter  is  now  washed  with 
a  little  water  and  dried.  It  is  then  freed  from  tarry  matters  by 
repeated  washings  with  commercial  benzine,  and  finally  dissolved 
in  alcohol  or  wood  spirit,  the  solution  being  re-precipitated  with 
water,  &c.,  again  and  again  until  the  product  is  sufficiently 
pure.  Absolute  purity  is  not  necessary  for  either  dyeing  or 
printing. 
Azaleine  is  soluble  in  water,  but  much  less  so  than  in  alcohol. 
For  dyeing  silk  and  wool,  alcoholic  solutions  are  preferred  ;  for 
printing  on  cotton,  a  dilute  alcoholic  is  thickened  with  gum. 
We  have  recently  heard  that  the  process  now  employed  by 
M.  Gerber-Keller  is  the  following : — 10  parts  of  aniline  are 
