376 
Anilin  Colors. 
Am.  Jour.  Pharm. 
Aug.,  1876. 
of  London,  now  at  Berlin,  who,  in  1857,  first  described  the  effect  of  tetrachloride  of 
carbon  on  anilin.  By  continued  experiments,  other  chemists  succeeded  in  perfect- 
ing this  process  (which  was  not  adapted  for  gaining  large  quantities  of  this  coloring 
matter),  by  finding  in  place  of  chloride  of  carbon  the  proto-  and  per-nitrate  of 
mercury,  and  finally  the  most  advantageous  substitute — arsenic  acid. 
Prof.  Hofmann,  by  farther  investigations,  discovered  that  chemically  pure  anilin 
as  well  as  chemically  pure  toluidin  do  not  produce  any  red  dye  in  a  workable  man- 
ner, but  that,  very  peculiarly,  a  mixture  of  both  does.  The  proper  proportion  of 
die  mixture,  1  part  of  anilin  to  2  parts  of  toluidin,  is  sought  to  be  attained  as  near 
as  possible  in  the  technical  process  for  manufacturing  the  fuchsin.  The  first  who 
-obtained  a  patent  for  the  production  of  anilin  red  with  arsenic  acid  was  Metlok,  an 
English  chemist.    The  best  and  most  practical  method  is  the  following: 
A  mixture  of  anilin  oil  for  red  and  arsenic  acid,  diluted  with  water,  is  heated  in 
a  distilling  apparatus  from  10  to  12  hours  at  a  temperature  of  1800  to  i9o°C.  The 
fused  mass  obtained  in  this  way  is  broken  into  small  pieces,  boiled  out  with  water 
the  undecomposed  arsenic  acid  as  well  as  the  arsenious  acid  which  is  formed  is 
neutralized  with  chalk,  and  immediately  after  the  color  is  dissolved  the  liquor  is 
filtered  through  felt  into  the  crystallization  vessels.  After  three  or  four  days  cool- 
ing, the  crystallization  of  the  fuchsin  has  taken  place,  and  the  mother  liquor  is  let 
off.  The  crystals,  dried  and  freed  from  all  dust  and  all  the  small  crystals,  repre- 
sent diamond  fuchsin  large  crystals,  the  smaller  crystals  passed  through  a  sieve 
diamond  fuchsin  small  crystals,  and  the  uncrystallized  part  at  the  bottom  of  the 
crystallization  tub  is  called  fuchsin  red  [ordinary). 
The  basis  of  this  peculiar  dye,  produced  as  above,  Prof.  Hofmann  has  called 
roseanilin  (rosein  base),  a  name  now  generally  adopted.  The  combination  of  this 
base  with  any  acid  furnishes  a  number  of  salts  ;  for  instance,  with  acetic  acid 
acetate  of  roseanilin.  The  oxalate,  sulphate  and  nitrate  of  roseanilin  are  of  little 
importance  for  dyeing.  For  the  production  of  the  pure  base,  the  common  acetate 
of  roseanilin  is  used  with  the  most  advantage.  The  boiling  solution,  by  adding  an 
excess  of  ammonia,  furnishes  a  crystalline  sediment  of  a  red  color,  which  represents 
the  base  in  a  tolerable  pure  state. 
About  the  year  1 856,  Perkins,  in  England,  being  occupied  with  experiments  to 
produce  quinia  artificially,  accidentally  discovei  ed  a  violet  color,  which,  having  been 
improved  by  several  chemists,  was  for  a  long  time  known  in  the  market  under  the 
name  of  Perkins""  Violet,  Anilin  purple,  Phenamin,  Indisin,  etc. 
After  red  and  violet  had  thus  been  discovered  and  practically  employed,  endeav- 
ors were  generally  made  for  producing  an  anilin  blue,  to  which  exertions  and  experi- 
ments the  different  violets  as,  violet  reddish,  violet  medium  shade  (Pensee)  and 
violet  blueish  (Panne),  all  three  soluble  in  alcohol,  owe  their  origin,  as  the  following 
method  shows  : 
By  heating  a  mixture  of  fuchsin  and  anilin  oil  (an  addition  of  acetate  of  soda 
facilitates  the  reaction)  five  to  eight  hours  at  a  temperature  of  1500  to  i6o°C,  the 
red  color  of  the  compound  is  gradually  changed  into  violet.    According  to  the  de- 
sired shade,  the  fused  mass  is  treated  with  acidulated  water,  the  residue  filtered  and  ' 
dried,  and  so  the  above  blueish-violets  are  obtained. 
