Am.  Jour.  Pharm.  \ 
Aug.,  1876.  J 
Anilin  Colors. 
377 
The  case  is  different  with  regard  to  blue.  If  1  part  of  fuchsin,  3  to  4  parts  of 
anilin  oil  and  1  part  of  acetate  of  soda  are  heated  as  above,  the  blue  color  is  formed. 
By  this  process  three  equivalents  of  phenyl  are  taken  up  by  the  fuchsin,  forming 
triphenyl-roseanilin  and  ammonia,  which  is  given  off.  Of  course,  only  the  pure 
anilin  is  used.  The  fused  mass  treated  with  concentrated  muriatic  acid,  and  after- 
wards, according  to  the  more  greenish  or  reddish  shade  which  is  wanted,  with  alco- 
hol, furnishes  the  blue  colors  soluble  in  alcohol,  namely,  blue  reddish  shade  (Bleu  de 
Lyons)  and  night  blue,  or  Bleu  de  lumiere. 
A  great  obstacle  against  a  larger  consumption  of  these  blues,  however,  was  their 
insolubility  in  water. 
Many  experiments  for  their  transformation,  at  last  led  to  a  treatment  analogous 
to  the  formation  of  the  sulphate  of  indigo,  and  the  success  was  a  brilliant  one,  by 
the  following  method  :  1  part  blue,  soluble  in  alcohol,  is  dissolved  in  5  to  6  parts 
of  common  66°  sulphuric  acid  5  the  solution  is  heated  to  a  temperature  of  1300  to 
i4o°C,  then  the  acid  is  neutralized  with  soda  or  potash,  and  the  precipitate  filtered 
and  dried.  The  sulphuric  acid  enters  by  this  process  into  the  blue,  and  forms 
anilin  blue-sulphuric  acid. 
According  to  the  more  reddish  or  greenish  shade  of  anilin  blue,  soluble  in  alco- 
hol, which  is  converted,  the  products  differ  in  shade,  and  furnish  the  anilin  blues 
soluble  in  water:  blue  reddish  shade  (Bleu  de  Lyons),  pure  blue  blueish,  pure  blue 
greenish  and  night  blue,  or  bleu  de  lumiere. 
If,  instead  of  soda,  lime  salts  are  used  for  the  neutralization  of  the  sulphuric  acid, 
the  blues  retain  nearly  the  same  shades,  but  acquire  the  property  of  dyeing  more 
easily  on  cotton  and  silk. 
The  blues  soluble  in  water  mentioned  so  far,  contain  at  least  two  equivalents  of 
sulphuric  acid  (S03).  If  the  sulpho  blue  solution  is  heated  only  to  300  to  40°C, 
and  then  neutralized  with  soda  or  caustic  lye,  the  monosulpho  salt  or  alkali  blue  is 
produced,  the  shades  of  which  are  distinguished  by  the  affixes  I  B  to  V  B. 
The  newest  product  in  this  branch,  diphenylamin  blue,  is  distinguished  by  its  pure 
greenish  tone  from  all  other  anilin  blues.  It  results  by  oxalic  acid  being  heated  with 
diphenylamin,  which  furnishes  the  first  product,  diphenylamin  blue,  soluble  in  alcohol, 
the  transformation  of  which  into  the  diphenylamin  blue,  soluble  in  ujater,  is  effected 
in  the  same  manner  as  above  mentioned  about  the  other  anilin  blues. 
Through  farther  investigations,  by  the  action  of  iodide  of  methyl  or  iodide  of 
ethyl  on  roseanilin,  Prof.  Hofmann  discovered  new  violets,  named  after  himself 
Hofmann  Violets,  and  shortly  afterwards  the  second  important  product  in  this  direc- 
tion, viz.,  the  iodine  green. 
These  Hofmann  Violets,  on  account  of  the  so  far  unattained  beauty  and  brilliancy 
of  their  color,  ruled  the  market  completely  for  some  years  in  all  primrose  or  primula 
{purple)  hues,  until  by  another  step  in  advance  they  were  again  improved  and  sur- 
passed in  the  following  manner:  Muriate  of  anilin  in  crystals,  when  mixed  with 
anilin  oil  and  woodnaphtha  (pyrolignous  spirit),  and  exposed  to  a  pressure  of  fifty 
atmospheres  at  a  temperature  of  2500  to  3oo°C,  is  converted  into  dimethyl-anilin, 
from  which,  through  a  simple  oxidation  by  the  assistance  of  chlorate  of  potassa  or 
chloride  of  copper,  the  methyl  violet  results. 
