Anilin  Colors. 
Am.  Jour.  Pharnu 
Aug.,  1876. 
Through  further  treatment  with  chloride  of  benzyl,  produced  by  the  action  of 
chlorine  gas  on  boiling  toluol,  the  bluer  shades  are  obtained,  as,  methyl  'violet  II  B 
to  V  B,  and  by  treating  them  with  iodine,  the  redder  hues — methyl  violet,  I  R  to  V  R. 
In  a  similar  manner,  as  the  iodine  violets  were  supplanted  by  the  methyl  violets, 
the  iodine  green,  formerly  predominant,  and  besides  the  little-known  Chinese  indigo 
(Luh-Chao),  the  only  color  in  existence  for  dyeing  night-green  shades,  has  been 
replaced  by  the  methyl  greens,  which  result,  also  as  a  second  product,  from  the  pro- 
cess of  making  methyl  violets,  and  are  produced  with  yellowish  and  blueish  hues  in 
crystals  and  in  powder. 
Muriate  of  anilin  in  cakes  (generally  called  anilin  salt,  like  the  muriate  of  anilin 
in  crystals)  serves  exclusively  for  the  production  of  anilin  black,  which,  when  mixed 
with  other  mordants  (chlorate  of  potassa,  sulphate  of  copper,  etc.)  and  gum  or  starch 
thickening,  and  printed  on  cotton  through  a  process  of  oxidation,  gives  a  black 
color  hitherto  unknown  in  equal  fastness,  and  therefore  has  become  of  very  great 
importance  for  all  cotton  print  works. 
By  introducing  nitrous  acid  into  toluidin,  and  subsequent  oxidation  by  means  of 
bichromate  of  potassa,  there  is  formed  another  valuable  color — the  saffranin. 
Naphthalin,  treated  like  benzol  or  toluol,  as  above  mentioned,  furnishes  the  nitro- 
naphthalin  and  naphthylamin,  from  the  last  of  which,  by  the  action  of  nitric  acid,  is 
produced  the  Martins  yellow. 
With  the  exception  of  this  color,  so  far  the  naphthalin  colors  afforded  little  in- 
terest for  industrial  use.  The  possibility  is,  however,  not  excluded — in  fact,  it  is 
very  probable,  as  this  hydrocarbon  stands  between  benzol  and  anthracene — that  in  a 
short  time  we  may  be  able  to  form  still  other  naphthalin  colors,  which,  standing  be- 
tween the  madder  and  anilin  colors,  would  unite  the  fastness  of  the  former  with  the 
beauty  of  the  latter. 
Phenic  acid,  likewise  produced  by  the  distillation  of  coal  tar,  when  treated  witb 
oxalic  acid,  gives  rosolic  acid,  and  this,  under  pressure  with  ammonia  (NH3),  coral- 
lin. 
The  newest  and  most  beautiful  member  of  the  family  of  these  dyes  is  the  eosin 
(Aurora).  It  is  also  a  derivative  from  benzol,  and  obtained  by  introducing  bro- 
mine into  the  fluorescein  (very  interesting  for  its  play  of  colors),  for  the  preparation 
of  which  phtalic  acid  and  resorcin  are  employed. 
The  production  of  eosin  is  still  in  its  infancy,  but  to  judge  from  the  results  dur- 
ing the  short  time  which  has  elapsed  since  its  introduction,  it  promises  to  be  of  great 
importance  in  the  future,  as  it  not  only  fully  supplies  the  place  of  the  shades  of 
rose-pink  colors  obtained  with  carmine  of  safflower,  but  surpasses  them  considerably 
in  beauty. 
The  brown,  known  by  the  name  of  <vesu<vin,  is  a  product  of  oxidation  from  nitro- 
benzol  ;  it  dyes  all  shades  of  Havana  browns. 
We  conclude  this  division  with  the  important  product  from  carbolic  acid,  gener- 
ally known  as  a  yellow  dye,  the  consumption  of  which  is  great,  especially  for  all 
yellow  tints  on  wool,  and  which  has  been  introduced  into  the  trade  in  two 
forms,  both  chemically  pure — picric  acid  in  crystals  and  in  amorphous  powder 
(C6H3(N02)3). 
