560         PRODUCTION  OF  ALIZARIN  FROM  NAPHTHALIN. 
the  hydrogen  resulting  from  the  action  of  the  zinc  on  the  sul- 
phuric acid,  becomes  two  atoms  of  ammonia  (N  0),  which  is 
found  as  sulphate  of  ammonia  in  the  mother  liquor.  Some 
sulphurous  acid  is,  however,  evolved  during  the  experi- 
ment. 
The  author  gives  the  following  method  for  preparing  the  bini- 
tro-naphthalin  used  in  this  process.  Three  to  four  parts  of  mono- 
hydrated  nitric  acid  (sp.  gr.  1'5)  are  placed  under  a  chimney 
with  a  good  draught,  and  one  part  of  naphthalin  gradually  and 
cautiously  added  in  small  quantities  at  a  time,  keeping  the  liquid 
constantly  stirred.  Each  addition  of  the  naphthalin  causes  a  noise 
like  the  immersion  of  heated  iron  into  water.  On  cooling,  the 
liquid  sets  into  a  crystalline  mass,  which  is  drained,  then  washed 
to  remove  the  acid,  and  dried.  It  constitutes  the  binitro-naph- 
thalin  almost  completely  pure. 
M.  Roussin  states  that  the  alizarin  obtained  by  his  process 
possesses  all  the  characteristics  and  reactions  of  ordinary  mad- 
der.alizarin.  It  is  almost  insoluble  in  water,  soluble  in  alcohol 
and  ether.  It  volatilizes  between  215^  and  240*^  C,  yielding  a 
yellow  vapor,  which  deposits  red  needle-like  crystals.  It  dis- 
solves in  alkalies  with  the  characteristic  color,  and  is  precipita- 
ted by  acids.  Like  madder-alizarin,  it  furnishes  most  beautiful 
lakes,  and  dyes  the  same  pure  tints.  The  elementary  ana- 
lysis of  this  artificial  alizarin,  however,  has  not  yet  been 
made. 
The  author  has  also  described  some  other  reactions  of  binitro- 
naphthalin,  by  which  colored  products  are  obtained.  By  treating 
it  with  a  protosalt  of  tin  dissolved  in  caustic  alkali,  and  heating 
the  mixture  in  a  water-bath,  a  precipitate  is  obtained,  which 
when  well  washed  is  of  a  violet  blue  color,  and  dissolves  in  alco- 
hol, furnishing  a  deep  violet  solution  which  dyes  perfectly. 
A  concentrated  and  boiling  solution  of  cyanide  of  potassium 
also  acts  energetically  upon  binitro-naphthalin.  The  liquid  be- 
comes reddish  brown.  When  cold,  the  precipitate  is  well 
washed.  It  dissolves  in  boiling  water  and  alcohol,  yielding  a 
deep  blue  solution. — London  Fharm,  Journ.  July,  1861. 
