350  Action  of  Sulphuric  Acid  on  Oleic  Acid.  {Am/U^f^rm- 
with  20  c.c.  of  indigo  solution  and  1  litre  of  water.  The  perman- 
ganate solution  is  then  added  gradually  (about  three  drops  in  two 
seconds],  the  mixture  being  stirred  continually.  The  end  of  the 
reaction  is  ascertained  by  the  change  of  color  from  light  green  to  pure 
yellow.  At  this  stage  the  edge  of  the  basin  exhibits  a  reddish  tinge, 
the  appearance  of  which  indicates  the  completion  of  the  oxidation. 
To  analyze  barks,  the  author  proceeds  as  follows :  10  gms.  of  the 
bark  previously  dried  at  100  are  boiled  out  repeatedly  with  water 
until  iron  paper  ceases  to  give  a  reaction  indicative  of  tannin.  The 
infusion  is  then  made  up  with  water  to  1  litre,  and  a  portion  filtered 
through  a  dry  filter-paper ;  5  or  10  c.c.  of  the  filtrate  is  now  titrated 
with  permanganate.  50  c.c.  of  the  filtered  extract  is  precipitated  with 
gelatin,  salt,  and  kaolin,  aud  10  or  20  c.c.  of  the  filtrate  titrated. 
The  permanganate  values  obtained  are  calculated  into  percentage  of 
tannin  contained  in  the  bark  according  to  Xeubauer's  equivalent,  63 
oxalic  acid  =  -41*57  tannin. — Jour.  Chem.  Soc,  1886,  p.  496. — Ding!. 
Pohjt.  Jour.,  cclix. 
ACTIOX  OF  SULPHURIC  ACID  ON  OLEIC  ACID. 
By  A.  Sabaxeieff. 
The  author  has  investigated  the  product  of  the  action  of  sulphuric 
acid  on  oleic  acid,  employed  as  a  mordant  under  the  name  of  "  alizarin 
oil/3  The  oleic  acid  used  in  the  experiments  was  prepared  from  oil 
of  sweet  almonds,  and  thoroughly  purified  ;  it  solidified  at  6°  to  a 
white,  crystalline  mass,  melting  at  14c ;  in  the  liquid  state,  it  was 
perfectly  translucent  and  free  from  any  taste  or  smelL 
Oleic  acid  cooled  down  to  at  least  6°,  when  it  becomes  crystalline, 
was  treated  with  sulphuric  acid;  the  reaction  under  these  conditions 
is  not  violent,  and  the  temperature  does  not  rise  considerably, 
although  the  products  of  the  reaction  are  the  same  as  when  oleic 
acid  is  used  in  the  liquid  state.  An  evolution  of  sulphurous  anhy- 
dride is  rarely  observed.  The  reddish-brown  product  of  the  reaction, 
when  treated  with  water,  separates  into  two  layers,  of  which  one 
consists  of  aqueous  sulphuric  acid  only ;  the  other  (which  on  neutrali- 
zation with  alkali  gives  the  so-called  alzarin  oil)  was  dissolved  in 
ether,  and  subsequently  treated  with  water,  in  which  a  portion  only  is 
soluble. 
The  portion  insoluble  in  water  consists  partly  of  a  solid  substance, 
