304 
The  Tannin  of  Cloves. 
Am  Jour.  Pnarrn. 
June,  1895. 
It  will  be  seen  that  the  preceding  reactions  point  to  a  similarity 
of  the  tannin  of  cloves  to  that  of  galls  rather  than  to  the  tannin  of 
white  oak  bark. 
Action  of  Heat. — 0-5  gramme  of  the  tannin  were  heated  with  a 
few  cubic  centimetres  of  glycerin  to  1500  C,  for  twenty  minutes. 
The  heat  was  then  gradually  raised  to  1900  C,  at  which  tempera- 
ture it  was  maintained  for  a  short  time.  The  resulting  mixture  was 
allowed  to  cool.  It  was  then  shaken  with  several  portions  of  ether, 
which  removed,  and,  upon  evaporation,  left  a  crystalline  substance. 
This  was  dissolved  in  water.  The  aqueous  solution  reacted  as 
follows : 
Calcium  hydrate,  red  color  ;  becoming  a  precipitate. 
Ferric  chloride,  green  or  brownish-green  color. 
Ferric  acetate,  green  or  brownish-green  color. 
Ferrous  sulphate,  no  change. 
Action  of  Acids. — Two  grammes  of  the  tannin  were  added  to  IOO 
c.c.  of  2  per  cent,  (absolute  gas)  hydrochloric  acid.  The  liquid  was 
heated  to  boiling,  whereby  a  large  part  of  the  tannin  was  dissolved 
in  a  few  minutes  with  the  production  of  a  reddish-brown  solution. 
When  the  liquid  had  been  boiling  for  an  hour  all  of  the  tannin  had 
entered  solution.  After  the  lapse  of  three  hours  the  boiling  solu- 
tion had  separated  a  dirty  substance,  but  no  red  precipitate  of 
phlobaphene  character.  The  liquid  was  then  allowed  to  cool,  the 
insoluble  substance  filtered  out  and  the  filtrate  shaken  several  times 
with  ether.  The  mixed  ethereal  solutions  when  allowed  to  evaporate 
left  a  crystalline  substance,  whose  water  solution  reacted  in  a  way 
to  indicate  gallic  acid,  as  follows  : 
Potassium  cyanide,  red  color  that  faded,  but,  upon  agitation,  was  restored. 
Potassium  hydrate,  green  color. 
Ferric  chloride,  blue  color,  turning  to  green. 
Ferrous  sulphate,  violet  color,  turning  to  brown,  in  neutral  solution. 
Ammoniacal  silver  nitrate,  reduced. 
Fehling's  solution,  reduced. 
Lead  oxyacetate,  precipitate. 
Lead  acetate,  precipitate,  filtrate  not  pptd.  by  lead  oxyacetate. 
Pine  shaving  and  HC1,  no  violet  or  red  color. 
The  dirty  substance  that  separated  while  the  liquid  was  boiling 
was  treated  with  hot  alcohol,  in  which  it  was  almost  entirely  solu- 
ble.   The  solution  so  obtained  was  set  aside  to  allow  the  alcohol 
