ON  RUMICINE. 
155 
hot  alcohol  on  its  cooling,  the  author  obtained  rumicine  (unfor- 
tunately in  very  small  quantity)  in  the  form  of  a  pure  yellow, 
crystalline  mass,  with  a  golden  lustre.  The  previously  men- 
tioned light-golden-brown,  crystalline  mass  was  analysed,  and 
gave  results  agreeing  with  the  formula  proposed  by  Gerhardt 
for  chrysophanic  acid,  C28  H10  O8. 
C  69  59  69-64  28=rl68  6942 
H  4-36  4-59  10  10  4-13 
0  ..        8     64  2645 
This  substance  was  evidently  still  contaminated  with  a  small 
quantity  of  a  body  containing  more  carbon  or  less  oxygen, 
which  was  also  indicated  by  its  darker  color. 
That  rumicine  does  not  merely  possess  a  similar  per  centage 
composition  with  chrysophanic  acid,  but  that  it  is  also  identical 
therewith,  is  shown  by  its  behaviour  towards  reagents. 
Rumicine  dissolves  with  extraordinary  difficulty  in  cold  water  ; 
it  dissolves  more  readily  in  ether,  and  still  more  in  strong  alco- 
hol. When  heated  upon  platinum-foil,  it  fuses  and  emits  fumes 
of  an  intense  yellow  color,  whilst  a  portion  remains  in  the  form 
of  a  vesicular  coal,  which,  when  more  strongly  heated,  burns 
away  without  residue  ;  if  the  same  experiment  be  made  in  a 
test  tube,  the  colder  portion  of  the  latter,  becomes  coated  with 
a  yellow  deposit,  which  appears  crystalline  and  of  a  golden  lus- 
tre under  the  microscope.  It  concentrated  sulphuric  acid,  it 
dissolves  with  an  intense  red  color ;  and,  when  the  solution  is 
diluted,  is  thrown  down  again  in  yellow,  voluminous  flakes.  In 
alkalies,  it  dissolves  very  readily,  with  a  splendid  dark-red  color 
(in  potash  much  more  easier  than  in  ammonia):  it  is  precipi- 
tated without  alteration  from  these  solutions  by  acids.  The  so- 
lution in  potash  becomes  violet-blue,  and  darker  by  evapora- 
tion. Potash  is  the  best  for  rumicine.  The  ammoniacal  solu- 
tion gives  a  lilac  precipitate  with  neutral  acetate  of  lead,  and  a 
beautiful  rose-colored  one  with  alum. 
The  alcoholic  solution  of  rumicine  gives  a  reddish-white  pre- 
cipitate with  an  alcoholic  solution  of  basic  acetate  of  lead  (but 
none  at  all  with  the  neutral  acetate),  which  is  converted  into  a 
rose-colored  precipitate  by  boiling  with  water.  With  acetate 
of  copper  in  alcohol,  it  gives  a  blackish-green  precipitate,  which 
