404  Ex tr actum  Gossypii  Radicis  Fluid.  {^sepu^e™ 
retained  that  color,  and  remained  free  from  any  deposit  whatever. 
The  preparation  made  with  dilute  alcohol  underwent  the  same  change 
of  color,  but  formed  a  precipitate  in  the  course  of  three  or  four  weeks. 
Similar  changes  were  observed  in  the  tinctures  prepared  with  the  men- 
strua named  ;  but  an  old  bark  which  had  been  collected  about  one  year 
yielded  with  stronger  alcohol,  at  once,  a  deep-red  colored  tincture,  and 
the  fluid  extract  prepared  from  it  with  this  menstruum  remained  per- 
fectly transparent  after  three  months. 
To  determine  whether  the  menstruum  used  had  taken  up  the  gelati- 
nous principle,  the  residue  left  after  making  the  fluid  extract  was  dried, 
divided  into  four  equal  parts,  and  treated  with  mixtures  of  one  part  of 
water,  with  respectively  four,  three,  two  and  one  measure  of  strong 
alcohol ;  the  tinctures  were  of  a  light  wine-red  color,  and  after  three 
months  produced  no  precipitate.  Some  of  the  fluid  extract  made  with 
strong  alcohol  was  mixed  with  an  equal  bulk  of  water  and  filtered  from 
the  resin ;  the  clear  red-colored  filtrate  soon  commenced  to  separate  a 
precipitate,  which  rapidly  increased.  It  seems,  therefore,  as  if  the 
gelatinous  principle  was  dissolved  by  strong  and  diluted  alcohol,  but 
retained  in  solution  by  the  former. 
The  gelatinous  precipitate  from  Tilden's  fluid  extract  was  found  to 
be  partially  soluble  in  solutions  of  ammonia,  potassa  and  soda,  the 
greenish-red  color  changing  afterwards  to  red. 
From  the  color  changing  from  a  pale  yellow  to  red,  in  making  the 
fluid  extract  from  the  fresh  root,  and  the  effect  that  alkalies  have  upon 
it,  the  probable  existence  of  a  chromogene  suggests  itself.  For  decol- 
orizing the  fluid  extract  several  reducing  agents  were  tried,  but  it  was 
found  impossible  to  entirely  remove  the  color.  Sulphurous  acid 
seemed  to  be  the  one  that  had  the  best  effect  upon  it,  but  not  suffi- 
ciently to  admit  of  further  experiment ;  it  is  probably  best  prepared 
from  the  fresh  root. 
The  fluid  extract  is  precipitated  purplish  black  by  ferric  sulphate, 
and  similar  by  plumbic  acetate. 
When  a  little  alcohol  is  added  to  the  solutions  of  mercuric  chloride, 
silver  nitrate,  barium  chloride  and  magnesium  sulphate,  no  precipitates 
are  produced. 
