520  Alkaloids  and  Alkaloidal  Drugs.  {K^^^\m: 
the  beaker  is  weighed.  The  hydrastine  is  left  in  perfectly  white 
crystals,  and  only  a  slightly  yellowish  tint  can  be  seen  on  the  sides 
of  the  beaker.  This  tint  is  probably  due  to  traces  of  canadine, 
which  becomes  yellow1  on  exposure  to  light.  Of  course,  instead 
of  shaking  out,  the  method  of  perforation  may  be  used  if  preferred. 
For  the  estimation  of  berberine  a  current  of  dry  air  is  passed 
through  the  Soxhlet  till  all  the  ether  is  removed,  the  Soxhlet  con- 
nected with  an  Erlenmeyer  containing  40  or  50  c.c.  of  alcohol,  and 
the  extraction  continued  till  the  alcohol  comes  out  colorless.  The 
alcoholic  extract,  containing  berberine  and  considerable  quantities 
of  extractive  matter,  is  poured  out  into  an  evaporating  dish,  the 
Erlenmeyer  washed  out  with  hot  water  and  a  little  dilute  acetic 
acid,  the  washings  added  to  the  evaporating  dish,  and  the  latter 
kept  on  a  water-bath,  adding  water  from  time  to  time  till  all  the 
alcohol  has  disappeared.  A  little  more  diluted  acetic  acid  is  now 
added,  the  dish  covered,  and  when  completely  cold  its  contents  are 
filtered  into  an  Erlenmeyer  having  the  capacity  of  about  300  or 
400  c.c.2 
Six  to  eight  c.c.  of  acetone  are  added  to  the  contents  of  the 
Erlenmeyer,  of  which  the  washings  of  the  dish  and  the  filter  have 
been  added,  and  then  a  10  per  cent,  solution  of  sodium  hydrate  is 
added,  drop  by  drop,  till  the  precipitate  first  formed  ceases  to  dis- 
appear on  shaking,  and  the  liquid  acquires  a  strongly  alkaline 
reaction.  The  Erlenmeyer  is  then  stoppered  and  shaken  in  circu- 
lar direction  for  about  ten  or  fifteen  minutes,  and  then  set  aside  in 
a  cool  place  for  two  or  three  hours.  The  berberine-acetone3  sepa- 
rates out  in  crystals,  some  of  which  adhere  to  the  sides  of  the  ves- 
sel. The  supernatant  liquid  is  then  poured  on  a  small  filter,  the 
precipitate  washed  once  or  twice  by  decantation,  and  then  on  the 
filter,  till  the  washings  are  colorless.    The  filter  is  then  pierced 
1  E.  Schmidt,  1894;  Arch.  d.  Pharm.,  232,  141. 
2  In  the  remaining  procedure,  the  simplest  way  would  be  to  precipitate  the 
berberine  with  hydrochloric  or  nitric  acid,  but  in  this  case  a  considerable 
amount  of  extractive  matter  contaminates  the  precipitate,  and  the  estimation 
would  fall  out  too  high,  though  the  error  in  this  respect  might  be  compen- 
sated in  some  extent  by  the  solubility  of  the  hydrochloride  or  nitrate  in  water. 
But  the  best  way  is  to  purify  the  berberine  by  converting  it  into  berberine- 
acetone,  regenerate  the  alkaloid  by  means  of  sulphuric  acid,  and  then  esti- 
mate it  volumetrically  by  standard  potassium  iodide. 
:{  Gaze,  Arch.  d.  Pharm.,  1890,  607. 
