340  Pharmaceutical  Assaying.  {Am'jn^'imaTm' 
to  be  extracted  with  about  100  cc.  absolute  alcohol,  containing  4  per 
cent,  of  concentrated  soda-solution,  by  means  of  gentle  heat ;  evapo- 
rate to  one-quarter  volume,  acidify  with  acetic  acid,  and  exsiccate  ;  the 
triturated  residue  is  extracted  with  cold  benzol.  On  evaporating  this 
benzol  solution  the  chrysophanic  acid  (with  a  little  resin)  will  be  in 
weighable  condition. — Method  Hager. 
Exhaust  the  rhubarb  with  cold  water,  evaporate  the  solution,  dry 
the  residue,  extract  with  benzol,  evaporate  the  benzol  solution,  which 
on  cooling,  etc.,  will  deposit  the  chrysophanic  acid. — Method  Schloss- 
berger. 
Take  5  grammes  finely-powdered  rhubarb,  1*5  grammes  tartaric 
acid,  mix  thoroughly,  introduce  into  a  Tollen's  apparatus,  and  reper- 
colate  with  50  cc.  of  chloroform  at  about  65-70°  C,  evaporate,  take 
up  with  chloroform,  evaporate  and  weigh  as  "  chrysophanic  acid." — 
Method  Drescher. 
N.  B. — These  methods,  all  and  each,  do  not  claim  to  isolate  the 
pure  "  chrysophanic  acid."  but  they  are,  nevertheless,  serviceable 
enough  for  practical  purposes. 
'Jalap. — We  are  all  familiar  with  the  U.  S.  P.  process  of  preparing 
"  Resina  Jalaps."  We  use  it  for  assaying  this  drug,  which  owes  its 
activity  to  the  amount  of  resin  in  it.  I  have  made  numerous  assays 
of  jalap,  but  the  U.  S.  P.  method  has  often  not  given  me  satisfaction. 
The  resin  will  sometimes  not  separate  for  days  out  of  the  water. 
I  use  the  following  method,  devised  by  me :  5  grammes  (No.  50' 
powder)  jalap  are  mixed  with  an  equal  quantity  of  fine  sand ;  transfer 
to  a  filter,  add  gradually  250  cc.  of  boiling  water,  keeping  the  filter 
in  a  hot  water  jacket ;  after  draining  and  drying  the  filter,  remove 
the  dregs  therefrom,  cut  out  the  residue-ringed  zones  of  the  filter,  add 
to  the  dregs,  digest  the  whole  with  150  cc.  hot  alcohol,  filter,  wash 
filter  with  a  little  hot  alcohol,  evaporate  filtrate  to  small  bulk,  transfer 
to  small  beaker,  evaporate  to  dryness,  and  weigh.  The  resin  is  then 
further  tested  as  usual  for  its  purity.  (See  U.  S.  P.)  The  U.  S.  P. 
claims  12  per  cent,  of  resin,  the  Ph.  Germ.,  10  per  cent,  as  a  mini- 
mum ;  both  figures  are  too  high  for  the  jalap  of  our  commerce.  The 
highest  I  have  found  is  8.5  per  cent.1 
Newakk,  N.  J.,  May,  1889. 
1  Two  of  the  eight  samples  of  jalap  assayed  by  Mr.  W.  L.  Turner  yielded  10.36 
and  19  per  cent,  of  resin. — Am.  Jouk.  Phar.,  1888,  p.  379  ;  see  also  Ibid,  1887 r 
321-327).— Editor. 
