110 
Scammony  Resin. 
(  Am.  Jour.  Phami 
\     March,  1909. 
could  be  overcome  by  dilution  with  alcohol,  but  this  still  leaves  the 
second  and  greater  difficulty  as  it  was  originally,  hence  it  became 
necessary  to  use  water  as  a  diluent.  This  both  decreased  the  dark- 
ness of  the  solution  so  that  the  end  reaction  might  be  fairly  well 
observed  and  dissolved  the  resin-soap,  bringing  into  solution  for  easy 
titration  the  occluded  alkali.  Some  hydrolysis  of  the  soap  will 
undoubtedly  occur,  but  this  change  proceeds  slowly  as  is  evidenced 
by  the  facts :  ( I )  that  the  solution  after  neutralization  does  not 
again  become  alkaline  in  any  reasonable  length  of  time,  and  (2)  that 
variation  in  the  quantity  of  water  used  does  not  cause  perceptible 
difference  in  the  quantity  of  hydrochloric  acid  required  for  titration. 
In  view  of  the  above  facts  and  to  have  uniformity  in  determinations, 
so  that  such  errors  as  may  be  caused  by  the  hydrolysis  of  the  resin- 
soap  will  be  as  nearly  uniform  as  possible,  100  c.c.  of  water  were 
added  to  each  saponification  before  titration. 
The  saponification  values,  as  will  be  seen,  are  quite  uniform 
and  indicate  that  a  sharp  distinction  may  be  drawn  between  resin 
from  Convolvulus  Scammonia  and  from  the  false  or  Mexican  scam- 
mony, the  former  ranging  around  238  and  the  latter  a  little  below 
190.  Samples  4,  5,  6  and  7  were  known  to  be  true  scammony 
resin  as  before  stated;  samples  3  and  9  are  with  equal  certainty 
from  Mexican  scammony ;  sample  number  2  is  almost  entirely 
Mexican  scammony ;  while  samples  1  and  8  appear  to  contain  traces 
of  Mexican  scammony. 
Kremel  found  a  saponification  value  of  185.6  for  a  sample  of 
resin  scammony  and  180.2  for  one  of  Aleppo  scammony  (see 
Dieterich,  Anal,  of  Resins,  218) ,  but  the  purity  of  the  resin  as  regards 
ash  and  ether  solubility  is  not  given  with  the  results,  so  we  can 
form  no  exact  estimate  of  how  these  saponification  numbers  may 
compare  with  those  here  given. 
Cowie  obtained  results  quite  similar  to  those  I  have  obtained 
when  working  on  genuine  scammony,  but  there  is  a  wide  difference 
between  the  saponification  values  given  by  Cowie  and  Brander  for 
Mexican  scammony  and  those  above  recorded,  and  for  which  no 
reasonable  explanation  is  apparent  at  this  time. 
Ester  Value. — Little  need  be  said  regarding  the  ester  value  since 
it  is  nothing  more  than  the  difference  between  the  saponification  and 
the  acid  values,  and  as  the  acid  values  of  the  two  varieties  of 
resin  are  about  the  same,  the  ester  value  will  van7"  as  does  the 
saponification  value. 
