43°  Scammony  and  Resin  Scammony.  \k£ytl^e7mla' 
of  the  resins  obtained  from  the  Mexican  root  are  generally  less  than 
190.  Taylor,  using-  U.S. P.  ether,  found  that  both  the  Mexican  and 
the  true  scammony  resins,  with  the  exception  of  one  sample,  were 
at  least  99  per  cent,  soluble  in  ether.  This  does  not  agree  with 
the  statement  of  Cowie,  who  finds  that  true  scammony  resin  is 
soluble  from  96.4  per  cent,  to  100  per  cent,  in  ether  of  sp.  gr.  .720, 
while  three  samples  of  the  Mexican  resins  were  dissolved  only  to  the 
extent  of  68.6  per  cent,  to  72  per  cent.  Cowie  has  directed  attention 
to  the  varying  solubility  which  will  be  found  if  the  ether  used  in 
the  different  determinations  is  not  perfectly  uniform  in  quality. 
This  fact  may  account  for  the  discrepancies  between  Taylor's  and 
Cowie's  results.  A  more  detailed  discussion  of  this  point  will  be 
taken  up  later. 
The  resins  examined  in  this  work  were  all  purified  according  to 
the  U.S. P.  method,  i.e.,  extracting  with  boiling  alcohol,  with  pre- 
cipitation of  the  concentrated  extract  by  water  and  subsequent  dry- 
ing. In  order  to  insure  more  perfect  drying,  without  the  danger  of 
overheating,  all  our  resins  were  dried  in  the  following  manner. 
After  thorough  washing,  the  resinous  mass  was  freed  from  inclosed 
water  by  stirring  and  draining.  Tt  was  then  dissolved  in  alcohol, 
filtered,  and  the  alcoholic  solution  evaporated  to  a  thick  syrup,  which 
was  then  poured  on  thin  sheets  of  glass  and  dried  at  a  temperature 
slightly  below  ioo°.  The  results  show  that  the  moisture  content 
of  resins  dried  in  this  way  is  no  less  than  is  found  in  those  which 
have  been  dried  by  other  methods.  The  alcohol  was  certainly  elimi- 
nated, but  it  appears  that  a  temperature  above  ioo°  is  necessary 
to  remove  the  water  entirely.  The  U.S. P.  direction  to  dry  at  "  a 
gentle  heat  "  therefore  seems  inadequate.1 
The  moisture  determination  was  made  by  heating  the  powdered 
resin  on  a  watch  glass  for  one  hour  at  no°  to  1 1 5 0 .  Our  results 
are  practically  identical  with  those  of  Cowie  and  Taylor,  and  the 
same  is  true  of  the  percentage  of  ash. 
The  determination  of  the  acid  number  often  offers  considerable 
difficulty,  on  account  of  the  dark  color  which  the  solution  assumes 
almost  immediately  after  the  addition  of  any  alkali.  Recourse  was 
finally  had  to  the  method  of  Marx.2  Two  grammes  of  the  pow- 
dered resin  are  dissolved  in  a  large  flat-bottomed  porcelain  dish  in 
'The  French  Codex  directs  45°  C 
2  Chem.  Ztg.,  No.  16,  1910, 
