Am.  Jour.  Pharm.  \ 
December,  1917.  > 
Sodium  Benzoate. 
581 
chlorides  by  the  iodometric  method  described  above  are  negligible 
for  most  purposes  of  ordinary  laboratory  analysis.  The  sodium 
thiosulphate  solution  can  be  standardized  against  sodium  chloride 
which  previously  has  been  standardized  by  precipitation  with  AgN03, 
and  the  mean  of  the  three  determinations  taken  as  expressing  the 
strength  of  the  Na2S3Os  solution,  but  the  standardization  against 
pure  resublimed  iodine  answers  the  purpose  very  satisfactorily. 
This  method  of  iodometric  determination  of  chlorine  in  chlorides 
is  a  very  simple  operation,  inexpensive  and  accurate,  and  exceedingly 
quick;  the  entire  procedure  from  weighing  of  the  sample  to  the  titra- 
tion of  the  iodine  does  not  consume  more  than  15  minutes.  By  this 
same  method  HC1  in  a  mixture  of  hydrochloric  and  sulphuric  acids 
can  easily  be  determined  without  any  precipitation. 
This  method  also  will  serve  as  a  quick  qualitative  test  for  ascer- 
taining whether  a  given  sample  contains  chlorine  and  the  possible- 
amount. 
National  Carbon  Company,  Inc., 
Cleveland,  Ohio. 
A  COMPARISON  OF  AMERICAN  AND  ORIENTAL 
STORAX.1 
By  Stroud  Jordan. 
The  liquid  or  semi-liquid  balsam  obtained  from  "  Liquid  ambar 
styraciflua  "  known  in  the  United  States  as  "  sweet  gum,"  has  been 
recognized  for  a  long  while  and  samples  were  shown  at  the  Paris 
Exposition  in  1878.  This  material  resembles  liquid  storax  of  the 
Levant  and  shows  only  a  slight  variation  in  composition.2  It  gen- 
erally occurs  in  grayish  or  reddish  gray,  opaque  masses,  which  harden 
with  age  and  upon  exposure  to  the  air,  finally  becoming  very  brittle. 
The  fresh  balsam  is  a  clear,  yellow-brown,  semi-liquid  of  the  con- 
sistency of  honey  and  the  purified  "sweet  gum"  also  exhibits  the 
same  characteristics  although  it  is  not  so  fluid  as  the  fresh  material. 
The  hardened  gum  is  gathered  in  certain  localities  and  without  fur- 
ther preparation  is  used  as  a  chewing  gum. 
1  Reprinted  from  The  Journal  of  Industrial  and  Engineering  Chemistry, 
August,  1917. 
2U.  S.  D.  1 197)  19th  Ed.;  Gildemeister  and  Hoffmann,  "Volatile  Oils," 
1,  136;  Watts'  "Dictionary  of  Chemistry,"  1  (1874),  496. 
