494 
American  Pharmaceutical  Association.  {A 
The  Estimation  of  Chloroform. 
By  W.  A.  Puckner. 
To  10  c.c.  of  an  approximately  normal  alcoholic  solution  of  potas- 
sium hydroxid,  either  free  from  chlorides  or  else  of  a  known  chloride 
content,  and  contained  in  a  vial,  add  a  measured  volume  of  the 
chloroform-ether  mixture  representing  0-05-0  2  grammes  chloro- 
form,1 stopper  with  a  sound  cork,  cover  with  cloth  and  tie  this  down 
firmly,  mix  the  two  liquids  by  rotation,  then  place  the  vial  in  boiling 
water  in  such  a  way  that  at  no  time  the  contents  come  in  contact 
with  the  cork  and  retain  the  temperature  for  three  hours.  Remove 
the  vial  from  the  bath,  let  cool,  add  phenolphtalein  and  then  suffi- 
cient sulphuric  acid  to  exactly  neutralize  the  liquid,2  then  add  two 
drops  of  potassium  chromate  T.S.,  and  titrate  with  decinormal  silver 
nitrate.  Or  if  Volhard's  method  of  estimation  is  preferred,  add  to 
the  finished  digestion  10  c.c.  dilute  nitric  acid,  an  excess  of  deci- 
normal silver  nitrate,  5  c.c.  ferric  ammonium  sulphate  T.S.,  and  de- 
termine the  excess  of  silver  nitrate  with  decinormal  potassium  thio- 
cyanate.  In  either  case  1  c.c.  of  decinormal  silver  nitrate  represents 
0-003969  grammes  CHC13. 
The  Characterization  and  Classification  of  the  Sesquiterpenes 
In  this,  the  fourth  paper  on  the  sesquiterpenes,  the  authors  pro- 
pose a  system  of  classification  for  these  hydrocarbons  based  on  their 
structural  relationships.  According  to  this  system  they  may  be 
divided  into  five  classes,  as  follows : 
1  If  the  per  cent,  of  chloroform  in  the  mixture  is  not  even  approximately 
known,  1  c.c.  may  be  digested  with  25  c.c.  normal  alcoholic  potassium  hydroxid 
solution  for  one  hour,  and  the  residual  alkali  determined  with  normal  acid  and 
phenolphtalein,  when  the  c.c.  of  normal  alkali  which  disappeared, during  the 
dige&tion  multiplied  by  o  02977  will  give  the  amount  of  chloroform  contained 
therein  sufficiently  close  to  judge  the  quantity  to  be  taken  for  the  actual  deter- 
mination. 
2  This  acid  need  not  be  of  any  definite  strength  ;  an  approximately  normal 
acid  is  convenient.  ■ 
By  Oswald  Schreiner  and  Edward  Kremers. 
(1)  Chain 
(2)  Monocyclic 
(3)  Dicyclic 
(4)  Tricyclic 
(5)  Tetracyclic 
compounds  with  four  double  bonds. 
"  three  " 
a  «   two       «  <i 
one 
110 
