358  Preparation  of  Permanganate  Solutions.  {  Ava^l™  ri9*garnfc 
species  of  euonymus,  E.  Americanus,  has  orange-red  roots,  and, 
therefore,  could  not  possibly  yield  it. 
The  only  suggestion  that  I  can  offer  at  present  is  that  it  may  be 
derived  from  some  Araliaceous  or  Rutaceous  plant. 
For  some  years  past  I  have  noticed  that  the  euonymus  of  com- 
merce varies  in  its  activity,  even  when  obtained  from  the  same  manu- 
facturer, and  the  unrecognized  occurrence  of  the  false  euonymus 
may  possibly  account  for  this  difference.  It  has  probably  been  in 
commerce  for  some  years,  as  Greenish  ("  Materia  Medica,  1899," 
p.  217)  mentions  that  the  bark  has  occasional  small  transverse  scars, 
a  statement  which  is  copied  by  the  author  of  "  Pharmacopedia,"  p. 
166.  In  any  case,  it  will  be  advisable  for  pharmacists  to  give  pref- 
erence to  Euonymus  atropurpureus  bark,  which  shows  externally  a 
longitudinally  striated  cork  and  a  tangentially  striatified  liber  (best 
seen  under  a  good  lens  after  wetting  the  transverse  section  with  the 
finger),  and  delicate  threads  when  gently  broken  transversely,  and 
that  shows  the  medullary  rays,  consisting  of  a  single  row  of  cells. 
THE  PREPARATION  OF  N/100  PERMANGANATE 
SOLUTIONS. 
By  J.  O.  Halverson  and  Olaf  Bergeim. 
The  preparation,  standardization  and  conditions  of  use  in  volu- 
metric analysis  of  N  and  N/10  solutions  of  potassium  permanganate 
have  been  studied  with  some  care.1  Unfortunately,  however,  cer- 
tain of  the  precautions  which  have  thus  been  shown  to  be  necessary 
for  accurate  work  have  been  commonly  neglected  in  the  literature, 
even  in  handbooks  of  general  and  applied  analytical  chemistry.  As 
a  result  of  this  and  of  the  widening  application  of  permanganate 
titration  methods,  especially  in  biochemistry,  certain  methods  based 
on  this  principle  have  been  recently  suggested  which  possess  un- 
necessary inaccuracies.  Common  errors  are  the  use  of  too  much 
sulphuric  acid  in  titrations  and  a  lack  of  appreciation  of  the  great 
sensitivity  of  permanganate  solutions  to  traces  of  organic  matter. 
In  the  determination  of  very  small  amounts  of  substance,  as,  for 
1  See  Gooch's  "  Methods  in  Chemical  Analysis,"  1st  Ed.,  New  York.  Re- 
printed from  The  Journal  of  Industrial  and  Engineering  Chemistry,  February, 
1918. 
