422 
Quarterly  Review  on 
I  Am.  Jour.  Pharm. 
<•    September,  19 17. 
Rhubarb  Leaves  Poisonous. — The  sudden  death  of  a  person 
alleged  to  have  eaten  rhubarb  leaves  has  been  reported  from  Enfield, 
England.  The  symptoms  were  those  usual  in  cases  of  oxalic  acid 
poisoning.  Because  of  the  scarcity  of  vegetables  abroad  the  news- 
papers have  been  advising  their  readers  to  eat  stewed  rhubarb  leaves 
as  a  substitute  for  cabbage.  It  is  reported  that  a  similar  instance 
of  death  from  the  same  cause  occurred  in  1901.  The  leaves  are  not 
usually  used  as  food  but  nearly  everywhere  the  stalks  are  consumed 
in  the  form  of  sauce  and  in  pies.  The  leaves  and  stalks  contain 
citric,  malic,  and  oxalic  acids,  mainly  as  the  calcium,  magnesium  and 
potassium  salts.  As  is  well  known,  the  oxalic  acid  is  decidedly 
toxic.  Poisoning  from  eating  the  stalks  is  very  rare ;  in  fact  liter- 
ature contains  no  such  record.  The  stalks  seemingly  contain  less 
of  this  toxic  acid.  And  then  the  amount  eaten  at  a  single  meal  is 
very  small.  It  would  be  well  not  to  encourage  leaf  consumption 
{Jour.  A.  M.  A.,  June  30,  191 7,  p.  1954). 
D-Mannoketoheptose  :  A  New  Sugar  from  the  Avocado. — 
The  ripe  fruit  of  Persea  gratissima  contains  a  ketose  of  seven  car- 
bon atoms  which  was  isolated  in  the  crystalline  condition  and  found 
to  be  d-mannoketoheptose.  Its  formula  was  established  by  analysis 
of  its  bromphenyl  hydrazon  and  phenyl  osazon  and  by  a  comparison 
of  the  latter  derivative  with  the  osazon  of  mannoaldoheptose ;  also 
by  the  fact  that  it  yielded  the  two  epimeric  mannoheptits  on  reduction 
with  sodium  amalgam.  The  melting-point  of  the  new  sugar  regis- 
tered 1520  and  its  specific  rotation  +  29-°  Treated  with  yeast  no 
fermentation  was  manifested ;  it  was  not  changed  by  bromine  in 
aqueous  solution.  It  is  said  that  this  is  the  first  heptose  to  be  found 
in  nature  (Jour.  Biological  Chem.,  vol.  28,  2,  1917,  through  Jour. 
Franklin  Institute,  July,  1917,  p.  120). 
Impure  Picric  Acid  as  a  Source  of  Error  in  Creatine  and 
Creatinine  Estimations. — It  is  stated  that  some  specimens  of  this 
acid,  especially  those  bought  in  a  wet  condition,  contain  some  im- 
purity, and,  owing  to  the  more  or  less  intense  coloration  they  give 
when  neutralized  with  NaOH,  are  quite  unsuitable  for  use  in  the 
colorimetric  estimation  of  creatinine.  When  20  mils  of  saturated 
picric  acid  solution  are  treated  with  1  mil  of  19  per  cent.  NaOH,  the 
color,  after  fifteen  minutes,  should  be  not  more  than  about  twice  as 
deep  as  the  color  of  the  saturated  picric  acid  solution  (O.  Folin  and 
E.  A.  Doisy,  Jour.  Bio.  Chem.,  191 7,  28,  349,  through  The  Analyst, 
April,  1917,  p.  149). 
