Am.  jour.  Pharm.  )  Scientific  Abstracts.  289 
April,  1921.       )  1 
the  hydrocyanic  acid  is  lost  during  prolonged  maceration  of  the 
seeds  and  by  evaporation.  Linseed  grains  of  various  origin  (Indian, 
S.  American,  Russian,  French,  etc.),  yielded  about  0.02  per  cent, 
of  hydrocyanic  acid ;  linseed  cakes  yielded  up  to  0.38  per  cent.  It  is 
suggested  that  a  maximum  limit  of  0.02  per  cent,  of  hydrocyanic 
acid  should  be  fixed  for  linseed  cakes  used  for  feeding  animals. 
(Through  The  Analyst,  February,  1921.) 
Preserving  the  Green  of  Plants. — A  discovery  of  very  great 
interest  to  botanists  and  others  has  recently  been  made.  As  is  well 
known,  when  plants  have  been  dried  by  any  of  the  well-known  pro- 
cesses (such  as  under  pressure,  in  hot  sand,  or  by  sulphur  fumes), 
the  foliage  loses  most  of  its  natural  greenness.  To  get  anything 
resembling  a  life-like  effect,  the  leaves  have  had  to  be  artificially 
colored,  and  this  plan  has  not  proved  to  be  very  satisfactory.  The 
difficulty  has  been  entirely  surmounted  owing  to  the  fact  that  it  has 
been  found  possible  to  form  a  chemical  compound  with  the  chloro- 
phyll which  is  permanent. 
The  method  adopted  is  on  the  following  lines :  A  boiling  solu- 
tion of  copper  acetate  and  acetic  acid  is  prepared.  Into  this,  parts 
of  the  plant  to  be  preserved  are  steeped.  The  acetate  combines 
with  the  chlorophyll  and  forms  a  permanent  coloring  matter.  What- 
ever the  original  shade  of  green  may  be,  this  color  is  perfectly 
fixed.  The  drying  process  can  then  be  carried  forward.  Where 
the  particular  method  is  that  which  preserves  the  form,  as  in  the 
case  where  hot  sand  is  used,  the  plant  preserved  is  wonderfully 
life-like. 
The  steeping  in  the  copper  acetate  appears  to  have  no  effect 
On  the  flowers.  If  the  drying  is  carried  out  with  sand  or  sulphur 
fumes  the  original  hues  are  usually  well  preserved. 
The  plan  described  has  also  been  employed  in  the  preservation 
of  seaweeds  with  excellent  results.  For  the  brown  seaweeds  it  has 
been  found  needful  to  add  a  little  permanganate  of  potash  to  secure 
the  best  effect.  With  red  seaweed  certain  stains  are  used,  but  once 
the  right  color  is  secured,  the  copper  acetate  fixes  it  for  all  time. 
One  great  value  of  this  plan  is  that  the  plants  so  treated  do  not 
suffer  from  exposure  to  light.  After  some  months  of  standing  in 
direct  sunlight  the  treated  specimens  were  as  bright  green  as  if  they 
had  been  freshly  picked.    {American  Druggist,  February,  192 1.) 
