164 
PROCESS  OF  PRESERVING  PLANTS. 
pression  of  the  millet  seeds.  He  afterwards  tried,  with  no  greater 
success,  millet  deprived  of  its  pericarp  ;  rice  and  corn  did  not 
give  any  good  result ;  every  vegetable  substance  was  rejected, 
because  it  took  the  moisture  from  the  plants,  and  the  desiccation 
was  badly  and  slowly  effected. 
M.  Monty  then  tried  yellow  river  sand  ;  he  was  obliged  to  give 
it  up  because  the  plants  retained  the  sand.  He  was  induced  to 
make  use  of  the  white  sand,  known  by  the  name  of  freestone 
(the  sand  of  Etampes  answers  very  well  for  this  operation). 
After  having  sifted  this  sand  in  order  to  separate  the  coarser 
particles,  he  separated  the  finest  particles  by  levigation,  dried 
the  sand  and  used  it  for  enveloping  the  plants  in  boxes,  which 
he  afterwards  exposed  to  the  sun  or  to  the  heat  of  a  baker's 
oven.  The  experiment  succeeded  very  well ;  afterwards,  Monty 
used  sea-sand,  which  gave  less  satisfactory  results. 
Ten  years  ago,  M.  Stanislas  Martin  proposed,  under  the  name 
of  embalment  of  plants,  a  process  of  preservation,  in  which  he 
likewise  employed  dry  sand,  but  without  pointing  out  the  pre- 
cautions to  be  taken,  and  without  which  the  operation  could  not 
succeed. 
Every  one  noticed  at  the  Universal  Exposition  the  magnificent 
flowers  prepared  by  M.  Keutz  Swartz.  We  had  an  idea,  at  this 
time,  to  investigate  the  means  by  which  these  plants  had  been 
preserved.  One  of  us  possessing  an  apparatus  in  which  a  vacuum 
may  easily  be  made,  we  tried  desiccation  out  of  contact  with  the 
air  and  at  a  low  pressure,  without  obtaining  very  satisfactory 
results  ;  we  likewise  tried  the  process  by  ventilation,  which  dries 
rapidly  and  perfectly  preserves  the  color,  but  which  has  the 
serious  inconvenience  of  deforming  the  corolla  and  mutilating  the 
leaves  ;  all  the  organs  of  plants  become  extremely  friable  by 
desiccation  ;  thus  ventilation  had  to  be  abandoned. 
We  then  tried  dry  sand,  and  without  being  aware  of  M.  Monty's 
experiments,  we  were  led  by  degrees  to  introduce  into  the  process 
the  modifications  which  he  had  recommended  as  indispensable  ; 
that  is  to  say,  the  selection  of  the  sand  in  small  equal  grains,  and 
washing  it  to  remove  the  dust ;  but,  in  our  opinion,  these  pre- 
cautions are  still  insufficient,  and  after  numerous  trials,  we  have 
stopped  at  the  following  process : — 
We  take  white  sand  in  equal  grains,  which  we  pass  through  a 
