PROCESS  OF  PRESERVING  PLANTS. 
165 
hair  sieve,  it  is  washed  with  a  large  quantity  of  water  in  order  to 
remove  the  finer  particles,  and  the  washing  is  continued  until  the 
water  goes  perfectly  limpid.  The  sand  is  then  dried  in  the  sun 
or  in  an  oven,  or,  which  is  better  still,  it  is  raised  to  about  150° 
C.  (302°  F.),  being  kept  constantly  agitated  in  a  basin.  We 
then  pour  in  for  25  kilogrammes  of  sand,  a  mixture  of  20  grammes 
of  stearic  acid,  and  20  grammes  of  spermaceti ;  it  is  mixed  and 
bruised  with  the  hand  so  as  to  cover  every  grain  of  sand  with 
some  of  the  grease. 
We  then  put  a  layer  of  this  sand  into  a  box  of  any  length  and 
width,  but  of  the  height  of  about  12  centimetres  (nearly  five 
inches) ;  the  bottom  of  this  box  is  let  in  by  means  of  a  groove, 
and  should  be  capable  of  being  easily  removed.  On  the  bottom 
is  a  grating  of  iron  wire  of  very  large  mesh.  The  layer  of  sand 
being  well  established  the  plants  are  arranged  in  it,  taking  care 
to  open  the  leaves  and  to  mould  the  corolla  in  sand  which  is 
added  with  great  care,  the  plants  are  covered  with  sand,  and  it 
is  best  to  keep  to  this  unique  layer ;  we  take  care  to  put  the 
least  possible  quantity  of  sand  on  the  leaves  and  stems  ;  we  cover 
the  box  with  a  sheet  of  papeV,  and  carry  to  a  drying  stove,  or  an 
oven  heated  to  from  40°  to  45°  C.  (1049  to  113°  F.) ;  the  de- 
siccation proceeds  very  rapidly ;  when  it  is  supposed  to  be  finished, 
the  bottom  of  the  box  is  removed;  the  sand  passes  through  the 
iron  grating,  and  the  plants  remain ;  they  are  brushed  with  a 
badger  hair-brush,  and  are  kept  as  we  shall  presently  direct. 
The  greased  sand  adheres  very  slightly  to  the  plants,  and  it  is 
always  easy  to  remove  it;  it  is  often  sufficient  to  give  gentle 
blows  for  all  the  sand  to  fall,  provided,  however,  that  the  plants 
have  not  been  collected  while  still  moist ;  we  have  likewise  re- 
marked, that  it  is  better  to  collect  them  before  the  anthesis  is 
completely  operated  ;  it  may  be  finished  by  steeping  the  plant 
by  its  base  into  a  small  quantity  of  water ;  for  rather  fleshy 
plants,  the  vacuum  singularly  hastens  desiccation. 
However,  we  must  add  that  sand,  whether  greased  or  not, 
cannot  be  employed  for  preserving  plants  which  are  covered  with 
a  viscid  varnish,  the  hyoscyamus,  for  example ;  in  this  case  it  is 
absolutely  necessary  to  use  millet  seed  or  rice,  as  Monty  did. 
We  may,  indeed,  make  two  layers  of  plants ;  but  it  is  not 
prudent  to  exceed  that  number.    The  box  with  a  moveable  bot- 
