CONSTITUTION  OF  THE  WAX  OF  MYRICA  CERIFERA.  341 
of  the  water  in  the  retort  had  passed  over,  the  distillate  was  found 
to  contain  a  few  globules  of  fused  fat  floating  on  its  surface  ; 
these  were  collected  and  their  fusing  point  taken  ;  it  was  found 
to  be  identical  with  that  of  the  substance  previous  to  distillation, 
thus  proving  conclusively  the  absence  of  the  more  volatile  fatty 
acids. 
One  hundred  grammes  were  taken,  and,  after  solution  in  alco- 
hol, were  subjected  to  fractional  precipitation,  the  method  orig- 
inally proposed  by  Heintz  being  employed  under  the  following 
modification.  The  alcoholic  solution  of  the  fatty  acids  was  made 
of  such  strength  that  the  degree  of  saturation  at  which  a  pre- 
cipitate separated  on  cooling  to  the  ordinary  temperature  of  the 
atmosphere,  was  almost,  but  not  quite,  attained.  The  solution 
was  measured  and  one-tenth  part  was  poured  into  another  ves- 
sel, this  portion  was  then  precipitated  as  accurately  as  possible 
by  a  saturated  alcoholic  solution  of  acetate  of  lead.  The  pre- 
cipitate, together  with  the  fluid  in  which  it  was  suspended,  was 
now  poured  back  into  the  remaining  portion  of  the  solution, 
and  the  whole  heated  to  ebullition,  and  maintained  at  that  tem- 
perature until  the  precipitated  lead  salt  was  redissolved  and  the 
fluid  was  brought  to  nine-tenths  of  its  original  bulk.  The 
whole  was  then  set  aside  to  cool,  by  which  the  precipitate  was  a 
second  time  thrown  down.  This  precipitate  was  collected  on  a 
filter  and  dried,  as  the  first  fraction.  A  portion  of  the  filtrate 
equal  to  that  first  taken  was  now  precipitated  accurately  with 
acetate  of  lead,  the  precipitate  with  the  fluid  in  which  it  was 
suspended  was  poured  back  into  the  rest  of  the  solution,  the 
whole  heated  and  evaporated  until  brought  to  eight-tenths  of 
its  original  bulk,  and  after  cooling,  the  precipitate  collected  and 
dried  as  the  second  fraction.  This  operation  was  repeated  until 
nine  fractions  in  all  had  been  obtained,  the  fluid  to  be  precipita- 
ted occupying  successively,       i,  1,  -,  1,  -   -,  -,  and  I  0f 
^J     &  J  '   10'  10'  10'  10'  10'  10'  io'   io'  10'  UL 
its  original  bulk.  The  last  portion  of  fluid  containing  the  tenth 
fraction  gave  no  precipitate  with  acetate  of  lead,  and  upon  exa- 
mination was  found  to  contain  the  ethylic  ethers  of  the  fatty 
acids  with  but  very  little  free  acids. 
Of  the  fractional  precipitates  thus  obtained,  the  1st,  2d,  3d, 
7th,  and  9th  were  further  examined.    They  were  decomposed 
