568 
rochleder's  proximate  analysis. 
due  in  question  of  the  watery  decoction  which  is  not  precipitated  by  ether 
because  it  is  soluble  in  a  mixture  of  ether  and  alcohol.  Its  presence  may 
be  easily  recognized  when  the  residue  which  remains  after  the  expulsion  of 
the  ether  and  the  alcohol  is  treated  with  moderately  diluted  hydrochloric 
acid.  The  fluid  becomes  turbid  when  a  little  of  this  body  is  present,  and 
a  separation  of  oily  globules  on  the  surface  of  the  acid  fluid  ensues,  and  a 
separation  of  resinous  flocks  when  it  exists  in  larger  quantity,  takes  place, 
diffusing  a  peculiar  odor  of  an  ethereal  oil.  I  have  met  with  this  sub- 
stance in  plants  of  the  most  varied  families,  so  that  it  may  be  recognized 
as  one  of  the  most  widely-spread  constituents  of  the  vegetable  kingdom, 
although  it  does  not  exist  in  all  plants.  This  substance  was  found  by 
Ka waller  in  the  Pinus  sylvestris,  and  analyzed  by  him,  and  termed  j^iwipi- 
crine.  It  is  a  copulated  carbohydrate,  which  is  broken  up  by  hydrochloric 
acid  into  sugar  and  an  ethereal  oil,  of  which  the  great  part  becomes  a  resin 
when  separated. 
As  the  precipitates  which  sugar  of  lead  and  subacetate  of  lead  produce 
in  the  watery  decoction  of  the  material  under  examination  are  not  abso- 
lutely insoluble  in  water,  it  is  intelligible  that  always  after  the  separation 
of  the  lead  by  sulphuretted  hydrogen  a  fluid  is  obtained,  and  by  the  con- 
centration of  the  fluid  a  residue  results  which  contains  small  quantities  of 
those  substances,  the  bulk  of  which  were  precipitated  by  the  salts  of  lead 
above  named  ;  so  that  indeed  by  the  addition  of  a  little  subacetate  of 
lead  always  a  little  precipitate  forms  in  this  residue,  though  not  much. 
When  these  small  quantities  of  dissolved  substances  are  impeding  the  sep- 
aration of  other  bodies,  they  must  be  removed  by  subacetate  of  lead, 
and  the  lead  then  separated  by  sulphuretted  hydrogen. 
We  often  find  it  stated  in  accounts  of  analysis  that  the  sugar  of  the 
watery  decoction,  which  frequently  acts  very  injuriously  in  the  investigation 
of  the  other  constituents,  must  be  destroyed  by  fermentation  with  the  aid 
of  yeast. 
But  a  removal  of  the  sugar  in  this  way  can  only  give  occasion  too  easily 
to  delusions.  When  no  constituents  are  present  which  undergo  in  contact 
with  yeast  a  splitting  up,  the  constituents  still  may  be  decomposed  by  the 
yeast  and  the  fermenting  sugar.  It  has  been  long  known  that  urea,  which 
is  not  decomposed  by  yeast,  breaks  up  into  carbonic  acid  and  ammonia 
when  it  is  in  a  solution  of  sugar  which  is  set  with  yeast  into  fermentation. 
Other  substances  also  may  be  decomposed  in  a  similar  way  when  they  are 
contained  in  a  fermenting  solution  of  sugar.  On  that  account  this  destruc- 
tion of  the  sugar  by  fermentation  must  only  be  undertaken  as  an  aid  for 
the  isolation  of  one  or  more  constituents  when  it  has  been  already  dis- 
covered that  none  of  the  constituents  undergo  by  this  method  a  splitting 
up  or  an  alteration. 
The  precipitate  which  was  obtained  by  sugar  of  lead  in  the  watery  de- 
coction never  probably  contains  an  organic  base;  on  the  contrary,  one  or 
(To  be  continued.) 
