^"seprissa*"""*}        Polyhydric  Alcohols  and  Borax.  451 
slightly  in  excess,  were  heated  together  to  a  temperature  of  140°  C. 
The  deliquescent  mass  thus  obtained,  which  gave  no  green  flame  re- 
action, was  extracted  with  anhydrous  ether.  The  ethereal  solution 
upon  spontaneous  evaporation  yielded  a  body  which  apparently  crys- 
tallized in  feathery  tufts  and  gave  an  intensely  green  flame  reaction. 
Absolute  alcohol  extracted  from  the  original  mass  the  same  substance, 
together  with  unaltered  manitol  and  sodium  borate.  The  body  thus 
obtained  was  easily  soluble  in  absolute  alcohol  and  this  solution  was 
faintly  acid  in  reaction.  Water  likewise  dissolved  this  substance,  and 
the  aqueous  solution,  which  was  strongly  acid,  yielded  the  reactions 
for  boric  acid  and  also  for  manitol.  The  residue  which  had  been  ex- 
tracted with  ether  was  found  to  contain  sodium  metaborate.  An 
aqueous  solution  of  borax  was  treated  with  an  aqueous  solution  of 
mannitol,  until  strongly  acid,  and  evaporated  to  dryness ;  then  exposed 
for  some  time  to  a  temperature  a  little  exceeding  100°  C.  Ether  ex- 
tracted from  this  mass  the  substance  above  described.  These  experi- 
ments indicate  that  the  action  of  mannitol  upon  borax  gives  rise  to 
the  formation  of  a  boric  ether  in  which  some  of  the  hydroxyl  of  the 
manitol  is  replaced  by  an  equivalent  amount  of  the  boric  radical. 
This  substance,  which  may  be  termed  mannitol  borin,  is  decomposed 
by  water,  yielding  manitol  and  boric  acid;  the  acidity  of  aqueous 
mixtures  of  mannitol  and  borax  is,  therefore,  due  to  this  acid.  There 
are  probably  many  secondary  reactions  involved  when  aqueous  mix- 
tures of  mannitol  and  borax  react  and  some  of  these  doubtless  give 
rise  to  the  formation  of  the  bodies  described  by  Klein.  It  has  already 
been  observed  that  a  mixture  of  mannitol  and  borax,  unlike  a  mixture 
of  glycerol  and  borax,  does  not  impart  a  green  color  to  the  flame, 
although,  as  the  above  experiments  show,  a  substance  possessing  this 
property,  namely,  mannitol  borin,  is  present  in  the  mixture.  Klein 
{Bull.  8oc.  Chem.,  xxix,  368)  supposes  that  this  is  due  to  the  inter- 
ference of  mannitol,  which,  acting  like  tartaric  acid,  masks  the  green 
flame  reaction  of  boric  acid  when  heated  with  it.  This  is  a  possible 
explanation,  but  the  fact  may  also  be  due  to  dissociation,  as  I  have 
shown  that  it  is  in  the  instance  of  a  similar  phenomenon  which  will 
be  considered  later  on. 
Action  of  Dextrose  icpon  Borax. — The  first  experiments  upon  this 
subject  were  made  with  commercial  glucose.  An  aqueous  solution  of 
this  substance  was  mixed  in  excess  with  an  aqueous  solution  of  borax 
until  the  mixture  was  strongly  acid ;  the  solution  was  evaporated  ta 
