456  Polyhydric  Alcohols  and  Borax.  {^"^kilVusi''^' 
mation  of  sodium  metaborate  and  a  boric  ether  or,  if  water  be  present, 
free  boric  acid.  There  are  no  doubt  many  secondary  reactions  involved ; 
in  fact,  one  such  reaction  has  just  been  under  discussion.  The  principal 
properties  of  these  bodies  have  been  described,  but  whether  they  are 
mono-,  di-,  or  tri-borins,  has  not  directly  been  determined.  In  the 
case  of  glycerol,  however,  there  can  be  little  doubt  that  the  substance 
produced  is  glycerol  in  which  all  the  three  hydroxyl  groups  are  sub- 
stituted by  the  boric  radical  (C3H5BO3).  The  following  equations 
symbolize  the  action  of  glycerol  upon  sodium  pyroborate  and  similarly 
other  polyhydric  alcohols : 
2C3H,(OH)3+(2mB02.BA)=^C3H,B03+3H20+2NaB02. 
But  inasmuch  as  water  itself  is  a  product  of  the  decomposition,  the 
above  reaction  is  never  complete  save  at  high  temperatures,  owing  to 
the  conversion  or  partial  conversion  of  the  borin  into  boric  acid  under 
the  influence  of  the  water,  thus^ — 
C3H,B03+ 2Hp=C3H,(OH)3 + H^BO,. 
In  aqueous  solutions  the  reaction  may  be  thus  represented  in  one 
equation — 
2C3H,(OH)3-h(2NaB02,BA)  +  3H20= 
2NaB02 + 2H3BO3 + 2C3H,(OH)3. 
This  is  a  reaction,  which,  taken  by  itself,  might  be  attributed  to 
what  has  been  called  ^'  catalysis,"  for  the  glycerin  remains  unchanged 
at  the  close  of  the  reaction.  It  is,  however,  now  manifest  that  the 
production  of  a  boric  ether  is  the  determining  cause  of  this  reaction, 
which  is  thus  brought  under  the  category  of  chemical  action  and  the 
use  of  a  fictitious  explanation,  if  at  any  time  legitimate,  is  here  rendered 
superfluous. 
Not  only  are  the  results  of  this  investigation  interesting  on  the  side 
of  the  polyhydric  alcohols  but  also  as  additional  evidence  in  favor  of 
regarding  anhydrous  borax  as  a  sodium  pyroborate ;  that  is,  a  com- 
pound of  boric  anhydride  with  sodium  metaborate. — Pharm.  Jour,  and 
Trans.,  July  21,  1883. 
^  Cf.  the  experimental  investigations  of  Berthelot  ("Ann.  Chim.  Phys." 
[3],  Ixv,  Ixvi,  Ixviii)  ;  Menschutkin  ("  Ber.,"  x,  1728)  on  "  Etherification 
also  the  admirable  discussion  of  the  whole  subject  by  Berthelot  ("  Essai  de 
Mecanique  Chimique,"  vol.  ii,  pp.  79-95). 
