454  Polyhydric  Alcohols  and  Borax.        { ^""sept'issa™* 
sodium  metaborate.  These  results  agree  precisely  with  those  predicted 
from  previous  observation  of  the  action  of  dextrose  and  levulose  upon 
borax.  Thus  the  acidity  of  mel  boracis  is  due  to  boric  acid  which  has 
been  produced  by  the  action  of  the  dextrose  and  levulose  contained  in 
the  honey  upon  borax  in  presence  of  water.  Mel  boracis  also  contains 
sodium  metaborate. 
EluGidation  of  a  Secondary  Reaction. — I  have  previously  shown 
(^^Pharm.  Jour.''  [3],  xiii,  257)  that  it  is  a  property  characteristic  of 
polyhydric  alcohols  to  render  a  solution  of  sodium  pyroborate,  which 
is  normally  alkaline,  acid  in  reaction,  the  original  alkalinity  being 
restored  upon  heating.  Since  that  time  I  have  had  the  opportunity 
of  trying  this  reaction  with  some  pure  glycocine  (prepared  by  Mr.  T. 
S.  Dymond),  a  substance  which  resembles  dextrose  and  allied  carbohy- 
drates in  its  principal  properties.  This  substance,  unlike  dextrose,  did 
not  yield  the  reaction  with  sodium  pyroborate,  in  accordance  with  the 
prevision  from  the  fact  that  it  is  not  a  polyhydric  alcohol  but  amido- 
acetic  acid  (CH^NH^COOH). 
This  altogether  interesting  and  anomalous  behavior  of  the  poly- 
hydric alcohols  towards  a  solution  of  sodium  pyroborate,  I  am  now, 
after  having  made  clear  the  general  nature  of  their  action  upon  this 
substance,  able  to  explain.  The  experiments  now  described  show  that 
these  alcohols  in  presence  of  water  liberate  boric  acid  from  sodium 
pyroborate,  sodium  metaborate  being  at  the  same  time  produced.  It 
seemed  probable  that  this  characteristic  behavior  was  in  reality  due  to 
a  secondary  reaction  occurring  between  the  free  boric  acid  and  the 
sodium  metaborate  and  was  in  no  way  directly  affected  by  the  presence 
of  polyhydric  alcohol.  Subsequent  experiment  has  completely  con- 
firmed this  conjecture.  The  pure  sodium  metaborate  (NaB02),  the 
aqueous  solution  of  which  is  alkaline,  was  very  faintly  acidified  by  the 
addition  of  boric  acid;  this  solution  as  it  was  slowly  raised  to  the 
boiling  point  gradually  regained  its  alkalinity,  which  again  disappeared 
as  the  liquid  became  cool,  the  indications  being  observed  with  the  aid 
of  phenol  phthalein. 
The  addition  of  large  excess  of  water  produced  an  effect  similar  to 
that  of  heat.  These  same  phenomena  are  observed  when  sodium 
pyroborate,  the  aqueous  solution  of  which  is  likewise  alkaline,  is  sub- 
stituted for  sodium  metaborate  and  when  other  acids  are  employed  in 
the  place  of  boric  acid.  Let  a  solution  of  sodium  pyroborate  be  made 
neutral  or  faintly  acid  with  boric  or  with  hydrochloric  acid  and  the 
