62 
ON  MELEZITOSE,  A  NEW  SPECIES  OF  SUGAR. 
uble  in  boiling  ordinary  alcohol.  Absolute  alcohol  added  to  a 
concentrated  aqueous  solution  of  melezitose,  precipitates  it  slowly 
under  the  crystallised  form ;  its  aqueous  solution  left  to  spon- 
taneous evaporation  becomes  syrupy  and  remains  for  a  long  time 
without  crystallising. 
Melezitose,  dried  at  110°  C.  (230°  F.)  presents  the  same 
composition  as  cane  sugar,  and  corresponds  to  the  formula 
Q12H11Q11.  Below  140p  C.  (284°  F.),  it  fuses  into  a  trans- 
parent liquid,  without  undergoing  any  appreciable  alteration. 
Its  reactions  are  like  those  of  cane  sugar.  It  does  not  percep- 
tibly reduce  the  potassio-tartrate  of  copper,  and  is  not  destroyed 
at  100°  C.  (212°  F,),  by  the  alkalies ;  but  concentrated  sul- 
phuric acid  carbonises  it  cold ;  under  the  influence  of  boiling 
hydrochloric  acid,  it  rapidly  turns  brown.  Dilute  sulphuric 
acid  metamorphoses  it  at  100°  C.  (212°  F.)  into  a  sugar 
analogous  to,  or  identical  with,  glucose,  capable  of  reducing  the 
potassio-tartrate  of  copper,  and  destructible  at  100°  C.  (212P  F.) 
by  the  alkalies.  Nitric  acid  converts  it  into  oxalic  acid, 
without  mucic  acid.  Ammonio-acetate  of  lead  precipitates 
it.  Melezitose,  treated  with  yeast,  ferments  only  slowly  and 
incompletely,  and  sometimes  does  not  do  so  at  all ;  but  when 
it  has  been  modified  by  sulphuric  acid,  it  ferments  immediately, 
and  is  almost  entirely  converted  into  alcohol  and  carbonic  acid. 
Its  rotary  power,  at  20°  C.  (68°  F.),  deduced  from  a  solution 
of  l-5th,  and  brought  to  the  tint  of  passage,  is  equal  to  -j-90°«3. 
A  solution  containing  1-1 00th  of  sulphuric  acid  deviated  -|-1707', 
heated  to  100Q  C.  (212°  F.)  for  ten  minutes,  +12°2';  for  an 
hour,  +9°'8;  two  hours,  9°8 . 
Thus,  the  rotary  power  of  melezitose  is  higher  by  one-fourth 
than  that  of  cane  sugar ;  under  the  influence  of  sulphuric  acid, 
it  diminishes  more  slowly  than  that  of  cane  sugar,  and  does  not 
change  in  sign,  whereas  cane  sugar  is  interverted;  this  remark 
is  essential.  The  rotary  power  of  modified  melezitose  is  almost 
identical  with  that  of  glucose. 
These  characters,  added  to  the  feebler  saccharine  taste  and 
the  much  greater  difficulty  of  fermentation,  distinguish  melezi- 
tose from  cane  sugar. 
Trehalose  is  distinguished  from  melezitose  by  its  rotary  power, 
4 
