%dZl^' }     Inversion  of  Cane  Sugar  in  Syrups.  41 1 
sugar,  but,  after  being  stored  for  five  months  in  a  corked  bottle 
which  had  been  placed  in  a  cool",  dark  place,  yielded  a  very  heavy 
precipitate  of  cuprous  oxide  when  tested  with  Fehling's  solution, 
indicating  that  much  of  the  cane  sugar  had  been  inverted. 
The  tests  made  at  that  time  being  qualitative  only,  the  thought 
occurred  to  me  recently  to  make  a  series  of  quantitative  tests  to 
determine  exactly  how  much  of  the  cane  sugar  was  converted  into 
reducing  sugar,  and  the  following  work  was  therefore  undertaken. 
On  January  28,  1915,  1000  Cc.  of  syrupus  were  made,  following 
the  directions  on  page  435  of  the  U.  S.  P.  VIII  for  the  cold  per- 
colation process,  and  the  same  day  1000  Cc.  of  syrupus  were  made 
by  the  method  on  page  435  of  the  U.S.  P.  VIII  for  the  hot  process,, 
each  sample  being  placed  in  a  sterilized  glass-stoppered  bottle. 
The  syrup  made  by  percolation  had  a  specific  gravity  of  1.3 148 
at  25 0  C,  and  the  sample  made  by  the  hot  process  had  a  specific 
gravity  of  1.3 126  at  25 °. 
A  quantity  of  syrup  from  each  bottle  was  immediately  weighed 
in  tared  100  Cc.  graduated  flasks  and  water  added  to  make  100  Cc, 
and  the  reducing  sugar  in  50  Cc.  of  this  solution  determined  by  the 
following  method  of  Walker  and  Munson : 
( 1 )  Preparation  of  Solutions  and  Asbestos. 
(a)  Solutions.— Use  solutions  (a)  and  (b)  and  (c)  as  given  on 
page  42,  under  Soxhlet's  modification  of  Fehling's  solution. 
(b)  Asbestos. — Prepare  the  asbestos,  which  should  be  the  amphi- 
bole  variety,  by  first  digesting  with  1  :  3  hydrochloric  acid  for  two  or 
three  days.  Wash  free  from  acid  and  digest  for  a  similar  period 
with  soda  solution,  after  which  treat  for  a  few  hours  with  hot  alka- 
line copper  tartrate  solution  of  the  strength  employed  in  sugar 
determination.  Then  wash  the  asbestos  free  from  alkali,  finally 
digest  with  nitric  acid  for  several  hours,  and,  after  washing  free 
from  acid,  shake  with  water  for  use.  In  preparing  the  Gooch 
crucible,  load  it  with  a  film  of  asbestos  one- fourth  inch  thick,  wash 
this  thoroughly  with  water  to  remove  fine  particles  of  asbestos ;  finally 
wash  with  alcohol  and  ether,  dry  for  thirty  minutes  at  ioo°  C,  cool  in 
a  desiccator,  and  weigh.  It  is  best  to  dissolve  the  cuprous  oxide  with 
nitric  acid  each  time  after  weighing  and  use  the  same  felts  over  and 
over  again,  as  they  improve  with  use. 
