PIIENIC  ACID,  ITS  MANUFACTURE  AND  PROPE   R  ' 
starch  grains.  M.  Maiche  takes  advantage  of  difference  of 
specific  gravity,  in  order  to  obtain  a  complete  separation  ;  he 
makes  use  of  centrifugal  force,  by  which  the  specifically  heavier 
bodies  are  thrown  farthest  off.  The  mode  of  operation  is  the 
following : — A  mixture  of  raw  starch  and  two  parts  of  water  is 
introduced  into  a  sort  of  drum  of  copper,  turning  on  its  axis  at 
the  rate  of  1,000  to  1,200  revolutions  per  minute  ;  as  soon  as 
the  velocity  attains  450  turns,  the  starch  commences  to  be  sepa- 
rated, and  collects  in  a  compact  mass,  adhering  to  the  sides  of 
the  vessel ;  all  the  impurities  remain  in  the  water,  in  the  centre, 
which  is  easily  drawn  off,  while  the  perfectly  white  and  pure 
starch  can  be  removed  in  lumps.  All  amylaceous  matters  can 
be  treated  by  this  method,  and  the  extraction  of  the  starch,  which 
formerly  required  several  weeks,  now  takes  place  in  a  few 
minutes.  The  return  is  much  greater,  for  100  kilogs.  of  rice, 
costing  less  than  100  kilogs.  of  wheat,  give  more  than  20  francs 
worth  of  starch.  There  is  then  no  reason  for  employing,  in  the 
manufacture  of  starch,  wheat  which  gives  the  best  and  most  nu- 
tritious flour,  and  the  chief  principle  of  nutrition  of  which,  the 
gluten,  is  almost  entirely  lost  by  the  process  actually  employed. 
F.  Moigno. 
London  Chem.  News,  July  19,  1867. 
PHENIC  ACID,  ITS  MANUFACTURE  AND  PROPERTIES. 
We  give  an  extract  from  the  excellent  lecture  given  at  the  So- 
ciety for  the  Encouragement  of  National  Industry,  on  Phenic 
Acid  and  its  Compounds,  by  Dr.  Crace-Calvert.  It  is  well 
known  that  when  coal  is  heated  to  a  low  degree  in  retorts  or  dis- 
tillatory apparatus  it  gives  off  substances  that  can  be  classed 
into  four  groups. 
1.  Gaseous  products  furnishing  light,  heat,  and  motive  power. 
2.  Water  containing  ammoniacal  salts,  which  can  be  purified 
by  well-known  chemical  means,  and  utilized  in  agriculture  and 
in  the  industrial  and  medical  arts. 
3.  A  thick,  black,  sticky  mass  of  a  repulsive  odor,  to  which 
the  name  of  tar  has  been  given,  and  which  passes  over  along 
with  the  above-named  products. 
