276       Recent  Literature  Relating  to  Pharmacy.  \Km-^nl:\mxm' 
heats  until  the  mixture  is  brown  and  gas  bubbles  are  evolved.  The 
mixture  is  then  removed  from  the  flame  and  allowed  to  stand 
until  colorless,  whereupon  I  c.c.  of  solution  of  mercuric  sulphate 
(red  mercuric  oxide,  5  grammes ;  concentrated  sulphuric  acid,  20 
c.c;  water,  100  c.c.)  is  added  and  the  liquid  boiled.  If  citric  acid 
be  present  (even  0  5  per  cent.)  a  white  cloudiness  or  precipitate 
occurs.  H.  V.  Arny. 
MICROSCOPIC  EXAMINATION  OF  WHEAT  FLOUR. 
E.  Collin  (Rep.  Pharm.,  1898,  438,  from  your.  Pharm.  et  Chimie) 
has  given  wheat  flour  and  its  adulterants  a  careful  study.  The  arti- 
cle begins  with  an  elaborate  description  of  the  histology  of  the  fruit 
of  wheat,  and  then  compares  its  flour  with  that  of  likely  organic 
adulterants — rye,  rice,  corn  and  barley.  The  characteristics  of 
wheat  flour  are  the  size  and  shape  of  the  starch  granules  and  the 
shape  of  the  lumen  of  wheat  hairs  chancing  to  be  present — the 
latter  differing  from  those  found  in  rye  by  being  flat  at  the  base. 
The  aleuron  masses  found  in  wheat  flour  are  apt  to  be  mistaken 
for  rice  starch,  but  the  iodine  test  will  distinguish  the  two 
substances. 
Rye  starch  is  about  the  same  size  and  shape  as  the  average  wheat 
starch  granule,  and  this  fact  makes  rye  the  best  adulterant  of  flour. 
Lucas,  however,  claims  that  from  a  flour  mixed  with  rye,  the  yield 
of  gluten  is  always  lessened,  citing  that  a  wheat  flour,  from  which 
24-6  per  cent,  of  gluten  was  obtained,  on  adulteration,  with  6  per 
cent,  of  rye,  yielded  only  22-8  per  cent,  gluten,  and  after  10  per 
cent,  of  rye  had  been  added,  the  gluten  yield  was  but  20-4  per  cent. 
The  article  emphasizes  these  statements  without  special  particulars. 
Rice  starch  can  be  easily  detected  in  flour  by  the  different  form 
and  size  of  the  granules,  those  of  rice  measuring  not  more 
than  8  microns,  while  the  wheat  granules  are  usually  28  to  35 
microns.  The  rice  starch  can  be  easily  separated  from  the  wheat 
starch  by  kneading  the  flour  under  a  stream  of  water  (whereby  the 
gluten  is  obtained),  and  allowing  the  wash  water  to  settle,  which  it 
does  in  three  layers,  the  lowest  containing  the  wheat  starch,  and 
the  central  one,  the  wheat  integuments  and  the  rice  starch.  Other 
suggested  adulterants  are  sawdust  (distinguished  by  the  peculiar 
markings  of  the  walls  of  the  wood  cells),  mildew  (caused  by  care- 
less handling  of  the  flour)  and  darnel.  H.  V.  A. 
