■^"^iJne'^'issr™"}       Analytical  Researches  and  Investigations.  299" 
The  sulphate,  CgHjoN^Oa,  H2SO4,  is  very  readily  obtained  by  dis- 
solving the  wffeine  in  about  ten  times  its  weight  of  hot  alcohol,  to 
which  sufficient  HgSO^  has  been  added  to  impart  a  strongly  acid 
reaction.  Upon  cooling  it  separates  in  the  form  of  well-developed^ 
transparent,  short  needles,  which  are  grouped  in  rosettes. 
Coffeine-gold  chloride,  CsR,o^fi2,  HCl  +  AuClg  +  2H2O,  forms 
golden -yellow,  shining  laminse. 
The  formiate,  acetate,  hidyrate,  and  valerianate  were  likewise  formed ; 
they  were  all  anhydrous,  and  it  is  only  to  be  observed  that  the  acetate- 
shows  the  deviating  composition  03111,^^402(0211402)2. — Ibid,  from 
Ibid,  p.  175. 
The  Detection  of  Picric  Acid.  By  G.  Ohristel. — For  the  detection 
of  picric  acid  in  beer,  the  author  recommends  the  following  method  of 
procedure :  200  ccm.  of  beer  are  evaporated  on  a  water- bath  to  a 
syrupy  consistence ;  the  residue  is  brought  into  a  small  flask,  50  ccm.  ■ 
of  alcohol  (90  per  cent.)  are  added,  the  liquid  allowed  to  stand  for 
24  hours  with  frequent  active  agitation,  filtered,  and  the  residue  treated 
again  with  30  ccm.  of  alcohol.  The  mixed  filtrates  are  evaporated  to 
a  syrupy  consistence,  to  the  residue  4-5  drops  of  dilute  sulphuric  acid 
(1 : 3)  are  added,  and  to  the  mixture,  contained  in  a  test-tube,  which 
may  be  closed  with  a  cork,  5  to  6  times  its  volume  of  ether  is  added. 
The  mixture  is  actively  agitated,  the  ether  decanted,  and  the  operation 
repeated  with  a  fresh  portion  of  ether,  and  the  addition  of  2  or  3  drops 
dilute  H2SO4.  The  mixed  etherial  solutions  are  allowed  to  evaporate, 
the  residue  diluted  with  water  to  the  measure  of  5-10  ccm.,  filtered 
and  neutralized  with  ammonia  water.  In  this  solution  the  picric  acid 
may  be  detected  by  the  known  methods ;  a  very  delicate  reagent  there- 
fore is  potassium  cyanide.  0.2  gm.  of  powdered  sugar  with  which 
0.0001  gm.  of  picric  acid  was  mixed,  affi)rded  a  fine  rose-red  color  ou 
the  addition  of  one  drop  of  solution  of  potassium  cyanide. — Ibid  from 
Ibid,  p.  190. 
The  Detection  of  Rice  Flour  in  Buckwheat  Flour.  By  Aug.  Lehn^ 
— About  1  gm.  of  the  flour  was  warmed  upon  a  water-bath,  with  2 
gms.  of  concentrated  solution  of  potassa  and  water^  until  a  paste  had 
become  formed,  and  hydrochloric  acid  then  added.  With  rice  flonr 
the  paste  became  yellowish,  and,  on  the  addition  of  HOI,  white. 
With  buckwheat  the  paste  was  dark  green,  and,  after  treatment 
with  HCl,  assumed  a  red  color. 
With  a  mixture  of  the  two  the  paste  became  green  in  spots,  and,, 
with  HOI,  of  a  flesh  color. — Ibid,  from  Pharm.  Centralhalle,  4,  p.  130. 
