Am.  Jour.  Pharm.  ) 
December,  1920.  ) 
Current  Literature. 
935 
on  a  glass  slide  with  a  few  drops  of  a  mixture  composed  of  one  part 
of  a  five  per  cent,  sodium  chloride  solution  and  either  three  or  ten 
parts  of  concentrated  glacial  acetic  acid,  and  covered  with  a  cover- 
glass.  The  acid  is  evaporated  in  the  usual  manner  over  the  flame. 
This  mixture  maybe  preserved,  ready  for  use,  for  some  time.  (From 
Munchener  medizinische  Wochenschrift,  Munich;  through  Jour. 
Amer.  Med.  Assoc.,  October  2,  1920.) 
Estimation  of  Caffeine  in  Coi^i^kk  Mixtures  and  So- 
Cai,i.kd  CaffeineIvESS  Coi^f^kS. — B.  Vautier  {Ann.  Chim.  anal. 
AppL,  1920,  2,  168-172.) — ^The  method  of  estimating  caffeine 
previously  described  {Analyst,  191 8,  43,  410),  gives  sufficiently 
accurate  results  in  the  analysis  of  ordinary  coffees,  but  in  the  case 
of  coffees  or  mixtures  poor  in  caffeine  it  is  necessary  to  eliminate 
the  sources  of  error  in  the  sublimation  process,  either  by  estimating 
the  nitrogen  in  the  crude  product  or  by  purifying  the  residue  of  alka- 
loid. In  the  first  method  the  crude  caffeine  is  heated  in  a  Kjeldahl 
flask  with  10  Cc.  of  sulphuric  acid,  5  Gms.  of  potassium  sulphate, 
and  0.5  Gm.  of  crystallized  copper  sulphate,  and  the  ammonia 
distilled,  Congo  red  being  used  as  indicator.  A  blank  estimation 
should  be  made  under  the  same  conditions,  each  one  Cc.  of  N/10 
acid  corresponds  with 0.00485  Gms.  of  anhydrous  or  0.00530  Gm.  of 
hydrated  caffeine.  In  the  second  method  the  solution  of  crude 
caffeine  is  evaporated  to  dryness  on  the  water  bath  with  o .  i  to 
0.2  Gm.  of  sodium  carbonate,  and  the  residue  repeatedly  treated 
with  small  portions  of  chloroform,  which  does  not  dissolve  the  sodium 
salts  of  the  humic  acid-like  impurities.  The  united  filtrates  from 
the  insoluble  residue  are  evaporated  to  dryness  and  the  purified 
caffeine  dried  at  100°  C.  A  caffeineless  coffee  yielded  0.13  per 
cent,  of  caffeine  by  the  sublimation  method,  0.05  per  cent,  calcu- 
lated from  the  nitrogen,  and  0.05  to  0.06  per  cent,  after  purifica- 
tion with  chloroform.    (From  The  Analyst,  September,  1920.) 
Identification  of  Sui^phonaIv  and  Trionai^. — W.  Zimmermann 
{Apoth.  Zeit.,  1920,  35,  27;  through  Chem.  Zeit.  Rep.,  1920,  44,  176.) — 
An  odor  of  mercaptan  is  observed  when  o.  i  Gm.  of  sulphonal  and 
trional  is  fused  with  o.i  Gm.  of  sodium  salicylate,  and  the  mass 
then  boiled  with  water;  if  5  drops  of  alcohol  and  5  drops  of  concen- 
trated sulphuric  acid  are  added,  followed  by  a  further  5  drops  of 
the  acid  after  one  minute,  and  the  mixture  then  warmed,  a  turbid 
red-colored  solution  is  obtained  having  an  odor  of  methyl  salicylate. 
