160  Analytical  Researches  and,  Investigations.  {^^'^^^II'ia^^ 
dition  of  alkali  and  a  little  resorcin.  The  above  mentioned  character- 
istic red  coloration  of  the  liquid  then  ap])ears. — Fharm.  Centralhalle, 
1882,  No.  2,  p.  15,  from  Ber.  d.  Oest.  Ges.,  iii,  p.  75. 
Examination  of  Beer.  By  Prof.  DragendoriF. — In  the  examina- 
tion of  beer  for  foreign  bitter  principles  the  following  method 
has  been  found  to  yield  good  results.  About  2  liters  of  the  beer 
are  heated  on  the  water-bath  until  the  carbonic  acid  gas  and  about 
half  of  the  water  have  become  expelled.  To  the  liquid,  while 
still  hot,  basic  acetate  of  lead,  containing  as  much  oxide  as  possible,  is 
added,  and  finally  ordinary  basic  acetate  of  lead  with  the  addition  of 
ammonia  water,  until  a  precipitate  is  no  longer  produced ;  the  precipi- 
tate, which  should  not  be  waslied,  is  quickly  filtert'd,  in  order  to  pro- 
tect it  from  the  carbonic  acid  of  the  air,  and  from  the  filtrate  the 
excess  of  lead  precipitated  by  the  required  amount  of  sulphuric  acid. 
The  quick  deposition  of  the  sulphate  of  lead  may  be  accomplished  by 
the  addition  of  about  40 drops  of  an  aqueous  solution  of  gelatin  (1:20) 
before  adding  the  sulphuric  acid.  The  liquid,  after  being  again 
filtered,  should  no  longer  taste  bitter,  if  the  beer  7/as  unadulterated.. 
For  further  examination  ammonia  water  is  added  to  the  liquid  until 
all  the  the  sulphuric  acid  and  a  portion  of  the  acetic  acid  is  neutralized 
(until  methyl-violet  is  no  longer  rendered  blue  by  a  few  drops  of  the 
liquid),  and  evaporated  on  the  water-bath  to  from  250  to  300  cubic 
centimeters.  The  residue  is  mixed  with  4  times  its  volume  of  absolute- 
alcohol,  in  order  to  precipitate  the  dextrin,  etc.,  the  mixture  well  agi-^ 
tated,  and,  after  standing  for  24  hours  in  a  cool  place,  filtered.  After 
again  removing  the  larger  part  of  the  alcohol  by  distillation  the  acid 
liquid  is  successively  agitated  with  petroleum  ether,  benzol  and  cliloro- 
form,  and  this  operation  repeated  with  the  same  solvents  in  the  stated 
order,  after  having  previously  rendered  the  liquid  decidedly  alkaline 
with  ammonia  water. 
Pure  beer,  prepared  from  malt  and  hops,  when  treated  according  to< 
this  method  shows  the  following  behavior  : 
A.  Absorbed  from  the  acid  solution. 
1.  Petroleum  ether  (boiling  at  from  33  to  60°C.j  takes  up  but  very 
little  of  the  solid  and  liquid  constituents  of  beer,  among  the  latter  the 
fusel  oil  which  is  contained  in  all  beers.  The  solid  portion  of  the 
evaporated  residue  obtained  by  agitation  with  the  petroleum  ether 
has  scarcely  a  bitter  taste,  and  is  dissolved  by  concentrated  sulphuric 
acid,  sulphuric  acid  and  sugar,  as  also  by  nitric  acid  with  but  a  slight 
