NEW  METHOD  FOE  DETECTING  SULPHUR  IN  HOPS.  849 
A  NEW  METHOD  FOR  DETECTING  THE  PRESENCE  OF  SULPHUR 
IN  HOPS. 
By  Dk.  Rud.  Wagner. 
The  question,  whether  or  not  a  sample  of  hops  has  been  treated 
with  sulphurous  acid  during  the  drying,  is  one  of  more  than  or- 
dinary difficulty  to  decide. 
The  brewers  of  Bavaria  pour  water  on  &  handful  of  the  hops, 
and  place  in  the  mixture  a  silver  spoon,  and  imagine  that  if  the 
hops  have  been  sulphured,  black  stains  of  sulphuret  of  silver  will 
be  produced  on  the  spoon. 
This  test  is  a  very  uncertain  one,  and  scarcely  succeeds  once 
in  ten  times.  A  comparatively  very  large  amount  of  sulphurous 
acid  is  required  in  order  to  produce  a  stain  of  sulphuret  on  the 
surface  of  the  silver,  in  which  case  it  can  be  detected  better  by 
the  smell  than  by  any  chemical  test.  Now  when  it  is  considered 
that  commonly  1  lb.  of  sulphur  is  used  to  2  cwts.  of  hops,  that 
fully  a  fourth  of  this  quantity  remains  unburnt,  that  more  than 
half  of  the  sulphurous  acid  escapes  into  the  atmosphere,  owing 
to  the  method  employed,  it  will  be  seen  how  small  a  proportion 
of  sulphurous  acid  is  efficaciously  applied. 
This  small  proportion  of  sulphurous  acid  can  only  be  disco- 
vered by  the  silver-test  when  the  hops  have  been  sulphured  a 
short  time  previous  to  its  application  (eight  to  fourteen  days:) 
and  in  this  case  an  observable  stain  of  sulphuret  only  appears 
when  the  mixture  of  hops  and  water  has  been  left  to  itself  at  a 
moderate  temperature  for  several  days,  when,  in  consequence  of 
the  fermentation  which  takes  place,  the  sulphurous  acid  is  re- 
duced to  sulphur.   To  an  opinion  recently  put  forth,  that  metal- 
lic silver  was  capable,  in  the  absence  of  organic  matter,  of  con- 
verting sulphurous  acid  into  sulphuric  acid  and  sulphur,  the 
author  can  by  no  means  assent,  as  he  has  convinced  himself  by 
experiment,  that  metallic  silver  may  remain  in  contact  with  a 
very  dilute  watery  solution  of  sulphurous  acid  for  a  fortnight, 
without  the  smallest  stain  of  sulphuret  appearing  on  its  surface. 
An  examination  with  a  magnifying  lens,  in  order  to  ascertain 
from  the  form  and  color  of  the  lupulin,  whether  the  hops  have 
been  sulphured,  is  no  longer  possible  in  the  present  condition  of 
the  hop  trade  of  Bavaria,  where  the  hops  are  not  treated  with 
