460  FACTS  AND  THEORIES    OF  FERMENTATION. 
of  fine  sand,  all  coarser  and  finer  particles  being  removed  by 
sieves  of  different  sizes.  It  was  chosen  as  being  better  adapted 
to  this  purpose  than  nearly  any  other  substance,  being  readily 
obtained  pure  and  clean,  possessing  an  uniform  composition, 
ready  solubility  and  absence  of  color;  it  could  also  be  heated  to 
212°  F.  without  injury  to  its  physical  properties.  The  washing 
tube  and  water  were  used  to  prevent  any  organic  matter,  dust, 
etc.,  being  mixed  with  the  sugar  in  the  filter  tube,  the  presence 
of  which  might  lead  to  errors  in  the  subsequent  examinations. 
The  air  was  dried  after  leaving  the  water  by  the  chloride  of  cal- 
cium, in'  order  that  no  possibility  might  exist  of  the  germination 
of  the  sporules  favored  by  the  moisture,  that  would  otherwise  be 
carried  into  the  sugar,  and  which,  if  it  had  taken  place,  might 
cause  them  to  vegetate,  and  thus  transmit  the  germs  from  particle 
to  particle,  until  finally  carried  over  by  the  air  into  the  flask  a. 
On  the  30th  Nov.,  1854,  f  pint  of  warm  ale  wort,  fresh  from 
the  brewery,  was  put  into  the  experimental  flask  a,  and  about  six 
ounces  of  the  same  into  the  beaker  glass  i,  about  the  same  quan- 
tity also  poured  into  a  bottle  and  left  exposed  to  the  air.  The 
filter  tube  was  now  filled  with  the  sugar,  previously  heated  in  an 
air  bath  to  212°  for  30  minutes.  The  joints  now  being  made 
air  tight,  the  contents  of  the  flask  a  were  brought  into  ebullition, 
which  was  continued  until  the  tubes  leading  to  the  filter  and  to 
the  canister  were  heated  throughout.  The  stopcock  I  was  now 
opened,  and  the  water  permitted  to  escape  drop  by  drop,  the  air 
entering  through  the  tube  k,  and  passing  through  the  whole  ap- 
paratus to  replace  it.  The  water  was  allowed  to  run  out  at  the 
rate  of  four  gallons  in  24  hours,  being  renewed  once  a  day  ;  of 
course  the  same  quantity  of  air  would  pass  through  the  flask  a 
within  that  time;  the  temperature  of  the  room  65°  F.  On  the 
4th  of  December  the  liquid  in  the  open  bottle  was  covered  with 
bubbles,  and  a  very  thin  pellicle  formed  on  the  surface.  The 
contents  of  the  flask  a,  and  of  the  beaker  glass  i,  remained  un- 
altered. Dec.  5th.  The  liquid  in  the  beaker  glass  showed  a  little 
mould  on  the  surface.  Dec.  6th.  The  mould  was  very  percep- 
tible in  the  beaker  glass  ;  a  few  globules  were  visible  in  the  liquid 
when  under  the  microscope.  Dec.  9th.  The  liquid  in  the  beaker 
glass  had  apparently  passed  through  the  alcoholic  fermentation 
and  become  very  acid,  smelling  strongly  of  vinegar ;  it  was  full 
