ON  THE  ORIGIN  OF  FERMENTS. 
165 
per  cent,  of  sodium  appears  to  be  as  great  as  that  between  mer- 
cury and  zinc,  with  this  important  difference,  however,— in  the 
former  case  the  wetted  "  metal  does  not  suffer  the  least  trace 
of  amalgamation.  Even  when  foreign  metals,  such  as  lead,  tin, 
zinc,  silver,  are  purposely  added  to  the  sodium-amalgam,  the 
platinum  surface  suffers  no  disintegration. 
When  the  amalgam  has  been  rubbed  on  with  a  cloth,  until  the 
whole  surface  is  brilliantly  metallic,  water  is  applied,  which 
oxidises  the  sodium  and  allows  the  cohesion  of  the  mercury  to 
assert  itself.  On  wiping  the  mercury  off,  the  platinum  surface 
is  left  in  admirable  condition  for  the  burnisher.  I  suppose  the 
sodium  to  act  here  chiefly  as  a  diluent,  diminishing  thereby  the 
cohesion  of  the  mercury  and  allowing  the  adhesion  between  that 
metal  and  the  platinum  to  predominate, — a  result  which  is  cer- 
tainly assisted  by  the  mercury  enabling  the  sodium  to  offer  a 
clean  surface  to  the  platinum,  and  so  allowing  the  specific  ad- 
hesion between  the  two  latter  metals  to  be  exhibited. 
I  am,  &c.  F.  G. 
Laboratory,  University  of  Edinburgh. 
—Chem,  News,  Nov,  1860. 
ON  THE  ORIGIN  OF  FERMENTS. 
Br  M.  L.  Pasteur. 
Among  the  questions  arising  during  the  researches  which  I 
have  undertaken  on  the  subject  of  fermentations,  properly  so 
termed,  there  is  none  more  worthy  of  attention  than  that  which 
relates  to  the  origin  of  <'<•  ferments.'''  Whence  proceed  these 
mysterious  agents,  so  feeble  in  appearance,  and  yet  in  reality 
so  powerful ;  which  in  the  minutest  quantity,  measured  by 
weight,  and  with  insignificant  external  chemical  characters, 
possess  such  extraordinary  energy  ?  It  is  in  an  attempt  to 
solve  this  problem  that  I  have  been  led  to  the  study  of  the  so- 
termed  spontaneous  generation. 
In  the  communication  which  I  had  the  honor  of  submitting  to 
the  Academy  on  the  6th  of  February  last,  I  mentioned  only  a 
a  single  fluid  appropriate  for  the  development  of  Infusoria  and 
Mucedinea,  although  I  gave  a  general  method  applicable  to  all 
liquids. 
