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ON  ACETIC  FERMENTATION. 
property  of  cadmium  in  certain  combinations  ;  also,  in  the  fact, 
that  while  the  mean  melting  point  of  the  constituents  composing 
it  is  much  higher  than  that  of  those  composing  the  old  fusible 
metals,  it  melts  at  a  much  lower  temperature, — being  more  fu- 
sible than  any  other  alloy  yet  known  consisting  of  but  three 
metals. 
It  has  a  clear,  brilliant  metallic  lustre  that  does  not  readily 
tarnish.  Its  color  is  a  bright  bluish  grey,  resembling  platinum  : 
when  cast,  its  free  surface  presents  a  white,  frosted  appearance. 
It  is  very  flexible  in  thin  plates,  and  breaks  with  a  hackly  frac- 
ture ;  but  when  thicker  bars  are  broken,  the  fracture  is  smooth, 
resembling  that  of  tempered  steel.  It  is  malleable,  but  not  per- 
fectly so.  In  hardness  it  is  about  the  same  as  bismuth,  and  about 
the  same  as  an  alloy  of  two  parts  of  lead,  and  one  part  of  tin,  or 
"coarse  solder,"  which  it  resembles  more  nearly  in  other  re- 
spects. 
It  may  be  that  more  approved  methods  of  measuring  tem- 
perature will  give  the  alloy  a  still  lower  melting  point  than 
above  ascribed  to  it,  as  I  see  that  the  experiments  made  by 
Lipowitz*  with  my  "  fusible  metal  "  indicate  for  it  a  much 
greater  fusibility  than  my  measurements.— Amer.  Jour.  Science 
and  Arts,  March,  1862. 
ON  ACETIC  FERMENTATION. 
By  M.  Pasteur. 
Pasteur  has  observed  that  the  cryptogamic  plants  of  the  genus 
Mycoderma  possess  the  remarkable  property  of  transforming 
alcoholic  liquids  into  acetic  acid.  The  following  are  some  of 
the  experiments  of  this  skilful  chemist : 
1.  A  species  of  mycoderm  is  developed  on  the  surface  of  any 
liquid  containing  phosphates  and  albuminous  matters.  When 
the  whole  surface  of  the  liquid  is  covered  with  it,  the  generative 
liquid  is  removed  from  the  plant  by  a  syphon,  and  is  replaced 
by  pure  alcohol  diluted  with  water.     The  mycoderm  swells 
*  Dingler's  Polytechnisches  Journal,  clviii,  376,  Lipowitz  found  that 
"  Wood's  fusible  metal"  when  made  of  8  parts  of  lead,  15  parts  bismuth, 
4  parts  tin  and  3  parts  cadmium,  fused  at  60°  C.  (140°  F.) — Eds. 
