ANovJemberPhl!97n-}  LacttC  Add.  599 
THE  MANUFACTURE  AND  APPLICATIONS  OF  LACTIC 
ACID.1 
By  Ai,an  A.  Cufwn. 
This  paper  consists  of  extracts  from  notes  on  observations  taken 
during  seven  years'  experience  in  the  manufacture  of  lactic  acid  on 
a  large  scale,  on  lines  laid  down  by  my  predecessor,  Mr.  Chas.  E. 
Avery.  While  some  of  my  facts  are  not  new,  considerable  work 
having  been  done  very  recently  on  this  subject,  and  while  none  of 
my  investigations  have  been  carried  farther  than  the  daily  exi- 
gencies of  manufacture  required,  yet  I  trust  that  from  the  ex- 
ceptional opportunities  that  I  have  had,  they  may  be  found  of 
interest. 
The  lactic  acid  industry  dates  back  about  twenty  years,  when  Mr. 
Avery  began  his  investigation,  which  resulted  in  the  process  which  he 
covered  from  1 88 1  to  1885  by  American  and  foreign  patents.  The 
production  of  lactic  acid  on  a  large  scale  by  fermentation  is  interest- 
ing because  it  employs  micro-organisms  to  split  up  the  glucose 
molecule  into  two  molecules  of  ethylidene  lactic  acid.  The  micro- 
organism that  does  this  work  is  well  known  as  the  bacillus  acidi 
lactici.  This  bacillus  has  been  described  variously — not  from  any 
inaccuracy  of  the  observer,  but  because  it  is  of  great  variety  itself, 
a  certain  variety  developing  most  rapidly  in  a  certain  medium.  The 
bacillus  which  does  the  work  in  a  highly  nitrogenous  saccharine 
solution  is  a  large  species.  Its  form  is  a  double  truncated  cone, 
averaging  in  length  2to  2^  millimetres,  and  about  I  millimetre  in 
diameter.  It  has  the  tendency  of  all  lactic  bacteria  to  link  itself 
together  in  pairs  or  short  chains.  The  most  abundant  lactic 
bacteria  in  sour  milk  are  only  millimetre  long,  but  a  little 
thicker  in  proportion  than  those  found  in  my  saccharine  solutions. 
The  manufacture  of  lactic  acid  has  three  divisions :  The  prepara- 
tion of  the  saccharine  solution,  the  fermentation,  the  conversion  of 
the  fermented  liquor  into  commercial  lactic  acid.  The  source  from 
which  the  saccharine  solution  is  obtained  is  not  important.  The 
location  of  the  factory  determines  the  raw  material  that  can  furnish 
a  glucose  liquor  most  cheaply.  The  proportional  composition  of 
the  saccharine  solution  is  very  important.  For  complete  decompo- 
sition the  saccharine  solution  should  not  vary  between  the  limit 
1  The  Journal  of  tlve  Society  of  Chemical  Industry \  June  30,.  1897. 
