6oo  Lactic  Acid.  {  SJ&JS&'ftg* 
I -05  to  1-075  SP  ?r-l  f°r  technical  reasons  the  higher  density  is 
preferable.  A  solution  of  that  density  will  contain  from  jy2  to  1 1 
per  cent,  of  saccharine  matter.  It  is  not  essential  to  have  all 
the  saccharine  matter  in  the  form  of  grape  sugar.  In  fact, 
it  seems  to  be  advantageous  to  have  10  to  15  per  cent,  of  it  as  cane- 
sugar,  which,  becoming  inverted  in  the  process,  furnishes  fresh  mate- 
rial, as  it  were,  for  the  ferment.  To  do  its  work  thoroughly,  the 
lactic  bacillus  needs  to  be  well  nourished  by  nitrogenous  matter. 
The  most  convenient  form  for  this  nitrogenous  material  is  as 
it  comes  from  vegetable  life,  as  extracted,  for  instance,  from  bran 
by  the  action  of  boiling  water  and  dilute  acid.  At  different  times  I 
have  used  material  obtained  from  animal  and  mineral  sources.  In 
the  laboratory  it  is  difficult  to  detect  material  differences.  On  the 
large  scale,  I  prefer  a  vegetable  source  ;  there  seems  to  be  a  com- 
plete utilization  of  the  material.  The  amount  of  nitrogenous  mate- 
rial should  be  at  least  8  per  cent,  of  the  saccharine  constituents.  I 
assume  by  nitrogenous  matter  a  body  of  substantially  the  compo- 
sition of  albumin,  containing  15  to  20  per  cent,  of  nitrogen  in  com- 
plex form.  Perhaps  it  would  be  more  accurate  to  say  the  total 
nitrogen  should  be  nearly  2  per  cent,  of  the  saccharine  material, 
and  preferably  combined  with  carbon.  If  a  mineral  food  is  to  be 
employed,  ammonia  salts  should  be  in  larger  proportion  than 
nitrates.  A  low  percentage  of  phosphates  will  suffice,  and  the  pres- 
ence of  such  potassium  does  not  seem  to  be  essential. 
The  requisite  saccharine  solution  made  up  and  boiled  for  at  least 
an  hour,  to  make  sure  of  sterilization,  is  conveyed  into  the  fermen- 
tation tank.  There  it  is  rapidly  cooled  to  550  C.  or  lower,  not  going 
below  450,  and  impregnated.  Impregnation  takes  place  at  a  higher 
temperature  than  observers  have  generally  stated,  a  peculiarity  per- 
haps arising  from  the  large  scale  at  which  the  work  is  carried  on.  I 
may  state  here,  in  a  general  way,  that  the  modified  conditions 
caused  by  working  the  bacteria  on  a  large  scale  give  an  oppor- 
tunity for  variation  from  laboratory  results.  A  large  body  of  fer- 
mentable liquor  is  less  susceptible  to  foreign  spores,  more  energetic 
in  its  development,  and  productive  of  more  obvious  results  than  a 
solution  such  as  is  usually  found  in  the  laboratory.  Consequently 
I  feel  that  the  chemist,  who  is  to  investigate  and  utilize,  to  the 
fullest  extent,  nature's  great  oxidizing  agent,  the  mycoderma  aceti, 
and  nature's  great  reducing  agent,  the  bacillus  butyrici,  must  be  as 
