622  Production  of  Glycerin  from  Molasses.  {Am~  $™t' i^™' 
possible  without  stopping  fermentation.  The  earlier  the  addition  of 
the  alkali,  the  higher  the  yield  of  glycerin  will  be.  It  is  necessary 
that  the  yeast  be  "  worked  up  "  by  making  a  "  bub,"  and  it  has  been 
observed  that  the  presence  of  ammonium  chloride  in  the  fermenting 
liquid  augments  the  yield  of  glycerin.  The  most  favorable  tempera- 
ture for  the  fermentation  is  30-32 0  C,  and  the  fermenting  liquid 
should  not  vary  from  these  limits  of  temperature  for  any  consider- 
able period.  Higher  temperatures  lead  to  a  loss  of  alcohol  and 
glycerin,  and  to  the  formation  of  objectionable  substances,  whilst 
smaller  yields  of  glycerin  are  obtained  at  lower  temperatures.  The 
most  favorable  concentration  for  the  sugar  solutions  lie  between 
17.5  and  20  Gms.  of  sugar  per  100  Cc.  It  has  been  found  that,  when 
fermentation  is  complete  according  to  the  method  above  outlined, 
20-25  per  cent,  of  the  sugar  originally  present  in  the  liquid  is  con- 
verted into  glycerin,  and  practically  all  the  remainder  into  alcohoi 
and  carbon  dioxide.  The  nature  of  other  substances  which  are 
formed  has  not  yet  been  determined.  It  is  mentioned  that  when  the 
sodium  carbonate  has  been  added  to  the  fermenting  solution  in 
sufficient  quantity,  a  copious  precipitate  is  formed,  the  evolution  of 
gas  ceases,  and  the  yeast  apparently  lies  dormant  for  a  while.  The 
precipitate  eventually  disappears  and  the  fermentation  again  pro- 
ceeds. It  is  essential  that  this  precipitate  should  form,  and  that  the 
fermenting  liquid  lie  quiescent  for  a  while.  The  addition  of  the 
sodium  carbonate  in  solid  form  has  been  found  to  produce  better 
results  than  if  it  be  added  in  the  form  of  a  solution. 
A  description  is  next  given  of  the  process  as  carried  out  on  a 
commercial  scale,  using  inedible  "  black  strap  "  Porto  Rico  molasses. 
The  yeast  starter  or  "  bub  "  is  first  prepared  in  the  following 
manner.  Yeast  No.  657  (see  above)  was  seeded  with  a  platinum 
loop  into  150  Cc.  of  sterile  grape  juice,  and  allowed  to  ferment  to 
the  final  degree.  Fifteen  Cc.  of  this  was  then  added  to  150  Cc.  of 
sterile  grape  juice,  and  when  fermentation  had  finished  75  Cc.  was 
added  to  800  Cc.  of  a  solution  of  sterilized  "  black  strap  "  molasses 
at  21.20  Balling  (about  sp.  gr.  1.085).  As  soon  as  brisk  fermenta- 
tion had  set  in,  3  Gms.  of  soda  ash  was  added  and  the  bottle  shaken 
until  solution  was  complete.  After  fermentation  had  resumed,  and 
when  it  had  reached  its  final  point,  the  whole  of  the  liquid  was 
added  to  2  gallons2  of  a  similar  "  black  strap  "  molasses  solution, 
1  The  gallon  referred  to  in  this  article  is  the  U.  S.  gallon.  The  factor 
for  the  conversion  into  the  British  gallon  is  0.834. 
