Am. Jour.  Pharm.l 
November,  1897.  J 
Lactic  Acid. 
603 
and  a  specific  gravity  of  1-20,  and  contains  about  J  per  cent,  of 
lactic  anhydride. 
The  applications  of  lactic  acid  to-day,  while  limited,  are  increasing. 
The  majority  of  all  that  is  produced  is  used  by  the  woollen  dyer  as 
an  assistant  in  mordanting  with  bichromate  of  potassium.  For  this 
purpose  I  believe  it  has  advantages  which  the  technical  world  is 
beginning  to  appreciate.  Without  discussing  at  length  the  compara- 
tive merits  of  tartaric,  oxalic  and  lactic  acids,  I  will  just  mention 
the  advantages  which  are  claimed  for  lactic  acid,  namely,  greater 
reducing  power,  greater  solubility  of  itself  and  its  salts,  and  less 
corrosive  action.  The  first  claimed  advantage,  the  greater  reducing 
power  of  lactic  acid  toward  chromium  salts  and  chromic  acid,  is 
geherally  admitted  in  comparison  with  oxalic  acid,  and  also  in  the 
case  of  tartaric  acid,  although  the  fact  that  tartaric  acid  reduces 
chromium  salts  more  quickly  has  led  to  some  discussion.  Admitted 
that  lactic  acid  has  the  greater  reducing  power,  the  value  of  this 
propei  ty  in  the  dye-bath  is  not  yet  absolute,  as  with  many  coloring 
matters  I  do  not  find  that  the  best  results  are  obtained  with  the 
chromium  reduced  to  its  lowest  terms.  Yet,  if  lactic  acid  does  the 
most  economical  reducing,  it  is  but  a  question  of  correct  proportion- 
ing of  the  recipe  to. obtain  the  desired  shade  at  the  lowest  cost. 
The  second  and  third  advantages — greater  solubility  and  less  corro- 
sive action — are  unquestioned.  In  corroboration  of  my  estimate  of 
the  value  of  lactic  acid  in  the  woollen  industry,  the  following 
statistics  of  lactic  acid  are  submitted.  In  1894  the  dye-houses  of 
the  United  States  and  Canada  used  about  400,000  pounds  of  lactic 
acid,  while  none  was  used  in  England  or  Europe.  In  1895  there 
was  a  domestic  consumption  of  1,000,000  pounds,  and  a  foreign 
consumption  of  500,000  pounds;  in  1896  the  domestic  consumption 
was  1,200,000  pounds,  and  the  foreign  1,000,000  pounds. 
Lactic  acid  is  used  to  a  very  limited  extent  in  the  calico-printing 
industry.  Some  discharge  effects  can  be  obtained  advantageously 
with  it.  In  most  instances,  however,  the  hygroscopic  nature  of  the 
acid  is  injurious  in  its  effect  on  colors  which  have  to  be  steamed. 
Next  to  the  woollen  industry,  the  most  important  application  for 
lactic  acid  is  in  the  preparation  of  hides  for  tanning.  The  efficiency 
of  the  bran  drench  for  removing  the  lime  from  the  skin,  and  making 
it-porous  and  in  good  condition  for  receiving  the  tannage,  is  due  to 
the  lactic  acid  produced  by  the  fermentation  of  the  bran.    A  dilute 
