354 
SPONTANEOUS  SAPONIFICATION  OF  OILS  IN  SEEDS. 
mention  here,  although  it  has  no  connection  with  what  has  gone 
before,  because  I  think  it  may  explain  why  potash  and  soda,  which 
are  such  energetic  bases,  nevertheless  saponify  fatty  bodies  far 
more  slowly  than  lime.  It  appeared  probable  that  this  depended 
upon  the  circumstance,  that  milk  of  lime  mixes  with  fatty  bodies 
far  better  than  a  solution  of  potash  or  soda.  The  following  ex- 
periment renders  this  explanation  very  admissible.  When  a 
neutral  oil  is  dissolved  in  hot  alcohol,  and  an  alcoholic  solution 
of  potash  is  added  to  it,  the  mixture,  if  brought  to  boiling,  is 
instantly  saponified  ;  water  does  not  separate  from  it  the  least 
trace  of  fatty  matter,  and  the  addition  of  muriatic  acid  to 
to  the  solution  furnishes  fatty  acids,  which  are  completely  solu- 
ble in  alkalies  and  in  alcohol.  In  the  same  way,  if  an  oil  be 
mixed  with  an  excess  of  concentrated  sulphuric  acid,  the  saponi- 
fication takes  place  instantaneously  and  completely;  the  whole  of 
the  oil  is  converted  into  sulpho-fatty  acids  and  sulpho-glyceric 
acid.  In  the  two  cases  here  referred  to,  the  saponification 
is  immediate,  because  the  bodies  brought  in  contact  and 
those  formed,  mix  in  all  proportions,  and  thus  present  very 
numerous  and  intimate  points  of  contact. 
The  saponification  of  neutral  fatty  bodies  by  potash  or  soda 
with  alcohol  instead  of  water  as  the  solvent,  might  be  usefully 
adopted  in  lectures,  as  it  occupies  almost  less  time  in  its  realiza- 
tion than  in  its  description  ;  and  hitherto  this  curious  reaction, 
performed  under  ordinary  conditions,  required  far  too  much  time 
to  be  capable  of  execution,  even  on  a  very  small  scale,  in  the 
presence  of  an  audience  during  a  lecture.  The  same  facility  of 
execution  applies  also  to  the  saponification  of  oils  by  concen- 
trated sulphuric  acid. 
As  I  have  mentioned  the  3ulpbo-fatty  acids  of  M.  Fremy,  I 
may  add  that  the  residues  of  the  purification  of  colza-oil  are 
principally  composed  of  these  acids  and  sulphogly eerie  acid. 
These  residues,  the  price  of  which  has  almost  suddenly  risen 
from  five  francs  to  more  than  sixty  francs  per  100  kilogrms., 
are  employed  in  tanning,  and  especially  in  the  manufacture  of 
beet-root  alcohol,  to  destroy  the  froth  produced  during  the  fer- 
mentations. The  manufacturers  who  make  use  of  them  should 
bear  in  mind  that  these  residues  are  not,  as  they  suppose,  oil 
contaminated  by  the  coloring  and  carbonaceous  matters  produced 
