Am.  Jour.  Pharni. 
Jan.,  1886. 
Several  Official  Ointments 
3 
wax  mixtures  are  much  harder,  but  less  smooth  and  regularly  grained, 
as  a  result  of  the  great  difference  in  the  fusibility  of  the  components. 
On  becoming  rancid,  or  when  subjected  to  variable  temperatures,  the 
wax  and  spermaceti  ointments  do  not  disintegrate  into  a  fluid  and 
solid  portion  peculiar  to  the  transformation  of  unmixed  lard  under 
similar  conditions. 
It  appears  that  certain  fats,  under  zymotic  influence,  in  the  presence 
of  water,  assimilate  this  and  generate  a  new  order  of  fats  and  free 
fatty  acids.  The  fatty  acids  and  the  corresponding  glycerides  that 
are  susceptible  of  these  changes  belong  to  the  acrylic  series,  the  acids 
of  which  are  represented  by  the  general  formula  CnH2n_202.  Oleic 
acid  is  the  most  common  and  best  known  member  of  this  class. 
Acrylic  acids,  on  fusion  with  potash,  absorb  the  oxygen  of  water, 
expelling  the  hydrogen  while  generating  two  new  acids  of  the  fatty 
series,  the  members  of  which  have  the  general  formula  CnH2n02. 
Acrylic  acids  are  also  directly  transformed  into  fatty  acids  by  the 
assumption  of  nascent  hydrogen.  The  first  reaction  may  be  expressed 
by  the  following  equation,  in  which  n  of  course  has  a  different  value 
for  each  formula : 
°(CnH2n_A)+20H2=XC.H2n02)+"(CnH2n02)+2H. 
Since,  in>  the  rancidification  or  fermentative  transformation  of 
acrylic  acids  or  their  glycerides,  no  hydrogen  is  eliminated,  the  change 
may  occur  as  shown  in  the  following  equation,  the  n  of  each  formula 
having  a  distinct  value : 
2°(CnH2n_202)+20H2=°(CnH2ll02)+XCnH2n02)+"(CnH2n02). 
This  reaction  seemingly  explains  the  peculiar  disintegration  of  fats 
containing  olein.  Some  of  the  resulting  glycerides  or  free  fatty  acids 
will  be  more,  and  a  portion  less,  fusible  than  the  original  components, 
and  therefore  have  a  stronger  disposition  to  separate  from  each  other. 
The  free  acids  near  the  base  of  the  fatty  series — as,  for  instance,  acetic, 
propionic,  butyric,  etc. — are  strongly  odorous  and  irritant,  while  the 
higher  members,  such  as  palmitic,  stearic,  etc.,  are  inodorous,  non- 
irritant  and  bland. 
Stearic  acid,  known  in  commerce  as  hard  stearin,  is  a  white,  crys- 
talline, odorless  and  tasteless  solid,  firmer  than  spermaceti  and  more 
tenacious  than  wax.  Its  fusion-point  is  quite  low,  being  69°C.  It 
melts  readily,  and  promptly  congeals  on  cooling.  During  the  melting 
a  portion  rises  in  vapor,  hence  the  temperature  should  not  be  raised 
