Am.  Jour.  Pharm. 
July,  1910. 
Analysis  of  Ointments. 
325 
and  acidulating  with  hydrochloric  acid  ),  supersaturating  the  liquid 
with  sodium  carbonate,  evaporating,  extracting  with  ether-alcohol 
(i+3)  and  weighing  the  remaining  glycerin  after  drying  at 
90^5°  c. 
Borax  and  Bone  Acid. — Two  to  five  grammes  of  the  sample  are 
rendered  decidedly  alkaline  with  sodium  hydroxide  in  a  platinum 
dish  and  heated  on  the  water  bath  until  free  from  water.  The 
residue  is  carefully  ignited,  the  ash  taken  up  with  20  c.c.  water  and 
hydrochloric  acid  added  drop  by  drop,  until  all  is  dissolved.  The 
liquid  is  transferred  to  a  100  c.c.  flask,  0.5  gramme  of  calcium 
chloride,  a  few  drops  of  phenolphthalein  and  a  10  per  cent,  solution 
of  caustic  soda  added  until  a  permanent  slight  pink  color  is  produced. 
Finally  25  c.c.  of  lime  water  are  added  and  the  volume  made  up 
to  100  c.c.  The  solution  is  well  mixed  and  filtered  through  a  drv 
filter.  To  50  c.c.  of  the  filtrate  sufficient  normal  sulphuric  acid  is 
added  until  the  pink  color  disappears,  then  methyl  orange  and  the 
addition  of  the  acid  continued  until  the  yellow  is  just  changed  to 
pink.  A  fifth  normal  solution  of  caustic  soda  is  now  added  till  the 
liquid  assumes  a  yellow  tinge,  excess  of  soda  to  be  avoided.  The 
carbonic  acid  is  expelled  by  boiling,  the  solution  cooled,  a  little 
phenolphthalein  and  an  equal  volume  of  glycerin  added  and  titrated 
with  standard  sodium  hydroxide  until  a  permanent  pink  color  is 
obtained.12  One  c.c.  of  fifth  normal  soda  solution  represents  0.0124 
grammes  crystallized  boric  acid  or  0.0191  grammes  borax  (ioH20). 
On  titrating  the  boric  acid  50  c.c.  of  glycerin  should  be  present  for 
each  0.1  gramme  of  the  acid. 
Chemical  Constants  of  Fats,  Oils  and  IV axes. — Refractive  index, 
iodine  number,  acid  number  and  saponification  number.  In  some 
cases  it  is  advisable  to  resort  to  the  determination  of  one  or  several 
of  these  constants,  for  example,  as  a  proof  of  the  presence  of  a 
certain  fat,  indicated  by  physical  appearance  or  qualitative  test,  and 
the  absence  of  other  fats  or  oils.  For  instance,  an  excipient  is  found 
to  be  lanolin  from  its  appearance  and  the  cholesterin  reactions,  yet 
the  analyst  may  not  be  sure  that  no  other  fat,  possibly  lard  or  tallow . 
is  also  present,  particularly  when  alcohol  or  water  soluble  admixtures 
have  been  separated  previously  from  the  fat  bases  and  its  physical 
character  somewhat  altered. 
Total  Nitrogen. — The  determination  of  the  nitrogen  content  is 
frequently  indicated  to  either  quantitate  a  constituent  of  the  sample, 
