j  12  Assay  Processes  of  US. P.  IX.  {Am^™h]?wm' 
The  processes  outlined  in  this  article  will  show  the  wide  range 
of  chemical  knowledge  that  the  pharmacist  should  possess. 
In  no  school  where  chemistry  is  taught,  except  in  those  institu- 
tions making  chemistry  a  specialty,  is  the  subject  of  chemistry  taken 
up  so  fully  as  it  is  taught  in  pharmacy  colleges.  There  is  hardly  a 
branch  of  chemistry  that  has  not  some  pharmaceutical  bearing  and 
it  is  not  surprising  then  that  this  subject  receives  the  consideration 
it  does. 
U.  S.  P.  Assay  Processes. 
As  is  well  known  today,  the  U.  S.  Pharmacopoeia  and  the  Na- 
tional Formulary  are  the  legal  standards  for  drugs,  chemicals  and 
their  preparations.  The  methods  of  assay  given  therein  must  be 
strictly  followed  in  every  instance :  this  cannot  be  too  strongly  em- 
phasized. 
In  reviewing  the  assay  processes  of  the  new  U.  S.  P.  in  a  gen- 
eral way,  one  sees  that  quite  a  number  of  changes  have  taken  place, 
some  quite  radical.  It  is  almost  impossible  in  the  time  allotted  to 
the  subject  to  touch  upon  all  the  details,  so  that  in  a  large  number 
of  instances  a  generalization  of  the  methods  will  alone  be  consid- 
ered ;  but  where  any  general  method  offers  any  special  features,  these 
will  be  taken  up  at  greater  length. 
There  have  been  several  errors  observed  in  the  quantities  given 
under  some  of  the  assays,  so  that  the  writer  does  not  wish  it  under- 
stood that  the  amounts  given  have  been  verified.  It  had  been  his 
intention  to  have  done  so  had  he  had  sufficient  time  to  complete  this 
paper  in  the  time  originally  allotted  to  him. 
For  example,  under  potassium  chlorate  the  quantity  of  acidu- 
lated ferrous  sulphate  is  insufficient.  The  amount  of  iron  sulphate 
is  only  .750  Gm.,  whereas  the  quantity  required  for  the  oxidation 
by  .1  Gm.  potassium  chlorate  is  1.400  Gms.  Again  on  page  221, 
under  ammoniated  mercury,  it  is  directed  to  multiply  the  weight  of 
mercuric  sulphide  found  by  .162.    This  is  wrong,  it  should  be  .862. 
ACIDIMETRY  AND  ALKALIMETRY. 
The  following  acids  are  assayed  by  titrating  with  normal  alkali : 
Acetic,  citric,  hydrobromic,  hypophosphorous,  sulphuric,  tartaric 
and  trichloracetic. 
Boric  acid  is  also  titrated  with  normal  alkali,  but  gylycerin  is 
used  with  it.  * 
