468 
Purity  of  Commercial  Aspirin. 
Am.  Jour.  Pharm. 
July,  1 9 1 9. 
The  melting  point  should  not  be  lower  than  the  present  official 
standard.  An  experience  of  a  very  large  number  of  samples  shows 
that  the  best  samples  melt  at  approximately  1360.  Such  specimens 
have  a  decisive  melting  point,  varying  within  a  degree  in  consecu- 
tive determinations,  and  there  is  a  sense  of  stability  which  is  lacking 
with  the  lower  figures.  Samples  which  have  given  subsequent 
trouble  in  practical  experience  have  almost  invariably  been  those 
melting  below  1330  C. 
It  is  sometimes  urged  that  since  one  of  the  main  objects  in  the 
use  of  acetylsalicylic  acid  is  to  provide  salicylic  acid  in  an  esterified 
form,  from  which  it  is  liberated  under  certain  conditions  by  gradual 
hydrolysis,  the  occurrence  in  aspirin  of  small  amounts  of  compounds 
such  as  salicyl-salicylic  acid,  which  is  itself  used  in  medicine,  is  not 
a  matter  of  real  importance.  What  may  be  said  for  or  against  this 
from  a  pharmacological  standpoint,  or  to  what  extent  such  contami- 
nation might  be  allowed  in  the  drug,  cannot  be  entered  into  here, 
but  if  this  were  agreed  to  then  a  test  limiting  values  would  be  essen- 
tial unless  it  is  found— and  there  is  a  good  deal  to  be  said  for  this — 
that  the  present  official  tests  with  a  definite  limit  for  the  free  sali- 
cylic acid  are  such  as  will  ensure  a  product  of  a  sufficient  degree  of 
purity  for  all  medicinal  purposes,  while  not  demanding  refinements 
the  attainment  of  which  would  throw  an  undue  burden  on  the 
manufacturer  without  any  practical  or  commensurate  advantage  to 
the  patient. 
Aspirin  Tablets. 
There  seems  to  be  an  inclination  in  some  directions  to  look  upon 
tablets  as  mysterious  composts  in  which  very  questionable  ingre- 
dients may  be  safely  hidden,  and  one  finds  a  good  many  disappoint- 
ments in  examining  these  products.  In  the  case  of  aspirin  tablets 
excessive  free  acid,  very  high  ester  and  excessive  excipient  bal- 
anced by  deficient  aspirin  are  the  chief  faults.  On  examining  a 
series  of  what  may  be  called  "  standard  "  makes  all  were  found  to 
be  excellent  products  in  very  close  agreement,  but  none  was  of  that 
superlative  quality  in  relation  to  any  other  as  one  might  expect. 
Disintegration  is  a  property  occasionally  lost  sight  of,  and  one 
brand  of  "  chemist's  own  label "  variety,  after  digesting  in  water  for 
two  days,  required  firm  pressure  with  a  glass  rod  to  break  it  up. 
The  desideratum  is  that  the  tablet  should  be  of  good  appearance, 
clean  cut  and  pressed,  able  to  withstand  carriage — whether  in  bulk 
