78     Pharmacopoeia — View  of  Analytical  Worker.     { ^ebru^mi0' 
Oil  of  Turpentine. — The  test  for  petroleum  benzin,  kerosene,  or 
similar  hydrocarbons,  may  prove  unreliable  if  allowed  to  stand  over- 
night. 
Oil  of  Thyme. — French  chemists  say  that  potassium  hydroxide 
should  be  used  in  the  assay  for  phenols  as  sodium  hydroxide  will 
eliminate  carvacrol. 
Opium. — It  is  impossible  to  adopt  a  method  for  this  drug  that 
will  suit  all  analysts.  Certain  it  is  that  the  conditions  have  much  to 
do  with  the  results.  My  only  suggestions  are  to  work  as  nearly  as 
possible  at  the  same  temperature,  about  25 °  C,  allow  the  freshly 
precipitated  morphine  to  stand  the  same  length  of  time,  and  use 
lime  water  that  is  U.S.P.  strength.  Comparative  results  will  then 
be  obtained. 
Pancreatin, — The  assay  is  not  ideal,  as  there  is  no  sharp  line 
between  the  dextrin  reaction  and  the  starch  reaction.  The  five- 
minute  digestion  period  must  be  accurately  measured  if  compara- 
tive results  are  expected.  Thirty  seconds  difference  in  time  of 
digestion  will  show  results  widely  divergent.  It  is  wise  to  transfer 
the  thick  starch  paste  from  the  flask  in  which  it  was  boiled  to  a  clean 
one,  straining  through  cheese  cloth  if  lumps  are  present.  Often  lumps 
will  adhere  to  the  sides  and  not  be  converted,  and  later  will  give  an 
elegant  starch  reaction. 
Pepsin. — It  is  difficult  to  press  egg  albumin  through  a  No.  40 
sieve,  a  quick  method  is  to  squeeze  it  through  strong  cheese 
cloth  while  still  warm,  immediately  weigh,  add  the  dilute  acid  and 
shake  vigorously,  which  will  completely  disintegrate  the  albumin. 
Comparative  results  are  only  obtained  by  closely  following  every 
detail  in  the  digestion. 
Phenol. — Care  must  be  exercised  in  obtaining  the  sample  for 
analysis.  A  good  way  is  to  cut  the  crystals  from  a  drum  that  has 
just  been  opened  and  immediately  transfer  to  a  perfectly  dry  bottle, 
melt  and  obtain  congealing  point.  The  assay  of  phenol  is  both 
rapid  and  very  accurate. 
Resin  of  Scammony. — Perhaps  this  resin  is  not  completely  soluble 
in  oil  of  turpentine  as  required,  as  a  sample  made  directly  from 
Scammony  root  by  U.S.P.  method,  fails  to  completely  dissolve. 
Sugar  of  Milk. — The  test  for  absence  of  cane  sugar  is  fallacious. 
Thymol  Iodide. — An  official  method  for  assay  is  desirable  as 
divergent  results  are  obtained  by  different  methods. 
