Am.. lour.  Pliarm.  ) 
Feb.,  1883.  j 
Prescription  Scales  and  Weights. 
79 
detection  is  not  easily  understood — but  that  such  must  occur,  and  that 
frequently,  cannot  be  controverted.  It  was  the  exception  to  find  weights 
of  less  denomination  than  two  grains — and  from  this  standard  u})  to 
scruples  and  drachms,  the  accretions  of  dirt  and  accumulated  corrosion 
rendered  their  denomination  almost  illegible.  It  will  occur  to  the 
minds  of  the  reflecting,  that  if  there  be  no  otlier  incentive  to  remedy 
such  an  existing  state  of  things,  pride  should  at  least  prompt  to  a 
proper  appreciation  of  the  importance  to  every  pharmacist  of  being 
provided  with  an  accurately  adjusted  balance  for  prescription- weighing, 
not  such  as  are  needed  in  analytical  investigations,  but  a  good,  practi- 
cally constructed  balance,  capable  of  weighing  with  accuracy  one  grain. 
The  fractions  of  this  unit  can  easily  be  made  by  mechanical  sub-di- 
vision in  the  usual  way — by  placing  the  weighed  portion  upon  a  piece 
of  glazed  paper  and  dividing  with  the  edge  of  a  small  spatula — prac- 
tice will  quickly  make  perfect  in  this,  and  the  apothecary  with  the  ex- 
ercise of  no  more  than  ordinary  care,  need  have  no  fear  of  error.  The 
inaccuracy  of  the  prescription  scale  is  mainly  due  to  neglect  and  care- 
less misuse.  The  instruments  are,  doubtless,  all  good  enough  at  the 
start,  and  should  receive  the  same  scrupulous  attention  as  the  vest- 
pocket  chronometer.  The  prescription  scale  being  viewed  and  made  as 
a  delicate  piece  of  mechanism,  should  not  be  misused,  and  a  good  rule 
is  not  to  subject  it  to  heavier  weighing  than  say  twenty  grains — this 
saves  it  from  incessant  use — for  all  other  purposes  between  this  weight 
and  that  of  a  half-ounce,  the  ordinary  hand  scale  of  English  or  Ger- 
man manufacture,  with  pans  suspended  by  silken  cords,  is  most  con- 
venient and  best  adapted.  With  the  beam  support  taken  between  the 
thumb  and  forefinger  of  the  left  hand,  and  the  scale  raised  almost  to  a 
level  with  the  eye,  the  spatula  or  spoon  in  the  right  hand,  dexterous, 
skillful  and  accurate  weighing  can  readily  be  done.  Such  scales  are 
usually  furnished  in  a  neat  box,  which  affords  a  permanent  receptacle, 
and  by  being  placed  upon  the  shelf  or  counter,  are  at  all  times  readily 
accessible.  In  the  use  of  these  some  practice  becomes  necessary,  but 
the  requisite  dexterity  is  easily  acquired,  and  once  adopted  few  will  be 
willing  to  dispense  with  their  use.  Experience  has  demonstrated  that 
the  best  form  of  scale  for  prescription  purposes  is  the  even  beam  bal- 
ance, the  sensitive  point  of  contact  or  friction  being  the  one  knife 
edge.  By  looking  carefully  after  the  cup-shaped  indenture  on  w^hicli 
this  impinges,  such  scales  will  last  the  apothecary^s  natural  life  time 
and  never  cause  him  reproach.    As  it  is  the  pride  of  the  perfect  house- 
