Am.  Jour.  Phariu.  \ 
August,  1902.  J 
Drops  as  Dose  Measures, 
379 
carefully  done  (and  there  is  every  reason  to  believe  that  it  was),  the 
main  object-lesson  to  be  obtained  from  it  is,  that  we  can  expect  little 
or  no  uniformity  in  comparative  results  or  the  number  of  drops  to 
be  obtained  from  different  dropping  surfaces.  It  will  be  noted  that 
drops  of  the  first  liquid  quoted,  from  a  shop  bottle,  are  apparently 
smaller,  while  those  of  the  second,  tor  no  evident  reason,  are  larger 
than  those  dropped  from  either  a  glass  stopper  or  a  minim  measure. 
There  are  other  discrepancies  of  the  same  kind  in  the  list  as  quoted  ; 
in  fact,  the  irregularities  are  so  apparent  and  so  great  that  they 
would  certainly  appear  to  suggest  that  every  dropping  surface  is  a 
law  unto  itself  with  each  and  every  liquid.  So  that,  even  if  we  know 
the  comparative  number  of  drops  of  one  or  more  liquids,  dropped 
from  two  different  surfaces,  we  cannot  with  any  degree  of  certainty 
predict  what  the  number  of  drops  of  any  additional  liquid  would 
be,  calculating  from  the  available  data  for  only  one  of  the  dropping 
surfaces. 
Despite  this  evident  variation  in  the  different  results  obtained,  it 
has  been  proposed  that  the  coming  Pharmacopoeia  include  a  defini- 
tion of  a  standard  drop  and  a  description  of  a  standard  dropper, 
this  official  standard  to  be  based  on  that  adopted  by  the  French 
Codex.  This  latter  authority  says  that  20  drops  of  distilled  water 
should  weigh  1  gramme.  The  Swiss  Pharmacopceial  Revision  Com- 
mittee is  also  considering  a  proposal  for  an  official  definition.  This 
is,  that  a  drop  of  distilled  water  is  the  one  twenty-fifth  part  of  a 
gramme,  or  that  25  drops  of  distilled  water  should  weigh  1  gramme. 
The  Germans,  however,  have  demonstrated  to  their  own  satisfaction, 
that  neither  of  these  quantities  are  reasonably  constant,  and,  accord- 
ing to  one  investigator,  a  drop  of  distilled  water  is  the  fourteenth 
part  of  a  gramme,  while,  according  to  another,  it  takes  13-8  drops 
to  weigh  a  gramme.  In  our  own  country,  at  the  present  time,  it  is. 
popularly  supposed  that  a  drop  is  equivalent  to  about  the  sixteenth, 
part  of  a  gramme,  or  1  minim. 
A  more  reasonable  and  practical  standard  would  be  to  accept  a 
drop  of  water  as  being  equivalent  to  the  tenth  part  of  a  gramme. 
This  would  certainly  be  a  convenient  number  to  remember,  and 
would  also  be  in  harmony  with  the  metric  system  of  weights  and 
measures.  In  addition  to  this,  it  would  represent  the  most  readily 
obtained  drop  of  water,  dropping  in  seconds,  from  the  greatest 
variety  of  dropping  surfaces,    iruch  a  drop  might  be  defined  as 
