396 
Size  of  Drops. 
r  Am.  Jour.Pharm. 
I    August,  1883. 
In  1830,  Durand^  called  attention  to  a  series  of  experiments  by  Dr. 
Shuttleworth,  and  their  appreciation  by  the  College  of  Physicians  of 
London,  and  gave  as  the  conclusion  from  experiments  of  his  own, 
that  the  practice  of  prescribing  fluid  medicines  by  drops  is  altogether 
objectionable/'  and  that  ignorance  of  the  conditions  affecting  size  of 
drops  may  lead  to  serious  consequences.  After  summing  up  the  usual 
conditions  of  density  of  liquid,  cohesion  of  particles,  shape  of  the 
mouth  of  the  vessel,  etc.,  he  remarks,  besides,  in  every  instance,  the 
first  drops  poured  from  any  vase  are  always  smaller  than  those  subse- 
quently obtained.^'  There  is  no  indication  whatever  that  he,  in  the 
most  indirect  manner,  intends  to  allude  to  the  condition  of  the  bottle 
as  to  fullness,  but  simply  to  a  fact,  which  the  author  has  not  verified, 
that  the  few  drops  first  passing  over  the  lip  of  the  vessel  are  smaller 
than  the  subsequent  ones. 
In  1858,  Bernoulli^  gave  results  of  investigations  with  great  accu- 
racy, "  keeping  in  view  the  nature  of  the  vessel,  the  temperature,  the 
rapidity  of  dropping,  and  other  circumstances  calculated  to  affect  the 
weight." 
In  1860,  Proctor^  calls  attention  to  the  well-established  variation  in 
size  of  drops,  with  form  and  size  of  vessel,  with  density  and  viscosity 
of  liquids,  "  and  according  to  some  other  of  its  qualities  not  yet  well 
understood.'' 
In  1864,  Quin,  in  the  Druggist  and  Chemist,^  prefaces  an  abstract 
of  very  careful  and  exhaustive  investigations  by  Guthrie  of  the  con- 
ditions affecting  the  size  of  drops  by  a  remark  upon  "  the  difficulty  of 
obtaining  a  standard  drop,  a  difficulty  which  is  still  more  increased  by 
the  knowledge  that  even  when  the  same  vessel  and  liquid  are  used  the 
differences  are  almost  as  great  as  those  already  cited." 
Parrish,  on  experimenting  with  ounce  vials  of  water,  found,  in  seven 
trials,  the  drops  required  for  a  fluidrachm  to  vary  between  thirty-two 
and  sixty-five. 
Guthrie  investigates  most  fully  "  the  physical  relations  existing 
between  the  matter  on  which  the  drop  is  formed,  the  liquid  constitut- 
ing the  drop  itself,  and  the  medium  through  which  it  passes,"  a  con- 
^  "  American  Journal  of  Pharmacy,"  vol.  1,  p.  165. 
2 " Schweizer.  Zeitschr.  f.  Pharm.,"  1858,  pp.  97—100;  Am.  Jour.  Phar., 
vol.  xxxi,  p.  441. 
^"Lon.  Pharm.  Jour.,"  July  2,1860;  Am.  Pharm.  Jour.,  vol.  xxxii, 
p.  428. 
*Am.  Jour.  Phar.,  vol.  xxxvi,  p.  522. 
