3?2 
Drops  as  Dose  Measures. 
J  Am.  Jour.  Pharm. 
I      August.  1902. 
can  obtain  drops  that  will  vary  little  or  not  at  all  from  any  desired 
standard  that  we  care  to  name.  Let  us  consider,  for  example,  the 
equivalent  adopted  by  the  French  Codex.  The  original  standard 
was  no  doubt  established  by  the  use  of  a  so-called  "  Sallerones  drop- 
ping flask."  This  device  is  usually  figured  in  French  and  also  in 
German  books  on  Pharmacy,  but  is  practically  unknown  in  this 
country.  It  consists  of  a  small  Florence  flask,  with  a  tubulature  at 
the  side  placed  at  such  an  angle  that  the  drop  is  formed  squarely 
on  the  end  or  mouth  of  the  tube.  In  the  more  reliable  flasks  the 
end  of  this  tube  is  ground  flat  so  as  to  prevent  any  tendency  of  the 
fluid  to  creep  upward  and  in  this  way  increase  the  dropping  surface 
of  the  tube,  and  also  the  weight  of  the  resulting  drop. 
A  second  reliable  method  of  obtaining  correlating  results  is  to 
have  a  pipette,  or  dropping  funnel,  with  an  opening  of  the  required 
outside  diameter  (3-3  mm.)  and  having  the  lower  end  ground,  as  in 
the  case  of  the  Sallerone  dropper.  If  this  apparatus  is  firmly  fixed 
in  a  burette  holder,  and  the  portion  above  the  outlet  or  dropping 
surface  be  kept  dry,  we  can  secure,  with  a  reasonable  amount  of 
accuracy,  20  drops  of  distilled  water  to  a  gramme. 
A  tube  on  the  pipette  principle  is  not  so  satisfactory.  This  is 
partly  due  to  the  quiver  and  shake  that  is  necessarily  imparted  by 
compressing  the  bulb  or  nipple,  but  more  largely  to  the  gradual 
creeping  up  of  the  liquid  and  the  consequent  increase  in  the  cross 
section  of  the  dropping  area,  resulting  in  a  corresponding  increase 
in  the  size  and  weight  of  the  drop.  As  has  been  pointed  out  on  a 
previous  occasion,  a  slight  tilting  of  the  pipette  has  a  somewhat  simi- 
lar effect,  by  increasing  the  surface  from  which  the  drop  is  being 
formed. 
•  Admitting  then  that  drops,  as  ordinarily  produced,  are  necessarily 
variable,  and  that  it  is  practically  impossible  to  obtain  uniform 
results,  the  question  naturally  arises,  Why  should  we  not  dispense 
with  drops  entirely  and  endeavor  to  introduce  some  more  definite 
measure  of  capacity?  While  this  is  no  doubt  possible  in  some 
cases,  still  it  must  be  remembered  that  drops  are  of  advantage  in 
the  administration  of  many  forms  of  remedies.  For  instance,  in 
cases  where  the  relative  amount  of  a  drug  or  preparation  is  of 
importance,  or  where  the  dose  of  some  potent  remedy  is  to  be 
alternately  increased  and  decreased.  Among  remedies  that  are 
occasionally  given  in  this  way,  we  might  mention  the  different  solu- 
