Am.  JouT.  Pharm. ) 
May,  1881.  J 
A  Plea  for  Minim  Pleasuring. 
227 
mouth  will  materially  alter  the  size  of  the  drops ;  the  holding  of  the 
hottle  in  different  positions  will  also  change  the  volume  of  the  drops. 
Many  other  modifying  influences  are  mentioned,  until  the  question 
•comes  home  to  us,  Hoav  shall  we  l)ring  order  out  of  this  chaotic 
problem  ? 
If  we  turn  to  our  chemical  physics  we  find  that  the  cohesive  force  of 
liquids  is  modified  under  different  conditions. 
The  converse  of  this  is  also  true.  All  liquids  tend  to  form  spheres. 
This  will  be  seen  in  the  dew  drops,  globules  of  mercury,  etc. 
In  liquids  there  are  two  forces  at  play,  viz.,  the  cohesive  force  and 
the  force  of  gravity.  Both  of  these  are  modified  by  the  density  of 
the  liquid  and  the  conditions  present.  The  attraction  of  cohesion 
strives  to  arrange  the  molecules  in  an  orderly  manner,  while  the  gravi- 
tative  force  strives  to  draw  the  mass  towards  its  centre. 
Looking,  then,  at  the  j^i'oblem  from  this  light,  it  seems  reasonable 
lo  conclude  that  much  of  the  diversity  of  observation  in  the  size  of 
different  drops  has  arisen  because  the  same  conditions  are  not  always 
present. 
It  would  be  almost  impossible  to  have  the  same  conditions  of  vol- 
ume, temperature,  friction  and  density  present  in  like  preparations 
made  by  different  persons,  and  hence  would  arise  a  variance  in  obser- 
vation in  the  size  of  a  drop  when  attempted. 
The  size  of  a  drop  will  depend  materially  on  the  amount  of  liquid 
iin  the  bottle,  the  distance  it  has  to  traverse  before  leaving  the  lip  of 
the  bottle,  the  temperature  of  the  liquid  and  also  its  density. 
When  a  drop  begins  to  form,  the  different  molecules  wdll  commence 
-to  collect  around  a  common  centre,  and  arrange  themselves  in  a  defi- 
jiite  order,  and  they  will  continue  to  collect  around  this  centre  just  so 
long  as  the  friction  of  the  drop,  plus  the  cohesive  force,  can  overcome 
±he  gravitative  force.  But  just  as  soon  as  the  gravitative  force  is 
greater  than  the  frictional  force,  plus  the  cohesive  force,  the  drop  will 
separate. 
Now,  all  this  difference  of  observation  has  arisen  from  the  fact  that 
the  volume  of  liquid  and  the  frictional  force  have  not  been  taken  into 
consideration  in  the  different  experiments. 
It  would  be  impossible  to  know  whether  the  same  conditions  were 
always  present  to  different  observers,  and  there  will  always  be  a  dis- 
similarity in  results,  and  it  is  for  this  reason  that  I  should  like  to  see 
±he  minim  become  the  unit  for  all  small  measures.  ■ 
