82  Remington  Pharmaceutical  Stills.  {A§vg}fi&£i5fiL' 
superseded  by  a  condenser  which  may  be  thoroughly  washed  out 
by  running  a  swab  through  the  seven  short  tubes. 
The  fact  which  has  often  been  overlooked  in  considering  the 
condensation  of  vapors  is  that  a  tube,  either  straight  or  spiral,  10 
leet  long  and  of  y2  inch  inside  diameter,  has  not  the  same  con- 
densing power  as  ten  tubes,  I  foot  long  and  y2  inch  inside  diameter, 
although  both  have  the  same  extent  of  surface.  That  containing 
the  ten  tubes  would  present  an  inlet  for  the  vapor  ten  times  as 
Improved  Remington  Still. 
large  as  that  containing  the  one  tube  and  would  thus  allow  the 
vapor  to  pass  into  and  condense  in  the  tubes  that  much  faster.  In 
the  ten  short  tubes  the  vapor  is  cooled  suddenly  by  exposure  to  a 
large  cold  area. 
Another  important  point  which  must  not  be  overlooked  is  that 
the  two  methods  of  distillation,  by  the  alembic  form  and  the  retort 
form,  are  radically  different  in  principle.  In  the  alembic  the  con- 
densation takes  place  in  the  inside  surface  of  the  head,  in  the  retort 
