RATE  AT  WHICH  LIQUIDS  FLOW  THROUGH  SYPHONS.  377 
As  an  illustration,  I  may  give  the  periods  required  to  draw  off 
the  liquids  named  in  the  following  table  by  a  syphon  of  some- 
what narrow  quill  tubing  from  a  phial  holding  a  little  more  than 
4  oz.  ;  the  position  of  syphon  and  temperature  (60°  F.)  being 
the  same  in  all  cases : — 
Water,       .....       74  seconds 
Ether,        .  .       .       .       48  « 
Bisulph.  carbon.,  .  .  .  47  " 
Whiskey,  914  sp.  gr.,  ...  182  " 
Here  it  will  be  seen  that  the  differences  are  somewhat  remark- 
able, and  although  this  was  rather  a  narrow  syphon,  the  follow- 
ing results  will  show  that  the  variations  can  be  as  great  by  em- 
ploying the  tubing  in  common  laboratory  use  for  drawing  off  the 
liquids  over  precipitates,  &c.  Poiseuille,  by  employing  capillary 
tubes  and  somewhat  elaborate  apparatus,  has  obtained  similar 
results,  and  of  greater  scientific  accuracy,  of  course.  Professor 
Graham  has  likewise  employed  capillary  tubes  in  his  valuable 
experiments  "On  Liquid  Transpiration,"  but  the  much  greater 
ease  with  which  one  can  compare  the  flow  of  separate  liquids  by 
means  of  a  common  bottle  and  syphon  may  not  be  without  its 
use,  and  especially  as  a  guide  to  interesting  results  in  more 
elaborate  investigations. 
The  narrower  the  syphon  the  greater  difference  is  always 
found  between  the  rate  of  efflux  of  various  liquids.  I  will  not 
give  any  illustration  of  this  statement,  as  numerous  experiments 
uniformly  confirmed  it.  The  same  is  the  case  when  the  long 
limb  of  the  syphon  approaches  the  level  of  the  short  one.  As 
an  indication  of  the  differences  to  be  obtained  by  more  nearly 
equalising  the  syphon  limbs,  I  will  quote  the  following  ex- 
periments : — 
The  bottle  employed  held  7300  grs.  water,  was  about  4J  inches 
deep,  syphon  a  little  over  ^th  inch  bore  nearly  uniform  through- 
out. In  experiments  in  first  column  long  limb  18 J  inches  longer 
than  short  limb  ;  2d  column  9  Jth  inches  was  cut  off  long  limb  ;  3d 
column  9 J-  inches  more  cut  off  long  limb,  leaving  it  only  \  inch 
below  level  of  short  limb.  Temperature  in  all  cases  60°  F.  On 
repeating  the  same  experiment  twice,  seldom  more  than  one  second 
difference  was  obtained. 
