ON  A  PROCESS  OF  FRACTIONAL  CONDENSATION.  457 
time,  would  cause,  in  the  aggregate,  a  serious  loss  of  material,  I 
would  call  special  attention  to  the  clamp  joint  as  the  best  which 
I  have  tried.  Before  falling  upon  this  device  I  had  used  ex- 
clusively the  vulcanized  caoutchouc  joints,  which  were  found  to 
answer  a  good  purpose,  in  most  cases,  except  that  they  required 
too  frequent  renewal.  I  have  found  the  cloth  covered  with  vul- 
canized caoutchouc  preferable  to  the  common  caoutchouc  tubing. 
In  the  smaller  sizes  of  apparatus  I  have  the  end  of  the  worm  itself 
project  far  enough  from  the  bath  to  connect  directly  with  the 
retort  by  means  of  a  perforated  cork,  without  the  use  of  an  addi- 
tional connecting  tube. 
The  upper  end,  h,  of  the  elevated  worm  is  brought  out  through 
the  side  of  the  bath  at  a  point  about  three  inches  below  the  top  ; 
so  that,  when  working  with  a  low  temperature  of  the  bath,  the 
worm  may  still  be  completely  covered  with  oil,  and  also  give 
sufficient  space  above  the  worm  for  the  expansion  of  the  oil  when 
higher  temperatures  are  employed.  To  avoid  contaminating 
the  atmosphere  of  the  laboratory  with  the  disagreeable  fumes 
which  are  given  off,  in  large  quantity,  from  such  a  mass  of 
heated  oil,  the  top  of  the  bath  is  tightly  closed  with  a  sheet-iron 
cover,  from  which  a  small  funnel,  A,  fig.  1,  conducts  these  fumes 
to  a  chimney. 
In  the  larger  apparatus,  the  vapors  which  succeed  in  passing 
through  the  heated  worm  are  conducted  downward  into  a  cooled 
worm  contained  in  a  bath  of  water,  ii,  fig.  2,  and  the  liquid  pro- 
duct is  collected  in  the  receiver,  k.  The  cold  bath,  ii,  contains 
two  condensing  worms, — one  for  each  apparatus, — and  is  large 
enough  to  condense  for  both  without  the  necessity  of  renewing 
the  water.  I  have  represented  two  apparatuses  combined,  as  it 
will  be  found  more  economical  of  time  to  operate  with  two  at 
once.  In  the  smaller  apparatus,  for  the  table,  a  Liebig  con- 
denser may  be  conveniently  substituted  for  the  cold  worm,  as 
shown  in  fig.  1. 
For  collecting  liquids  which  boil  below  the  common  tempera- 
ture, when  such  are  present,  I  attach  a  refrigerator,  B,  fig.  2, 
which  is  provided  with  two  block-tin  condensing-tubes, — one  for 
each  apparatus.  These  are  bent  in  a  zigzag  form,  and  attached 
to  the  inner  sides  of  the  refrigerator.    The  lower  ends  of  the 
