NEW  PROPERTIES  AND  USES  OF  NAPHTHALIN.  551 
is  then  drawn  off,  and  the  crystals  are  reduced  to  a  powder 
in  a  mortar.  It  is  then  put  into  felt  sacks  or  a  centrifuge  for 
the  purpose  of  removing  the  moisture  which  may  have  been  re- 
tained among  the  crystals.  This  mass  is  then  subjected  to  a 
gradually  increased  hydrostatic  pressure,  after  which  it  is  trans- 
ferred into  an  iron  vessel  provided  with  a  coil  for  heating  by 
steam,  and  a  stirrer  which  must  be  so  arranged  that  it  can  be 
operated  while  the  vessel  is  closed.  When  melted,  a  few  per 
cent,  of  soda  lye  is  mixed  with  it  for  the  purpose  of  separating 
the  carbolic  acid  and  certain  resins.  The  liquid  obtained  is 
blown  off  after  a  short  time,  and  the  operation  repeated  ;  finally 
the  mass  is  washed  with  water  until  all  alkaline  reaction  has 
ceased.  The  liquid  naphthalin  is  then  mixed  with  a  small  per- 
centage of  oil  of  vitriol  of  45°  Baume,  which  is  allowed  to  re- 
main with  it  from  two  to  three  hours,  at  a  temperature  of  212° 
Fahrenheit,  when  the  naphthalin  is  transferred  to  cast-iron  stills 
capable  of  withstanding  a  high  heat.  It  will  overflow  at  a  tem- 
perature of  410°  Fahrenheit,  in  a  thick  stream.  If  the  still  is 
sufficiently  large,  100  pounds  of  naphthalin  may  be  easily  ob- 
tained within  twenty  minutes.  The  water  of  the  condensing 
tank  must  be  kept  at  170°  Fahrenheit,  the  receiver  being  also 
kept  in  water  of  that  temperature.  When  the  heat  in  the  dis- 
tilling vessel  has  reached  a  temperature  of  450°  Fahrenheit  the 
receiving  vessels  are  changed.  After  the  oil  has  all  run  over, 
the  remainder  of  the  ovefflow  is  worked  up  with  a  new  portion. 
Finally  the  substance  is  poured  into  conical  cylinders  of  glass, 
metal,  or  moistened  wood,  in  which  it  soon  solidifies,  and  in  con- 
tracting separates  from  the  sides.  It  is  thus  formed  into  sticks, 
like  sulphur. 
ON  SOME  NEW  PROPERTIES  OF  NAPHTHALIN. 
The  naphthalin  obtained  in  this  way  is  similar  to  alabaster, 
cracks  easily  in  the  warm  hands,  and  becomes  negatively  electric 
on  being  rubbed  with  silk.  Its  specific  weight  at  66°  Fahren- 
heit, as  indicated  by  Yohl,  is  1-15173  ;  it  melts  at  174°,  and 
boils  at  452°. 
Melted  naphthalin  absorbs  a  large  quantity  of  atmospheric  air, 
which  is  given  off  in  cooling.    This  expulsion  is  so  turbulent 
