^sepHiilTL''  }        Bansens  Water- Air  Pump,  etc,  401 
wholesale  and  retail  petroleum  traders,  a  covered  screen  (which  gives 
results  similar  to  those  obtained  in  the  half-filled  cup)  being  directed 
to  be  employed.    It  is  to  be  hoped  that  this  standard,  which  has  been 
accepted  by  all  parties  interested  in  the  sale  of  mineral  oils,  will  rig- 
idly be  adhered  to  in  any  attempt  at  further  legislation  respecting 
these  liquids.    In  a  Bill  now  (June  1871)  before  Parliament,  the  oils 
are  directed  to  be  tested  in  a  covered  cup,  and  the  defining  clause  de- 
scribes "petroleum"  as  being  a  certain  liquid  giving  off  inflammable 
vapor  below  85°  Fahrenheit.    It  is  to  be  expected  that  this  is  the 
exact  equivalent  of  the  foregoing  standard — that  petroleum  flashing 
at  85°  in  the  closed  vessel  would  flash  at  100°  in  the  open  vessel.  If 
not,  one  section  or  other  of  oil  traders  will  probably  prevent  the 
maturation  of  the  Bill  j  a  result  to  be  avoided  if  possible,  for  fresh 
legislation  is  sorely  needed.    My  own  testing  apparatus  is  so  con- 
structed as  to  give  results  such  as  just  indicated,  results  which  I  be- 
lieve to  be  in  exact  accordance  with  the  intentions  of  the  Legislature. 
I  may  state,  shortly,  that  this  is  a  modification  of  what  is  known  in 
trade  as  "  Miles's  instrument,"  with  a  screen  five  inches  high  ;  no 
cover  to  the  screen,  and  with  the  front  third  of  the  smoke-holes  of 
the  outer  casing  permanently  closed.     The  removal  of  the  cover  of 
the  screen  produces  no  difference  in  the  flashing-point  of  a  sample  of 
petroleum,  the  walls  of  the  screen  being  sufficiently  high  to  protect 
the  cup  from  draughts  in  an  ordinary  room  ;  still  I  operate  without 
it,  to  avoid  objections  that  might  be  raised  against  the  apparatus  in  a 
court  of  law,  no  special  mention  of  a  cover  to  the  screen  being  made 
in  the  Petroleum  Act  (1868).    I  close  up  the  front  "smoke-holes" 
(as  I  called  the  holes  through  which  escape  the  products  of  combus- 
tion of  the  flame  that  heats  the  water-bath),  in  order  to  avoid  a  slight 
inconstancy  of  results  caused  possibly  by  draughts  from  these  aper- 
tures.   Miles's  instrument,  as  sold  to  the  public,  gives  results  which 
are  close  to  those  I  obtain  by  the  slight  modification  I  have  described, 
but  the  latter  gives  me  those  results  with  greater  constancy  and  cer- 
tainty.— London  Pharm.  Jour.,  July  15,  1871. 
BUNSEN'S  WATER-AIR  PUMP  AND  ITS  USE  FOR  FILTERINa 
LIQUIDS. 
The  principle  of  this  apparatus  is  not  a  new  one  ;  it  depends  upon 
the  action  of  the  water,  while  falling,  to  carry  air  down  with  it,  and 
26 
