Am  juiy'-if93arm"}     The  Flash-Point  in  Mineral  Oils.  363 
2-inch  cup  covered  on  the  top.  The  filling,  heating,  light  applied, 
etc.,  are  all  defined.  Holes  are  opened  in  the  lid  for  a  moment  to 
apply  the  light  at  specified  intervals,  and  the  point  got  is  very 
definite.  The  question  is :  What  relation  has  the  point  so  got  to 
the  point  of  danger  ?  Is  the  Abel  flash-point  itself  the  point  of  danger, 
or  is  danger  to  be  feared  only  at  a  much  higher  temperature  ? 
Before  a  Parliamentary  Committee  some  years  ago,  a  witness  said 
there  was  no  danger  at  all  until  the  temperature  of  the  American 
fire  test.  The  flash-point  is  the  lowest  temperature  at  which  the 
vapors  and  air  give  a  little  explosion  when  the  light  is  applied, 
going  instantly  out.  The  fire-point  is  the  lowest  temperature  at 
which  the  vapors  burn  continuously. 
A  particular  sample  of  oil  I  tested  flashed  in  Abel  test  at  780  F., 
in  the  old  Government  open  test  at  105 °,  and  fired  in  the  old  Gov- 
ernment open  test  apparatus  at  1220.  This  last  is  something  like 
the  American  fire  test.  Is  there,  with  this  oil,  no  danger  of  fire 
in  a  store  or  explosion  in  a  lamp  until  about  1200  F.  is  reached  ? 
A  moment's  thought  will  satisfy  us  that  although  a  little  cup  of 
oil  cannot  supply  sufficient  vapor  to  keep  up  a  constant  flame  until 
122°  F.  is  reached,  a  larger  surface  will  supply  vapor,  and,  when 
ignited,  heat  enough  to  produce  a  constant  flame  at  a  much  lower 
temperature.  I  tried  the  oil  mentioned  above  in  an  apparatus  like 
the  old  Government  open  test,  with  screen  around  and  partly  also 
on  the  top,  but  9  inches  in  diameter.  Applying  a  small  flame  every 
2°  at  a  half-inch  above  the  surface,  the  oil  ignited  explo- 
sively at  88°,  and  continued  to  burn  furiously.  Repeating  the 
experiment,  and  applying  the  flame  at  every  degree,  it  ignited  and 
burned  continuously  at  870,  and  the  flame  rapidly  increased  in  vigor. 
Making  the  same  apparatus  a  close  test  like  Abel's,  the  oil  ignited 
and  fired  (burned  continuously)  at  760  F.;  that  is,  with  a  9-inch  wide 
closed  test,  instead  of  the  2-inch  prescribed  by  act  of  Parliament, 
the  oil  not  only  flashed  but  fired  2°  below  the  flash  point  Abel's 
test,  and  when  open  it  fired  only  g°  above  the  Abel  test.  With  a 
wider  surface  of  oil,  the  flashing  and  firing  would  no  doubt  take 
place  at  even  a  lower  temperature.  These  experiments  prove,  if 
they  require  proving  at  this  time  of  day,  that  the  old  Government 
open  test  and  the  American  fire  test  are  altogether  deceptive,  and 
that  in  store,  barrel  or  tin  can,  the  flash-point  Abel  test  is  a  point  of 
real  danger,  and  that  for  oil  in  large  masses  the  danger  begins  even 
