400  lesting  Petroleum.  {^septXim"''- 
contact  of  the  acid  with  the  respiratory  organs.  In  the  case  described 
by  Gavin  P.  Tennent,*  where  half  an  ounce  of  Calvert's  carbolic  acid 
No.  4  was  taken  by  mistake,  death  occurring  after  a  month,  it  cannot 
perhaps  be  solely  attributed  to  the  effect  of  the  poison  ;  moreover,  it 
is  not  improbable  that  the  impure  carbolic  acids  of  commerce  may  be 
variable  mixtures  of  carbolic  acid  and  creasote. 
TESTING  PETROLEUM. 
By  Professor  Attfield. 
In  ascertaining  the  temperature  to  which  a  specimen  of  petroleum 
must  be  warmed  before  its  vapor  can  be  ignited,  different  experi- 
menters obtain  different  results.  The  fact  is  this  flashing-point" 
varies  according  to  circumstances  ;  unless,  therefore,  two  operators 
work  under  exactly  similar  conditions,  their  reports  will  not  coincide. 
In  the  British  Petroleum  Act  of  1868  somewhat  minute  directions  for 
applying  the  flashing  test  to  samples  of  petroleum  are  given  in  a 
schedule.  As  originally  drawn  up,  those  directions  were  supplied  to 
the  Government  by  Mr.  Abel,  Dr.  Letheby  and  myself,  and  related 
to  the  testing  of  the  liquid  when  contained  in  a  three-inch  half-filled 
cup.  After  they  left  our  hands,  they  were  made  to  apply  to  petro- 
leum contained  in  a  two-inch  full  cup ;  the  protection  from  draughts 
afforded  to  the  surface  of  the  liquid  by  the  upper  part  of  the  half- 
filled  cup  being  substituted  by  that  of  a  screen  so  placed  round  the 
full  cup,  that  the  efficiency  of  the  original  directions  should  not  be 
affected.  That  is  to  say,  a  sample  of  petroleum  flashing  at  100°  in 
the  unscreened  half-filled  cup  should  flash  at  100°  in  the  screened 
full  cup.  This  should  be  borne  in  mind  by  all  persons  testing  petro- 
leum, as  the  screen  can  be  so  constructed  or  so  arranged  as  to  cause 
flashing-points  to  be  above  or  below  the  standard  now  given.  Just 
before  the  Act  passed,  I  pointed  out  to  the  Government  that  the  al- 
teration would  lead  to  endless  disputes,  and  was  assured  by  letter 
(which  I  still  possess)  that  the  construction  of  the  apparatus  was  only 
varied  in  a  point  of  detail  to  meet  an  objection  ;  that,  in  short,  the 
screen  was  to  be  so  efficiently  disposed  as  not  to  interfere  with  the 
standard  previously  fixed.  I  may  add  that  one  year  later  (June  1869) 
in  a  Bill  for  consolidating  and  amending  the  Petroleum  Acts  of  1862 
and  1868,  this  standard  was  maintained  with  the  concurrence  of  the 
*  Glasgow  Med.  Journ.,  Novbr.,  1870. 
