44 
Notes  on  Aluminium  Flares. 
Am.  Jour.  Pharm. 
January,  1920. 
Barium  Nitrate . .  . 
Aluminium  
Potassium  Nitrate 
Sulphur  
Powdered  Shellac. 
55  parts 
2o  parts 
4  parts 
2o  parts 
I  part 
If  the  shellac  is  increased  to  3  per  cent,  or  5  per  cent,,  the  flare 
is  slower  in  burning,  but  loses  its  brilliancy.  In  general,  the  bril- 
liancy and  fierceness  of  burning  increases  with  the  percentage  of 
aluminium  up  to  fifty,  and  is  decreased  by  the  addition  of  such  sub- 
stances as  sulphur,  or  shellac,  or  borax,  or  castor  oil.  The  fiercest 
and  brightest  aluminium  combination  consists  of: 
Aluminium  in  fine  powder   i  part 
Barium  Nitrate   .     i  part 
If  this  mixture  is  packed  in  an  iron  tube,  say  V4  in.  bore,  and 
with  walls  of  Vifi  in.  thickness  of  metal,  it  will  melt  and  burn  the 
iron  like  so  much  paper.  As  combustion  proceeds  down  the  tube 
the  walls  fuse  and  molten  globules  of  white-hot  metal  fall  to  the 
ground.  If  a  tube  of  any  considerable  length  be  used  it  should  be 
stuck  in  the  ground  at  an  angle,  as  the  molten  metal  falling  vertically 
may  fire  the  composition  at  the  base  of  the  tube  and  cause  a  power- 
ful explosion.  Though  the  proportions  in  the  above  formula  give 
an  excess  of  aluminium  over  what  would  be  necessary  for  chemical 
equivalents,  the  mixture  is  much  fiercer  and  brighter. 
gives  a  mixture  which  more  nearly  corresponds  to  molecular  equiva- 
lents. 
Potassium  nitrate  may  be  used  instead  of  barium  nitrate  in 
these  combinations.  The  burning  is  slightly  slower,  and  the  light 
of  a  different  character,  as  may  be  imagined,  the  lilac  potassium 
flame  being  different  from  the  green  of  barium.  In  the  same  way 
the  mixing  of  borax  in  a  flare  gives  the  yellow  sodium  flame,  but  the 
intensity  of  the  aluminium  flame  makes  these  colored  effects  only 
slight  variations  from  the  characteristic  dazzling  "whiteness." 
Aluminium  flares  are  not  quite  so  "white"  as  magnesium  ones,  but 
the  heat  of  combustion  is  much  higher.  Simple  mixtures  of  alumin- 
ium powder  and  barium  nitrate  in  dry  powders  do  not  bind  well ' 
Aluminium  
Barium  Nitrate 
I  part 
3  parts 
