https://ww2aircraft.net/forum/threads/g ... 941.37290/
https://books.google.com/books?id=X4yHC ... lm&f=false
http://www.ww2f.com/topic/3193-rafluftw ... ary-bombs/
Lastly came the Phosphorbrandbombe C50A, C50B and C250A which contained a viscous mixture of oil, rubber and phosphorous. The C250A was even more effective, the filling consisting of petroleum, polystyrene and Phosphorous.
Sources : MvBean/Hogben, 'Bombs Gone' and Ramsey, 'The Blitz Then & Now : Vol. 1' .