igniter vs napalm

igniter

noun
  • Any device that is used to ignite something, especially a fuel mixture, or a charge of explosive 

napalm

noun
  • A highly flammable, viscous substance, designed to stick to the body while burning, used in warfare as an incendiary especially in wooded areas. 

verb
  • To spray or attack with napalm. 

How often have the words igniter and napalm occurred in a corpus of books? (source: Google Ngram Viewer )