Pop-its 4th of July Toy powered by silver fulminate coated sand friction explosion of super sonic gas expansion salute sound like a cap gun :)

A small cherry shaped paper sack filled with sand coated in ~2 mg of silver fulminate made of cigarette paper produce a small explosion & audible bang sound when the pop-it thrown against a hard surface, the audible crack solute a sharp output similar to that of a cap-gun. 

Fortunately the extremely high mass fraction of the sand to the friction sensitive explosion enables most of the explosion energy to dissipate by chucking the sand particles, so low energy that you can set one off in your hand with little if any risk of causing a physical injury, hence their low cost, retail sales & popularity with parents & children. 

Pop-its achieve global sales diffusion & worldwide popularity in the 1950's & became part of the Chinese New Year celebrations. In the USA they are sold in grocery stores & other retail locations year round & availability increases approaching July 4th independence day celebrations. 

Safe & fun to play with, pop-its will likely continue to be popular, even though they contain a wildly powerful explosive in tiny milligram quantities that produce the snap/ bang solute of supersonic gas expansion when the sand particles coated in the explosive rub together as the packet impacts something or is snapped in the fingers. 

Enjoy your pop-it fun people! Cheers & thanks for thinking about it with me :)