text: "Black snake" is a term that can refer to at least three similar types of fireworks: the Pharaohs snake, the sugar snake, or a popular retail composition marketed under various product names but usually known as "black snake". The "Pharaohs snake" or "Pharaoh's serpent" is the original version of the black snake experiment. It produces a more impressive snake, but its execution depends upon mercury (II) thiocyanate, which is no longer in common use due to its toxicity. For a "sugar snake", sodium bicarbonate and sugar are the commonly used chemicals. 
  Once lit, the fireworks emit smoke and spew out ash resembling a snake via an intumescent reaction. They remain on the ground and emit no sparks, flares, projectiles, or sound.