Wikipedia notes that petroleum jelly is only flammable when heated to a liquid. Petroleum jelly is a colorless semisolid mixture of hydrocarbons obtained from petroleum and used in lubricants and medicinal ointments, according to The Free Dictionary.
The melting point of petroleum jelly is around 99 degrees Fahrenheit, according to Wikipedia. The fumes are flammable, not the liquid itself, so a wick material is needed to ignite the jelly.
Wikipedia indicates that petroleum jelly was originally promoted as an ointment for scrapes, burns and cuts. As of 2014, petroleum jelly is primarily used as an ingredient in skin lotions and cosmetics. It provides skin care and protection by minimizing friction or reducing moisture loss.