Cosmoline: A yellowish or light-amber colored ointment like mass, having a slight fluorescence, petroleum like odor and taste (do not taste it please). Similar to Vaseline in properties, appearance, and thickness. It is the residue obtained in the distillation of petroleum oils and then purified. Cosmoline is a homogenous mixture of oily and waxy long-chain, non-polar hydrocarbons. It can range in color from white to yellow and differ from one another in consistency and shear strength. Cosmoline melts at 113°-125° F and has a flashpoint of 365° F.

Used for storage and preservation of firearms.

http://www.surplusrifle.com/shooting/cosmoline/index.asp