Birch bark is some pretty amazing stuff. It can be used for boats, water containers, boxes, and, most famously, as an excellent fire-starter. This is because of the oils embedded in the bark which allow it to be waterproof and to be extremely flammable.
This means the bark is an excellent firestarter even when wet. When you distil these oils into a separate container, the natural oils can be used to make a primitive oil lamp which will allow you to have some light away from your fire when SHTF.
Having a primitive oil lamp is a great trick if your flashlight runs out of batteries or you want to establish a few light sources around your campsite so that you don't have to carry a light around.
To learn how to make this excellent and reliable oil lamp, watch the video on the next page.