Glass - Smelting in Minecraft?
Glass
How to smelt items?
Items can be smelted in the Furnace. 
To smelt, just place the item in the top box and the fuel on the bottom. Fuel is required to light the furnace. There are many other compatible fuel sources like Lava Buckets, Charcoal, or Blocks of Coal.
After putting the item and fuel in the furnace, wait a while for your smelted item.
