This may have been in an auto repair shop,mercantile,or even a hotel where they had and or filled many fonts or lamp bases. With the metal framework it would stack so maybe a truck came around periodically full of these,picked up the empties and left full ones. Anyway in the closed position the spout was covered so the lampfiller would rotate the drum down to expose the spout and fill the lamp. The lower the level in the drum got,the farther it would be rotated down and still have controlled filling. Looks like it's about four or five gallons,empty now.The little vent pipe has come unsoldered. $125 plus shipping,paypal or check. Please PM me if interested.
Sold pending payment. Thanks Charlie and MTFCA.