If you could post a picture of the lantern in question it would greatly assist in the evaluation.
Generally... There are many different types that existed. Most of the 1840-50 era oil lanterns predominately used whale oil. throughout the 1850's whale oil continuously became more and more expensive. Thus many sought out alternative fuel oils made of tallow, fat etc... Depending on ones economic ability. The wicks and burners on these were much different than the oil lanterns that most are familier with. "Kerosene", aka coal oil, was fairly new product in the latter 1850's, and civil war era. It was also fairly expensive due to the then complex and difficult production process. The production of which was mostly limited to the Pennsylvania coal field regions at that time.
The kerosene market and proliferation of available lanterns designed for it didnt really take off till well post war when the production process was better perfected, making it more marketable and less expensive. The old kerosene lanterns that many refer to as a railroad lantern commonly seen in the old western movies such as was made by Dietz and some others with the flat single wick didnt come around till about a decade or more after the war. Despite the usage of such by many reenactors. because something looks old, it isnt always old enough for the civil war era.
If the lantern and tank is made of tin, a primary concern would be how much rust the lantern has. In many cases the most damage typically is inside the tank where moisture could have been trapped and a cause for internal corrosion. Always store and transport an oil lamp sitting upright to help prevent any leakage from the burner or its flange etc.
Lieut Frederick Sineath
14th Virginia Infantry Regt Co.I
- 106th Penna Vol Co.F