This is a very light cobalt FA & Co jar, marked in small letters around a pontil on the base.  It's a corker, sealed with a large cylindrical cork with sealing wax poured over the top.  It was a very popular closure in very early jars.  Before the early wax sealers and corkers people had only the option of soldering shut metal cans so though the sealing wax seems like a huge bother to us, it probably came as a wondrous labor saving device to people of the time.

FA & Co stands for Fahnestock Ahlbree and Co.