This thing is just cool... now that it's clean. It was almost black with soot and had thick, gooey contents all over the inside when I pulled it out of a basement.
It's big - 11 inches tall, 3-1/2 inches across at the base. Three-part mold with applied tapered top, six pin-sized vent marks on the shoulder, NO embossed marks anywhere. I would date it to around 1880 at first, except that it fluoresces strong, bright yellow-green under UV light. This, along with lack of embossed maker's mark or patent, could suggest either an earlier date (1840-1870), or a small local glass house using it's own molds and recycled civil war-era glass. The mold seams are also fairly thick and on the rough side, and quickly blend away to nothing less than an inch up the neck, which could suggest a much earlier date copying Rickett's patent.
Private label on the neck reads "Dawson Spangler Ephrata Pa". There is also printing on the outside edges of the neck label, but it's impossible to read anything more than a letter or two, even with macro photos.
That's what I know. More knowledgable contributions would be appreciated!