This is a vintage Ever Fresh or Everfresh Magnesia bottle embossed with the brand name across the top and "registered not refillable" across the base. The bottom is embossed with an Owens-Illinois glass mark with either a 1 on the left and a 9 on the right or a 6 on the left and a 1 on the right depending on how you hold the bottle. Best guess the vintage apothecary bottle was most likely made at the Charleston, WVA plant (#6) in 1941 as the Toledo Ohio plant (#1) appears to have not been operating in 1939. Magnesia was used as a laxative during the World War II era, with the most commonly known brand being Milk of Magnesia. My father, an avid bottle digger, discovered the bottle in the ruins of an old homestead in Virginia over 40 years ago. The bottle is in nice condition, free of breaks or cracks. Clarity is nice for a dug bottle although there is some calcification, especially in the neck area. The bottle measures about 8.25" x 2.75" For More information: https://www.bourbonex.com/forums/topic/266/bottom-of-glass-info-o-i https://glassbottlemarks.com/owens-illinois-glass-company/