James Swaim, M.D. established a proprietary medicine business in 1820. He offered Swaim's Panacea and Swaim's Stomachic Elixir until 1870, when William Swaim, possibly the son of James, took over. The six-cent Swaim private proprietary stamp was issued in April of 1863, and a second delivery was made in November of that year. These two deliveries accounted for 17,963 stamps, all on old paper.
The eight-cent James Swaim stamps were first issued in May of 1864, but it is unclear when they were last issued, and there is no way to separate the number printed from the number printed for William Swaim. They are known imperforate and die cut, and it is possible that a very small number were printed on silk paper and hand-signed, but most were printed on old paper. The copy shown is on old paper.
The William Swaim stamps were delivered around 1870, until January 29, 1883. They exist imperforate and die cut, and a few are known without signatures or with manuscript signatures. A total of 128,805 James and William Swaim stamps were issued on old paper, 139,477 on silk paper and 75,553 (presumably all William Swaim) on watermarked paper. The copy above is on watermarked paper.
After the proprietary taxes were repealed William Swaim had a facsimile stamp prepared to preserve the distinctive look of his packaging.