Henry T. Helmbold began his career in the patent medicine business in 1846 with Helmbold's Extract Buchu - cures diabetes, gravel, brick-dust deposits, irritations of the bladder and diseases arising from exposure or imprudence, etc. Other medicines were Helmbold's Highly Concentrated Compound Fluid Extract of Sarsaparilla for purifying the blood and Helmbold's Catawba Grape Pills, useful for all diseases requiring a cathartic remedy and superior to all other purgatives. Also Helmbold's Tolu, a cough mixture.
The four-cent stamp was the first to be issued, in May of 1864. It was last issued in April of 1872. 1,026,734 were issued on old paper, and 24,919 on silk paper. The copy above is on old paper.
The two-cent stamp was next, issued from July, 1864 to December 1872. 928,401 were printed on old paper and 2,338 on silk paper. The one above is on old paper.
The three-cent and six-cent stamps were issued at the same time, from June 1868 to June 1875. 83,835 of the green three-cent stamps were printed on old paper and 24,919 on silk paper. 1,448,461 of the black six-cent stamps were printed on old paper and 165,909 on silk paper. The three-cent above was printed on silk paper and the six-cent on old paper.
Henry T. retired in 1876 and his son Albert L. Helmbold took over the business. He had the dies of two of the stamps altered to reflect his ownership, but after relatively small printings used general issue stamps.
11,898 of the two-cent stamps were issued from 1876 until April 24, 1882, on silk, pink and watermarked papers. The copy above is on silk paper.
164,692 of the four-cent stamps were issued during the same time, also on silk, pink and watermarked papers. The copy shown is on pink paper. This shows up better on the full page scan than on the individual stamp.