The Arm & Hammer logo dates back to the 1860s. James A. Church ran a spice business known as Vulcan Spice Mills. According to the company, the Arm and Hammer logo represents Vulcan, the Roman god of fire and metalworking.
It is often claimed, incorrectly, that the brand name originated with or is related to tycoon Armand Hammer, who owned a considerable amount of Church and Dwight stock in 1980s and served on its Board of Directors.
The Arm and Hammer is also the symbol of the Socialist Labor Party of America (SLP). Originally a stylized representation of the Greek god of fire and forge, Hephaestos (Roman Vulcan), the muscular male arm with hammer in fist was used prior to the American Civil War as a symbol of the labor movement.
Parts of this article are taken from Wikipedia.