englishman william haynes patented a process in 1860 for separating sulfide and gangue minerals using oil. later writers have pointed to haynes's as the first "bulk oil flotation" patent, though there is no evidence of its being field tested, or used commercially. in 1877 the brothers bessel (adolph and august) of dresden, germany, introduced their commercially successful oil and froth flotation process for extracting graphite, considered by some the root of froth flotation. because the bessel process was used on graphite not gold, silver, copper, lead, zinc, etc, their work has been ignored by most historians of the technology.