on august 24, 1886, carrie everson received a patent for her process calling for oil[s] but also an acid or a salt, a significant step in the evolution of the process history. by 1890, tests of the everson process had been made at georgetown and silver cliff, colorado, and baker, oregon. she abandoned the work upon the death of her husband, and before perfecting a commercially successful process. later, during the height of legal disputes over the validity of various patents during the 1910s, everson's was often pointed to as the initial flotation patent - which would have meant that the process was not patentable again by later contestants. much confusion has been clarified recently by historian dawn bunyak.