john m. callow, of general engineering of salt lake city, had followed flotation from technical papers and the introduction in both the butte and superior mill, and at inspiration copper in arizona and determined that mechanical agitation was a drawback to the existing technology. introducing a porous brick with compressed air, and a mechanical stirring mechanism, callow applied for a patent in 1914 (some say that callow, a jackling partisan, invented his cell as a means to avoid paying royalties to minerals separation, which firms using his cell eventually were forced to do by the courts). this method, known as pneumatic flotation, was recognized as an alternative to the minerals separation process of flotation concentration. the american institute of mining engineers presented callow the james douglas gold medal in 1926 for his contributions to the field of flotation. by that time, flotation technology was changing, especially with the discovery of the use of xanthates and other reagents, which made the callow cell and his process obsolete.