Wilbert Bradley McCoy registered the brand name Hyki as a trademark for a "tonic for the scalp and hair" in 1912 (#89,127). He was a member of the Universal Scalp and Hair Remedy Co., of Cleveland, Ohio. He said they had been selling the brand since 1910. The pictures and descriptions shown here were provided by Michael Murro (view gallery).
A bottle of Pompeian Hair Massage I have says that it was sold for years as "Hyki." This wild tradecard I have (view) says it was sold at the House of Hyki in San Francisco.