The history of the use of hydrogen cyanide gas for execution purposes and the development of the gas chamber is strictly a United States phenomenon. Prior to 1890, hanging was the legally utilized procedure for execution in the United States. In an attempt to find a more humane procedure, the New York State Assembly adopted electrocution. Many other states followed by accepting electrocution. Others were not satisfied, for one reason or another, and sought a more humane procedure. Because hydrogen cyanide gas was being utilized for fumigation purposes, some states began to look at the possibility of gassing.
4.001 In the early 1920s. Arizona passed enabling legislation and contracted with Eaton Metal Products of Denver, Colorado; Casper, Wyoming; and Salt Lake City, Utah to construct their new execution system utilizing hydrogen cyanide gas. Eaton developed a gas chamber to contain the gas, a generator to manufacture the gas and a protocol to safely utilize the new equipment. Eaton subsequently installed chambers in Arizona, California, Colorado, Maryland, Mississippi, Nevada, North Carolina, Rhode Island and Wyoming. Missouri also utilized gas after the 1930s but their gas chamber, although as complex as the others, was constructed by a different company. Records at Missouri do not indicate who the builder was. The only major difference in all these chambers was whether they were for one or two executees.
4.002 In the years that have passed, most states have changed from gas to safer procedures. The only remaining states still utilizing gas are Arizona, California, Maryland, and Mississippi and some of these states are considering changing to the safer procedure of lethal injection.
4.003 It is extremely fortunate that although gas handling accidents have occurred, none has resulted in injury or death to gas chamber personnel as have accidents involving the use of hydrogen cyanide gas in other industries.