Even the fuel that fired an ironclad’s boilers was a threat. Coal, while not a new fuel used by the Navy, had the potential of becoming a silent killer. Fossil fuels require proper ventilation and this concept was not yet adequately understood by Civil War engineers.
Untold casualties, some fatal, occurred when crewmen either loaded wet bituminous coal in below-deck bunkers or bilge water contaminated the fuel. Both the Mississippi Squadron and the South Atlantic Blockading Squadron reported a number of cases of sailors being discovered either dead or unconscious below deck. The more fortunate were revived when exposed to the fresh air. Besides unconsciousness, surgeons described their patients as being cyanotic—blueness of the skin caused by oxygen starvation with foreheads and eyelids markedly swollen.
Learn more about Civil War naval medicine at www.CivilWarRx.com