"The charcoal iron is a self-heating device similar to a miniature cooking stove. Charcoal from wood or wood coals was normally used for fuel. Heating control was provided by vents which controlled the air/oxygen supply." Irons By Irons, page 33
This video demonstration on the use of a Charcoal Iron reminds us it's still used today in many undeveloped areas of the world.
Charcoal Irons are still being manufactured today. Here is an ad showing one particular model, the "Cock Brand", produced and distributed by Linyi Hantensi Trading Co., Ltd. of China. According to their website the main markets for these irons are Africa, Haiti and South America.