"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

Universal Charcoal Iron

Rare charcoal iron, made by the Universal Iron Co., Milwaukee, WI. Patent dates 1887-1891. Measures 7.5 x 7" x 3.75". Nicely inscribed. Sold by Hartzell's Auction Gallery at the Balestri Auction on 7/12/18 for $190.

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.