text: The method has been in use since World War I. Prior to this, the process and purity of hydrogen generation relying on steam passing over hot iron was difficult to control.  The chemical reaction uses sodium hydroxide (NaOH), ferrosilicon, and water (HO). While in the "silicol" process, a heavy steel pressure vessel is filled with sodium hydroxide and ferrosilicon,  and upon closing, a controlled amount of water is added; the dissolving of the hydroxide heats the mixture to about  and starts the reaction; sodium silicate, hydrogen and steam are produced. The overall reaction of the process is believed to be:
  : 2NaOH + Si + HO → NaSiO + 2H
  Ferrosilicon is used by the military to quickly produce hydrogen for balloons by the ferrosilicon method. The generator may be small enough to fit in a truck and requires only a small amount of electric power, the materials are stable and not combustible, and they do not generate hydrogen until mixed.
  One report notes that this method of hydrogen production wasn't thoroughly investigated for about century despite being reported by the US military in the beginning of 20th century.