Internal combustion engines

An internal combustion engine comprising:

• a chamber;
• inlet valving operable to admit constituents of a combustible mixture into said chamber for combustion of said combustible mixture in said chamber to provide an expanding gaseous mass in said chamber;
• outlet valving operable to release an outflow of a liquid contained in said chamber from said chamber under an influence of said expanding gaseous mass as an energy output of said chamber;
• and
• a fluid holder that is housed in said chamber, said fluid holder being disposed in a region of said chamber in which combustion of said combustible mixture takes place such that an aqueous fluid held by said fluid holder is disposed within said expanding gaseous mass so that said aqueous fluid is heated in a process to provide hydrogen that is combusted in said chamber and there being at least one flowpath past said fluid holder for said expanding gaseous mass to permit said expanding gaseous mass to act on said liquid.