I took out a gas fire and found a tiny fireplace, can I use it?

there are gas fire out there that don't need a chimney. but firstly get the chimney swept then you are certain that the chimney is safe to use for any fire. then after choosing whether you want coal/gas/oil or electric call the appropriate expert .coal/ wood or oil wrongly fitted do as with gas kill people every year. this is not to frighten you just to inform you