Glyoxal is fairly uncommonly sold at generalist chemical shops. It is similar in many respects to formaldehyde, and can substitute for formaldehyde in a number of use cases.If treated with hydroxylammonium hydrochloride, glyoxime is produced. Glyoxime can be doubly acetylated to diacetyl-glyoxime by acetic anhydride (which can be made from ketene). Diacetyl-glyoxime can be heated to decomposition to form cyanogen gas (very toxic, so do this outdoors only), which can be burned in a stream of oxygen to make the second hottest known flame.The third hottest is atomic hydrogen welding. The fourth in common use is oxyacetylene.I later found that ammonium oxalate can also be thermally decomposed to form cyanogen gas, so that is a less complicated option. Though the required temperature is somewhat higher.Cyanogen is difficult to store, very toxic, and prone to spontaneous polymerization, so it should be burned immediately when generated if you do this experiment. Do not attempt to store it. Do not make it indoors or in any poorly ventilated place. Use a supplied air respirator driven by a pump located some distance away or a filter cartridge tested on cyanogen and hydrogen cyanide.The flame is brilliant blue white. Use welding glasses or UV protective laser safety glasses.