Now that we've all figured out not to breathe the cyanide, the easiest way to retain 1 bar of acetylene in the water is to stopper the flask. The cobalt compound won't evaporate, but both reagents are gases. It shouldn't bee that hard to figure out to put a lid on it. A lid made of glass, if you're using external light, but why do that? This 380-500 nm light is very long wave for the general run of photocatalysis, coming way down into visible blues and greens. This reaction would probably work well with the most easily obtainable black lights, like for gemstone examination, or would certainly work well with a grow-light. So to do it, you could just seal the light source inside the reaction chamber. Scale, from paint can size to aquarium/terrarium size. Do it in batch mode, completely sealed, keep well away from it, then open it remotely.
Heat it to drive out dissolved gases, then make sure there's no HCN with a dab of sodium thiosulfate solution, acidulate with HCl, strip off the water at the aspirator and save the pyridine.HCl as the solid salt residue.
a half a pints a half a pound a half a world a half a round
Sidearm n. Flask neck tube.
