There is probably some mojo involved involved in making effective activated carbon. Looking at the related panel on the right there, I see TimAnderson's, "Improvised Gas Mask" instructable. https://www.instructables.com/id/GasMask/In this 'ible, Tim actually made his own charcoal from coconut shells. From the pictures, it looks like he was living on a tropical island at the time, so I am guessing the coconut shells were available for free.Where I live, in the Former US, we have this place called Walmart(r). It's a big department-type store, and at the store near where I live, activated charcoal can be found in the pet supplies section, more specifically the aisle that has supplies for aquariums and fishes. I mean for me, where I live, the aquarium supply aisle would probably be the place to go, for activated charcoal, and for me that would be easier than gathering coconut shells.Right. But how to do you know if your black, sooty, granules, however you find them, how do you know they are actually working, like adsorbing toxins and stuff?Well, in Tim's case, he attached that snorkel-thing-with-can-of coconut-charcoal to his face, and he says that while breathing through it, he could not smell fumes from varnishing his boat.So I guess to the way to test your black granules, is via kind of smell test. Set up a source of smellable gas, and observe if pulling that gas through your adsorber, makes the smell go away.I have seen a big list of air soluble chemicals,https://www.usairpurifiers.com/media/amaircare/Ama... rated on a scale of 1-through-4, with respect to how effective activated carbon is at adsorbing that chemical. I dunno. If you're contemplating a little science project here, an experiment to test your charcoal, I expect huffing onion fumes is probably safer than huffing napthalene mothballs, if you are trying to choose between those for your smellable gas source. The pdf linked above says both those substances, onions and napthalene, rate a "4" as substances easily adsorbed onto activated carbon.Also guessing the adsorber itself should not have a strong smell. For example if your ground up BBQ briquettes smell strongly of charcoal lighter, or mesquite, or some other kind of fragrant wood, that is probably NOT a good sign.