Some of us do something like this with iodine tablets in 5/8 dram lab vials. I never thought about using crystals; what size is your nitro vial? The vials I use are about the same size a .45ACP or 10mm Auto cartridge. (Or about as big around as an AA battery, about 2/3s as long.)
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-IronRaven

When a man dare not speak without malice for fear of giving insult, that is when truth starts to die. Truth is the truest freedom.