Before the hydrometer became a common instrument of the distiller there existed a method of proofing known as "gunpowder proof". It was a simple procedure and took advantage of readily available "tools". Bourbon and gunpowder were mixed in equal proportions in a small fireproof vessel and ignited. If the flame burned yellow the liquor was too strong, if it burned blue the proof was true. A yellow proofed liquor was mellowed with spring water until it burned blue. The proof of a blue flame spirit was about 100, or 50 per cent.
I have to think there is probably nothing more awesome than taking gunpowder and spirit, mixing it together, and setting it on fire...
