Definition: dilute alcohol, specific gravity 0.920, containing 49.5% by weight (57.27% by volume) of ethanol at 15.56°C. Originally in Great Britain it was the weakest alcohol that would permit ignition of gunpowder moistened with it. British proof spirit has a specific gravity of 0.9198 and contains 49.2% ethanol by weight, or 57.1% by volume at the temperature of 10.56°C.
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Examples: glitazone, GI cocktail, etc.