The potential alcohol level of beer or wine being made is measured by a Hydrometer. Before fermentation starts (at the time the yeast is pitched) the Hydrometer is floated in the beer wort or wine must. A reading is taken at the level the Hydrometer floats to; the surface of the liquid. This reading is the original, or starting, gravity. This number is read on the specific gravity scale of the hydrometer, and in recipes you will see it expressed as "0. G." or "S. G." - starting gravity.

After fermentation is over, at bottling time, another reading is taken with the hydrometer. This one is the final gravity, or terminal gravity. In recipes, it sometimes appears as "T. G." To find the alcohol content of the beer or wine, subtract the terminal gravity from the starting gravity and match that number with the alcohol scale on the hydrometer. A typical American beer might be S. G. 1.032 - T. G. 1.008 = .024. Twenty-four points on the specific gravity scale equals 3.2% on the alcohol scale. A heavy English ale would be about S. G. 1.054 - T. G. 1.016, or 5.3% alcohol.

19" Tube with a one way valve in the bottom. Designed to allow a sample in and retain it for testing with a hydrometer.