Function: The hydrometer indicates how many grammes one litre of liquid weighs.

The specific gravity of water is 1 000 grammes (1 kg) per litre. This is 1000 on the hydrometer.

990 grammes is 990 on the hydrometer.

1080 grammes is 1080 on the hydrometer on the scale.

Quality: Select a 300 mm long (preferably German) hydrometer. Do not use a cheap 200-250 mm model. Buy one of the same quality as those in the Widder range. Test the hydrometer in water to make sure it reads 1000.

Instructions: Pour the liquid to be measured in a tall measuring glass. The type of container is irrelevant as long as it is high enough to allow the hydrometer to float freely. Lower the hydrometer into the liquid. When it is floating freely, a reading is taken at the surface. The white scale indicates + and the coloured shows minus, that is, hydrometer degrees over and under 0.