LACTOMETER

an instrument employed to test the specific gravity of milk. By "specific gravity" is meant its weight in comparison with that of water, which is taken as a standard for all solid and liquid substances. Unadulterated milk is heavier than water--a can full of milk, for example, may weigh three pounds heavier than if full of water. The use of the lactometer or other test rests on the fact that a body will sink deeper into a light than into a heavy liquid. When a standard at which milk may be considered unadulterated is adopted, milk into which the lactometer will sink deeper is said to be of low specific gravity--which may mean that water has been added to it.