The Vermont maple law requires packaged maple syrup have a density of between 66.9 and 68.9 degrees Brix. Brix is a measure of sugar concentration in a pure sugar solution. Although we know there are other many dissolved minerals in maple syrup their concentration is low enough to allow the Brix scale to be used. In order to know if syrup is within the legal range of density a sugar maker must take measurements. The most common instrument used by sugar makers for measuring density is called a hydrometer. A hydrometer is a precisely graduated scale inside weighted glass bulb with a thin stem. The hydrometer will float at the correct number when the syrup is the correct density. The hydrometer will float higher or lower depending on the syrup temperature so knowing the temperature of the syrup is critical to getting accurate measurements. Hydrometers are fragile and if damaged will not produce accurate readings. Be sure to have at least one extra in the sugarhouse and have your hydrometers tested annually.