The ebullioscope is an instrument for determining the alcohol content of wine and beer by measuring the decrease of the boiling point of water induced by the alcohol.
From the mid-nineteenth century onwards traveling salesmen are equipped with such gauging instruments for quality testing during their journeys. After calibrating the instrument with boiling water it is possible to determine at constant air pressure the alcohol content to within 0.1% precision.
Text__naeU0KOeEd-WfYQ0GneCwQ_title=The Chemical Laboratory in the 20th Century\: Ebullioscope