This is an instrument used by alcohol distillers to measure the amount of water in the distilled alcohol. It is a glass floating hydrometer with two scales: a Gay-Lussac scale divided into centesimal parts (into hundredths) corresponding to the presence of 0, 1, 2….100% by volume of alcohol at 15° C. (the 0 division correspond to pure water, and the 100 division correspond to pure alcohol) and a Cartier scale for rough measurements from 10 to 45%. Joseph L. Gay-Lussac (1778-1850), French chemist; invented the hydrometer and alcoholmeter.