- Five-stemmed glass Sikers' hydrometers 13½ inches long, must be used in warehouse. Each stem covers 20 degree of indication. For shop inspection work, single-stemmed glass hydrometers of proper range or brass gilt Sikers' hydrometers may be used. These instruments must never be used to prove spirit for duty purposes and hollow-stemmed hydrometers open at the top must not be used on any account. Thermometers with wooden scale must not be used in warehouses.
