Signedlabel on sleeve: CENTRAL SCIENTIFIC CO. / LABORATORY SUPPLIES / APPARATUS CHEMICALS / CHICAGO, U.S.A.
marked on bottom: GERMANY
FunctionHope's apparatus illustrates how the density of water is the highest at a temperature of 4 degrees Celsius. One would start by placing two thermometers through the small orifices at the top and bottom section. Then, one would fill the cylinder with water. Initially the temperature of both thermometers will be the same, perhaps a little lower at the bottom.
Following this, one would put a mixture of ice and salt on the trough formed by the copper sleeve. This will start to cool down the water.
Initially, the temperature at the bottom will fall much faster than at the top. Then, as the temperature at the bottom reaches 4 degrees, it stops changing while the one at the top will keep falling. Close to the copper sleeve ice will start to build up.
Eventually, even the water measured by the top thermometer will reach zero degrees, while the temperature at the bottom will remain at four, and will only fall when the ice is very close.
Primary SourcesA very similar apparatus can be seen in E. Leybold Nachfolger, Catalogue of Physical Apparatus, Cologne, 1927, p. 287. The only difference is that the water outlet in this instrument's trough seems to point straight down.