Task
The density of glass samples is measured using the sink-float method developed by M. A. Knight. This means that each of the 6 test jars is filled with 2 glass specimens and 1 additional reference sample. The test jars are filled with a test liquid consisting of a mixture of bromine naphtalene or tetrabromoethane. This liquid is heated indirectly in a water bath with distilled water. The density of the test liquid must be greater than the density of the glass body when the measurement process begins. This causes the glass to float on the surface. When the measuring process begins, the bath temperature is slowly increased. This naturally also increases the temperature of the test liquid. Its density decreases as the temperature rises. The result is that the glass samples sink quickly or slowly, depending on their own density. After a certain amount of time, the glass bodies are passed through a light gate that automatically recognizes whether the tested object is the reference sample or the glass sample. The density of the glass samples is calculated and displayed depending on the various temperatures when they pass through the light gate as well as the associated times.