Chemical element of metals. Cu comes from Cuprum, Fe comes from Ferrum, Ag from Argentum. The symbols were not followed by a period (full stop) as with abbreviations. Later chemical elements were also assigned unique chemical symbols, based on the name of the element, but not necessarily in English. For example, sodium has the chemical symbol 'Na' after the Latin "natrium". The same applies to "W" (wolfram) for tungsten, "Fe" (ferrum) for iron, "Hg" (hydrargyrum) for mercury, "Sn" (stannum) for tin, "K" (kalium) for potassium, "Au" (aurum) for gold, "Ag" (argentum) for silver, "Pb" (plumbum) for lead, "Cu" (cuprum) for copper, and
Melting-point apparatus operator of the apparatus records the temperature range starting with the initial phase-change temperature and ending with the completed phase-change temperature. The temperature range that is determined can then be averaged to gain the melting point of the sample being examined. Apparatuses usually have a control panel that allows the starting and final temperatures, as well as the temperature gradient (in units per minute), to be programmed. Some machines have several channels, which permit more than one sample to be tested at a time. The control panel might have buttons that allow the start and end of the melting point