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
CU convoys CU 23, CU 24, CU 28, CU 30, CU 33, and CU 35 included troopships and are sometimes identified with a TCU prefix. Convoy CU 24 sailed in two sections with troopships in TCU 24A and ammunition ships in TCU 24B. A total of 2255 ships crossed the Atlantic in CU convoys until convoy CU 73 made the last departure from New York on 30 May 1945. Submarines sank three loaded United States tankers from CU convoys: Empty ships travelling westbound on similar routes were designated UC convoys. Seventeen ballasted tankers departed from Liverpool on 15 February 1943 as convoy