Can you use melting point to determine the identity of an unknown solid? A piece of gray metal appears to be melting. The metal is observed to begin to melt when the temperature of its container is approximately 29°C. The metal is most likely . A 2 column table with 5 rows. The first column is labeled Substance with entries copper, lead, mercury, tin, gallium. The second column is labeled Melting Point with entries 1,085 degrees Celsius, 327.5 degrees Celsius, negative 38.6 degrees Celsius, 232 degrees Celsius, 29.78 degrees Celsius.