Why do you think the ancient process of casting bronze is called "lost wax casting"?

"Lost wax" or "cire perdue" casting is one of the oldest ways of creating bronze sculptures, with examples dating to approximately 3700 B.C. having been found in Nahal Mishmar (the Cave of Treasure) in Palestine. This technique was also practiced in the Indus Valley culture, with examples from ca. 3500 BC having been found in Mohenjodaro and Harappa. The technique was also commonly used in ancient Egypt and in Graeco-Roman antiquity. 

Metal is difficult to shape with the traditional instruments used for sculpture in other materials such as wood or stone, especially using Bronze Age tools. The point of using the lost wax technique was that it enabled sculptors to create a model statue in a different material and then use that original to make a mold with which to cast a bronze sculpture. The technique allows the casting of a bronze sculpture with a bronze layer of the desired thickness rather than made of solid bronze.

First, the artist creates a rigid outer mold and then a layer of wax of the desired thickness of the bronze on the inner side of the mold, which in turn fits precisely around the model. Thin tubes run from the wax layer to the outside of the outer shell. Molten bronze is poured in, liquifying the wax which runs out or is "lost" in the process, and is replaced by bronze.