You can't see the steam coils that are melting this raw sugar, he remarked. "They go round the inside of the tanks. But after the liquid is drawn off you can see them. When first melted the sugar is far from pure; you would be astonished at the amount of dirt mixed with it. Many of these impurities boil up to the surface and over and over again we skim them off. But even after that we have to wash the sugar by various processes. After it has been separated, clarified, and filtered it comes out a clear white liquid, and is ready for the vacuum pans, where the water is evaporated and the sugar crystallized."