At this point we allow the evaporating The process of turning from liquid into vapour. basin to cool and then weigh it again. If the water sample contained any dissolved solids, the mass of the empty evaporating The process of turning from liquid into vapour. basin will have increased. That's because the water has evaporated but the dissolved solids will have formed crystals on the surface of the evaporating The process of turning from liquid into vapour. basin.