Chemical Potentials

Abstract

It is fairly seldom that we find resources in the form in which we need them, which is as pure substances or, at least, strongly enriched in the desired substance. The best known example is water: While there is some sweet water available on the earth, salt water is predominant, and that cannot be drunk, nor can it be used in our machines for cooling (say), or washing. Similarly, natural gas and mineral oil must be refined before use, and ore must be smelted down in the smelting furnace. Smelting was, of course, known to the ancients - although it was not always done efficiently - and so was distillation of sea water which provided both, sweet water and pure salt in one step, the former after re-condensation. Actually, in ancient times there was perhaps less scarcity of sweet water than today, but - just like today - there was a large demand for hard liquor that had to be distilled from wine, or from other fermented fruit or vegetable juices.