An interesting experiment has been tried. A certain amount of hydrogen gas and eight times as much of oxygen gas were weighed separately, by means of very delicate instruments. Then through great heat the two were caused to unite into water, and the water also was weighed. It was found to be just as heavy as the two gases together had been; and quite naturally so, since neither of the two gases had lost or gained in weight. This kind of union is called “chemical.” French people are fond of “eau sucré.” A lump of sugar is dropped into a glass of water, and it disappears. But it has not been destroyed. It has not ceased to be sugar. No mysterious union has taken place between the sugar and the water. Neither water nor sugar has changed its nature; and no fresh substance has come into existence in their stead. The water is there, as it was before. The sugar is there too, not visible, but to be found out by our sense of taste. It has only been separated by the water into such minute particles that we cannot see them. This is a case of mixing, not of chemical union. When we think of the characteristics of Sea Water, as compared with Fresh Water, we have to do with simple mixing. As sugar floats, unseen but not untasted, in tea or coffee; so salt floats, unseen but not untasted, in ocean waters. Such a thing as absolutely pure water is very rare. No matter how clear a stream may seem to us, it holds a vast number of specks of material, collected from earth and air. Once a scientific man had some, most carefully distilled, which seemed to be of crystal purity. But he put it under the strong beam of an electric lamp, and, alas, for human powers! after so doing he could only declare that the idea of purity was ludicrous. If it is so with distilled water, the less said the better about common drinking-water. It may be well for our peace of mind that we have not stronger sight. Ocean-water holds about two hundred times as much dissolved material as ordinary fresh water. The different kinds of substances found in any particular water-supply determine the character of that water, making it sweet or sour or salt, rendering it health-giving or death-dealing. Something has been said about the drying away of sea-water, and the leaving of salt behind. A remarkable instance of salt thus left is seen in the Rann of Cutch, a flat Indian plain, about a hundred and ninety miles long, and half as wide. During the south-west monsoon the ocean waters are forced by powerful winds up the Gulf of Cutch to a considerable height, overspreading the Rann, which for a time is turned into a shallow lake. When dry weather comes, the water vanishes, partly retiring, partly evaporating; and a salt-strewn desert is left, varied by sand-ridges, green spots, and little lakes, but covered principally by “sheets of salt crust.” My father, when there many years ago with his Regiment, noted down his impressions of the scene.