It has been somewhat difficult to crowd a description of torpedoes and mines into the small space of one chapter, and so many details have had to be omitted, but the above descriptions give the broad, general principles underlying practically all forms of these terrible weapons. CHAPTER IX GOLD RECOVERY There has always been something very fascinating about gold. Even in ancient times it was prized above all other things, and apparently it was comparatively plentiful. It is estimated, for example, that King Solomon possessed over £4,000,000 worth of it, while the little gift which the Queen of Sheba brought him was of the handsome value of £600,000, so that she too must have been plentifully supplied with it. Probably it was more easily come by in those days, owing to the richness of the primitive deposits, the best of which, perchance, have been worked out. In one respect gold differs from all other metals (with the single exception of platinum, which is scarcer still) in that it appears naturally as gold, not as ore. The little pieces of gold lie in the mine ready to be picked out, and so if the deposit in which it occurs be near the surface, and the particles be of any considerable size, they are sure to be found. A savage may be, and often is, very anxious to secure weapons and tools of iron, little knowing that the very ground upon which he stands is possibly of iron ore. He covets the single article of iron, and in some cases is willing to give much gold for it, or ivory, or some such treasure, while thousands or millions of tons of iron lie at his feet, only he does not recognise it, nor would he know how to utilise it if he did. For iron, like all other metals except the two just referred to, is found naturally in combination with something else, generally oxygen, and the combination bears no resemblance at all to the metal. The red rust so familiar to us on iron is a combination of iron and oxygen, and it is fairly typical of the kind of state in which iron is found in the earth. Nor would anyone recognise copper ore, lead ore, tin ore, or any of the ores, any better than iron ore. All are difficult to recognise. It is said that the highest compliment that a Cornish miner--the finest metalliferous miners in the world come from Cornwall, or are the product of Cornish influence--the highest compliment that such a man can pay to another is to say that "he knows tin," meaning that he can tell tin ore when he sees it. Contrasted with these other metals, gold is easy to find. It does, it is true, under certain conditions, form chemical compounds with other things, as, for instance, in gold chloride, which is present in sea-water, but it does not oxidise as the others do, and so when it is in the earth it is in the bright yellow grains such as (if they be large enough) can easily be recognised at sight.