enables us to detect it in a piece of rock, where it may not be distinctly visible. There are two substances which look exceedingly like gold;--copper and iron pyrites, substances familiar to most of us. We need never be puzzled to distinguish them. Gold is a soft metal, softer than iron, copper, and silver, although harder than tin or lead. It will scratch tin or lead; but it will be scratched with the other metals. That is to say, you can scratch gold with a common knife. Now, iron pyrites is harder than steel, and therefore a knife will fail to scratch it. Gold and iron pyrites, therefore, need never be mistaken for each other by any man who has a piece of steel about him. Copper pyrites can be scratched with steel. But then there is another very familiar property of gold, by which, in this case, it can be distinguished. Gold is very malleable; beat on it with a stone, and it will flatten, but not break; and when it breaks, it shows that it is torn asunder, by the thready, fibrous nature of its fracture. Beat with a stone on copper pyrites, and it immediately begins to crumble. No acid, by itself, can affect gold; but a mixture of one part nitric, and four parts muriatic acid, is called Aqua Regia, because in this mixture gold does dissolve. A common test for gold, in commerce, is to put nitric acid over it, which has no action if the gold be true. There is, also, a hard smooth stone, called Lydian stone, or flinty jasper, by the mineralogists, and _touchstone_ by the jewelers, on which gold makes a certain mark; and the character of the streak made on such a stone will indicate pretty well the purity or value of the gold that makes it. We have said that when the gold occurs in a deep-seated vein, combined with other minerals, its extraction becomes no longer a simple process. Let us now point out generally what the nature of this process is, and then we shall conclude our brief discussion; for what else we might say, either lies beyond our present purpose, or has been made, by the talking and writing of the last two years, sufficiently familiar to all listeners or readers. Mr. Gardner, superintendent of the Royal Botanic Garden of Ceylon, thus describes the process of extracting gold out of the mine of Morro Velho. This mine, when St. Hilaire visited it, was considered as exhausted; it is now one of the richest in Brazil. Thus Mr. Gardner writes of it: