It is altogether probable from experiments tried by Stanislas Muenier and others, that the sudden removal of pressure is a sufficient cause of superheated water and mineral substances flashing into steam and lava. The geysers are evidently formed by varying temperature and interruption of flow by removal of pressure. Mr. Fanques, in an article in the _Popular Science Monthly_ for August, 1880, says: “Discovery of microliths enclosed in volcanic rocks is a proof of immediate formation of crystals.” The phenomena attending the recent eruptions in Java demonstrate the incredible force and chemical effects of superheated steam. Modern researches and experiments in mechanical and chemical forces have greatly modified the views once entertained by geologists, and I think that it will now be conceded that repeated volcanic disturbances, taken in connection with the action of glaciers, will account for most, if not all, the phenomena discoverable in the gold fields and mountains of California. As a rule, gold-bearing veins in clay or talcose slates have the gold more evenly diffused than those found in the harder rocks, where pockets of crystals, pyrites and gold will most likely be found. If gold is found in seams or masses it will be very free from impurities, and the quartz itself will be most likely white and vitreous. When gold is found in or near to a lode that has been decomposed, it will be found porous and ragged, but if it has been deposited some distance from its source it will be more or less rounded and swedged by contact with the stones and gravel that were carried with it by the stream of water or ice that conveyed it to its placer. In the beds of the ancient and more modern rivers the gold is much more worn than that found in the ravines or gulches, and the coarser gold will be found at the bottom, the scale gold in the gravel above, and the fine or flour gold in the mixture of clay, gravel and sand nearer the surface. The scale gold, no doubt, has been beaten by repeated blows of stones brought in contact with it while moving in the bed of the stream, and the flour gold is that reduced by the continual attrition of the moving mass upon the gold.