There is a prospect that the seat of government of California will be removed from San José to the proposed new city of Vallejo, about twenty miles above San Francisco, near the Straits of Carquinez, and at the junction of the Napa and San Pablo Bays. The new city has already been surveyed, and a company of influential capitalists organized, with the determination to "go ahead," whether the capital is or is not established at this point. The site no doubt presents many advantages for a large commercial city, not possessed by San Francisco. The distance from the "Golden Gates," (as the entrance from the Pacific to the succession of bays connected with the harbor of San Francisco is termed) is about the same as San Francisco. The harbor is one of the safest and most commodious in the world, and the commissioners appointed by the general government to make surveys and decide upon the best location, have to recommend Mare's Island, half a mile from Vallejo, as the naval depot of the United States in California. The climate of Vallejo is delightful, and the place is never subjected to those strong and cold northerly winds which render San Francisco so disagreeable as a residence and so dangerous as a commercial city. There is plenty of marble for building purposes in the immediate vicinity of Vallejo, and plenty of limestone at a convenient distance, and easily obtainable. The new city will command a most beautiful view of San Pablo Bay and of the country adjacent, and the Napa valley (through which the Napa River flows, and near the mouth of which the city is located,) and the Sonoma valley in the vicinity are among the most fertile in California. Near Vallejo are also mineral springs, possessing similar properties, and said to equal the celebrated Congress Springs at Saratoga. CHAPTER XIII. THE MINERALOGICAL AND OTHER CHARACTERISTICS OF GOLD, AND THE MODE OF DISTINGUISHING IT WHEN FOUND; TOGETHER WITH THE ASSAY, REDUCTION, AND REFINEMENT OF GOLD. For the purpose of presenting all that is connected with that precious metal, that has built up a state within a few years, and of making the reader fully acquainted with all that is necessary for the gold-seeker to know, we will now describe, in some detail, the natural history, character of gold, and the mode of determining its presence and value. Gold _invariably_ exhibits something of the peculiar yellow color which it is known to possess in a pure state; but this color is modified by various metals with which it may be mixed. Thus it may be described as having various shades of gold-yellow; occasionally approaching silver-white, occasionally resembling brass-yellow of every degree of intensity, and even verging on steel-gray in some specimens from South America.