So, too, of “chemical affinity,” we do not know exactly why it acts as it does, or what its force really consists in; we can only say that it depends on the different motions and appetencies or repulsions of the atoms of the various kinds of matter being made manifest, when such atoms are loosened from their previous condition by heat or what not, and so being rendered free, are able, through their inherent qualities and attractions, to arrange themselves afresh under the new conditions, in the order compelled by such endowed qualities and attractions. We can only judge of motion, or force, or energy by witnessing its effects; and when we say that gunpowder or coal contain in them a store of potential energy, we only know that they do contain the capacity for producing movement and doing work. The gunpowder will, if inflamed, expand suddenly by the production of gases resulting from chemical changes induced by heat, and in such explosion will give liberty to enormous force. And so likewise as to coal: on being subjected to chemical change by heat, it will, though in a less rapid way, give off its equivalent of force or energy; but as to what this acting force or energy really is, we know nothing more than that it is motion—and as to what potential force is, we know nothing more than that it is the capacity for movement in store. SOME GERMAN ART AND ARTISTS. If it is true, as Emerson affirmed, that “It never was in the power of any man or any community to call the arts into being,” that “they come to serve his natural wants, never to please his fancy,” then Berlin offers in her new National Gallery a fine illustration of this theory. In 1841 King Frederick William IV engaged the architect Stüler to draw a plan of a building, after the style of a Corinthian temple, which should inclose a fine room, serviceable as a lecture hall for the University, an exhibition hall for pictures, or a public audience room. They determined to locate this building just back of the Royal Museum, on the so called “Museum Island.” The king died before his plan was developed. In March, 1861, the Swedish consul, J. H. W. Wagener died in Berlin, leaving as a legacy to the state his collection of pictures, which was known in the city as the “Wagener Collection,” which occupied several rooms in the “Kunst Akademie.” In these same rooms every two years was held the exhibition for German artists, accompanied with the never ceasing regret that the accommodations were so poor. So necessity originated the idea of utilizing the “Corinthian Temple,” then about to be built, not for a “city hall,” according to the intention of Frederick William IV, but for an “art museum,” exclusively for German art. The thought of such a magnificent temple for their future works inspired all ambitious German artists, for it was understood that whenever anything superior was produced it should pass into the public possession, thus rendering the sale of great works possible, and