As regards the preparation and filling of cavities, there are so many conflicting conditions, that we must be governed entirely by the case before us; but to be thorough in our preparation, we must so shape the cavity as to have the walls nearly plumb, uniform margin, slightly undercut. In proximal cavities there may be a groove or pit at cervical wall, but do not have it too near the margin, on account of its liability to produce fracture, and consequent failure at that point. On grinding surfaces, cut out all fissures leading into cavity, and be careful to have no angles. The margin, after all, is the most important point; for just here failure begins, especially at the cervical wall, and care should be taken to thoroughly remove all softened structure, and aim to reach a solid foundation. These margins should be carefully trimmed and burnished, and thus our cavity is ready for the filling. We often hear practitioners decry the rubber-dam, and boast of their skillful use of the napkin; but, gentlemen, many are the failures consequent! For in deep proximal cavities, the dam is invaluable in keeping guard against oozing moisture from the gums, which, without this precaution, will flow upon the filling without our knowledge. The dam adjusted, we proceed to form a mass of non-cohesive gold, and where the walls are strong enough, we can continue with this material throughout. But where cohesive gold is necessary, we should cover our borders, as far as possible, with soft foil; for this is more adaptable to the walls. Another advantage to be found in non-cohesive gold, is its pliability, ease of starting, and rapidity in finishing. We should thoroughly condense from beginning to end, whatever may be the kind of foil used. Filing and finishing is too often hurried through, leaving a surplus of material at the cervical wall, or lapping the edges--another sure cause of failure; and every care should be directed to finish in such way that an instrument passing over the line of demarkation cannot detect it. After filing, we would use pumice, either on a strip of orange-wood, or by some other convenient means, and then polish. The same general rule holds good in amalgam work, and the main cause of failure in these cases is that lack of thoroughness in finishing.