Aluminium Bronze

A ruloor two is giveu inTheAluminium World in regard to obtaining the best castings with aluminium brouze, in order to ayoid the difficulties which are so freqnently met with in meltiug. An essential point mentioned is the special care to be taken not to overheat the metal, the fact being that, if it be heated to too high a temperatura, the aluminium will oxidize, the oxide which is thus formed ruaking theentire casting what artisans term "dirty," and the metal will also be spongyfrom the presence of large amounts of occluded gases. The scum, too, which floats ou top of he melted brouze in the crucible must je prevented from going into the body of the casting, this being practicable by n'oviding the casting with suitable skini ?ates. The greatest trouble in making jronze eastings, however, arises from he shrinkage of the metal, which is very great - a difHculty which is overeóme if the casting have a large siuking iead and "risers, " it being necessary, lowever, in ruauy cases to inake the inking head fully as large as the castug.