Summary

Metal powders are solid materials which are distinguished from large pieces of metals by their small size and by the immensel high ratio of surface to volume. Their large specific surface plays an important role wherever surface reactions take place. Densi­ fication and shrinkage of a powder mass depends to a large extent on the specific surface area. The large specific surface of powders also contributes to the development of several potentially hazardous properties such as pyrophoricity (flammability), explosivity, and toxicity. Much information has been published concerning the pyrophoricity and explosivity of metal powders. However, with respect to the toxi­ city of metal powders, Miss Brakhnova's book is unique: it is the most comprehensive book on this subject. There are dangerous properties; there are no dangerous materials. Some materials can be hazardous to the uninformed, can have properties that are dangerous if misapplied. They pre­ sent no danger at all as long as we are aware of these properties and know how to handle them. The key to their proper use is to be aware of such characteristics. Itis to the great credit of Miss Brakhnova that she has called some potentially hazardous prop­ erties of metal powders to our attention.