Letters to the Editor
Twenty‐five millionths of a gram of beryllium per cubic meter of breathed air can cause acute lung disease. Industrial users of beryllium have standard practices to protect the workman. It is important that all scientists and technicians learn how to work safely with beryllium and its compounds.
Physicists often leave the new ground they break for others to till and to cultivate. Solid state physics, the author finds, is unique because physicists are continuing its exploitation. This, he thinks, may be a new pattern for other fields from which the frontier has withdrawn. This article is taken from a speech given at the dinner meeting of the American Physical Society's Division of Solid State Physics in Cleveland on March 11, 1949.