perience of the authors in teaching, research, and clinical work for a score of years. Thus, the theoretic portion of the chapter on carbohydrates is based on a paper by the writer which was awarded the Edward Longstreth Medal of Merit by the Franklin Institute. The chapter on enzymes is based in part on the experience of the writer in working in that field in the Food Research Laboratoryof the U.S. Bureau of Chemistry, in part on his researches on insectivorous plants which were awarded the Certificate of Merit of the Franklin Institute. The reviewer has overlooked the fact that the book contains standard methods for the analysis of foods, milk, water, and blood, and the recently devised procedures for the determination of urea by means of urease, the colorimetric determination of reducing substances and the nephelometric determination of albumin in the urine, and the determination of neutral fat, fatty acids, and soaps in the feces, as well as discussions of such timely subjects as basal metabolism, cold storage, the separation of the amino acids, and the measurement of liver function. The writer, as co-author of the book, requests that you give to this letter the same publicity as was accorded the review. JOSEPH
SAMUEL HEPBURN
Hahnemann Medical College, Philadelphia, Pa.
In view of the available good books on Physiological Chemistry and Clinical Chemistry the reviewer sees no reason for the existence of the book discussed immediately above, except for the authors' local use. H. BOYD WYLIE University of Maryland Baltimore, Md.
Secret Metal Test Detects Criminals. A secret process that allows themetallurgist to detect marks on steel that a thief or wrongdoer thinks he has entirely obliterated has been developed as a result of research by metallurgists of the U. S. Bureau of Standards. The method originated when the experts were asked to study an army pistol with identikation number badly mutilated. Through their efforts the weapon was h e d into a valuable piece of criminal evidence. The method used has since been employed extensively by police officials. Details of the process will not be revealed for reasons of public safety but it is explained that it rests upon the fact that metals, generally regarded as dead and inert, are actually alive in the sense that they retain in their internal structure evidence of their past history and experience.-Sciace Senice
