During the past three decades the organic chemist has become in creasingly used to take advantage of more and more complex instrumenta tion and physical measurements in lieu of laborious, time-consuming and often ambiguous chemical transformations. Mass spectrometry is perhaps the most recent, most complex and most expensive addition to this field. In view of the astonishingly quick acceptance of nuclear magnetic reso nance by the organic chemist it is, in retrospect, surprising that he has neglected mass spectrometry for such a long time. This can be explained, in part, by the complexity of...