Polarized Light Microscopy and Supplementary Techniques

The Armour Research Foundation has for the past six years been especially active in publishing crystallographic data for common and important compounds. During this period nearly eighty complete descriptions have been published as monthly contributions in Analytical Chemistry (1). At least eight other laboratories have collaborated with the Foundation on publications in this series. The net result of this activity is to increase the number of adequately described compounds available for analytical purposes. When a reasonable proportion of the common everyday compounds have been described in this way, analytical methods based on the use of polarized light microscopy and other allied crystallographic techniques will become more useful. That these data will be useful for analytical purposes is shown by Table I where the accuracy possible in measuring two crystallographic properties is compared with the accuracy possible in measuring melting points. This paper has the aim of increasing the number of contributions of crystallographic data by carefully outlining the methods and techniques used in accumulating the data necessary for a complete description. Since the methods of polarized light microscopy are very adequately covered in such texts as Chamot and Mason (2), Hartshorne and Stuart (3), and Wahlstrom (4), this paper will only illustrate the integration of these techniques into a complete description.