Excerpt from Arpa-Nbs Program of Research on High Temperature Materials and Laser Materials: Reporting Period July 1 to December 31, 1969 In this sense of providing support for the strategy for the development of needed materials, the present program has come to focus upon two problem areas, Diffusion in Oxides, and Properties of Laser Materials. The arpa support for the other areas listed in the Table of Contents in this Report is being phased out, and will for the most part cease with the present reporting period, although the work on Properties of Refractory Borides, which is included in a separate propo sal to arpa, may be continued for another six months. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.