There are numerous criteria for measuring the growth and development of branches of chemistry. This valuable book illustrates a particular aspect of the growth of organosilicon chemistry. The extent of this field has developed so greatly in recent years that it now is desirable to reclassify parts to bring together hitherto frag­ mented and relatively disparate sections. This has been accomplished by the presently available large units which have been deSignated as "organosilicon heterocompounds. " Simplified expressions of such classification are structural units of the general type C - Si - heteroelement and heteroelement-C - Si, in which there are attached to the organosilicon moiety elements such as oxygen, nitrogen, metals, etc. This arrangement per­ mits the correlation of extensive material, which will be invalu­ able to chemists in many areas, both in and out of organosi- con chemistry. Because of the wealth of information, the authors are currently engaged in the preparation of companion volumes arranged on this general principle. The scope is broad, and includes material which will prove highly interesting and useful to those in academic, industrial, and governmental circles. There is not only a wide coverage of the literature generally, but the listings of patent references and of general reviews and books are among the most complete so far presented.