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.

One of the characteristics of the development of chemical science in the middle of the present century is the vigorous pro gress of the "third chemistry," which is often named now the chemistry of heteroorganic compounds. Then in the last decade, among specialists in this field there has been a marked increase in interest in heteroatomic organic derivatives of silicon, i. e. , heteroorganic silicon compounds. However, until recently this new class of chemical substances, which is extremely interesting theoretically and practically, has been without a single specialized monograph which systematizes and generalizes all progress in the heteroorganic chemistry of silicon. The first attempt in this direction was our book "Heteroorganic Compounds of Silicon" [42 (F), 17 (S) *], which appeared at the end of 1966 and was published as an English translation in the USA in 1969. However, as follows from its subtitle "Derivatives of Inorganic Elements," this mono graph could not cover the whole broad field of the chemistry of heteroorganic compounds of silicon. The main reason for this was above all the abundance and variety of original investigations of organosilicon derivatives of inorganic elements, which was un expected even to the authors themselves. As a result of this the planned length of the book compelled us to omit the sections on organosilicon compounds of phosphorus and sulfur, which had al ready been prepared for publication.

One of the characteristics of the development of chemical science in the middle of the present century is the vigorous pro gress of the "third chemistry," which is often named now the chemistry of heteroorganic compounds. Then in the last decade, among specialists in this field there has been a marked increase in interest in heteroatomic organic derivatives of silicon, i. e. , heteroorganic silicon compounds. However, until recently this new class of chemical substances, which is extremely interesting theoretically and practically, has been without a single specialized monograph which systematizes and generalizes all progress in the heteroorganic chemistry of silicon. The first attempt in this direction was our book "Heteroorganic Compounds of Silicon" [42 (F), 17 (S) *], which appeared at the end of 1966 and was published as an English translation in the USA in 1969. However, as follows from its subtitle "Derivatives of Inorganic Elements," this mono graph could not cover the whole broad field of the chemistry of heteroorganic compounds of silicon. The main reason for this was above all the abundance and variety of original investigations of organosilicon derivatives of inorganic elements, which was un expected even to the authors themselves. As a result of this the planned length of the book compelled us to omit the sections on organosilicon compounds of phosphorus and sulfur, which had al ready been prepared for publication.