ABSTRACTS OF TECHNICAL ARTICLES 539 



Coatings and the Mechanism of Corrosion — Surface Preparation for the 

 Application of Coatings — Types of Metallic Coatings and Methods of 

 Application — -Zinc Coating by Hot-Dipping Process — Zinc Coating by 

 Electroplating and Cementation — Protective Value of Zinc Coatings — 

 Cadmium Coatings and their Protective Value — Tin Coatings — Nickel 

 and Chromium Coatings — Coatings of Copper, Lead, Aluminum and 

 Miscellaneous Metals — Coatings of Noble and Rare Metals — Methods of 

 Testing Metallic Coatings — Composition of Paints and Mechanism of 

 Film Formation — The Durability and Evaluation of Paints — Paint 

 Practices — Miscellaneous Coatings. 



"The active interest manifested during the past few years in in- 

 vestigations on the general subject of the corrosion of metals has led 

 to the carrying-out of long-time exposure tests which yielded much new 

 basic information having a direct bearing on our knowledge of the 

 useful life of coatings and coated metals. The authors have wisely 

 incorporated a great deal of this information in the discussion of the 

 different types of coatings. Likewise, it has been deemed desirable 

 to devote considerable space to the preliminary preparation of metal 

 surfaces before the application of the coating since the quality of any 

 coating is so dependent upon this factor. 



"The new monograph, therefore, covers a much broader field than 

 did the previous one which was really a pioneer in the field of metallic 

 coatings. The investigator of the abstruse problems of corrosion as 

 well as the materials engineer seeking practical help in combating this 

 problem by preventing corrosion by protecting the surface will find 

 this volume a veritable mine of information on all phases of the 

 subject." 



A Synthetic Speaker.^ Homer Dudley, R. R. Riesz, and S. S. A. 

 Watkins. This synthetic speaker is an electrical device manipulated 

 by keys and levers for the production of synthetic vocal sounds and 

 their combination into speech. The device was developed as an in- 

 teresting educational exhibit by the Bell System at the San Francisco 

 Exposition and the New York World's Fair. 



From a buzzer-like tone and a hissing noise as raw material, the 

 operator skillfully shapes speech by manipulating the controls to give 

 inflection and the sound spectrum that differentiates one speech sound 

 from another. 



This paper covers the development of the device and the training 

 of the operators to demonstrate it. 



* Jour. Franklin Institute, June 1939. 



