FOREWORD
The lack of definite information relative to the construction of selenium cells has led the writer to put in this form the results of some of his experiments. The method described was originated by Mr. C. E. Fritts but the apparatus used was developed by the writer.
Despite the fact that sensitive cells are very difficult to construct by the methods in vogue the use of apparatus described practically eliminates failures, the cells, almost without exception, being useful for one purpose or another.
This is by no means the last word on the subject. Many improvements are possible and have been pointed out in the text. Should these instructions but serve to interest others in the fascinating study they will have served their purpose.
Thos. W. Benson.
Philadelphia, Pa.
CONTENTS
| PAGE | ||
| CHAPTER I | ||
| Selenium, the Element | [ 1] | |
Discovery, Naming and Classification. Where Found and Method of Extraction. Three Forms, Amorphous, Vitreous and Metallic. | ||
| CHAPTER II | ||
| Consideration of Cell Types and Their Characteristics | [ 5] | |
Factors in Design. Bildwell Cell. Application of Selenium and Annealing. Ruhmer Cell. Bell and Taintor Cell. Mercadier Cell. Gripenberg Cell. Theory of Operation. | ||
| CHAPTER III | ||
| The Construction of Fritts Selenium Cell | [20] | |
Description of Hot Press. Accessories for Press. Other Apparatus Required and Supplies. Preparing Copper Plate. Applying Selenium. Treating in Hot Press. Application of Gold Foil. Assembling Cell. | ||
| CHAPTER IV | ||
| Testing and Maturing Selenium Cells | [32] | |
Two States. Testing and Maturing Set. Accessories for Set. Construction of Rheostat Arm for Wheatstone Bridge. Measurement of Cells by Bridge Method. Tests for Light Sensitiveness. Proper Voltage. Classification of Cells. Testing for Polarization. Treating with A. C. Raising Resistance of Cells. Testing for Current Generation. Reconstruction of Useless Cells. Measurement of Cells by Substitution Method. Sealing Cells. | ||
| CHAPTER V | ||
| Applications of Selenium Cells | [51] | |
Photometric Applications. Transmission of Speech Over Beams of Light. Automatic Control of Light Buoys and Isolated Lights. As Recorder of Sunlight. Astronomical Applications. Talking Pictures. The Phonoptican, How the Blind May Read by Sound. Controlling Mechanisms at a Distance. Electric Dog. Use in Cable Telegraphy. Burglar Alarm. Selenium Batteries, Current Generators. Telephonic Properties. Effect of Different Current Sources on Sensitiveness of Cells. | ||
| CHAPTER VI | ||
| The Care of Selenium Cells | [62] | |