SELENIUM CELLS
Reading edition
THE CONSTRUCTION, CARE AND USE OF SELENIUM CELLS WITH SPECIAL REFERENCE TO THE FRITTS CELL
BY THOS. W. BENSON
NEW YORK SPON & CHAMBERLAIN, 120 Liberty Street LONDON E. & F. N. SPON, Limited, 57 Haymarket, S. W. 1919
Copyright, 1919 By Thomas W. Benson VAIL-BALLOU COMPANY BINGHAMTON AND NEW YORK
APPRECIATIVELY DEDICATED TO J. A. STELTZER
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
LIST OF ILLUSTRATIONS
FIG. PAGE
1. Bildwell Cell 7
2. Ruhmer Cell 10
3. Bell and Taintor Cell 12
4. Mercadier Cell 14
5. Gripenberg Cell 15
6. Fritts Cell 17
7. Hot Press with Cell in Place 21
8. Details of Hot Press (elevation) 22
8. Details of Hot Press (plan) 22
9. Platen for Cell; and Template for Applying Selenium 24
10. Fiber Pieces for Enclosing Cell 26
11. Mode of Assembling Cell 30
12. Testing and Maturing Set 33
13. Layout and Wiring Diagram of Testing Maturing Set 35
14. Connections for Buzzer and Induction Coil to Produce Alternating Current 36
15. Connections for Interior of Rheostat Box 38
16. Circuit for Wheatstone Bridge Measurement 40
17. Circuit for substitution Method of Measurement 47
18. Showing Cell ready for Assembly with Four Complete Cells in background 49