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PROCEEDINGS OF THE AMERICAN ACADEMY. 



Two specimens of the molybdenite were made into the form of resist- 

 ance thermometers by depositing heavy copper-plated areas near the 

 two ends of thin pieces of the molybdenite and soldering thin copper 

 strips to the copper plate. For insulation a thin strip of mica was 

 placed over the molybdenite, and one of the copper leads was bent back 



TEMPERATURE 



Figure 11. Effect of temperature on electrical resistance of molybdenite. 



over the mica so that both leads ran away parallel with the mica insu- 

 lation between. The whole conductor was then placed between two mica 

 strips and inserted in a flattened brass tube. The tube was then mashed 

 tight together so as to clamp securely the molybdenite and its leads. 

 The end of the tube adjacent to the molybdenite was soldered up. The 

 leads were brought out at the other end of the tube and connected 

 to binding posts insulated by a hard rubber head from the tube. 



The two molybdenite resistances thus mounted are called No. 50 and 

 No. 51. The dimensions of the molybdenite used in No. 50 were not 

 recorded. The molybdenite in No. 51 was .65 cm. wide by .7 cm. long ; 

 the thickness was about .3 mm. 



