Cond 



uctivity of Cop 



pei 



fused with M 



ica. 





Graph 



N( 



3. 8. 







Temperature 

 °C. 



Resistance 





Temperature, 



Resistance 



(Ohms). 







°C. 



(Ohms). 



370 



■219 







124 



•261 



335 



•207 







115 



•200 



315 



•200 







108 



•176 



29S 



•188 







104 



•172 



260 



•173 







101 



•169 



247 



•164 







98 



•169 



240 



•164 







95 



•168 



230 



•162 







92 



•163 



221 



•157 







90 



•164 



204 



•152 







87 



•164 



190 



•147 







84 



•163 



180 



•139 







80 



•165 



173 



•136 







78 



•167 



167 



•136 







65 



•176 



160 



•135 







61 



•176 



154 



•130 







59 



•177 



136 



•333 







58 



•176 



130 



•317 







41 



•185 



127 



•300 











287 



(k) Ferro- Silicon. — A sample of commercial ferro-silicon 

 was also investigated. It was found to be very brittle and 

 difficult to grind up into regular form for examination. 

 In studying a sample, leading wires of iron were used, as 

 platinum fused readily at the junction when the ferro-silicon 

 was raised to a high temperature. When a graph was drawn 

 between temperatures as abscissae and resistance as ordinates, 

 the result was a straight line showing that the resistance 

 varied directly as the temperature, just as in the case of 

 ordinary pure metals. (See Graph No. 7.) 





Graph No 



7. 







Temperature 



Resistance 





Temperature 



Resistance 



°C. 



(Ohms relative). 







°C. 



(Ohms relative) 



280 



•092 







148 



•078 



259 



•089 







139 



•077 



246 



•088 







126 



•076 



226 



•085 







118 



•075 



214 



•084 







109 



•074 



202 



•083 







96 



•073 



185 



•082 







84 



•071 



176 



•081 







79 



•070 



165 



•079 







71 



•070 



c. 



Experiments by Miss Giles. 



In these experiments a micrographic study was made of the 

 plane polished surfaces of the fused copper-mica mixtures 

 referred to above. These were made both when the mixtures 



