286 Sub-Lieut. A. L. Williams on the Electrical 



The hardness was above that of glass, and the material was 

 much more brittle than copper-mica and had more metallic 

 lustre. X-ray examinations showed the mixture to be 

 homogeneous. The specific gravity in Case No. 1 was 3*7, 

 and in Case No. 2 was 4. The specimens studied were quite 

 irregular in shape, but from a rough examination of the sizes 

 of the samples, it appeared that the sample which had the 

 higher mica-content was the one which had the higher 

 specific resistance. 



(c) Aluminium and Mica. — No fusion was obtained 

 between aluminium and mica. The two seemed to remain 

 entirely separate. 



(d) Antimony and Mica. — The antimony when heated gave 

 off dense clouds of vapour, leaving nothing to fuse with 

 the mica. 



(e) Bismuth and Mica. — The same results were obtained 

 as with antimon3 r . 



(f) Cobalt and Mica. — Cobalt and mica were fused on the 

 iron plate in the same manner as the copper and mica. The 

 cobalt-mica had a very dull black colour and was very 

 brittle, but hard enough to scratch glass. Platinum wires 

 were fused in the ends with difficulty, and the resistance at 

 ordinary temperatures was very great. When heated red 

 hot with a bunsen fin me, a current of about *020 ampere 

 was obtained, using the 110 circuit. 



(g) Nickel and Mica. — When nickel and mica were fused, 

 the substance produced was very similar to cobalt-mica. 

 When it was heated red hot, a current of about '001 ampere 

 was obtained, using the 110 circuit. 



(h) Manganese and Mica. — Mica and manganese did not 

 seem to mix at all. In one test, the manganese was found 

 to form a complete shell around the mica, and in other cases 

 an X-ray photograph showed the two to be quite separate. 



(i) Silicon and Copper. — It did not seem at all easy, if 

 indeed possible, to fuse copper and silicon. The two sub- 

 stances appeared to be quite separate after fusion. 



(j) Selenium and Copper. — These fused quite readily and 

 formed a dull black substance with very little or no lustre. 

 The resistance was found at various temperatures and a 

 graph, No. 8, drawn. The specific gravity was 66, and the 

 hardness less than that of glass. With this mixture it will 

 be seen that a discontinuity occurred in the resistance tem- 

 perature measurements at about 150° C. The explanation of 

 this result does not appear evident at present. 



