ON STANDARDS OF ELECTRICAL RESISTANCE. 



359 



21-6 

 21-8 



21-8 



22-0 



Length 1-6187 m. 



No. III. 

 565 

 570 

 573 

 572-5 

 Zero-point at 514. 



20-8 

 21 

 21 

 21 

 "Weight 2-7151 grammes. 



Resistance of metregramme of wire No. 



No. 

 No. 



Gold. 



Three gold wires were tried. 



No. I. from Australian gold. 

 No. II. from English coin. 



I. 1-0000. 



II. 1-0005. 



III. 1-0011. 



No. 



III. from English coin. 



The metal was first dissolved in nitro-hydrochloric acid, the excess of 

 acid was then evaporated off, and the salt largely diluted with water to 

 precipitate the chloride of sUver. After filtering the gold was precipitated 

 by sulphiu-ous acid, the precipitate collected in a small beaker, and washed 

 four times with hydrochloric and nitric acid alternately. After drying it 

 was fused with borax and nitrate of potassium and cast. It was again fused, 

 and finally cast in the mould. 



Wire No. I. 



Lead. 

 With lead very good results were ohtaiaed. Five wires were determined. 



