1894.] Specific Resistance of Pure Electrolytic Copper. 



65 



In the determination of the specific gravity, both the hydrostatic 

 balance method and the picnometer method were used. The latter 

 method was found to give more accurate results. A point of great 

 importance was the estimation of the temperature of the specimens 

 during measurement. To obtain as great accuracy as possible in the 

 temperature readings, an apparatus similar to a calorimeter was 

 employed for enclosing the coil of wire whilst it was measured. A 

 standard thermometer divided in tenths of degrees centigrade was 

 used, placed in the vessel containing the sample of wire. It was read 

 at a distance by means of a telescope. 



The arrangement is represented by fig. 1. It consists of three 



FIG. 1. 



cylindrical tinned iron vessels arranged concentrically one inside the 

 other. The section of the two outer vessels (fig. 1) is distinguished 

 by the shading from that of vessel 3. The vessels formed three water- 



VOL. LVI. F 



