364 



REPORT 1864. 



Connexions of amalgamated platinum were first used, but did not give 

 good results. It was found that the amalgamation was imperfect. The mer- 

 cury adhering to the platinum was rubbed off against the ends of the tube, 

 and the resistance varied with the height of the mercury in the bent tubes. 

 The platinum was amalgamated by dipping it into a mixture of mercury and 

 sodium amalgam. The sodium was then oxidized and chssolved off by dip- 

 ping the platinum in a little dish of water and hydi'ochloric acid. The ter- 

 minal was then drawn through a dish of clean mercury, so that the water 

 floated off. The platinum was then for the time beautifully amalgamated ; 

 but the mercury soon drained off when the plate was exposed to the air, and 

 could be easily rubbed off even when the platinum was immei'scd in mercmy. 



Mercury. 



Temperature of coil. 



18 

 18 

 18 

 18 



o 



19-G 

 21-0 

 20-8 

 Wts. reduced to 



Wt., temp. 



•1 

 •4 

 •4 

 •8 



grins. 



.... 24-7021 



.... 24-6930 



.... 24-6950 



21°:— 



24-6958 

 24-6930 

 24-6940 



Tube N"o. I. 



Reading of 

 bridge-scale. 



346 

 349-2 

 349.2 

 348 

 Zero-point 515 



19-6 

 19-9 

 20-0 

 20-0 



Tube No. II. 



188 

 186-8' 

 186-5 

 186-5 



Wt. 



at 21-2 

 , 21-6 



grms. 



. 12-3140 

 . 12-3132 



Temperature of wire. 



l°8-2 

 18-6 

 18-8 

 18-0 

 Length 0-9365 m. 



19-0 

 1905 

 19-1 

 19-1 



Length 0-6563 m. 



Tube Ko. III. 



19-0 

 19-0 

 19-1 

 ^ 19-15 grms. 



Wt. at 22-2 8.2894 



„ 22-2 8-2836 



633-5 

 633-1 

 631-7 

 631-3 



18-9 

 18-8 

 18-8 

 18-8 

 Length 0-5497 m. 



