the Cation in Voltaic Combinations. 457 



in a U-tube in ice and brine. After the liquid had increased 

 considerably in volume, and absorption of chlorine appeared 

 to have ceased, a part was transferred to a dried stoppered 

 bottle in ice and brine, and the rest mixed with distilled 

 water to form the saturated solution. The results obtained 

 with this freshly-made chloride were quite similar to those 

 with the purchased substance, except that the latter left an 

 undissolved residue when added to water, apparently bro- 

 mine. 



18. Dry bromine chloride does not conduct the current. 

 This is remarkable, considering its great likeness to the corre- 

 sponding iodine compound. Two platinum wires sealed in 

 separate glass tubes were connected up in circuit with a very 

 sensitive reflecting-galvanometer, and cells giving an elec- 

 tromotive force of 5 volts. On immersing the projecting 

 ends of the wires in the chloride (either the purchased sub- 

 stance or that freshly prepared and kept in the freezing-mix- 

 ture) I could not, with certainty, detect the smallest de- 

 flexion. If the wires were allowed to touch the glass sides or 

 bottom of the bottle under the liquid, there was a deflexion of 

 several centimetres on the scale. I believe this was probably 

 due to the formation on the glass surface of a conducting 

 film of hydrated chloride from moisture on the glass. The 

 effect was less if the glass vessel had been very carefully dried 

 just before. A solution of bromine chloride in benzol is also 

 nonconducting, and the same effect occurs on touching the 

 glass with the wires. 



19. When dry, bromine chloride was arranged as the elec- 

 trolyte of a voltaic combination with zinc and platinum plates ; 

 there is, as would be expected, no current observable, and 

 when these metals were carefully insulated with paraffin and 

 kept from touching the glass under the liquid, there was only 

 a comparatively small and irregular deflexion produced in 

 the electrometer. 



20. Bromine chloride, when added to water, forms a hy- 

 drated chloride, and when the aqueous solution was electro- 

 lysed between platinum poles, gas was given off from both 

 anode and cathode, and the liquid lost its colour. The positive 

 pole tarnished very soon, but neither smell nor colour of free 

 chlorine or bromine was detected. Probably hydrochloric and 

 hydrobromic acids were formed. A positive pole of carbon rod 

 partially disintegrated, and the negative platinum blackened 

 after some time. When a gradually increasing E.M.F. was ap- 

 plied to the platinum poles immersed in the aqueous solution, 

 the ratio of current to applied E.M.F. became sensibly constant 

 at about '01 D. The heat of combination Br, CI is *012 of the 

 heat-equivalent of the action in the Daniell. The curve BrCl 



