392 



Mr. W. Coldridore on the Electrical and 



the conductivity improved and became comparable with that 

 of the alcoholic solution. 



After passing the direct current for thirty hours, a slowly 

 diminishing polarization-current was registered producing at 

 first a deflexion of thirty scale-divisions. The electrolysed 

 product contained some stannous salt. 



On passing dry sulphuretted hydrogen into the cold ethereal 

 solution an emulsion is formed, and the tetrachloride separates 

 at the bottom of the ether. The distinction between the 

 action of ether and of alcohol under these circumstances will 

 be adverted to in Part II. 



IV. Effect of Strong Aqueous Solution of Hydrochloric 

 Acid. — Instead of taking, as in the previous experiments, a 

 V-tube for the electrolytic cell, a cell of the same pattern was 

 used as that described and devised by Mr. Fitzpatrick (Brit. 

 Assoc. Reports). It is a glass cylinder closed at the ends, 

 where wires leading to the circular platinum electrodes enter; 

 and midway between the electrodes there is an open tube 

 fused into the cylinder. A drop of strong hydrochloric acid 



was poured down the central tube on to the surface of the 

 chloride : as long as it remained unmixed the effect was nil, 

 but on admixture the cell conducted. The same E.M.F. was 

 used as in B. I , II., III., viz. that of twenty-five storage 

 secondary cells and a polarization-current of approximately 

 2 x 10~ 7 C.G.S. units, which is equivalent to a scale-deflexion 

 of sixty scale-divisions. The act of mixing was accompanied 

 by the evolution of heat and by the formation of a subsequently 

 dissolved gelatinous substance. This reverse current was con- 

 stant at the temperature of the" room for nearly an hour : this 

 constancy and its high E.M.F. led me to observe it at differ- 

 ent temperatures. The primary current ran for three minutes; 

 at a temperature of 31° the polarization-current gave a de- 

 flexion which diminished from 77 scale-divisions to 56 in the 

 course of fifteen minutes ; at a temperature of 41° it fell from 

 79 to 63 scale- divisions in twelve minutes; at 51°, from 79 to 

 55 in ten minutes ; at 71°, some hydrochloric acid boiled off 

 explosively ; at 90° more was expelled, the polarization w T as 

 weaker, and decayed from 55 to scale-divisions deflexion at 

 96° C. 



