260 



Mr. G. Gore on a momentary 



[Jan. 28, 



The effect of cold upon the aqueous acid was briefly examined, the result 

 being that a comparatively small amount of hydrofluoric acid lowers the 

 freezing-point of water very considerably. 



The chemico-electric series of metals &c. in acid of 10 per cent, and in 

 that of 30 per cent, were determined. In the latter case it was as 

 follows : — zinc, magnesium, aluminium, thallium, indium, cadmium, tin, 

 lead, silicon, iron, nickel, cobalt, antimony, bismuth, mercury, silver, 

 copper, arsenic, osmium, ruthenium, gas-carbon, platinum, rhodium, pal- 

 ladium, tellurium, osmi-iridium, gold, iridium. Magnesium was remark- 

 ably unacted upon in the aqueous acid. The chemico-electric relation of 

 the aqueous acid to other acids with platinum was also determined. 



Various experiments of electrolysis of the aqueous acid of various degrees 

 of strength were made with anodes of platinum. Ozone was evolved, 

 and, with the stronger acid only, the anode was corroded at the same 

 time. Mixtures of the aqueous acid with nitric, hydrochloric, sulphuric, 

 selenious, and phosphoric acids were also electrolyzed with a platinum 

 anode, and the results are described. 



III. " On a momentary Molecular Change in Iron Wire." 

 By G. Gore, F.R.S. Received November 14, 1868. 



Whilst making some experiments of heating a strained iron wire to red- 

 ness by means of a current of voltaic electricity, I observed that, on discon- 

 necting the battery and allowing the wire to cool, during the process of 

 cooling the wire suddenly elongated, and then gradually shortened until it 

 became quite cold. 



On attempting, some little time afterwards, to repeat this experiment, 

 although a careful record of the conditions of the experiment had been kept, 

 it was with some difficulty, and after numerous trials, that I succeeded in 

 obtaining the same result. Having again obtained it, I next examined and 

 determined the successful conditions of the experiment, and devised the 

 following arrangement of apparatus. 



A A (fig. 1) is a wooden base 61 centimetres long and 15*5 centimetres 

 wide. B and C are binding-screws ; they are provided with small brass mer- 

 cury-cups fixed in the heads of the screws for attachment of the wires of a 

 voltaic battery. D is a binding-screw for holding fast the sliding wire 

 hook E. F is a cylindrical binding-screw, fixed to the sliding wire G, 

 which is held fast by the binding-screw B. H is the iron or other wire 

 (or ribbon) to be heated : one end of this wire passes through the screw F 

 and is tightly secured by it, whilst the other end is held fast by the cylin- 

 drical binding-screw I ; the binding-screw I has a small projecting bent 

 piece of copper wire secured to it, which dips into a little shallow dish or 

 cup of mercury, J ; and the mercury in this cup is connected by a screw 

 and strip of brass to the binding-screw C. K is a stretched band of vul- 

 canized india-rubber, attached at one end to the hook of the wire E, and 



