Roy ul Society. 59 



remain, and may be examined at leisure. These are different 

 phenomena from those displayed by spongy platinum when it 

 forces hydrogen and oxygen to combine. 



Appendix. — Continuation of the investigation at the laboratory 

 of the Royal Mint, London, by the kind permission of Mr. 

 Roberts : — 



The alloy was dried in vacuo over sulphuric acid. It was then 

 heated in vacuo by means of a Sprengel pump, when it decom- 

 posed, and the resulting gas was collected over mercury. It was 

 found to have twenty- seven times the volume of the original 

 solid. Analysis of the gas proved it to contain nitrogen and 

 hydrogen. The results of a further examination will shortly be 

 given. 



June 23, 1869. 



IX. Proceedings of Learned Societies. 



ROYAL SOCIETY. 

 [Continued from vol. xxxvii. p. 474.] 



Jan. 28, 1869. — John Peter Gassiot, Esq., Vice-President, in the 



Chair. 

 rpHE following communications were read : — 

 ■*■ "Ona momentary Molecular Change in Iron Wire." By G. 

 Gore, F.R.S. 



Whilst making some experiments of heating a strained iron wire 

 to redness by means of a current of voltaic electricity, I observed that, 

 on disconnecting the battery and allowing the wire to cool, during 

 the process of cooling the wire suddenly elongated, and then gra- 

 dually shortened until it became quite cold. 



On attempting, some little time afterwards, to repeat this expe- 

 riment, 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 ob- 

 tained it, I next examined and determined the successful conditions 

 of the experiment, and devised the following arrangement of appa- 

 ratus. 



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

 timetres wide. B and C are binding-screws ; they are provided with 

 small brass mercury-cups fixed in the heads of the screws for attach- 

 ment 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 cylindrical binding-screw I ; 

 the binding-screw I has a small projecting bent piece of copper wire 



