Royal Society. 535 



pcrcha covering was about four times as great. Hence the 

 thickness of the equivalent Leyden phial must have been 



As the surface of the wire amounted to 8300 square feet, we 

 may infer that if the gutta-percha had only the same (and it 

 probably has a little greater) inductive capacity as glass, the in- 

 sulated wire, when the outer surface of the gutta-percha was 

 uninsulated, would have had an electrical capacity equal to that 

 of an ordinary Leyden battery of 8300 square feet of coated 

 glass jji'd of an inch thick. 



Iuverclog, Arran, 

 June 1854. 



LXXV. Proceedings of Learned Societies. 



ROYAL SOCIETY. 



[Continued from p. 474.] 

 March 8, 1855.— Sir Benjamin Brodie, Bart., V.P., in the Chair. 



r I "'HE following paper was read : — 



-*- *' On Circumstances modifying the Action of Chemical Affi- 

 nity." By J. H. Gladstone, Ph.D., F.R.S. 



The question intended to be solved in this communication is, — 

 what takes place when two binary compounds AB and CD are 

 brought together under such circumstances that both they them- 

 selves and the products of their mutual action remain free to react ? 

 Do they, according to a generally received opinion, remain unaltered, 

 or, should the affinities so preponderate, become simply AB and 

 CB ? Or do A and C, according to Berthollet's view, divide them- 

 selves in certain proportions between B and D, the said proportions 

 being determined not solely by the difference of energy in the affini- 

 ties, but also by the difference of the quantities of the bodies ? And, 

 supposing the latter to be the correct view, do the amounts of AD 

 and CB produced by the reaction, increase progressively with the 

 relative increase of AB, or do sudden transitions occur, such as 

 Bunsen and Debus have recently observed in certain cases where the 

 products were removed at once from the field of action ? 



A reply was sought in the colours produced upon mixing different 

 salts in aqueous solution. There were not many coloured salts suit- 

 able for the purpose, as it generally happens that a base gives the 

 same colour with whatever acid it is combined, and vice versa ; but 

 the compounds of sesquioxide of iron were peculiarly adapted to 

 the requirements of the experiment, as some are intensely coloured 

 while others are nearly colourless. 



The circumstances that attended the formation of the blood-red 

 sulphocyanide were first fully examined. On mixing known quan- 

 tities of different ferric salts with known quantities of different Mil- 



