602 BEPOET^1891. 



4. Report on the Bibliography of Solution, — See Reports, p. 273. 



6. Report on the Properties of Solutions. — See Reports, p. 273. 



6. Report on the Bibliography of Spectroscopy. — See Reports, p. 264. 



FRIJDA Y, A UG UST 21 . 



The following Report and Papers were read : — 



1. Report of the Committee on the Formation of Haloids. 

 See Reports, p. 274. 



2. The Spontaneous Ignition of Coal. J3(/ Professor YiviAN B. Lewes. 



Ever since Berzelius first suggested that the heat evolved by the oxidation of 

 the pyrites in coal might have an important bearing on spontaneous ignition, it 

 has been adopted as the popular explanation of that phenomenon, and although 

 the researches of Richter and others have gone far to disprove it, this theory is the 

 generally accepted one. It can be shown, however, that the coals most liable to 

 spontaneous ignition often contain as little as 0'8 per cent, of pyrites, and rarely more 

 than 2 per cent., and if this amount were concentrated in one spot, instead of being 

 spread over a very large mass, and if it were entirely oxidised with the greatest 

 rapidity, instead of taking months and often years to complete the action, the total 

 rise of temperature would be totally inadequate to account for ignition of the coal, 

 which requires a temperature of 370° C. to 477° C, according to its characteristics. 

 The liability to spontaneous ignition also does not increase with percentage of 

 pyrites, whilst heaps of pure pyrites free from carbonaceous matter never show any 

 tendency to serious heating. 



The true explanation of the ignition of coal is partly physical and partly che- 

 mical. Freshly won coal has the power of absorbing from 1'.5 to 3 times its volume 

 of oxygen from the air, and this being rendered chemically highly active, partly 

 by compression and partly by elimination of nitrogen, attacks some of the bitu- 

 minous hydrocarbons in the coal, converting them into carbon dioxide and water 

 vapour. Many causes tend to aifect the rapidity of this action, which is the real 

 source of the heat, and directly the temperature begins to rise, unless the heat 

 evolved can freely diifuse itself, the chemical action is so energetic that ignition 

 quickly follows. Up to 38° C. the absorption of oxygen, and consequent chemical 

 action, goes on so slowly that there is little or no chance of undue heating ; but 

 directly this temperature is exceeded, with some classes of coal ignition is only a 

 question of time and mass. The action of mass, condition, and temperature can be 

 beautifully traced in the statistics of spontaneous ignition in coal cargoes, whilst 

 the bunker fires, which are now becoming perilously frequent on the fast liners, are 

 due entirely to rise in temperature from the bunker bulkheads being too close to 

 the hot air up-cast shafts from the boilers and furnaces. 



3. On Nickel Carbon, Oxide and its Application in Arts and Manufactures. 

 By LuDwiG MoND, F.R.S. 



The existence of a volatile compound of nickel and carbonic oxide was first 

 discovered in the author's London laboratory in October, 1889, in the course of an 



