OXYUKN AND ITS SALINE COM HI NATIONS 175 



is, the maximum possible temperature of the flame of the sulphur 

 burning in air will be 1974 C. In the combustion of the sulphur 

 in oxygen the heat evolved (2250 units) can only pass to the '1 grains 

 of sulphurous anhydride, and therefore the highest possible tempera- 

 ture of the flame of the sulphur in oxygen will be =~- or 7L'">s . 



O'ol 



In the same manner it may be calculated that the temperature of char- 

 coal burning in air cannot exceed 2700, while in oxygen it may attain 

 10100 C. For this reason the temperature in oxygen will always be 

 higher than in air, although (judging from what has been said re- 

 specting detonating gas) neither one nor the other temperature will 

 nearly approach the theoretical quantities. 



Among the phenomena accompanying the combustion of certain 

 substances, the phenomenon of flame attracts attention. Sulphur, 

 phosphorus, sodium, magnesium, naphthalene, cvrc., burn like hydro- 

 gen with a flame, whilst in the combustion of other substances no 

 flame is observed, as, for instance, in the combustion of iron and 

 of charcoal. The appearance of flame depends on the capacity of the 

 combustible substance to yield gases or vapours at the temperature of 

 combustion. At the temperature of combustion, sulphur, phosphorus, 

 sodium, and naphthalene pass into vapour, whilst wood, alcohol, oil, &c., 

 are decomposed into gaseous and vaporous substances. The com- 

 bustion of gases and vapours forms flames, and therefore a flame is 

 composed of the hot and incandescent gases and vapours produced by co/n- 

 bustion. It may be easily proved that the flames of such non-volatile 

 substances as wood contain volatile and combustible substances formed 

 from them, by placing a tube in the flame and drawing air from 

 it with an aspirator. Besides the products of combustion, com- 

 bustible gases and liquids, previously in the flame as vapours, collect in 

 the aspirator. For this experiment to succeed -i.e., in order to really 

 extract combustible gases and vapours from the flame it is necessary 

 that the suction tube should be placed inside the flame. The com- 

 bustible gases and vapours can only remain unburnt inside the flame, 

 for at the surface of the flame they come into contact with the oxy.vvn 

 of the air and burn. 42 Flames are of different degrees of 



42 Faraday proved this by a very convincing experiment on a candle flame. It one 

 arm of a bent glass tube be placed in a candle flame above the wick in tin 1 dark pert ion 

 of the flame, then the products of the partial combustion of the stearin will pass up the 

 tube, condense in the other arm, and collect in a flask placed under it iti-. ''' a- heavy 

 white fumes which burn when lighted. If the tube be raised into the upper lumi- 

 nous portion of the flame, then a dense black smoke which will not inflame aeeiimulates 

 in the flask. Lastly, if the tube be let down until it touches the wick, then little 

 but stearic acid condenses in the flask. 



