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Radiaticyn of Rough and Polished Surfaces. 299 



the portion of his memoir yet published) to pass over without 

 any attempt at explanation, certain chemical phenomena of 

 constant occurrence, which follow directly from the principles 

 of the theory to which he has objected. 



These are, 1*^, The evolution of sulphuretted hydrogen, in 

 quantities far exceeding what are to be explained by the reac- 

 tion of carbonaceous matter upon sulphates, or any of those 

 other processes which sometimes produce it on the surface of 

 the earth. 



9.dly^ The disengagement of sal-ammoniac, for although one 

 of the constituents of this compound, the muriatic acid, might 

 arise from the decomposition of sea-salt by aqueous vapour, the 

 other one, the ammonia, implies the presence of free hydrogen 

 as well as of nitrogen gas, near the focus of the volcanic action. 



3J/z/, The circumstance, which I have substantiated in so 

 many cases, that I begin to believe it almost universally true, 

 that the atmospheric air exhaled from volcanos, and indeed 

 generally from the interior of the earth, is deprived in a greater 

 or less degree of its proper proportion of oxygen. That pro- 

 cesses, therefore, by which this principle is abstracted, are going 

 on extensively within the globe cannot be denied, and hence I 

 conceive that any theory, which attempts to account for vol- 

 canic action, witliout taking notice of so essential a phenome- 

 non, ought to be regarded as imperfect, and unsatisfactory. 



Upon the alleged Injluence which the Roughness and the Polish 

 of Surfaces exercise upon the Emissive Power of Bodies, in 

 reference to the Experiments of Professor Sir John Leslie. 

 By M. Melloni. 



When we measure the intensity of calorific radiation which 

 takes place from the two sides of a metal vessel filled with boil- 

 ing water, having the one of its longitudinal sides highly po- 

 lished and brilliant, and the other, though at first polished, yet 

 subsequently more or less streaked or furrowed with emery, or 

 with the graver, or the file, we discover that the quantity 

 of heat emitted by the streaked or unpolished surface, is always 

 superior to that which emanates from the brilliant one. These 

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