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 XIII. Intelligence and Miscellaneous Articles. 



ON THE COMPOSITION AND THE INDUSTRIAL USE OF THE GASES 

 ISSUING FROM METALLURGIC HEARTHS. BY L. CAILLETET. 



nPHE remarkable investigations of H. Sainte-Claire Deville on dis- 

 -*- sociation, in opening to science a new path of research, have 

 likewise promised to interpret a great number of metallurgical 

 phenomena which had till then remained unexplained. 



By collecting the gases which circulate in the hottest part of the 

 furnaces in which iron is worked, I have been able, by means of 

 apparatus similar to M. Deville' s, to prove that the composition of 

 those gases, suddenly cooled, is totally different from the results 

 given by the analyses of Ebelmen. That skilful metallurgist, unac- 

 quainted with the phenomena of dissociation, collected the gases by 

 slowly aspirating them by means of a long tube — which necessarily 

 brought about the combination of their dissociated elements. 



In Ebelmen's analyses the reaction seems almost always com- 

 plete, while the cooling undergone by the gases shows that smoke 

 and carburetted gases can subsist in presence of oxygen at the tem- 

 perature of welding iron. 



The gases collected at the top of the grating of an annealing-oven, 

 at a point where the temperature is such that the eye cannot sup- 

 port the brightness of the bricks raised to a most intense whiteness, 

 contain : — 



Oxygen 13-15 



Carbonic oxide 3*31 



Carbonic acid 1*04 



Nitrogen (by difference) . . 82-50 



100-00 

 Independently of the carbonic oxide, there is found in the oxi- 

 dizing atmosphere of the oven a large excess of finely divided carbon, 

 which deposits itself on the tube, hot and cold, which serves for the 

 aspiration. 



In metallurgic works the gases issuing from welding-fires are 

 generally conducted beneath generators, which thus produce with- 

 out expense the supply necessary for the working of engines. The 

 gases, therefore, rapidly cool against the walls of the boiler • thus, 

 after traversing a length of 15 metres, their temperature is below 

 500°. They are then formed of 



Oxygen 7'65 



Carbonic oxide 3*21 



Carbonic acid 7 -42 



Nitrogen (by difference) . . 81*72 



100-00 



It may be concluded from this analysis that the quantity of 



oxygen has diminished by nearly one half, in reacting, not upon 



the carbonic oxide, of which the proportion has changed but little, 



but upon the finely divided carbon, which exists in large quantity, 



