THE 



AMERICAN JOURNAL OF SCIENCE 



[THIRD SERIES. 1 



Art. XLI. — On the Deportment of Charcoal with the Halo- 

 gens, Nitrogen, Sulphur, and Oxygen / by W. G. Mixter. 



Charcoal containing the Halogens. 



The difficulty in obtaining amorphous carbon fairly pure is 

 a serious obstacle in an investigation of its properties. Kirwan* 

 observed in the year 1785 that charcoal after prolonged and 

 intense ignition contains hydrogen. The recent handbooks 

 and dictionaries of chemistry state that the hydrogen may be 

 removed by heating the charcoal in chlorine, while the older 

 dictionaries contain nothing on the subject. The writer has 

 been unable to learn who is the author of the method or to- 

 find any mention of analytical tests for chlorine in charcoal 

 purified by ignition in chlorine. Berthelot and Petitf treated 

 wood charcoal with hydrofluoric and hydrochloric acids, next 

 with chlorine at a red heat, and finally calcined it in a Perrot 

 furnace. Their charcoal was doubtless free from chlorine. 

 Weber:}: for his work on the specific heat of carbon prepared 

 amorphous carbon by heating wood charcoal to bright redness 

 for fifteen minutes in a stream of chlorine in order to remove 

 hydrogen. It would be interesting to know that the distin- 

 guished experimenter proved the absence of chlorine in the 

 charcoal he used. Wright and Luff§ heated sugar charcoal for 

 two hours in chlorine and then ignited it for six hours in 

 platinum over a blowpipe to remove chlorine. Their analyses 

 of two preparations are as follows : 



*Kopp, Geschichte der Chemie, iii, 289. f Bulletin, 1889, ii, 90. 



\ Phil. Mag , IV, xlix, 161, 276. § Jour. Chem. Soc, xxxiii, 17. 



A.M. Jour. Sol— Third Series, Vol. XLV, No. 269.— May, 1893. 

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