the Halogens, Nitrogen, Sulphur and Oxygen. 369 



is passed over hot chlorinated charcoal hydrochloric acid, which 

 is not retained by hot charcoal, is formed very slowly. Assum- 

 ing that chlorine combines chemically with glowing charcoal, 

 the question is, Does the chlorine unite directly with the 

 carbon ? Berzelius* stated, " In wasserfrei Chlorgas wird ein 

 wohlausgegliihte Kohle bei keine Temperatur verandert." 

 IsTothing was said about testing the charcoal for chlorine. Recent 

 writers state that carbon and chlorine do not unite directly, and 

 the foregoing results with the diamond, graphite and gas car- 

 bon are in accord with this view. Chlorine, however, combines 

 at high temperatures with charcoal which is not pure carbon 

 but contains hydrogen and the latter is apparently replaced by 

 chlorine in the chlorination of charcoal. Gas carbon contain- 

 ing - 035 per cent of hydrogen does not take up chlorine, 

 while sugar charcoal with 0'07 per cent of hydrogen does. 

 Further experiments are necessary in order to determine 

 whether sugar charcoal and gas carbon with a like content of 

 hydrogen differ in their deportment towards chlorine. 



Nitrogenous Charcoal. 



Animal charcoal is known to contain nitrogen and to yield 

 cyanogen to molten alkalies but the amount is not given, 

 although doubtless known to manufacturers of animal charcoal 

 and cyanides. It is stated on page 365 of this Journal that 

 lampblack retains no nitrogen after ignition in dry nitrogen. 

 This accords with the accepted fact that charcoal does not com- 

 bine at high temperature with free nitrogen. The results of 

 the following experiments show that charcoal not only retains 

 nitrogen at very high temperatures when once combined with 

 it, but also fixes it when ignited in an atmosphere of com- 

 pounds of it such as ammonia and the oxides of nitrogen. In 

 the decomposition of these bodies by glowing charcoal the 

 nitrogen may be regarded as in the nascent state. The lamp- 

 black used in the tests was the " Diamond Black" variety 

 described on page 364 of this Journal. 



Experiment 1. — Lampblack was heated to redness for an 

 hour and a half in dry ammonia gas, and while the tube was 

 hot the ammonia was displaced by dry nitrogen. The product 

 contained 3 - 17 per cent of nitrogen. On heating the nitrogenous 

 lampblack for half an hour to a red heat in vacuo some am- 

 monia came off owing to hygroscopic moisture, and the per- 

 centage of nitrogen fell to 2*68 per cent. 



Experiment C B. — Hard-pressed lampblack was heated for an 

 hour to the highest heat of a gas combustion furnace in a por- 

 celain tube through which dry ammonia gas was passed. The 



*Lehrbuch des Chemie, 1843, i, 301. 



