the Halogens, Nitrogen, Sulphur and Oxygen. 36 



perhaps chlorides, during the intense ignition. The following 

 is the analysis of dechlorinated sugar charcoal for hydrogen : 

 1-4964 grams of the carbon which had been heated to dull red- 

 ness and cooled in a desiccator were placed in a combustion 

 tube and then heated again to dull redness while a slow current 

 of dry air was passing through the tube to expel if possible all 

 water. The carbon did not appear to burn. The chloride of 

 calcium tube was then attached and the combination made with 

 oxygen. 0*073 per cent of hydrogen was obtained. Another 

 determination with 1*089 gram not heated until placed in the 

 combustion tube gave 0*065 per cent. 



Experiment 8. — Gas carbon in lumps was ignited in chlorine 

 and then was allowed to cool in a current of dry nitrogen. 

 Two tests failed to reveal any chlorine in the gas carbon thus 

 treated. Finely pulverized gas carbon was also found to take 

 up no chlorine at a red heat. 



As gas carbon does not combine with chlorine the question 

 was suggested : Will charcoal from which chlorine has been 

 expelled by heat take up chlorine again % The following 

 results show that it will. 



Experiment 9. — The dechlorinated sugar charcoal of 7 

 was found to contain 3*24 per cent and the dechlorinated 

 lampblack 2*82 percent of chlorine after ignition in chlorine. 



Experiment 10. — Lampblack and sugar charcoal were ignited 

 for two hours in dry hydrochloric acid gas, and while hot 

 the gas was displaced by dry air. The lampblack contained a 

 minute trace and the sugar charcoal 0*26 per cent of chlorine. 



Experiment 11. — Dry hydrogen was passed over the com- 

 pact chlorinated lampblack of % At ordinary temperature no 

 hydrochloric acid appeared, while at a temperature a little 

 below redness the acid came off for three hours, and at a red 

 heat more acid came off. A test showed that the charcoal still 

 contained a little chlorine. 



Experiment 12. — Lampblack and sugar charcoal were ig- 

 nited for two and a half hours in bromine vapor which was 

 finally displaced from the hot tube by a current of dry air. 

 The lampblack was found to contain 3*04 per cent of bromine, 

 and after exposure in vacuo to a red heat for two hours it con- 

 tained 1*49 per cent of bromine. The sugar charcoal absorbed 

 only 25 per cent of bromine, most of which it lost on ignition 

 in vacuo. 



Experiment 13. — This experiment was conducted like the 

 preceding, iodine being used. The lampblack contained 

 2*04 and the sugar charcoal 0*63 per cent of iodine, both prepa- 

 rations retaining but a trace of iodine after ignition for three 

 hours in vacuo. 



