the Halogens, Nitrogen, Sulphur and Oxygen. 375 



off occluded sulphur and was then found to contain 0*29 per 

 cent of sulphur. Carbon disulphide was not produced in this 

 experiment nor was it likely to be formed since the tempera- 

 ture of the furnace was sufficient to decompose it as was 

 proved experimentally. 



.Experiment 5. — Filter paper nearly free from ash was 

 charred at a dull red heat in vapor of sulphur and the latter 

 was displaced by hydrogen. The product contained 29*1 per 

 cent of sulphur. 



Experiment 6. — Filter paper in loose rolls was placed in a 

 large glass tube and was then wet with a saturated solution of 

 sulphur in carbon disulphide. The latter was driven off and 

 a considerable quantity of solution of sulphur was poured into 

 the tube. After the carbon disulphide was expelled from the 

 tube again the paper was charred by gradually heating to 

 incipient redness, and dry hydrogen was passed through the 

 tube during the heating and cooling. Two estimations of sul- 

 phur in the charcoal gave 4646 and 46-60 per cent. This 

 sulphurized charcoal yielded nothing to boiling carbon disul- 

 phide and gave up no sulphur to a boiling solution of potas- 

 sium hydroxide. 



Experiment 7. — This was made as nearly as possible like the 

 preceding. The product contained 43 64 per cent of sulphur 

 and exhibited the same negative deportment towards carbon 

 disulphide and potassium hydroxide. 



The results show that nearly pure amorphous carbon takes 

 up but little sulphur, while a soft charcoal containing much 

 hydrogen and oxygen takes up considerable even from carbon 

 disulphide. The sulphur is chemically combined as Berzelius 

 held, for it is not removed by solvents even from charcoal 

 which is nearly one half sulphur. 



Combustion of Charcoal in Oxygen. 



The paper by H. B. Baker' 55 ' on combustion in dry oxygen 

 suggested a lecture experiment to show that charcoal will not 

 burn in dry oxygen as readily as it does in the gas containing 

 water. For this purpose Hoffman's experiment^ was modified 

 by allowing the oxygen in the apparatus shown in fig. 1, to 

 dry for a day or longer by contact with phosphorous pentoxide 

 contained in a short tube just below the bulb. The charcoal 

 was hung on the small wire above the spoon and was intensely 

 heated, cooled in carbon dioxide and then placed in the ap- 

 paratus. To carry out the experiment the wire was heated by 

 electricity until the charcoal was glowing at the point of con- 



* Jour. Chem. Soc, xlvii, 349. 



f Beriehte der cleutsch. chem. Gesellsch., ii, 251. 



