582 MB H. BRKRKTON BAKER ON COMBUSTION IN DRIED OXYGEN. 



Sulphur was then further purified as follows : Some powdered sulphur was 

 resublimed, and as it might contain hydrogen, or some compound of hydrogen, it 

 was melted in a slow stream of sulphur chloride vapour, and distilled several times in 

 an atmosphere of this substance. Some hydrochloric acid gas was produced, showing 

 that this precaution was not needless. One end of the tube was sealed and the other 

 bent and fixed into one neck of a dry WOULFF'S bottle. The other neck was con- 

 nected with a water pump which maintained a nearly complete vacuum in the 

 apparatus. The sulphur was kept at a temperature of 150-180 by an Argand 

 burner. In this way all the sulphur chloride was got rid of. 



Experiment II. A tube was sealed up containing this purified sulphur in oxygen, 

 and was left drying for five days as before. It was heated over an Argand lamp with 

 a comparison tube containing some of the purified sulphur in moist oxygen. 



The moist sulphur was seen to burn with a sudden flash, while the dry sulphur was 

 distilled several times backwards and forwards in the tube without any visible 

 combustion. Analysis of the contents of the dry tube showed that only -p/th of the 

 oxygen had been converted into sulphur dioxide. 



Combustion of Carbon Bisulphide in Oxygen. 



The union of these two substances as brought about by an electric spark is well 

 known to be extremely energetic. It seemed of interest to investigate whether 

 dryness has the same effect on the burning of carbon bisulphide as it has on the 

 burning of each of its constituents when heated separately in oxygen. 



Purification of Carbon Bisulphide. About 50 c.c. of the commercial substance 

 were distilled five times from white wax, and in this way the liquid lost most of 

 its unpleasant odour. To get rid of hydrogen compounds, as far as possible, it was 

 sealed with a small quantity of chloride of sulphur in thick glass tubes and heated to 

 180 in an air bath for several days. The contents of the tube were distilled, the 

 first portion only which distilled over at 46 being taken. This was shaken with pure 

 mercury at intervals for several days until the metal remained bright after several 

 hours' contact. The purified liquid was again distilled and sealed up with some 

 phosphorus pentoxide. This drying agent seems to have no action on the bisulphide. 



5 cubic centimetres of the vapour were collected over dried mercury, and to this 

 vapour was added three times its volume of dried oxygen. A plug of phosphorus 

 pentoxide was introduced, and the tube was left for twelve days. At the end of that 

 time a spark of the smallest possible length from a small coil with one bichromate cell 

 was passed through the mixture. The mixture exploded with a bright flash, leaving 

 a deposit of sulphur on the sides of the tube. 



A second experiment was tried in the same way, the mixture being allowed to dry 

 for six weeks. The result was the same. 



Two more experiments were made. Long tubes were carefully dried ; phosphorus 



