4 Jones, Union of Hydrogen with Sulphur. 



the soda in the test glass as at B. The level of the 

 soda in the tube was then marked and the sulphur heated 

 to the boiling point. In a very short time afterwards it 

 was found that the increase in volume of the gas, caused 

 by the expansion, was overcome, and the soda rose 

 steadily above the original level. Some hydrogen there- 

 fore had disappeared from the tube, and this can only be 

 accounted for by supposing that it had united with the 

 sulphur to form sulphuretted hydrogen which was 

 absorbed by the soda. 



In still another way the union of hydrogen with 

 sulphur was shown. A piece of sulphur sealed up in a 

 tube with hydrogen was heated for a short time in a bath 

 of boiling sulphur.^ When cold the point of the tube was 

 broken under soda solution, which rose so as to fill the 

 tube entirely. That the union of the two elements was 

 accomplished without change of volume was shown by 

 the slow entrance of the soda into the tube. 



From these experiments it is evident that the chemists 

 who have affirmed the synthesis of hydrogen sulphide 

 from its elements have been correct in their observations. 

 With regard to the temperature at which the reaction 

 takes place, it was found to be very near to the boiling 

 point of the sulphur. No combination takes place at the 

 melting point, as has been affirmed, if the sulphur used 

 is pure, but if roll sulphur (which always contains sulphur- 

 etted hydrogen) be employed that gas is given off at the 

 beginning of the experiment. 



Hydrogen and Selenium. 



The readiness with which hydrogen unites with 

 selenium has been long known. According to Ditte^ 



^ See also Hautefeuille. Compt. Rend. vol. 64, p. 610 (footnote). 

 2 Cotnpt. Rend. vol. 74, p. 980. 



