258 



ELEMENTARY GENERAL SCIENCE 



Sulphuretted 



tin, 



Quantitative Composition of Sulphuretted Hydrogen. 

 EXPT. 276. In order to determine, at least partially, the com- 

 position of sulphuretted hydrogen, a tube (Fig. 130) should 

 be about half filled with the gas over mercury (since it is slightly 



soluble in water). In the 

 bent portion a piece of tin 

 is placed, and strongly 

 heated by a Bunsen burner, 

 the end of the tube being 

 closed to prevent the mer- 

 cury being driven out by 

 the expansion of the gas. 



The tin, when thus heated, 

 FIG. ISO.-Compo^tion^of Sulphuretted abgtracts the sulphurj and 



forms tin sulphide, leaving 



the hydrogen. Observe the volume of the hydrogen when 

 the tube is again cool and see that the gas is really hydrogen. 

 It is thus found that Sulphuretted hydrogen contains its 

 own volume of hydrogen. 



For the above experiment and others in which a solid has to 

 be heated in a closed 

 volume of a gas, the 

 apparatus shown in 

 Fig. 131, designed by 

 Mr. C. M. Stuart, 

 Head Master of St. 

 Dunstan's College, 

 Catford, is very con- 

 venient. The U-tube 

 contains a small quan- 

 tity of mercury, just 

 sufficient to fill the 

 bend, and the solid is 

 placed in the bulb of 

 the tube ca, which is 

 then fixed to the U- 

 tube by indiarubber 



tubing as shown. The gas is passed through from 6 until it is 

 considered that all the air is displaced. A little more mercury is 

 then poured into the U-tube, the level xy noted, and the drawn- 

 out end a having been sealed by a Bunsen flame the solid may 

 be heated. 



FIG. 131. Arrangement for Heating a Solid in a 

 closed Volume of Gas. 



