204 METALLOIDS. 



504. SECOND METHOD. Another method 



Show how com- . -,->-> 



.position by is to measure the gases obtained by the 



7al 9 culated y ^ same method of decomposition. Two 

 from measure, measures of hydrogen are thus obtained for 

 every single measure of oxygen. The chemist then pro- 

 ceeds to calculate the relative weight. Knowing before- 

 hand that hydrogen is the lighter gas, weighing but 

 one-sixteenth as much as the same quantity of oxygen, 

 he infers that the double volume obtained in the above 

 experiment, weighs but one-eighth as much as the 

 oxygen obtained in the same decomposition. The 

 result of this indirect process is the same as that stated 

 at the conclusion of the last paragraph. 

 Describe the Q5- THIRD METHOD. A third method 



third method, consists in the reproduction of water from 

 mixed hydrogen and oxygen, observing at the same 

 time the quantities in which they combine. This may 

 be readily effected in a test-tube. The gases being 

 introduced into the tube in about the right proportion, 

 and in small quantity, its extremity is 

 then intensely heated. A slight explo- 

 sion and combination of the gases is the 

 result, and the water rises to take their 

 place, mingling with the small quantity 

 of water produced in the experiment. Any excess of 

 either gas remains uncombined. Whether this surplus 

 is oxygen or hydrogen, may be readily proved by 

 methods previously given. This excess being sub- 

 tracted from the quantity of the same gas originally 

 used, shows the proportion in which the combina- 

 tion has occurred. 



