352 



SCIENTIFIC RECREATIONS. 



into an inverted cylinder full of water, standing in a basin of water. The 

 sodium liberates the hydrogen by removing the oxygen from the liquid. 

 WATER-SYMBOL H 2 ; ATOMIC WEIGHT 18. 



At page 59 of this volume we said something about water, and remarked 

 (as we have since perceived by experiment) that " water is composed of 



Fig. 339. Preparation of hydrogen with furnace. 



oxygen and hydrogen in proportions, by weight, of eight of the former to 

 one of the latter gas ; in volume, hydrogen is two to one " ; and we saw- 



Fig. 340. Apparatus for generating hydrogen by flask. 



that "volume and weight \ve:e very different things." This we will do well 

 to bear in mind, and that, to quote Professor Roscoe, "Water is always made 

 up of sixteen parts of oxygen to two parts of hydrogen by weight " ; sixteen 

 and two being eighteen, the combining weight of water is eighteen. 



We can prove by the Eudiometer that hydrogen when burnt with 



