44 THE BOOK OF THE LANTERN. 



short time ago in an article in " Chambers's Journal." From 

 that article I will now give the following extract : 



" Any manual of chemistry will inform us that oxygen 

 is the most widely-diffused element in nature. It enters 

 into the composition of air, of water ; it is found in nearly 

 all earths and rocks; and forms more than one half of 

 animal and plant life. In fact it is not too much to say 

 that oxygen forms one-half of the globe and its belongings ; 

 but of course it is combined with other elements. Chemists 

 can tell us of a dozen different methods of isolating this 

 gas ; but the one most usually adopted is to'subject a salt of 

 potash (potassic chlorate), which is extremely rich in 

 oxygen, to heat in a retort, when it quickly parts with that 

 gas, which can be collected in a suitable containing vessel 

 for use. To show the extent to which this salt is used for the 

 production of oxygen, we may mention that we were lately 

 informed by a London dealer that he sold yearly one 

 hundred tons of potassic chlorate, and that he had reason to 

 believe that it was nearly all used for the production of gas. 

 This quantity of the salt would afford, roughly speaking, 

 nine hundred thousand cubic feet of oxygen, and we must 

 not forget that this is the amount dispensed through one 

 dealer only. The natural question which arises as to what 

 purposes this gas is applied, we shall deal with presently. 

 We have preferred to show, first, that there is an enormous 

 demand for oxygen, so that the importance of a new 

 industry for producing it may be at once appreciated. 



" Oxygen forms one-fifth of the air which we breathe, the 

 other four-fifths consisting of an inert gas called nitrogen. 

 And it is important that we should remember that the 



