10 THE AIR AND THE GASES IN IT. 



bining number for hydrogen is 1 ; for carbon, 6 ; for 

 sulphur, 16 ; for iron, 28. 



And it is found that 9 pounds of water consist of 8 

 pounds of oxygen and 1 pound of hydrogen ; and that 

 28 pounds of iron unite with 8 pounds of oxygen to form 

 rust or oxide of iron. &quot; Take, for example, 9 pounds of 

 water, pass its steam over a known weight of pure iron 

 turnings, heated red-hot in an earthen tube. No steam 

 escapes from the tube, only air, which may be inflamed 

 and burned. It is hydrogen gas, one of the constituents 

 of water. That liquid has been decomposed. What has 

 become of its oxygen ? It has united with and oxidated 

 the iron. What proportion of the water did it form? 

 8-9ths.&quot; If the iron be weighed, it will be found 8 poiinds 

 heavier. Subtracting from the 9 pounds of water, 8 of 

 oxygen, the balance, 1, is hydrogen.* 



If the experiment be very carefully conducted, it will 

 be found that 28 &quot;pounds of iron have been converted into 

 iron rust, and that all the rust formed by 8 pounds of 

 oxygen weighs 36 pounds. 



The several elements, or simple, uncompounded sub 

 stances, are, for convenience, represented by the initial 

 letters, and the proportions in which they unite by num 

 bers placed a little above them. Chemists suppose that 

 it is only the least possible, indivisible particles of matter 

 01- atoms, that unite, and that the atoms combine, 1 with 

 1, or 1 with 2, or with 3, or 2 with 3, and so on. 



Oxygen is represented by ; Hydrogen by H ; Nitro 

 gen by N ; Carbon by C ; Sulphur by S. HO is water, 

 I M -cause one atom of hydrogen is supposed to unite 



* Dana s Muck Manual, p. 44. Whoever wants to ^et a vast deal of knowl 

 edge upon the subject of fertilizers, philosophically stated, in a small compass, 

 may consult this valuable volume. 



