CHAPTER V 



Carbonic Acid Gas 



By dissolving sugar or salt, water acquires 

 a different taste — the taste of sugar or salt. 

 Similarly, by dissolving carbon the air receives 

 new properties and takes the name of carbonic 

 acid gas. All subtle, and generally invisible, 

 substances such as air, are called gases. Air 

 is a gas, and after having dissolved carbon it 

 remains a gas. As for the word carbonic, it 

 comes from carbon, the scientific name for 

 coal. 



This gas, or air impregnated with carbon, 

 is an invisible substance, the presence of 

 which can only be detected by indirect 

 methods. The following is the simplest of 

 these methods : We dilute in water a small 

 quantity of slack lime, the white paste 

 obtained by masons when they pour water 

 on to the limestone, in order to make their 

 mortar. The resulting liquid is as white as 

 milk and is called whitewash. By means j)f 



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