THE JOURNEYING ATOMS 



two or more elements is a simple affair, but a chemi- 

 cal mixture introduces an element of magic. No 

 conjurer's trick can approach such a transforma- 

 tion as that of oxygen and hydrogen gases into 

 water. The miracle of turning water into wine is 

 tame by comparison. Dip plain cotton into a mix- 

 ture of nitric and sulphuric acids and let it dry, and 

 we have that terrible explosive, guncotton. Or, 

 take the cellulose of which cotton is composed, and 

 add two atoms of hydrogen and one of oxygen, and 

 we have sugar. But we are to remember that the 

 difference here indicated is not a quantitative, but a 

 qualitative one, not one affecting bulk, but affecting 

 structure. Truly chemistry works wonders. Take 

 ethyl alcohol, or ordinary spirits of wine, and add 

 four more atoms of carbon to the carbon molecule, 

 and we have the poison carbolic acid. Pure alcohol 

 can be turned into a deadly poison, not by adding 

 to, but simply by taking from it; take out one atom 

 of carbon and two of hydrogen from the alcohol 

 molecule, and we have the poison methyl alcohol. 

 But we are to remember that the difference here 

 indicated is not a quantitative, but a qualitative 

 one, not one affecting bulk, but affecting structure. 

 In our atmosphere we have a mechanical mixture 

 of nitrogen and oxygen, four parts of nitrogen to 

 one of oxygen. By uniting the nitrogen and oxygen 

 chemically (N 2 0) we have nitrous oxide, laugh- 

 ing-gas. Ordinary starch is made up of three dif- 



207 



