A WONDERFUL WORLD 



list of hydrocarbons — gaseous, liquid, and solid — 

 called paraffins, that are obtained from petroleum 

 and that are all composed of hydrogen and carbon, 

 but with a different number of atoms of each, like a 

 different number of a's or b's or c's in a word. 



WTiat an enormous number of bodies Nature forms 

 out of oxygen by uniting it chemically with other 

 primary elements! Thus by uniting it with the 

 element silica she forms half of the solid crust of 

 the globe; by uniting it with hydrogen in the pro- 

 portion of two to one she forms all the water of the 

 globe. With one atom of nitrogen united chemically 

 with three atoms of hydrogen she forms ammonia. 

 With one atom of carbon united with four atoms of 

 hydrogen she spells marsh gas; and so on. Carbon 

 occurs in inorganic nature in two crystalline forms, 

 — the diamond and black lead, or graphite, — 

 their physical differences evidently being the result 

 of their different molecular structure. Graphite is a 

 good conductor of heat and electricity, and the dia- 

 mond is not. Carbon in the organic world, where it 

 plays such an important part, is non-crystalline. 

 Under the influence of life its molecules are differ- 

 ently put together, as in sugar, starch, wood, char- 

 coal, etc. There are also two forms of phosphorus, 

 but not two kinds; the same atoms are probably 

 united differently in each. The yellow waxy variety 

 has such an affinity for oxygen that it will burn in 

 water, and it is poisonous. Bring this variety to a 



59 



