LECTURE VII. 



CHEMICAL ELEMENTS AND THEIR MUTUAL RELATION, 



Argumeii '.;// may rest on collocation alone. Charac- 



ter <>' learned from the I'ery proofs of II is t. \ist- 



-Xionbcr of elements kno^n. Results secured by 

 their nature and relative quantity. /-'i.ied law s of combi- 

 : alter nor force lost. rillars of o> 



dilution o! 



Hibrium* how restored in the four elements. Balanced 

 affinity. .\ature of their , // specially 



considered. Its coin pounds. The air. Original Condition 

 :atter. Oxygen in the air a residual substance. Essen- 

 tial to animals. Helps form the tissues aihl secures actiri- 

 ty. I*roduce* artificial light and heat. Common ami act- 

 Ozone. . Ijfini/y of c < :cd by tempera- 



ture. //; U of flame. Its inflammable com- 



pounds.- f' properties fitting it for a ligJit- 



producer. Combines with carbon to produce light. Sum- 

 mation of properties. /. for organic structures. 

 :ant change in animal bodies. Relation of hydrogen 

 to nitrogen. Xitrogen adds to iceight of atmosphere. 

 Moderates the action of hydrogen. \egative properties.. 

 '.re of its compounds. Carbon. Different forms. 

 Supplements oxygen in combustion. As an element, al- 

 ways solid. Coal. Indestructible at common temperature. 

 Carbonic a. 



IN our last lecture we considered the law of varia- 

 tion among species, by which varieties are produced 

 in the animal and vegetable kingdom. That sub- 

 ject completed all we have to say of the adaptations 

 to the physical wants of the animal kingdom. The 



