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attraction, the power by which different species of 

 matter tend to unite into one compound. Various 

 kinds of matter unite with different degrees of force : 

 thus sulphuric acid and magnesia unite with more 

 readiness than distilled vinegar and magnesia ; and if 

 sulphuric acid be poured into a mixture of vinegar 

 and magnesia, in which the acid properties of the 

 vinegar have been destroyed by the magnesia, the vine- 

 gar will be set free, and the sulphuric acid will take 

 its place. This chemical attraction is likewise called 

 chemical affinity. It is active in most of the pheno- 

 mena of vegetation. The sap consists of a number of 

 ingredients, dissolved in water by chemical attraction ; 

 and it appears to be in consequence of the operation 

 of this power, that certain principles derived from the 

 sap are united to the vegetable organs. By the laws 

 of chemical attraction, different products of vegetation 

 are changed, and assume new forms : the food of 

 plants is prepared in the soil ; vegetable and animal 

 remains are changed by the action of air and water, 

 and made fluid or aeriform ; rocks are broken down 

 and converted into soils ; and soils are more finely 

 divided and fitted as receptacles for the roots of 

 plants. 



The different powers of attraction tend to pre- 

 serve the arrangements of matter, or to unite them in 

 new forms. If there were no opposing powers, there 

 would soon be a state of perfect quiescence in nature, 

 a kind of eternal sleep in the physical world. Gravi- 

 tation is continually counteracted by mechanical 

 agencies, by projectile motion, or the centrifugal 



