62 Vital Physics. 



into that particular aggregation ? No doubt, from form 

 itself being a special part of the constitution of every atom 

 in each class of element, as of gold, silver, iron, lead, 

 nitrogen, iodine, etc. 



For how can it be that certain elements unite with other 

 elements, as chlorine with lead, gold, copper, iron, etc., and 

 in each of these its union tends to disintegrate, loosen, and, 

 aided by water, to liquefy several elements of greater or less 

 density and hardness, so that the inherent attractive powers 

 are much enfeebled or rendered partially nugatory; but 

 when added to a liquid salt of silver the mass separates 

 itself from previous combinations, and falls down as a solid, 

 the closeness of whose ultimate atoms, each for the other, 

 excludes the water or the caloric from widely separating 

 their respective atoms ? 



It is said that this is a matter of chemical affinity. 

 Granted that it is a matter of affinity, is not iron capable of 

 attracting carbon and oxygen with great facility, especially 

 the latter, the same with sulphur and its oxides, and in each 

 of these attractive force on either side binds the respective 

 elements to each other in a close and compact manner, so 

 that iron can closely attach itself to other elements, and 

 so can silver, both as an oxide and as a nitrate ? But iron 

 refuses to unite with chlorine as a solid salt, but with silver, 

 whose attraction of atoms for each other is by no means so 

 strong as that observed in iron, unites to chlorine with 

 intense affinity ; not because it is an element of any strong 

 attractive force in itself between its own particles, for, 

 comparing silver with iron, it is not so tough as iron, and it 

 melts at a lower temperature. 



This contrast in the degree of affiance in two elements so 

 opposed to each other can resolve itself only into a mutual 

 affinity for each other, powerfully aided by the mutual 

 adaptation of form to each other. 



