ATTRACTION. 13 



Electricity has the property of causing bodies to pos- 

 sess an attractive influence. If a glass ruler, or stick of 

 sealing wax, be rubbed with any soft warm substance, as 

 flannel, fur, or woollen cloth, it becomes excited, and on 

 being presented to any light body, as pith, paper, fccc., it 

 will cause it to fly towards it. 



Galvanism is of a similar nature to electricity, but its 

 influence is exerted rather in the way of decomposition. 

 The cause both of electric and galvanic action has not 

 yet been satisfactorily determined by philosophers. 



Magnetic attraction is also of a similar character to 

 electric attraction ; indeed, electricity, galvanism, and 

 magnetism, seem very intimately connected. The at- 

 tractive power of the magnet was known to the ancients, 

 although they were not aware that a needle, or thin piece 

 of iron, rubbed with it, would give it the property, when 

 suspended, of pointing towards the poles. The magnet, 

 aided by galvanic action, has been recently found to 

 possess enormous power ; that in the Adelaide Gallery 

 has been made to support a weight of more than 400 Ibs. 



The second kind of attraction is that which exists be- 

 tween the particles of bodies, as the attraction of Cohe- 

 sion, and Chemical attraction, or affinity. When the 

 force of attraction operates on atoms of the same spe- 

 cies, it is called the attraction of cohesion, or of aggre- 

 gation ; and when on atoms of different substances, it 

 is called chemical attraction, or affinity. 



By Cohesion is meant that power by which the atoms 

 of bodies are united together, of which there are dif- 

 ferent degrees. The atoms of a stone cohere more firmly 

 than those of jelly, and the atoms of jelly more than 

 those of water, and the atoms of water more than those 

 of air. The cause of this has been reasonably attri- 

 buted to the shape of the atoms ; those that cohere most 

 firmly being as it were of a dove-tailed shape, so as to 

 render the mass compact and firm. The spherical shape 

 of drops of water, as also of particles of quicksilver, has 

 been attributed to this kind of attraction. The chief 

 antagonist to the attraction of cohesion is heat. 



The ascent of water or other liquid in small tubes, 



