192 LECTURES. 



SOMATOLOGY. 



(1.) Somatology {acDixa and .^.o^'oc) treats of the general properties of 

 bodies. 



A body, a limited portion of matter. 



(2.) The general properties of bodies are certain simple phenomena 

 for the most part immediately obvious to our senses, and some of which 

 are essential to our perception of the existence of matter. 



In the present state of science we suppose that there are different 

 kinds of matter, endowed with different qualities or properties ; that 

 these enter into various combinations, while the quantity of each in 

 the universe remains the same. It is possible, however, that there 

 may be but one kind of matter and that the different properties are the 

 result of the different groupings of its parts. 



(3.) The following is a list of the general properties of bodies as 



recognized at the present time. 



1. Extension. / ^.^ . ^- c ll 



o T f 1 Tt \ -l^ecessary to our perception ot matter. 



3. Figure. 



4. Divisibility. 



5. Porosity. 



6. Compressibility. 

 T. Dilatability. 



8. Mobility. 



9. Inertia. 



10. Attraction, and 



11. Repulsion. 



12. Polarity. 



13. Elasticity. 



Of these, impenetrability, mobility, inertia, attraction, and repul- 

 sion, are general facts to which many particular facts may be referred. 



(4.) The general properties of matter are frequently divided into 

 two classes, essential and contingent properties ; but these are meta- 

 physical rather than pbysical divisions, and different authors are not 

 agreed as to what are the essential properties. 



It appears evident, however, that extension and impenetrability are 

 necessary to our perception of matter, or, in other words, without 

 them our senses would not be affected by matter. 



(5.) All the sreneral properties of matter are not to be considered as 

 ultimate facts of which no explanation can be given ; most of them, 

 as will be shown, can be accounted for by adopting the molecular 

 hypothesis of the constitution of matter. 



Besides general properties, different bodies possess peculiar proper- 

 ties which distinguish them from each other ; but the consideration 

 of these belongs to chemistry. 



Matter is found in three states or consistencies — solid, liquid, and 

 aeriform or gaseous, and to these may reasonably be added a fourth — 

 the etherial. 



^ Ultimate properties according to the 

 molecular hypothesis. 



