474 SEGREGATION. 



changes, let us look for the common interpretation of 

 them. 



In the chapter on " The Instability of the Homogene- 

 ous/ 7 it was shown that a uniform force falling on any aggre- 

 gate, produces unlike modifications in its different parts — 

 turns the uniform into the multiform and the multiform 

 into the more multiform. The transformation thus 

 wrought, consists of either insensible or sensible changes of 

 relative position among the units, or of both — either of 

 those molecular re-arrangements which we call chemical, or 

 of those larger transpositions which are distinguished as 

 mechanical, or of the two united. Such portion of the per- 

 manently effective force as reaches each different part, or 

 differently-conditioned part, may be expended in modify- 

 ing the mutual relations of its constituents ; or it may be ex- 

 pended in moving the part to another place; or it may be 

 expended partially in the first and partially in the second. 

 Hence, so much of the permanently effective force as does 

 not work the one kind of effect, must work the other kind. 

 It is manifest that if of the permanently effective force 

 which falls on some compound unit of an aggregate, little, 

 if any, is absorbed in re-arranging the ultimate components 

 of such compound unit, much or the whole, must show itself 

 in motion of such compound unit to some other place in the 

 aggregate ; and conversely, if little or none of this force is ab- 

 sorbed in generating mechanical transposition, much or the 

 whole must go to produce molecular alterations. What 



now must follow from this? In cases where none or only 

 part of the force generates chemical re-distributions, what 

 physical re-distributions must be generated ? Parts that are 

 similar to each other will be similarly acted on by the force; 

 and will similarly react on it. Parts that are dissimilar will 

 be dissimilarly acted on by the force; and will dissimilarlv 

 react on it. Hence the permanently effective incident 

 force, when wholly or partially transformed into mechanical 

 motion of the units, will produce like motions in units that 



