IDENTICAL CHANGES 



We cannot measure cohesion by mass, or mass 

 by cohesion. 



Taking for granted that the attraction theory is 

 correct, it would seem that the closer particles 

 were brought together, the greater would be their 

 power of cohesion. Such, however, is not always 

 the case. 



For while the withdrawal of heat always brings 

 the particles of substances closer together, it does 

 not always increase their power of cohesion. 



Iron, wood, steel and glass and numerous sub- 

 stances will show more cohesion at a hundred de- 

 grees of heat than at zero. Particularly does glass 

 in a semi-liquid or viscid state show more power 

 of cohesion than in any other state. 



It is apparent that cohesion cannot be consid- 

 ered as amenable to the inverse square or cube. 



Our notions of hardness, of temper, of ductile 

 strength, and capacity to resist crushing strain, 

 are more or less hazy and mixed up. 



And the laws and formulas governing strength 

 of material are arbitrary and uncertain. 



The thousand and one problems, growing out 

 of a consideration of cohesion, can never be solved 

 under the Hypothesis that cohesion is the result of 

 an occult attraction. And the data obtainable for 

 a study of cohesion is decidedly meagre, for every 

 substance, and every part of every substance, is a 

 law unto itself in cohesion. Then a rational con- 

 sideration of cohesion can consist only in a study 

 of the forms of substances, and of that which con- 

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