12 MORRIS LOEB 



let us not allow our feelings to warp our judgment, or a priori 

 reasoning to mislead our investigations. 



Of the various properties by which we recognize substance, 

 there are some which are necessary concomitants of the very 

 existence of matter, which appear to accompany matter 

 so faithfully, that no particle can boast of holding much more 

 than another. Among these we reckon extent, impermeability, 

 mobility, gravitation, inertia. . . . 



Then there are other properties which we do not hesitate 

 to term accidental; they are so loosely connected with the 

 substances that we do not recognize the substances as dis- 

 similar on that account. They might more properly be ap- 

 plied to the differentiation of energy. Such properties are 

 position, temperature, electrical or magnetic change. They, 

 indeed, may appear on one body more than on the other; but 

 exchange the proportionate quantities in the two bodies, as 

 well as we may, and yet we shall not be likely to confound one 

 body with the other. These are all transferable properties, 

 the one body gaining what the other loses. 



There are, however, yet other properties, more or less 

 concerned with the foregoing, which two bodies may not 

 possess in like degree, and which it is impossible for one body 

 to convey to the other. Substances differ in their behavior 

 toward the same form of energy or toward each other, in 

 the distribution of their mass in space (specific gravity), in 

 their effect upon our senses, and upon the animate organism 

 in general. These properties cannot be transferred from one 

 body to another; but one substance may modify by its pres- 

 ence the properties of another. Such are the properties 

 which really distinguish the different forms of matter, and it 

 is with these that chemistry has to do. 



The indivisible unit for the chemist is to be found in the 

 homogeneous substance; beyond this he must confess that 



