. 



>: M. 



matter in a body is to count the atoms in it The void spaces between the 

 mom* count for nothing. To those who identify matter with extension, tl,- 

 volume of space occupied by a body is the only measure of the quantity of 



mutter in it 



Of the different forms of the atomic theory, that of Boscovich may be tak.-n 

 M an example of the purest raonadism. According to Boscovich matter is made 

 up of atoms. Each atom is an indivisible point, having position in space, capal.U- 

 of motion in a continuous path, and possessing a certain mass, whereby a certain 

 Amount of force is required to produce a given change of motion. Besides this 

 the atom fa endowed with potential force, that is to say, that any two atoms 

 attract or repel each other with a force depending on their distance apart. The 

 law of this force, for all distances greater than say the thousandth of an inch, 

 an attraction varying as the inverse square of the distance. For smaller 

 distances the force is an attraction for one distance and a repulsion for another, 

 according to some law not yet discovered. Boscovich himself, in order to obviate 

 the possibility of two atoms ever being in the same place, asserts that the 

 ultimate force is a repulsion which increases without limit as the distance 

 diminishes without limit, so that two atoms can never coincide. But this 

 tflflffv an unwarrantable concession to the vulgar opinion that two bodies cannot 

 co-exist in the same place. This opinion is deduced from our experience of the 

 behaviour of bodies of sensible size, but we have no experimental evidence that 

 two atoms may not sometimes coincide. For instance, if oxygen and hydrogen 

 combine to form water, we have no experimental evidence that the molecule of 

 oxygen is not in the very same place with the two molecules of hydrogen. Many 

 persons 1 cannot get rid of the opinion that all matter is extended in length, 

 breadth, and depth. This is a prejudice of the same kind with the last, arising 

 from our experience of bodies consisting of immense multitudes of atoms. The 

 system of atoms, according to Boscovich, occupies a certain region of space in 

 virtue of the forces acting between the component atoms of the system and 

 any other atoms when brought near them. No other system of atoms can 

 occupy the same region of space at the same time, because, before it could do 

 so, the mutual action of the atoms would have caused a repulsion between the 

 two systems insuperable by any force which we can command. Thus, a number 

 of soldiers with firearms may occupy an extensive region to the exclusion of 

 the enemy's armies, though the space filled by their bodies is but small. In 

 this way Boscovich explained the apparent extension of bodies consisting of 



