446  W. A. Norton—Force of Effective Molecular Action. 
in a similar manner. The enlargement of the envelopes here 
alluded to consists in a recess of the effective envelopes from 
the central atoms. This should be attended with a certain 
diminution in the value of r, the distance between the centers 
of attraction and repulsion posited within the envelopes; and 
therefore with an increase in the value of p (= ef In fact 
ghe quantitive determinations I have given, when compared 
with the results of experiment, indicate that p is materially 
larger at the same temperature, for liquids and aeriform bodies 
than for solids. An important tendency of the diminution of 
the value of 7 in liquefaction, is to antagonize the expansion 
directly due to the enlargement of the effective molecules and 
the attendant diminution in the coefficient n. According as 
the one or the other of these two tendencies preponderates, the 
mass will expand, or contract in the act of liquefaction. In the 
case of any special solid or liquid, the diminution of 7 with a 
rise of temperature tends to diminish the expansion, and by 
increasing p to make the decrement of tenacity less. ny 
differences in the value of 7 that may subsist with molecules of 
different substances, at the same temperature, can only have 
the effect to alter the positions of the substances on the mole- 
eular scale. Any changes or differences that may occur in the 
value of 7, in the case of the gases, will have no effect on the 
molecules. At less distances the tendency should be to alter 
slightly the deviations from this law. : 
he value of the coefficient of attraction, n, depends on the 
excess of the attraction exerted by the central atom of a mole- 
cule on its envelope, over the repulsion exerted on it by the 
condensed luminiferous ether posited between the atom and 
envelope. The tendency of a recess of the envelope from the 
atom may be either to diminish, or augment the value of n. 
It thus may happen that by an increase of n, and a diminution 
of r, the value of # may be augmented by a certain rise of tem- 
perature ; as when a bar of wrought iron is heated up to about 
400° F. In the case of gases n may change somewhat with the 
temperature, and in the process of condensation. 
The normal type of solidity is a fixed distribution of the 
ultimate molecules at the angles of successive cubes; and the 
fundamental principle of the stability of every such elementary 
cube is that each molecule is in equilibrium, by itself, with 
_ each of the others. As the distances are unequal, this im- 
plies that & is smaller in the diagonal direction than in the 
