366 Lt. A. Hill—Notes on Argon and Helium. 
which, as temperature is reduced, increases until sufficient to 
unite the molecules into solid HCl. Hence although tis 
does become greater than f with reduction of temperature, the 
tendency towards dissociation is more than overcome by the 
increased force of aggregation between the HCO] molecules. 
Strictly this molecular force should be taken into account 
above, but I have omitted it to simplify the discussion. Com- 
pare here the following language of Dr. Méller: “ Scientists 
have proved that chemical action entirely ceases even before so 
low a temperature (—278°) is reached . . . The form of 
motion which we call affinity between different molecules 
seems at that temperature to be wholly extinct, but the other 
form of motion, the affinity between homogeneous molecules 
and between the atoms of which they are formed, does not 
appear to be much impaired by the lowest temperature we can 
produce.”* 
In general then we may roughly outline the gamut of changes 
produced by increments of heat energy as follows: 
ist. Absolute zero, no energy, maximum of force of aggre- 
gation, minimura of force of affinity, solid state. 
2d. Liquid state, first marked indications of the force of 
affinity (though weakly displayed by some solids under great 
pressures or certain electrical conditions), reduced force of 
aggregation. 
3d. Gaseous state, force of affinity stronger, of aggregation 
weaker. 
4th. Temperature where dissociation begins. 
5th. Temperature where dissociation is complete, and the 
force of aggregation completely overcome as between like 
atoms. Maximum of chemical affinity in fourth or fifth stage. 
6th. Temperature at which the dissociated atom has no 
affinity for any other atoms, like or unlike. 
Let’ us now consider the following table of melting and 
boiling points. 
Substance. Melting Point. Difference. Boiling Point. 
H? = Hydrogen ines — 243 
N? = Nitrogen —214° 19°6° a —194°4 
CO = Carbonic oxide —207- 17-0 3 — 190° 
A™ = Argon | —189°6 RG He Les —187 
@? = Oxygen — —182 
CH*= Methane —185°8 21:8 r 3 —164 
NO = Nitric oxide —167- 13°4 3 & — 153°6 
Cl? = Chlorine — 102: 68-4 | a& — 33°6 
Br? = Bromine — 72 66 2 5 + 59 
I? = Iodine +114 (| +184 
Hg = Mercury -—38°5 395°5 panes +357 
Cd = Cadmium +320 450°0 B +750 
Zn = Zine 420° 530 | ae abt. 950° 
ue = i apnea abt. ie acre \ as at ee temperature 
1 whim + avdt. 
Na = Sodium 95°5 large | = & at red heat 
K = Potassium . 60 mS yrs above red heat 
* F, P. Moller in Cod Liver Oil and Chemistry, p. 452. 
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