PROBLEMS OF INORGANIC CHEMISTRY. 35 



2. The volume-energy of gases is equal at equal temperature from 

 that at which volume-energy is zero — i. e., absolute zero. And it fol- 

 lows that those volumes of gases which possess equal volume-energy 

 contain equal numbers of molecules — again, a close connection with 

 atomic weights. 



3. The specific heats of elements are approximately inversely pro- 

 portional to their atomic weights; and of compounds to the quotient 

 of their molecular weights divided by the number of atoms in the 

 molecule. Specific heat and entropy are closely related; hence one of 

 the factors of thermal energy is proportional (nearly) to the recipro- 

 cal of the atomic weights. 



4. The ion carries in its migration through a solution one or more 

 electrons. Now, the ion is an atom carrying one or more charges — 

 one for each equivalent. Here we have the capacity for electric charge 

 proportional to the equivalent. 



5. The factors of chemical energy are atomic weight and chemical 

 potential; and as the former is identical numerically, or after multi- 

 plication by a simple factor with equivalent, electric potential is pro- 

 portional to chemical potential. 



We see therefore that surface, volume, thermal, electrical, and, no 

 doubt, other forms of energy have as capacity factors magnitudes, either 

 identical with, or closely related to, units of chemical capacity; while 

 kinetic and linear energy are not so related, except through the peri- 

 odic arrangement of the elements. 



It appears therefore to be a fundamental problem for the chemist 

 to ascertain, first, accurate atomic weights, and, second, to investigate 

 some anomalies which still present difficulties. In America, you have 

 excellent workers in the former branch. Mallet, Morley, Eichards and 

 many others have devoted their time and skill to perhaps the best 

 work of this kind which has been done; and F. W. Clarke has col- 

 lated all results and afforded incalculable help to all who work at or 

 are interested in the subject. Valuable criticisms, too, have been 

 made by Hinrichs; but it must be confessed that in spite of these, 

 which are perhaps the best determinations which have been made, the 

 problem becomes more, and not less formidable. 



There are lines of work, however, which suggest themselves as pos- 

 sibly likely to throw light on the question. First, there is a striking 

 anomaly in the atomic weight of nitrogen, determined by analysis and 

 determined by density. Stas obtained the number 14.04 (0 = 16), 

 and Eichards has recently confirmed his results; while Eayleigh and 

 Leduc consistently obtained densities which, even when corrected so as 

 to equalize the numbers of molecules in equal volumes, give the lower 

 figure 14.002. The difference is 1 in 350; far beyond any possible 

 experimental error. Eecently, an attempt to combine the two methods 

 has led to a mean number ; but that result can hardly be taken as final. 

 What is the reason of the discrepancy? Its discovery will surely ad- 



