RECORDS OF MEETINGS OF 1907 347 



2. The bands fall into three separate and definite spectral regions, 

 which are distinct from the regions where the salts of other acids, so far 

 as known, show reflection maxima. 



3. With few exceptions, an increase in the atomic weight of the base 

 causes a shift of all three reflection maxima tow^ard long waves by an 

 amount roughly proportional to the change in atomic weight of the base. 



II. The R61e Played by Oxygen in the Selective Reflection of Carbon- 

 ates, Nitrates, Sulphates and Silicates. — Combining with the data on car- 

 bonates the scattered observations of other observers on nitrates, sulphates 

 and silicates, the tentative h\-pothesis has been made that the oxygen atom 

 is the one chiefly responsible for the marked reflection observ^ed. 



The wave-lengths of the first reflection bands in CaCOg, KNO3,* CaSO^ 

 and MgSiOg' are plotted as abscissae and as ordinates the weights of the 

 acid-forming elements combined with O3 (C = 12, N = 14, |S = 24, and 

 Si = 28). 



The lines drawn show clearly that a small increase in the weight of 

 the acid-forming element produces a much greater displacement of the 

 reflection band than does the same increase in the weight of the base, and 

 this is in full agreement wnth the chemist's view^ of the relative strength 

 of the bands existing between the acid-forming element and oxygen, and 

 that between the base and oxygen. 



The results suggest a new and far-reaching method by which it may 

 some time be possible to express the dynamical relations existing between 

 the separate atoms of a molecule, and thus the present conception of chem- 

 ical bonds and linkages be given a broader significance. 



The paper appears in full in the Astrophysical Journal for November, 

 1907. Addendum, October, 30, 1907. 



By reducing the results to zero weight of the base and extending the 

 curve b to zero weight of the acid-forming element, the weight with O3 

 both in base and as acid-forming element is zero. Thus a wave-length is 

 found which is approximately that found by Angstrom for the absorption 

 of ozone. 



Also a second absorption band in ozone corresponds to the second car- 

 bonate bands, found at a longer wave-length. 



This is a very important confirmation of the assumption made, viz.: 

 that "the oxygen atom is the one chiefly responsible for the selective re- 

 flection observed." 



1 Two values are plotted for KNOa corresponding to the results obtained by two independ- 

 ent observers, Pfund and Coblentz. 



2 If a correction be applied to correct for Mg being lighter than Ca, this would bring the 

 MgSiOa point even nearer the line drawn. 



