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XLVI. On the remarkable Relationships between the Spectrum 

 of Water-vapour and the Line-spectra of Hydrogen and 

 Oxygen, and on the Chemical Structure of the two latter, 

 and their Dissociation in the Sun's Atmosphere. By Prof. 

 A. Grunwald*. 



BY means of a mathematical investigation into the changes 

 which the properties, and in particular the spectra, of 

 two gases undergo upon their chemical combination to form 

 a new substance, I have succeeded in discovering the law, as 

 simple as it is important, of a new mathematico- chemical 

 disturbance-theory ; and by its aid in finding very remark- 

 able relationships between the spectra of hydrogen and oxygen 

 on the one hand, and of water-vapour on the other, as well as 

 discovering the chemically compound nature of hydrogen and 

 oxygen by mathematico-spectral analysis, and in demonstra- 

 ting the dissociation of hydrogen in the sun's atmosphere. 



I. 



The above-mentioned fundamental theorem is as follows: — 

 " Let a be a primary chemical element, which is chemically 

 combined with other elements in a gaseous substance A, and 

 occupies the volume [a] in the unit-volume of A. Let the 

 substance A combine chemically with another gaseous sub- 

 stance, B, to form a third, C. In this combination let the 

 element a pass into a different chemical condition, a' ', giving 

 up (or in exceptional cases taking up) a certain quantity of 

 heat in order to permit the new compound to form, and in 

 consequence chemically contracting (or exceptionally expand- 

 ing) . Let the volume which it occupies in the body C, after 

 the new condition of chemical equilibrium has been established, 

 be [a'~\, when the quotient [a] : [a!~\ is generally a very simple 

 rational number in accordance with a known fundamental law 

 of chemistry. If this is the case, the wave-lengths A, of all 

 the rays which belong to the element a in the line-spectrum 

 of the free substance A, and are therefore radiated by it, are 

 related to the wave-lengths A/ of the corresponding rays which 

 the same element emits in the new chemical condition a' , in 

 which it exists in the more complex substance A within the 

 newly formed compound C, as the corresponding volumes [a] 

 and [a']." 



This theorem only holds good when the substances in ques- 

 tion are gases which are at a considerable distance from the 

 critical point of condensation, and are not under too great 



* Communicated by the Author from the Astr. Nachi\ Bd. 117. 



