362 Prof. A. Grrunwald on the Spectrum of Water-vapour 



A careful comparison of the spectra of hydrogen inten- 

 tionally mixed with various very small quantities of H 2 0- 

 vapour is much to be desired, and ought to produce the 

 experimental confirmation of the origin of the rays 3986, 

 4005, 4007, . . . 4201, &c. The ray 4158 lies very near to a 

 very weak ray, 4158*7, of the second so-called compound 

 spectrum of hydrogen observed by Dr. B. Hasselberg, it 

 indeed the latter be not identical with it, having its origin in 

 the presence of a trace of aqueous vapour. The same ray 

 was moreover observed in air and in oxygen, in the mode 

 adopted by Plucker. 



(4) a. u The wave-lengths of the elementary line- spectrum 

 of oxygen may be divided into two groups, (H/) and (O'), of 

 which the first consists of certain rays of the second compound 

 H-spectrum, which are converted into the corresponding rays 

 of the water-spectrum by multiplication with J." 



/5. " The groups (O f ) may be divided into two groups, (b') 

 and (O") ; so that the one (b f ) by multiplication by §§ passes 

 into a group of the corresponding wave-lengths of the H 2 0- 

 spectrum, but by multiplication by JJ- into a group of homo- 

 logous wave-lengths of the primary substance b chemically 

 combined in H, whilst the other group ( // ) may be con- 

 verted into a corresponding group of the H 2 0-spectrum by 

 multiplying it by* f." 



y. Finally, the last group (0 // ) may again be resolved into 

 two groups (b ff ) and (c) of wave-lengths. The first of these 

 (b ,f ) multiplied by §| gives a group of the H 2 0-spectrum, and 

 multiplied by |-g is reduced to a corresponding group of the 

 H-spectrum which belongs to the primary substance b in H. 



The second group (c) by multiplication by § is transformed 

 into a homologous group of H 2 0-rays." 



From these most important and remarkable relationships 

 and characteristic data, which are not derived from single 

 rays, but by the comparison of whole series of numerous rays 

 of oxygen, H 2 0-vapour, and hydrogen, we obtain by means 

 of the fundamental theorem I. easily, and at once, the che- 

 mical structure of oxygen in the interval of temperature in which 

 it radiates the elementary line-spectrum. If in fact H / , / , 

 b', // , b", c be the substances which, in their combined con- 

 dition within the oxygen, emit the above similarly-denoted 

 groups of rays, (H)', (O'), (&'), (0"), (&"), ™* if), and 

 [H'], [0'], [¥], [0"], [&"], and [c] be the volumes which 

 they occupy in a unit-volume of oxygen, we have the equations 



[H']=i [0']=4, 



[*'] + [0"] = [0'] = ^ ; 



