THE MEDICINAL SPRINGS OF SOUTH AFRICA. 22$ 



Of the definitely identitied lines due to metals only those of 

 lithium and sodium were seen in this concentrated residue. No 

 potassium, rubidium or caesium lines were found. 



The line 461.2 is i)robably not due to lithium, as the line 

 610.4 could not be found, and this line is of at least the same 

 intensity as the line 460.2. As only the line 670.8 could be located, 

 and that only with a strong discharge, it would seem as if only 

 traces of lithium were present. 



The line 554 coincides with that of barium, but is probably 

 not due to this meta], as it could be easily discerned in the con- 

 centrated residue, which had been twice treated with precipitants 

 of the heavy metals and alkaline earths. The absence of calcium 

 lines gives evidence that this metal has been completely removed, 

 so that the presence of any barium in this residue is most im- 

 likely. 



In the above spectroscopic tables the figures in the third 

 column are taken from a catalogue of spectra. Where no values 

 are given i^c.g., calcium chloride), the identification was efifected 

 by comparing a spectrum of the salt in the third column with 

 that of the saline residue. 



I desire to place on record my indebtedness to Dr. K. Renz, 

 of Windhuk, for placing analytical data and other information at 

 my disposal, to Dr. H. H. Green, of Onderstepoort, for assisting 

 me with relevant literature, to Major Haywood, S.A.P.. Bloem- 

 fontein, for obtaining supplies of water from the Winburg 

 Baths for me, and to my assistants, Messrs. V. A. Putterill, B.A., 

 and C. Brink, B.A., for their assistance in carrying out the 

 analyses of this water. 



{Read, July 9, 1918.) 



Solar Bombs. — An interesting phenomenon has lately 

 been investigated at the Mount Wilson Observatory. Spectro- 

 scopically it consists in the sudden appearance of a very brilliant 

 narrow band, including the region of Ha. the latter meanwhile 

 retaining its character of a dark line. As a rule this appearance 

 was found to last between one and three minutes, seldom con- 

 tinuing for as long as five to ten minutes. These " bombs " of 

 solar hydrogen are said to follow one anotlier, at intervals 

 from 10 to 20 minutes, like the balls of a Roman candle, and it 

 is suggested that they are caused by explosions in which only- 

 hydrogen is involved. As the dark hydrogen line Ha remains 

 unaltered, the level at which the explosions occur evidently lies 

 below the reversing layer, and it is thought that the eruptions take 

 place round and among active sun-spot groups. 



