Notes on Quantitative Spectra of Beryllium. 28.'5 



"Notes on Quantitative Spectra of Beryllium." By W. N. 

 HAETLEY, D.Sc., F.R.S., Royal College of Science, Dublin. 

 Received October 31, Read December 5, 1901. 



In a quantitative examination made in 1885 of all the known 

 methods of separating beryllium from aluminium and from iron, the 

 various precipitates obtained were dissolved and diluted to a known 

 volume corresponding with the amount of bases in solution. 



The solutions were spectrographically examined, and the photo- 

 graphs compared with others taken from solutions containing accu- 

 rately -weighed quantities of pure beryllia. The coil used was capable 

 of giving a 5-inch spark in air. In place of a Leyden jar a pane of 

 glass coated on each side with a square foot of tinfoil was used. The 

 electrodes* were Ceylon graphite as in other experiments, the sole 

 impurity in which was a trace of magnesium. 



The following tabulated statement gives the wave-lengths of the 

 lines, together with a description of the spectra photographed from 

 solutions of different strengths (see next page). 



The actual length of the line 2478*1, as rendered by solutions of 

 0-00001 per cent, and O'OOOOOl per cent, strength, is, in the former, 0'07, 

 and, in the latter, 0*05 of an inch. The normal length of the line at 

 this part of the spectrum is 0'22 of an inch. The quantity of sub- 

 stance yielding this spectrum is equivalent to one-millionth of a milli- 

 gramme of beryllium. As I have pointed out in the case of magnesium,! 

 so also is it with beryllium, that the sensitiveness of the spectrum 

 reaction may be increased ten thousand-fold by using a larger coil and 

 more powerful condenser, but leaving the striking distance between the 

 electrodes unaltered. The coefficient of complete extinction was there- 

 fore practically not attainable for all the lines, or, in other words, the 

 sensitiveness of the reaction is almost without limit. 



It will also be seen from my description of the spectra, which have 

 been quite recently re-examined, that the coefficient of extinction of the 

 two lines A 3130'3 and 2478'! had not been reached by the dilution 

 specified. 



A number of thin sections of the Dublin granite containing micro 

 scopic crystals of hexagonal form were examined some years ago. The 

 crystals were supposed to be apatite, but a very carefully executed 

 analysis disclosed the fact that the proportion of phosphoric acid con- 

 tained in 20 grammes of the rock was almost infinitesimal, and that on 

 warming thin sections, in which the hexagonal crystals were visible, 

 with nitric acid and ammonium molybdate, no deposit of yellow 



* ' Phil. Trans.,' 1884, Part I, p. 49. 

 t ' Phil. Trans.,' 1884, Part II, p. 325. 

 VOL. LXIX. X 



