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THE SPECTEUM OF THE EUBY— Part II.— AND THE 
ARTIFICIAL RUBY. 
By James Moir, M.A., D.Sc, F.C.S., F.R.S.S.Af. 
In Part I. (Trans. R. S. S. Afr., I. [2], 321) an account was given of 
the extraordinary spectrum of this gem, as seen with a small spectroscope. 
The ruby spectrum has now been thoroughly examined with good instru- 
ments (kindly lent me by the South African School of Mines and Tech- 
nology, Johannesburg). In all, eight absorption lines have been discovered 
in the spectrum, and all of these are of unusual narrowness, so that the 
spectrum is possibly the most remarkable of all known absorption spectra, 
being comparable only with those of neodymium and of reduced uranium 
solutions. 
The first three of these hair-lines constitute the system near B, 
described in Part I. The red transmission line has been found to be 
double, and is caused by the existence of two deep but narrow absorption 
bands (previously given as limited by \\6915 and 6945), with a hair-line 
absorption band almost exactly between them. The first absorption band 
has its sharp inner limiting edge at X6955 (diffraction instrument) or 
\6956 (Hilger's direct). It is a very deep band, shading off towards the 
infra-red as far as the a line. The second band (hair-line in centre of 
transmission) goes from \6942 to \6947 when observed with the narrowest 
possible slit and sunlight. With an ordinary slit it is invisible. The 
third resembles the first, but its sharp edge faces the infra-red, and it 
shades off towards the B line : the sharp edge with narrowest slit is at 
\6933 + 1, The measurement is difficult and requires concentrated sun- 
light : with an ordinary slit the margin of illumination is at about X6920, 
as stated in Part I. 
The other five lines are more easily observed in the artificial ruby, 
which gives exactly the same spectrum as the natural gem, but in an 
exaggerated form on account of its superior size and depth of colour. 
Only approximate measurements are possible. Line No. 4 is exceedingly 
faint and goes from about X6760 to X6790. Line No. 5 is near C, about 
of the distance therefrom towards B (X6610 + 10). 
The other three bands are strong and situated in the blue : Nos. 6 and 
7 form an equal narrow pair at X4775 and X4760 (approx.) respectively. 
