The Magnetic Separation of Lines 39 
By means of intervals, their multiples, and multiple factors, one 
obtains a most convenient method of comparing lines and sub- 
stances. The quadruplet principal series tvpes which Professor 
Runge found in Na, Cu, Ag, Al, Tl, Mg, Ca, Sr, are represented 
by a/3(4, 2). 
In yttrium there is one line, 3200.44, which may pessess these 
values, but the companion sextuplet is absent. It may be of type 
(15,7)a/11. The sextuplet principal series, a/3(5, 3, 1), found in 
the same substances, has a solitary representative in zirconium in 
the line 3483.70, but the companion quadruplet is absent. Hg., 
first subordinate series satellite, 3663.05, is probably represented 
in yttrium by 4199.46. The separations of the components of the 
yttrium line are a trifle smaller. One line, 3624.10, in zirconium 
is like two lines, 4128.49 and 3930.84, in yttrium. These lines are 
4 and 1 times 3a/11. Similarly there are five lines in zirconium 
whose separation is like two yttrium lines and the separations 
5a/11(3, 1). Among these there is considerable variation from 
the desirable accuracy. These lines are zirconium 4429.3, 4199.2, 
4043.8, 4024.2, 3296.6, and yttrium 4475.9 and 3449. Zirconium 
4590.8, barium 5997.4, and yttrium 3195.8, 4358.9, are types of 
a/2(3, 2, 1). These yttrium lines are the best duplications ob- 
served. The most prominent feature of the interval tables is the 
types (interval times factors) which are only once represented. 
As before mentioned, it requires four lines to make sure of a series. 
Hence the table excludes series except in zirconium under the 
interval .42. These lines are unequaily distributed in distances 
(in terms of vibrations per cm.). The intensities are also irreg- 
ular. The factors, by which the intervals must be multiplied to 
give the required separation, are very numerous, as well as pos- 
sessing a variety of combinations. The principal series and second 
subordinate series of the previousiy mentioned substances have 
the interval a@/3. This interval is represented by eleven lines in 
yttrium and zirconium, but only in two cases are the factors of 
proper magnitude and number to produce the series type. This 
leaves nine new types under this interval. 
Under a/11, an interval of the Hg first subordinate series and 
multiples of a/11, there are six yttrium, fifteen zircon, one neon, 
oo 
