ABUNDANCE OF THE CHEMICAL ELEMENTS. 
139 
less for the other elements specified. The remaining ele¬ 
ments, more than fifty in number, can hardly aggregate 
over one per cent, altogether, and not one of them could pass 
0‘05 per cent, in relative quantity. Some of them may be 
briefly considered in detail, as follows : 
Fluorine. —Abundant in fluor-spar and apatite and present 
in many rocks as a constituent of topaz or mica. If the 
phosphorus in the foregoing estimate, 0*09 per cent., represents 
mainly apatite, the proportional amount of fluorine would 
he *02 to *03, the minimum assignable value. 
Glucinum. —Widely distributed as beryl and easily over¬ 
looked in small traces. If determined, it would appear as a 
correction to the alumina. 
Boron. —-Comparatively abundant in tourmaline and dato- 
lite and conspicuous in certain volcanic waters; difficult to 
estimate. 
The Cerium Group. —According to Cross and Iddings, alla- 
nite is a wide-spread constituent of rocks. The same is true 
of monazite, as shown by Derby. These elements, together 
with thorium, zirconium, and the yttrium groups, would ap¬ 
pear as corrections to alumina. 
Nickel. —Frequent in rocks composed of or derived from 
olivine. Less than O’01 per cent. 
The Metallic Acids —stannic, molybdic, tungstic, columbic, 
and tantalic.—These, if determined, would form corrections 
to silica. The same is true to some extent of barium when 
present in rocks as sulphate. 
The Heavy Metals. —Widely distributed in rocks, according 
to Sandberger’s researches, but very small in quantity. 
In the larger items, say from oxygen down to the alkaline 
metals, the estimates here given do not differ very widely 
from others which have been long current in chemical and 
geological literature. They rest, however, upon fuller evi¬ 
dence, and the discussion is, perhaps, more complete. In 
the smaller items the new results display the greatest novelty, 
and future modifications are most likely. The comparative 
rarity of carbon and sulphur is, to say the least, surprising. 
15-Bull. Phil. Soc.. Wash. Vol. 11. 
