Note 61 — APPENDIX TO CHAPTER I.
Reading edition
Composition of the earth's solid crust in 100 parts by weight:—
Oxygen 44.0 to 48.7
Silicon 22.8 to 36.2
Aluminum 9.9 to 6.1
Iron 9.9 to 2.4
Calcium 6.6 to 0.9
Magnesium 2.7 to 0.1
Sodium 2.4 to 2.5
Potassium 1.7 to 3.1
(Roscoe's 'Lessons in Elementary Chemistry,' p. 8.)