Solid crust, Ocean, seven per Mean, including ninety-three per cent. air. cent. Oxygen 47.29 per cent. 85.79 per cent. 49.98 per cent. Silicon 27.21 „ „ „ „ 25.30 „ „ Aluminum 7.81 „ „ „ „ 7.26 „ „ Iron 5.46 „ „ „ „ 5.08 „ „ Calcium 3.77 „ „ 0.05 „ „ 3.51 „ „ Magnesium 2.68 „ „ 0.14 „ „ 2.50 „ „ Sodium 2.36 „ „ 1.14 „ „ 2.28 „ „ Potassium 2.40 „ „ 0.04 „ „ 2.23 „ „ Hydrogen 0.21 „ „ 10.67 „ „ 0.94 „ „ Titanium 0.33 „ „ „ „ 0.30 „ „ Carbon 0.22 „ „ 0.002 „ „ 0.21 „ „ Chlorin 0.01 „ „ 2.07 } „ „ 0.15 „ „ Bromin „ „ 0.008} „ „ „ „ Phosphorus 0.10 „ „ „ „ 0.09 „ „ Manganese 0.08 „ „ „ „ 0.07 „ „ Sulfur 0.03+ „ „ 0.09 „ „ 0.04+ „ „ Barium 0.03 „ „ „ „ 0.03 „ „ Nitrogen „ „ „ „ 0.02 „ „ Chromium 0.01 „ „ „ „ 0.01 „ „ —————— ——————— —————— 100.00 „ „ 100.000 „ „ 100.00 „ „ =24. Fluorin= is not mentioned in this table but it is stated that its probable percentage is 0.02 to 0.03 making it thus slightly more abundant than nitrogen. One of the chief points of interest in connection with this table is that the nitrogen which is regarded by most persons as one of the most abundant of the elements is almost the least abundant of those mentioned. THE MINERALS OCCURRING IN ROCKS. =25. The Soil=, as before stated, being comprised almost exclusively of decayed rocks, its characteristics would naturally be determined by the character of the minerals contained in the rocks. A rock may be composed of a single mineral or an aggregation of several minerals.