Again, sulphate of magnesia (common Epsom salts) can be very easily separated into two other substances,—sulphuric acid and magnesia; and in this instance, both these substances can again be subdivided—the acid into sulphur and oxygen, and the magnesia into a metallic body called magnesium and oxygen; but sulphur, oxygen, and magnesium are incapable of further division, and are therefore called ultimate elements.
These ultimate elements amount to 64 in number, according to the present state of our knowledge, and may be arranged in various ways; the simplest plan, perhaps, is dividing them into Non-metallic and Metallic elements.
The Non-metallic elements are:—1. Oxygen. 2. Hydrogen. 3. Nitrogen. 4. Chlorine. 5. Iodine. 6. Bromine. 7. Fluorine. 8. Carbon. 9. Sulphur. 10. Selenium. 11. Tellurium. 12. Silicon. 13. Boron. 14. Phosphorus. The last-named element is the connecting link with the metals through arsenic, which phosphorus closely resembles in its chemical properties.
The Metallic elements may be sub-divided into the metals of the alkalies, the metals of the alkaline earths, the metals of the earths, and the other metals sometimes called metals proper.
1st. The metallic bases of the alkalies:—potassium, sodium, lithium, ammonium, cæsium, rubidium.
2d. The metallic bases of the alkaline earths:—calcium, strontium, barium.
3d. The metallic bases of the earths:—aluminum, glucinum, zirconium, thorium, yttrium, erbium, cerium, lanthanum, didymium.
4th. The metals proper, the most important of which are:—platinum, gold, silver, mercury, copper, iron, tin, lead, nickel, zinc, bismuth, antimony, manganese, cobalt, arsenic.
Now, from these elementary bodies, united together in various proportions, is formed the infinite variety of substances around us, whether animal, vegetable, or mineral; in fact, a few only are generally employed:—in the case of animals and vegetables, oxygen, hydrogen, carbon, nitrogen, with occasionally some sulphur, calcium, phosphorus, and silicon, suffice for building up the beautiful forms of animated nature; while the fabric of our globe itself consists for the most part of the earths; silex, i.e., flint or crystal; lime, in the shape of chalk, marble, or limestone, such as our flagstones are composed of; slate and granite, which are compounds of aluminium, silica, and small quantities of oxide of iron, and sometimes a little potash, etc.; and through their masses are projected irregular streams—veins as they are termed—of the metals, either in a pure state, as is the case sometimes with gold, silver, platinum, mercury, and perhaps one or two others; or combined with one of the non-metallic elements, or with one another.
Late calculations have determined the composition of the earth’s solid crust in 100 parts by weight to be: