Applying the rule to determine the specific gravity of oxygen, the operation is as follows: * Possibly, according to modern researches, 0·693. Mixture of chlorate of potash with oxide of manganese, glass retort, spirit-lamp, ring-stand, pneumatic trough, and glass jars. Bottles and jars of oxygen. Table of the weight of oxygen. Binoxide of nitrogen in jar over a pneumatic trough. Prove that it is a test for oxygen; then prove the existence of oxygen in the atomspheric air. Phosphorus (clean) in a funnel; phosphorus (clean) in a bottle; with a little water for the production of ozone. Phosphorus, and a little disc of chalk on which the phosphorus may be lighted. A jar of oxygen for displaying the combustion of phosphorus. A jar of oxygen for displaying the combustion of charcoal. Bottles of ozonized air, and mode of its preparation. Paper imbued with iodide of potassium and starch. Silver leaf in bottle. Ether-jar and hot glass rod. The ozonometer of Schönbein described. Specimens of rock crystal. Flint sand. Tables of their composition. Specimens of granite, clay, slate. Silicified wood. Phosphorus thrown into water. Potassium thrown into water. Specimens of nitre and of chlorate of potash. Tables of their composition. Chlorate of potash and sulphuret of antimony or sugar. ALTHOUGH in these lectures it has never been professed by the directors of the Royal Institution to present a F strictly systematic course of instruction, yet it has been always considered an object to avoid adopting the opposite course. It has been thought desirable also to avoid desultory teaching, and to so arrange the various discourses that, although delivered by various persons, and on various subjects, they may yet form an alliance with each other, and present a tolerably connected scheme in the end. Influenced by this consideration, I have been induced to select the non-metallic elements, or the zootic elements, as a modern writer has termed them, as the subject of the present lectures, because the metallic elements have been recently discussed in the other theatre by Mr. Mansfield, and chemistry, as applied to the industrial arts, by my colleague, Mr. Brande. I do not propose to treat the subject in a purely chemical sense; to discuss the non-metallic elements in the order of their discovery; to pass under notice the various theories of which these elements have been the subjects, or even to make known all their minuter characteristics. My object is rather to treat of them broadly; to point out their more striking features; to consider them not only as chemical agents, but as fulfilling each its appointed function in the material universe. First, then, what do we mean by the term element? By it chemists understand, not a body incapable of subdivision into constituents,-for this assumption would imply a belief that the decomposing agencies of chemistry had already attained their finality, -that we had reached the limits of decomposition,that further progress in this direction would be impossible;-by the term element chemists understand any kind of matter which, up to the present time, has never been decomposed into constituents: hence such matter is considered to be an element provisionally, and subject to future modification. Of these elements we are at this time acquainted with sixtytwo or sixty-three, of which the names are given in a diagram: In this list the non-metallic elements are indicated by a cross, from which indication it will be seen that the metallic elements constitute a large majority of the whole, only thirteen out of the sixty-three being nonmetallic; and from within the limits of this narrow range of only sixty-three has Omnipotence selected the materials which compose our globe, and the living beings which inhabit it. Out of these all the diversified forms and beings of the world are made. From the dense masses of rocks and mountains amongst inanimate things, to the fleeting atmosphere which surrounds us from the simpler forms of animal or vegetable life to the most highly organised, however different one from another in aspect or in functions,— they have all been created out of these elements in the list of sixty-three. Nor is this all. By a wonderful power of adaptation, which bespeaks Omnipotence, our earth and its inhabitants are not made up of these sixty-three bodies equally distributed, but by far the greatest portion of terrestrial matter is composed of the thirteen non-metallic elements; and yet more strange, it will presently be demonstrated that between two-thirds of the whole material terrestrial universe, organic and inorganic, are composed of one alone of these non-metallic simple elements, OXYGEN. How great, then, must be the power of adaptation imposed on these elements, by which they are made to discharge so many functions, and to appear under so many different forms! |