The Romance of Modern Chemistry

■■■ ■■■ CONTENTS CHAPTER XXVT CHEMISTRY AND ELECTRICITY How chemical changes produce an electric current—Volta's cell PA°B —The harnessing of chemical energy—Electricity contributes to the advance of chemistry—Electrolysis—Sir Humphry Davy's, experiments—Refining of copper—How aluminium is obtained—A new feature in the Scottish Highlands. . 290 CHAPTER XXVII SOME INTERESTING FACTS ABOUT SOLUTIONS Sugar and salt dissolved in water—Solutions the scene of con- stant activity—Diffusion and osmosis—Behaviour of blood corpuscles in water and salt solutions—Freezing-point and boiling-point of solutions—How to get fresh water from salt water—Molecular suicide—An interesting procession . . 302 CHAPTER XXVIII FROM SOLUTIONS TO CRYSTALS How saltpetre is crystallised—The effect of sowing a super- saturated solution—The rate of crystallisation of phosphorus How the formation of crystals is induced by scratching__ Dry crystals which contain water—Curious changes of colour —Sympathetic inks—Crystals in metals, and how they are detected—A curious application of the Röntgen rays . , 314 CHAPTER XXIX GREAT EFFECTS FEOM SMALL CAUSES Significance of small quantities—How a little water makes a big difference—How gases are dried—Incandescent mantles and luminous paints—Catalytic actions—A revolution in the manufacture of sulphuric acid—How hydrogen may be burned at the ordinary temperature—Catalytic agents in the human ...................................................... CHAPTER XXX HOW TRIFLING OBSERVATIONS LEAD TO GBEAT DISCOVEBIES How Priestley discovered oxygen—A cut on the finger leads to the preparation of blasting gelatine—A cracked glass jar, and what it led to—An accident which played a part in the manufacture of synthetic indigo—A famous chemist just misses an important discovery—The detection of argon— The significance of a small difference in weight . . . 335 14