The Romance of Modern Chemistry

CONTENTS CHAPTER XVI BELOW ZERO ,. ....... PAGE Arctic exploration in chemical laboratories—Why salt and ice conspire to produce cold—Carbonic acid snow—Liquid air obtained by self-cooling—How liquid air is kept—Bacteria and seeds at very low temperatures—Liquid hydrogen and liquid helium—The absolute zero of temperature . . . 180 CHAPTER XVII CHEMISTRY AT HIGH TEMPEBATURES The distillation of metals—How partnerships are dissolved at high temperatures—The oxyhydrogen flame—The electric furnace—How sand may be converted into vapour—Calcium carbide and acetylene—Nitrogen from the air for agri- cultural purposes...............................193 CHAPTER XVIII CHEMISTBY OF THE STABS What is the composition of the sun and the stars ?—Meteorites —The marvellous power of the spectroscope—The solar spectrum—Elements in the eun—Helium and its story— How the spectroscope has led to the discovery of new elements—The Aurora Borealis....................203 CHAPTER XIX CHEMISTRY AND AGRICULTURE The chemistry of vegetable growth—How crops feed—Starch and sugar from carbon dioxide—The constituents of meadow grass—Nitrogen in the soil, and how it gets there—Assisting Nature—Concerning the various kinds of manure—Chili saltpetre and sulphate of ammonia—Bone dust and furnace slag......................................... 215 CHAPTER XX SUGAR AND STABCH Foodstuffs and their composition—Carbohydrates, fats, and pro- teids—What “sugar” really means—Beet sugar and cane sugar—How charcoal is used in purifying sugar—Glucose, and where it comes from—Arsenic in beer—Starch converted into sugar—Alcohol from cotton rags—Cellulose and cellu- loid ................................... > . 227 12