General Science

The Project Gutenberg EBook of General Science, by Bertha M. Clark This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at www.gutenberg.net Title: General Science Author: Bertha M. Clark Release Date: August 25, 2005 [EBook #16593] Language: English Character set encoding: ISO-8859-1 *** START OF THIS PROJECT GUTENBERG EBOOK GENERAL SCIENCE *** Produced by John Hagerson, Kevin Handy, Sankar Viswanathan and the Online Distributed Proofreading Team at http://www.pgdp.net GENERAL SCIENCE BY BERTHA M. CLARK, PH.D. HEAD OF THE SCIENCE DEPARTMENT WILLIAM PENN HIGH SCHOOL FOR GIRLS, PHILADELPHIA NEW YORK - CINCINNATI - CHICAGO AMERICAN BOOK COMPANY 1912PREFACE This book is not intended to prepare for college entrance examinations; it will not, in fact, prepare for any of the present-day stock examinations in physics, chemistry, or hygiene, but it should prepare the thoughtful reader to meet wisely and actively some of life's important problems, and should enable him to pass muster on the principles and theories underlying scientific, and therefore economic, management, whether in the shop or in the home. We hear a great deal about the conservation of our natural resources, such as forests and waterways; it is hoped that this book will show the vital importance of the conservation of human strength and health, and the irreparable loss to society of energy uselessly dissipated, either in idle worry or in aimless activity. Most of us would reproach ourselves for lack of shrewdness if we spent for any article more than it was worth, yet few of us consider that we daily expend on domestic and business tasks an amount of energy far in excess of that actually required. The farmer who flails his grain instead of threshing it wastes time and energy; the housewife who washes with her hands alone and does not aid herself by the use of washing machine and proper bleaching agents dissipates energy sadly needed for other duties. The Chapter on machines is intended not only as a stimulus to the invention of further labor-saving devices, but also as an eye opener to those who, in the future struggle for existence, must perforce go to the wall unless they understand how to make use of contrivances whereby man's limited physical strength is made effective for larger tasks. The Chapter on musical instruments is more detailed than seems warranted at first sight; but interest in orchestral instruments is real and general, and there is a persistent desire for intelligent information relative to musical instruments. The child of the laborer as well as the child of the merchant finds it possible to attend some of the weekly orchestral concerts, with their tiers of cheap seats, and nothing adds more to the enjoyment and instruction of such hours than an intimate acquaintance with the leading instruments. Unless this is given in the public schools, a large percentage of mankind is deprived of it, and it is for this reason that so large a share of the treatment of sound has been devoted to musical instruments. The treatment of electricity is more theoretical than that used in preceding Chapters, but the subject does not lend itself readily to popular presentation; and, moreover, it is assumed that the information and training acquired in the previous work will give the pupil power to understand the more advanced thought and method. The real value of a book depends not so much upon the information given as upon the permanent interest stimulated and the initiative aroused. The youthful mind, and indeed the average adult mind as well, is singularly non-logical and incapable of continued concentration, and loses interest under too consecutive thought and sustained style. For this reason the author has sacrificed at times detail to general effect, logical development to present-day interest and facts, and has made use of a popular, light style of writing as well as of the more formal and logical style common to books of science. No claim is made to originality in subject matter. The actual facts, theories, and principles used are such as have been presented in previous textbooks of science, but the manner and sequence ofpresentation are new and, so far as I know, untried elsewhere. These are such as in my experience have aroused the greatest interest and initiative, and such as have at the same time given the maximum benefit from the informational standpoint. In no case, however, is mental training sacrificed to information; but mental development is sought through the student's willing and interested participation in the actual daily happenings of the home and the shop and the field, rather than through formal recitations and laboratory experiments. Practical laboratory work in connection with the study of this book is provided for in my _Laboratory Manual in General Science_, which contains directions for a series of experiments designed to make the pupil familiar with the facts and theories discussed in the textbook. I have sought and have gained help from many of the standard textbooks, new and old. The following firms have kindly placed cuts at my disposal, and have thus materially aided in the preparation of the illustrations: American Radiator Company; Commercial Museum, Philadelphia; General Electric Company; Hershey Chocolate Company; _Scientific American_; The Goulds Manufacturing Company; Victor Talking Machine Company. Acknowledgment is also due to Professor Alvin Davison for figures 19, 23, 29, 142, and 161. Mr. W.D. Lewis, Principal of the William Penn High School, has read the manuscript and has given me the benefit of his experience and interest. Miss. Helen Hill, librarian of the same school, has been of invaluable service as regards suggestions and proof reading. Miss. Droege, of the Baldwin School, Bryn Mawr, has also been of very great service. Practically all of my assistants have given of their time and skill to the preparation of the work, but the list is too long for individual mention. BERTHA M. CLARK. WILLIAM PENN HIGH SCHOOL. CONTENTS CHAPTER I. HEAT II. TEMPERATURE AND HEAT III. OTHER FACTS ABOUT HEAT IV. BURNING OR OXIDATION V. FOOD VI. WATER VII. AIR VIII. GENERAL PROPERTIES OF GASES IX. INVISIBLE OBJECTS X. LIGHT XI. REFRACTION XII. PHOTOGRAPHY XIII. COLOR XIV. HEAT AND LIGHT AS COMPANIONS XV. ARTIFICIAL LIGHTING XVI. MAN'S WAY OF HELPING HIMSELF XVII. THE POWER BEHIND THE ENGINE XVIII. PUMPS AND THEIR VALUE TO MAN XIX. THE WATER PROBLEM OF A LARGE CITY XX. MAN'S CONQUEST OF SUBSTANCES XXI. FERMENTATION XXII. BLEACHING XXIII. DYEING XXIV. CHEMICALS AS DISINFECTANTS AND PRESERVATIVES XXV. DRUGS AND PATENT MEDICINES XXVI. NITROGEN AND ITS RELATION TO PLANTS XXVII. SOUND XXVIII. MUSICAL INSTRUMENTS XXIX. SPEAKING AND HEARING XXX. ELECTRICITY XXXI. SOME USES OF ELECTRICITY XXXII. MODERN ELECTRICAL INVENTIONS XXXIII. MAGNETS AND CURRENTS XXXIV. HOW ELECTRICITY MAY BE MEASURED XXXV. HOW ELECTRICITY IS OBTAINED ON A LARGE SCALE INDEX GENERAL SCIENCE CHAPTER I HEATI. Value of Fire. Every day, uncontrolled fire wipes out human lives and destroys vast amounts of property; every day, fire, controlled and regulated in stove and furnace, cooks our food and warms our houses. Fire melts ore and allows of the forging of iron, as in the blacksmith's shop, and of the fashioning of innumerable objects serviceable to man. Heated boilers change water into the steam which drives our engines on land and sea. Heat causes rain and wind, fog and cloud; heat enables vegetation to grow and thus indirectly provides our food. Whether heat comes directly from the sun or from artificial sources such as coal, wood, oil, or electricity, it is vitally connected with our daily life, and for this reason the facts and theories relative to it are among the most important that can be studied. Heat, if properly regulated and controlled, would never be injurious to man; hence in the following paragraphs heat will be considered merely in its helpful capacity. 2. General Effect of Heat. _Expansion and Contraction_. One of the best-known effects of heat is the change which it causes in the size of a substance. Every housewife knows that if a kettle is filled with cold water to begin with, there will be an overflow as soon as the water becomes heated. Heat causes not only water, but all other liquids, to occupy more space, or to expand, and in some cases the expansion, or increase in size, is surprisingly large. For example, if 100 pints of ice water is heated in a kettle, the 100 pints will steadily expand until, at the boiling point, it will occupy as much space as 104 pints of ice water. The expansion of water can be easily shown by heating a flask (Fig. I) filled with water and closed by a cork through which a narrow tube passes. As the water is heated, it expands and forces its way up the narrow tube. If the heat is removed, the liquid cools, contracts, and slowly falls in the tube, resuming in time its original size or volume. A similar observation can be made with alcohol, mercury, or any other convenient liquid. [Illustration: FIG. 1.--As the water becomes warmer it expands and rise in the narrow tube.] Not only liquids are affected by heat and cold, but solids also are subject to similar changes. A metal ball which when cool will just slip through a ring (Fig. 2) will, when heated, be too large to slip through the ring. Telegraph and telephone wires which in winter are