Chapter I: Front Matter

CONCERNING THE
NATURE OF THINGS

_By_

SIR WILLIAM BRAGG

K. B. E., D.Sc., F. R.S.

_Illustrated with Many
Diagrams and Plates_

HARPER & BROTHERS, PUBLISHERS
NEW YORK AND LONDON
MCMXXV

CONCERNING THE
NATURE OF THINGS

Copyright, 1925
By Harper & Brothers
Printed in the U. S. A.

CONTENTS

CHAPTER PAGE

Introduction xii

Preface to the English Edition xv

I. The Atoms of which Things are Made 1

II. The Nature of Gases 46

III. The Nature of Liquids 90

IV. The Nature of Crystals: Diamond 126

V. The Nature of Crystals: Ice and Snow 172

VI. The Nature of Crystals: Metals 215

Note 250

LIST OF PLATES

PLATE _Facing page_

I. (A) MODEL OF BISMUTH CRYSTAL.

(B) THE SHAKING SAND BOX 16

II. SHIMIZU-WILSON HAY TRACK APPARATUS 26

III. ALPHA RAY TRACKS 30

IV. (A) BAR MAGNETS ON SPIRAL SPRINGS. (B) MODELS OF ATOMS WITH ELECTRONS 34

V. (A) FLOATING MAGNETS. (B) CRYSTALS IN TUBE CONTAINING EMANATION 42

VI. (A) TUNING FORK OVER JAR. (B) FOG APPARATUS 60

VII. CIGARETTE SMOKE 66

VIII. EXPERIMENT SHOWING THE PRESSURE OF THE ATMOSPHERE 72

IX. CAVITATION CAUSING EROSION OF PROPELLER BLADES 98

X. (A) LARGE DROP OF ORTHOTOLUIDINE. (B) ONE SOAP BUBBLE INSIDE ANOTHER 104

XI. (A) CIRCLES CLEARED BY MINUTE DROPS OF OIL. (B) THE CAMPHOR BOAT 112

XII. (A) STORMY WATER, (B) OIL STILLING THE STORM, (C) GRAPE IN SODA WATER 118

XIII. CRYSTALLINE FORMS 134

XIV. (A) DIAMOND MODEL, (B) PLANE LATTICE IN THE DESIGN OF A WALL-PAPER 148

XV. THE CULLINAN DIAMOND 156

XVI. (A) LAYERS OF THE GRAPHITE CRYSTAL. (B) POSSIBLE FORMS OF THE BENZENE RING 160

XVII. SNOW CRYSTALS OF VARIOUS FORMS 172

XVIII. MORE SNOW CRYSTALS 174

XIX. A HALO AND MOCK SUNS 176

XX. (A) GLACIER ICE. (B) MODELS OF ICE STRUCTURE 188

XXI. (A) MODEL OF PENTANE, (B) X-RAY SPECTRUM OF A HYDROCARBON. (C) MODEL OF ROCK SALT 206

XXII. TWO PHOTOGRAPHS OF ALUMINIUM 216

XXIII. CRYSTAL GRAINS IN A SAMPLE OF STEEL 218

XXIV. ILLUSTRATING “CLOSE PACKING” 220

XXV. (A) CUBIC PACKING, (B) HEXAGONAL PACKING 222

XXVI. THE YIELDING OF ALUMINIUM UNDER STRAIN 230

XXVII. DAMASCUS BLADES 236

XXVIII. CEMENTITE CRYSTALS 238

XXIX. (A) CEMENTITE CRYSTALS BEING BROKEN UP AND ROUNDED OFF. (B) A NEEDLE SCRATCH IN A POLISHED PIECE OF SPECULUM METAL 240

XXX. EFFECT ON SPECULUM METAL OF RUBBING (WITH FINE EMERY) AND POLISHING (WITH ROUGED LEATHER) 242

XXXI. A CONTINUATION OF PLATE XXX 244

XXXII. EXPERIMENT SHOWING EFFECT OF TEMPERATURE ON ELECTRICAL RESISTANCE 246

LIST OF FIGURES

PAGE PAGE PAGE PAGE Figure 1 10 Figure 1A 18 Figure 2 28 Figure 3 35 Figure 4 57 Figure 5 68 Figure 6 69 Figure 7 70 Figure 8 73 Figure 9 74 Figure 9A 75 Figure 10 78 Figure 11 79 Figure 12 79 Figure 13 93 Figure 14 96 Figure 15 100 Figure 16 101 Figure 17 104 Figure 18 104 Figure 19 106 Figure 20 108 Figure 21 109 Figure 21A 109 Figure 22 117 Figure 23 122 Figure 24 123 Figure 25 124 Figure 26 133 Figure 27 134 Figure 27A 136 Figure 28 139 Figure 29 146 Figure 30 147 Figure 31 148 Figure 32 150 Figure 33 152 Figure 34 159 Figure 35 160 Figure 36 162 Figure 37 162 Figure 38 167 Figure 39 168 Figure 40 170 Figure 41 176 Figure 42 176 Figure 43 179 Figure 44 181 Figure 45 183 Figure 45A 184 Figure 46 189 Figure 47 191 Figure 48 192 Figure 49 196 Figure 50 205 Figure 51 208 Figure 52 209 Figure 53 219 Figure 54 222 Figure 55 225 Figure 56 226 Figure 57 229