Its varied Characters, and constant change of external Form--The Grain of Dust, its Properties and Powers--Combinations in inorganic Masses and in organized Creations--Our knowledge of Matter--Theory of Ultimate Atoms--The Physical Forces acting on the Composition of Masses--The certainty of the exercise of subtile principles, which are beyond the reach of experimental Science 1 CHAPTER II. MOTION. Are the Physical Forces modes of Motion?--Motion defined--Philosophical Views of Motion, and the Principles to which it has been referred--Motions of the Earth and of the Solar System--Visible Proofs of the Earth’s Motion on its Axis--Influence of the proper Motions of the Earth on the Conditions of Matter--Theory of the Conversion of Motion into Heat, &c.--The Physical Forces regarded as principles independent of Motion, although the Cause and often apparently the Effects of it 7 CHAPTER III. GRAVITATION. The Forms of Matter--Shape of the Earth--Probability of the Mass forming this Planet having existed in a Nebulous State--Zodiacal Lights--Comets--Volatilization of Solid Matter by Artificial means--The principle of Gravitation--Its Influence through Space and within the smallest Limits--Gravitating powers of the Planets--Density of the Earth--Certainty of Newton’s Law of the Inverse Square--Discovery of Neptune--State of a Body relieved from Gravitation--Experiment explaining Saturn’s Ring, &c.--General inference 21 CHAPTER IV. MOLECULAR FORCES. Conditions of Matter--Variety of organized Forms--Inorganic Forms--All matter reducible to the most simple conditions--Transmutation, a natural operation--Chemical Elementary Principles--Divisibility of Matter--Atom--Molecules--Particles--Molecular Force includes several Agencies--Instanced in the Action of Heat on Bodies--All Bodies porous--Solution--Mixture--Combination--Centres of Force--Different States of Matter (Allotropic Conditions)--Theories of Franklin, Æpinus, and Coulomb--Electrical and Magnetic Agencies--Ancient Notions--Cohesive Attraction, &c. 35 CHAPTER V. CRYSTALLOGENIC FORCES. Crystallisation and Molecular Force distinguished--Experimental Proof--Polarity of Particles forming a Crystal--Difference between Organic and Inorganic Forms--Decomposition of Crystals in Nature--Substitution of Particles in Crystals--Pseudomorphism--Crystalline Form not dependent on Chemical Nature--Isomorphism--Dimorphism--Theories of Crystallogenic Attraction--Influence of Electricity and Magnetism--Phenomena during Crystallisation--Can a change of Form take place in Primitive Atoms?--Illustrative Example of Crystallisation 50 CHAPTER VI. HEAT--SOLAR AND TERRESTRIAL.