Illustrations of existence of relations between greater or less

molecular energy and

(1) the actual valencies of the atoms in the molecules con-

sidered

(2) the distribution of reactions between the atoms in the

molecules

General considerations regarding relations illustrated in pars. 87

and 88.

Application of these considerations to prevalent views on valency

Apparent exceptions to that explanation of isomerism which is

based on the theory of valency

Properties of liquid and solid compounds are to some extent con-

Theory of valency not strictly applicable to phenomena suggested

by terms molecular compounds and atomic compounds.

Definition of molecular compounds impossible

Illustrations of phenomena exhibited by gases classed as molecular

compounds

Study of such phenomena leads to considerations belonging to

chemical kinetics

Relations between atomic weights and fusibility of elements.
and various physical constants

of elements

Illustrations of applications of periodic law :

(1) to predict properties of unknown elements

(2) to guide the study of properties of similar elements

'Odd series', 'even series', 'long periods', and 'typical elements'
Connections between general formulæ of classes of compounds and
atomic weights of elements in these compounds

Forms of highest oxides considered as periodic functions of atomic

weights of the elements

Valency considered as a periodic function of atomic weights of the

Attempts to determine thermal values of molecular decompositions

Thermal results applied:

(5) to neutralisation of acids by bases, and of bases by acids.

Influence of physical conditions, especially temperature, on ther-

mal value assigned to a chemical change

Examples to shew importance of considering such influence .

Influence of mass of reacting bodies on thermal value of a chemical

change

131

294

Thermal value of a chemical reaction is the sum of several partial

Illustrations of application of thermal methods to determine struc-

tural formulæ

Connections between boiling points and composition of hydrocarbons

Concluding remarks to this section

SECTION II. OPTICAL METHODS.

Statement of methods to be considered in this section

Formulæ for calculating the refraction-equivalent of a carbon

compound

Is the value to be assigned to the refraction-equivalent of an ele-

ment constant in all liquid compounds of that element?

Is there any connection between the nature of the atoms directly

bound to a given atom and the refraction-equivalent of that

atom?

Meaning to be assigned to the expression 'refraction-equivalent of

an atom'

Connection between the refraction-equivalent and the actual va-

lency of the atom of carbon

316

Application of refraction-equivalents to questions regarding struc-

tural formulæ

Specific rotatory power of substances

This constant depends on atomic composition of molecules, but
is also modified by reactions between optically active and
inactive molecules

van't Hoff's hypothesis regarding connections between molecular
structure and specific rotatory power

Illustrations of modifying influence exerted by optically inactive
substances on rotatory power of optically active compounds.
Connections between absorption-spectra and structure of molecules
of carbon compounds

Summary of section

SECTION III. METHODS BASED ON VALUES ASSIGNED TO THE

CONSTANT,

formula-weight

specific-gravity'

Explanation of constant considered in this section

150 334

Data to illustrate connections between this constant and composi-

tion of compounds

Data to illustrate connections between this constant and distribu-

tion of interatomic actions

SECTION IV. METHOD BASED ON 'ETHERIFICATION-VALUES'.

156

1

345

BOOK II. CHEMICAL KINETICS.

CHAPTER I. DISSOCIATION.

Introductory remarks on subject of this book

References to nascent actions and to molecular compounds as sub-

jects which require kinetical treatment.

Dissociation contrasted with decomposition

Relation between dissociation and pressure of gaseous products

Dissociation of calcium carbonate

Dissociation is a reversible process

Pfaundler's hypothesis to account for facts mentioned in last para-

graph.

168

360

Summary of characteristics of dissociation-processes

Illustrations of bearing of dissociation on determinations of vapour

View of Berzelius on same subject

Reference to work of Guldberg and Waage on this subject

Rough classification of miscellaneous facts regarding chemical

Sketch of the theory of 'cumulative resolution' proposed by Mills

Existence of some compounds only as members of a system from

which they cannot be obtained in a separate state.

Application of knowledge gained in this section to conception of

molecular structure

This hypothesis throws light on subject of nascent actions

Also on contact-actions and predisposing affinity.

391

Hicks's treatment of dissociation as a special case of equilibrium .

Reference to Horstmann's thermodynamical theory of dissociation

Willard Gibbs's thermodynamical treatment of equilibrium .

Foregoing paragraphs shew importance of obtaining measurements

of speed of chemical changes

Gladstone's work on this subject.

Work of Harcourt and Esson on the same subject

Menschutkin's determinations of velocity of etherification

References to Kajander's measurements of velocity of action of

acids on magnesium

Concluding remarks on results obtained in paragraphs 195—198 .

Recapitulation of general results obtained by Guldberg and Waage

Sketch of analytical methods employed in measuring amounts of

205

411

206

411

207

414

to gaseous systems

to cases of dissociation

208

414

209

415

Ostwald's development of the theory to determine relative af-

finities of acids

212

417

Examples of Ostwald's method of procedure

Relative affinities of HCl, H2SO1, and HNO

213

419

214

420