§ 1. Solution: Kirchhoff's, Gibb's, Duhem's and Van
t'Hoff's researches.

§ 2. Osmosis: History of phenomenon--Traube and
biologists establish existence of semi-permeable
walls--Villard's experiments with gases--Pfeffer
shows osmotic pressure proportional to concentration--
Disagreement as to cause of phenomenon.

§ 3. Osmosis applied to Solution: Van t'Hoff's
discoveries--Analogy between dissolved body and
perfect gas--Faults in analogy.

§ 4. Electrolytic Dissociation: Van t'Hoff's and
Arrhenius' researches--Ionic hypothesis of--Fierce
opposition to at first--Arrhenius' ideas now triumphant
--Advantages of Arrhenius' hypothesis--"The ions
which react"--Ostwald's conclusions from this--Nernst's
theory of Electrolysis--Electrolysis of gases makes
electronic theory probable--Faraday's two laws--Valency--
Helmholtz's consequences from Faraday's laws.


CHAPTER VI

THE ETHER

§ 1. The Luminiferous Ether: First idea of Ether due
to Descartes--Ether must be imponderable--Fresnel shows
light vibrations to be transverse--Transverse vibrations