Jöns Jacob Berzelius, Essai sur le théorie des proportions chimiques (1819). Translated in Henry M. Leicester and Herbert S. Klickstein, A Source Book in Chemistry 1400-1900 (1952), 260.
Jöns Jacob Berzelius, An Attempt to Establish a Pure Scientific System of Mineralogy (1814), trans. J. Black, 48.
“The nature of the chemical bond is the problem at the heart of all chemistry.”
New Chemistry (1957) by the editors of Scientific American, p. 65
Jöns Jacob Berzelius Essai sur la théorie des proportions chemiques (1819), 98. Quoted by Henry M. Leicester in article on Bessel in Charles Coulston Gillespie (editor), Dictionary of Scientific Biography (1981), Vol. 2, 94.
Introduction
Higher Mathematics for Chemical Students (1911)
Context: As an instance of the remarkably far-reaching effect which a single mathematico-physical concept has had upon the development of chemical theory, one has but to recall the state of chemistry just before the revival of Avogadro's law by Cannizzaro, to be impressed by its confusion. Relying solely upon their "chemical instinct," the leaders of the various schools of chemical thought had developed each his own theoretical system.... a host of... conceptions strove for supremacy. The strife was stilled, order and unity were restored, as soon as Avogadro's great idea was seen in its true light, and the concept of the molecule was introduced into chemistry. A formula which had required pages of reasoning from a purely chemical standpoint to establish, and that insecurely, was fixed by a single numerical result.
1920s, Viereck interview (1929)
Source: Seth, Dreams & Projections of Consciousness, (1986), p. 338 quoting from Session 269
