See Sturm, Chronik der Stadt Weissenfels (Weissenfels, 1846); and Gerhardt, Geschichte der Stadt Weissenfels (Weissenfels, 1907).
Gerhardt attempted a solution by investigating chemical reactions.
Gerhardt found that reactions could be best followed if one assumed the molecular weight of an element or compound to be that weight which occupied the same volume as two unit weights of hydrogen, and this assumption led him to double the equivalents accepted by Gmelin, making H= 1, 0 =16, and C = 12, thereby agreeing with Berzelius, and also to halve the values given by Berzelius to many metals.
The bases upon which Gerhardt and Laurent founded their views were not sufficiently well grounded to lead to the acceptance of their results; Gerhardt himself returned to Gmelin's equivalents in his Lehrbuch der Chemie (1853) as they were in such general use.
From the results obtained by Laurent and Gerhardt and their predecessors it immediately followed that, while an element could have but one atomic weight, it could have several equivalent weights.
From a detailed study of organic compounds Gerhardt had promulgated a " theory of types " which represented a fusion of the older radical and type theories.
The development of the atomic theory and its concomitants - the laws of chemical combination and the notion of atoms and equivalents - at the hands of Dalton and Berzelius, the extension to the modern theory of the atom and molecule, and to atomic and molecular weights by Avogadro, Ampere, Dumas, Laurent, Gerhardt, Cannizzaro and others, have been noted.
As early as 1842, Gerhardt in his Précis de chimie organique exhibited a marked leaning towards Dumas' theory, and it is without doubt that both Dumas and Laurent exercised considerable influence on his views.
According to Gerhardt, the process of substitution consisted of the union of two residues to fo- m a unitary whole; these residues, previously termed " compound radicals," are atomic complexes which remain over from the interaction of two compounds.
These views were extended by William Odling, and adopted by Gerhardt, but with modifications of Williamson's aspects.
In 1761 he went to St Petersburg with Gerhardt Friedrich Miller, the Russian historiographer, as Miller's literary assistant and as tutor in his family.
He next went to Paris, where he studied chemistry under Gerhardt, and on his return to London he was appointed director of the chemical laboratory at Guy's Hospital.
Gerhardt, " Beitrag zur Kenntniss der Kreideformation in Venezuela and Peru," Neues Jahrb., Beil.
Francke and Philipp Spencer, with Paul Gerhardt and his cousin Johann.
Buckingham, a bronze statue by Karl Gerhardt of Nathan Hale, a bronze tablet (also by Karl Gerhardt) in memory of John Fitch (1743-1798), the inventor; a portrait of Washington, purchased by the state in 1800 from the artist, Gilbert Stuart; and a series of oil portraits of the colonial and state governors.
The poet Paul Gerhardt (1607-1676) was pastor here and is buried in the parish church.
Gerhardt, Haile, 1871.
If we may pass by the doctrine of the Identity of Indiscernibles, which played a part of some importance in subsequent philosophy, and the Law of Continuity, which as Leibnitz represents it is, if not sheer dogma, reached by something very like a fallacy, Gerhardt, vi.
2 § 9, 17 § 4 (Gerhardt v.
Gerhardt, Geschichte der Mathematik in Deutschland, p. 282, and Plucker's life by A.