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V. Researches regarding the Molecular Constitution of the Volatile Organic Bases. 
By Dr. A. W. Hofmann, F.C.S., Professor of the Royal College of Chemistry of 
London. Communicated hy Sir James Clark, Bart., F.R.S. 
Received December 26, 1849, — Read January 17, 1850. 
The limited number of elementary substances which are concerned in the elabora- 
tion of the endless variety of organic compounds, long ago directed the course of 
chemical inquiry into the channel of speculations as to the mode in which the 
various constituents are grouped in bodies of this nature. The necessity of these 
speculations became more and more imperative as the boundary of the science ex- 
tended ; they were indeed forced upon us by the discovery of substances isomeric 
with each other which deprived us of the resort to mere quantity for the explanation 
of their contrasting qualities. Wild and incongruous though some of the views, pro- 
posed from time to time, may have been, it must be admitted that their influence 
upon the progress of chemistry has been most beneficial ; especially in the organic 
department of this science, it is to the theory of the compound radicals, the result of 
these speeulations, that we are indebted for the light which now begins to dawn upon 
the chaos of collected facts, even if we should never succeed in isolating these radicals. 
Among the various classes of organic substances, there is perhaps none of which, 
from an early period, chemists have so constantly endeavoured to attain a general 
conception as the group of compounds which have received the name of organic 
bases, all — and they are now very numerous — being capable of combining, like the 
metallic oxides, with acids, and being derived either from vital processes in animals 
or plants, or from a variety of artificial reactions conducted in the laboratory. 
The remarkable analogy between all these substances and ammonia, which in its 
turn imitates as it were in its chemical deportment the mineral oxides, naturally at- 
tracted the notice of chemists soon after Serturner’s discovery of the first of these 
alkaloids in the beginning of this century. Nor have they ever since been classified 
separately from ammonia ; philosophers have only differed as to the mode of their 
relation with the typical compound. 
Of the theories which have been enunciated respecting the constitution of the 
organic bases, there are two of chief importance, which may be designated as the 
ammonia- and the amidogen-theory, the former having been first proposed by Ber- 
zelius*, while the latter we owe to Liebig -f-. According to the former of the two 
* Traite de Chimie, vi. p. ii. 
t Handwdrterbuch der Chemie von Liebig, Wohler und Poggendorff, Bd. i. p. 699. Artikel Organische 
Basen. 
