28 REPORT—18638. 
CHEMISTRY. 
Address by A.W. Witt1amson, F.R.S., President of the Chemical Society, and 
Professor of Chemistry and of Practical Chemistry in University College, 
London. 
Berore the Section enters upon the business for which it meets, viz. the consi- 
deration of papers and reports upon special branches of chemistry and the chemical 
arts, it may not be unacceptable to cast a brief and cursory glance at some few 
topics illustrative of the tendencies of chemical science during the last few years, 
and of its applications to some of the manufacturing arts. 
One of the most remarkable features of the progress of our science is the rapid 
rate at which materials have been accumulating, by the labours of chemists in the 
so-called organic department of the science. The study of the transformation of 
organic bodies leads to the discovery of new acids, new bases, new alcohols, new 
ethers, and at a constantly increasing rate which is truly wonderful. Some of these 
new substances are found to possess properties which can at once be applied to 
practical manufacturing purposes, such as dyeing, &c., but the greater number of 
them remain in our laboratories, museums, and text-books, and serve to teach us 
new instances of the combining forces of matter. The influence of this rapid 
growth of materials upon our knowledge of principles, and of the laws of combina- 
tion which constitute the science of chemistry, has been simultaneous with the 
discoveries of the materials themselves; and the material and intellectual progress 
of organic chemistry have gone on so regularly hand in hand, that it is impossible 
to say which has done most in helping the other. It is, accordingly, observed that 
the science has been simplified by every important addition to her materials; 
instead of isolated unmeaning substances, with formule so complex and unintel- 
ligible as to be troublesome to chemists and truly distressing to learners, we have 
now definite and intelligible families of bodies, of which the members are most 
harmoniously united together by some law of composition, and whose connexion 
with neighbouring families is similarly clear and satisfactory. New discoveries 
are constantly coming in to fill up the gaps which still disfigure our growing system. 
In mineral or inorganic chemistry there is not the same scope for discovery at 
present, inasmuch as the elements which belong to it do not combine in those nu- 
merous proportions which occur among the chief elements of organic bodies. But 
yet mineral chemistry has not been standing still, for even the heavy metals, most 
remote in their properties from those volatile and unstable substances of organic 
chemistry, have been got in many instances to combine with them, and the organo- 
metallic bodies thus formed haye not only proved most valuable and powerful 
agents of decomposition, but they have served as a connecting link between the 
two branches of chemical science. A system of classification of elements is now 
coming into use, in which the heavy metals arrange themselves harmoniously with 
the elements of organic bodies, and in accordance with the principles which were 
discovered by a study of organic compounds. 
It is now many years since the attention of chemists was directed by a French 
Professor to some inconsistencies which had crept into our system of atomic 
weights. Gerhardt showed that the principles which were adopted in fixing the 
atomic weight of elementary bodies generally, required us to adopt for oxygen, 
carbon, and sulphur numbers twice as great as those generally in use for those 
elements. The logic of his arguments was unanswerable, and yet Gerhardt’s 
conclusions gained but few adherents. It is to be observed that for some years 
Gerhardt represented chemical reactions by so-called synoptic formule, which took 
no account of the existence of organic radicals. These synoptic formule represent 
in the simplest terms the result of a chemical reaction; but they give no physical 
image of the process by which the reaction is brought about. 
The introduction in this country of the watertype in connexion with poly- 
atomic as well as monatomic radicals was found to satisfy the requirements of the 
synoptic formule. Gerhardt was the first to adopt them from us. He gave, in his_ 
admirable ‘Traité de Chimie Organique,’ a system of organic chemistry on that 
plan, and his book has been of immense service to the development of our science. 
