ANNALS. 
OF 
PHILOSOPHY. 
INTRODUCTION TO VOL. XIII, 
Historical Sketch of the Improvements in the Chemical Sciences 
during the Year 1818. By Thomas Thomson, M.D. F.R.S. 
FROM the commencement of the Annals of Philosophy in the 
ear 1813 to the year 1817, I inserted in the January number an 
Wetoriecd sketch of the progress of science during t e preceding 
year. This sketch was confined chiefly to chemistry, and the 
sciences connected with it. I noticed indeed the different 
branches of mechanical philosophy, and slightly glanced at some 
of the departments of natural history. But the primary object 
of the Annals being chemistry, and my industry being exerted 
to introduce into them every chemical discovery of importance, 
which came to my knowledge, in what country soever it had 
been made, I considered myself as pretty well qualified by the 
course of reading which the editing of such a journal naturally 
required to give a tolerably complete view of the progress of 
chemistry during the preceding year. Hence it naturally hap- 
pened that these historical sketches often contained many 
important facts which want of room had prevented me from 
noticing in the previous numbers of the journal. I flatter 
myself, therefore, that they would be perused with some advan- 
tage by those of my readers who interested themselves in the 
science of chemistry, and Who could not but wish to become 
acquainted with the various additions which it had just received. 
My sudden removal to the University of Glasgow, in Oct. 1817, laid 
me under the necessity of interrupting these historical sketches : 
and after a trial of two years, IJ find it difficult to resume them 
at the usual time; for inthe months of October, November, and 
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