By W. a. SHENSTONE. 
T he objects of this communication are, first, to call 
attention to tbe classification of cbemical bodies into 
simple and compound bodies, termed respectively elements and 
compounds, and to remind you of our imperfect knowledge 
of tbe real relations of these elements and compounds to each 
other; secondly, to point out more distinctly than is usually 
done the very decided analogies which exist between the trans- 
formations of elements into their allotropes, and the formation of 
chemical compounds. 
Up to one hundred years ago, so far as records afford us any 
information, it appears that Chemistry existed rather as an Art 
than as a Science, Whether, at some earlier period, there was 
a Science of Chemistry is a question which I will not attempt 
to discuss now ; but it seems pretty certain that from early 
days till the time of Lavoisier (I am disregarding the phlogistians 
in making this statement) no comprehensive and prolific ex- 
planation of the nature of chemical phenomena gained sufficient 
attention to have been transmitted to us, 
I will endeavour to make the condition of this branch of 
knowledge, during the period I have alluded to, clearer to you by 
a very brief account of it. 
At the time of Pliny (1st century) the ancients were acquainted 
with several metals, as gold, silver, copper, tin, mercury, iroii-^ 
