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diat as yet we are not acquainted with any of the true 

 elements of matter ; many substances, formerly sup- 

 posed to be simple, have been lately decompounded, 

 and the chemical arrangement of bodies must be con- 

 sidered as a mere expression of facts, the results of 

 accurate statical experiments. 



Vegetable substances in general are of a very 

 compound nature, and consist of a great number of 

 elements, most of which belong likewise to the other 

 kingdoms of nature, and are found in various forms. 

 Their more complicated arrangements are best under- 

 stood after their simpler forms of combination have 

 been examined. 



The number of bodies which I shall consider as 

 at present undecomposed, are, as was stated in the 

 introductory lecture, two gasses that support combus- 

 bustion, seven inflammable bodies, and thirty-eight 

 metals. 



In most of the inorganic compounds, the nature 

 of which is well known, into which these elements 

 enter, they are combined in definite proportions ; so 

 that if the elements be represented by numbers, the 

 proportions in which they combine are expressed 

 either by those numbers, or by some simple multiples 

 of them. 



I shall mention, in few words, the characteristic 

 properties of the most important simple, substances, 

 and the numbers representing the proportions in 

 which they combine in those cases, wher^ they have 

 been accurately ascertained. 



