esses it is possible to recover its sulphur as sulphur", 

 and its iron as iron: so that we are compelled to be- 

 lieve, we cannot avoid the conclusion, that sulphide 

 of iron contains particles of sulphur and of iron. 

 But how small must be those particles! No yellow 

 particle is visible, not the minutest portion of lus- 

 trous metal, but dull brown miniature fragments of 

 the original mass. The elementary particles of sul- 

 phur and iron, or of the elements in any other com- 

 pound are, in short, too small to be seen. The mind 

 cannot conceive of a particle of anything (sulphur, 

 iron, sulphide of iron, or what not) so small but what 

 the next instant the imagination has divided it. Yet 

 we must have some common platform on which to 

 reason and converse. The difficulty is met by speak- 

 ing of these inconceivably small particles as atoms. 

 It is an expedient not perhaps altogether satisfac- 

 tory, but is the only one possible to the majority of 

 minds in the present state of knowledge and educa- 

 tion. We cannot speak of iodine aud iron uniting 

 lump to lump, as two bricks are cemented together 

 or blocks of wood glued together, for such is not the 

 kind of action. We cannot select a minute fragment 

 of each to regard as the combining portions, for the 

 minutest fragment we could obtain is visible. And 

 yet iodide of iron contains both iodine and iron, or, 

 at least, a given weight of the compound is obtained 

 from the same weight of .the constituents, and the 

 same weight of constituents is obtainable from an 

 equal weight of the compound. We might say that 

 molecules are concerned in the operation, but mole- 

 cules mean little masses of of what? Ther; is pos- 

 itively no word left with which to carry or. conver- 

 sation and description but atoms. Any other mode 

 of treating the matter is too subjective for general 

 employment. Moreover, any difficulty in forming a 



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