MODERN CHEMISTRY. 449 



doctrine still imperfect or faulty in parts, yet so far verified 

 by tests, and simplifying so much the relations of these very 

 numerous and complex bodies, that we cannot but admit a 

 strong presumption in its favour when compared with all 

 prior views on the subject. If the theory be not what is 

 true, it seems at least in close kindred and approach to it. 

 None, however, but a chemist can understand the difficulty 

 and ambiguity of these questions the doublesidedness of 

 all the objects and relations involved in them. Schemes 

 and hypotheses have been altered to meet exigencies, under 

 the same compulsion which created the crystalline spheres 

 and epicycles of the ancient astronomy. The history of 

 Chemistry speaks so largely of revolutions of doctrine, even 

 in the vital parts of the science, that it would be hardihood 

 to accept any one as final and complete. 



Closely connected with, and dependent upon, the same 

 great law of definite proportions, comes in the subject of 

 Organic Chemistry; presenting in its progress and attain- 

 ments one of the most signal triumphs of physical science, 

 and promising future results which in endless ways may 

 affect the welfare of mankind. No part of Chemistry so 

 wonderfully expounds the power which has been gained over 

 the elements of matter by the methods of analysis and 

 synthesis, submitted to strict numerical relations even in the 

 most complex compounds which nature or art place before us. 

 A still higher interest belongs to the subject as the Chemistry 

 of Life and of vital products ; of matter, whether animal 

 or vegetable in kind, organised under that mysterious power, 

 which has been termed the vital principle, in default of other 

 understanding of this wonderful operation of Providence in 

 the world. And yet further is it interesting, as extending 

 research to the numerous artificial compounds obtained from 

 the decomposition of these substances; a field of enquiry 

 prolific of curious and profitable results. It may be that no 



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