TRAINS OF REASONING. 291 



occurred of the transformation, at one stroke, of a 

 science which was still to a great degree merely expe- 

 rimental, into a deductive science. 



Transformations of the same nature, but on a 

 smaller scale, continually take place in the less ad- 

 vanced branches of physical knowledge, without ena- 

 bling them to throw off the character of experimental 

 sciences. Thus with regard to the two unconnected 

 propositions before cited, namely, Acids redden vege- 

 table blues, Alkalis make them green ; it is remarked 

 by Liebig, that all blue colouring matters which are 

 reddened by acids (as well as, reciprocally, all red 

 colouring matters which are rendered blue by alkalis) 

 contain nitrogen : and it is quite possible to conceive 

 that this circumstance may one day furnish a bond of 

 connexion between the two propositions in question, 

 by showing that the antagonist action of acids and 

 alkalis in producing or destroying the colour blue, is 

 the result of some one, more general, law. Although 

 this connecting of detached generalizations is so much 

 gain, it tends but little to give a deductive character 

 to any science as a whole ; because the new courses 

 of observation and experiment, which thus enable us 

 to connect together a few general truths, usually 

 make known to us a still greater number of uncon- 

 nected new ones. Hence chemistry, though similar 

 extensions and simplifications of its generalizations 

 are continually taking place, is still in the main an 

 experimental science ; and is likely so to continue, 

 unless some comprehensive induction should be here- 

 after arrived at, which, like Newton's, shall connect a 

 vast number of the smaller known inductions toge- 

 ther, and change the whole method of the science at 

 once. Chemistry has already one great generalization, 

 which, though relating to one of the subordinate 



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