Sentence:  <WSD>Metachemistry</WSD> includes orthodox chemistry. In orthodox chemistry, the chemist is concerned principally with the contents of acts of chemical understanding. In <WSD>metachemistry</WSD>, both the contents of the chemist's acts of chemical understanding, as well as the acts themselves, are of interest. 
Meaning of the word marked with <WSD> tags:  An extension of the ideas or methods of chemistry into other areas of inquiry.