Sentence:  Yet the information obtained is immense, and will, we suspect, when published in a readable form,— for <WSD>snippeting</WSD> spoils Mr. Senior's work,— have an important influence over public opinion.<!-- text continues and clearly notes that “extracts” of manuscripts are circulated; by itself this section could be poetically referring to text being trimmed variously, not extracted --> 
Meaning of the word marked with <WSD> tags:  Act of snippeting, excerpting.