Overuse of "Which" Clauses

The relative pronoun "which" is frequently used where "that" should be used. Thus, "which" clauses are often overused. One of the most common misuses is when the relative clause using "which" appears at the end of a sentence with no clear reference.

Example of unclear reference using "which"

Substrate B can be isolated with good yield from crude extract or the acid precipitate from the synthesis of raziline, which is somewhat toxic and is environmentally unsafe.

In this sentence, what is toxic? Crude extract, the acid precipitate, or raziline? The "which" clause can modify any of the nouns in the sentence. It is necessary to revise this sentence following these steps:

1. The writer would first need to identify the noun that the "which" clause is supposed to modify. What is toxic? The answer is the "acid precipitate."
2. Then, the writer would need to replace the pronoun with this noun and write a new sentence.

One possible revision follows:

Example of revision

Substrate B can be isolated with good yield from crude extract or the acid precipitate from the synthesis of raziline. The acid precipitate is somewhat toxic and is environmentally unsafe.

Again, it is common for these clauses to appear at the end of sentences in a first draft. It is important to look for these ambiguous clauses and edit them. Editors call this process "which hunting"!

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