scrape a mixture off <of a stick> on a stone floor

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park sang joon

Senior Member
Matches were invented when pharmacist John Walker tried to scrape a mixture of potassium chlorate and antimony sulfide off of a stick on a stone floor and it burst into flames.
[Source: Reading for Results Ninth Edition by Laraine Flemming]
I don't know in my example what role "of/ of a stick" plays.
So I'd like to hear of the role of "of / of a stick" from you.
Thank you in advance for your help.
  • Truffula

    Senior Member
    English - USA
    You may want to read this topic link summarizing the "off of" combination:

    Here is another thread:

    I think the summary of the threads linked above is that 'off of' means the same as 'off' and is used more in American English than British English; some or most non American speakers find it an informal usage; some or most American English speakers find the two are often interchangeable, especially in sentences such as yours.
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