friends" or "He was a friend of (the number of) my father's (friends)," when it may be supposed that the person spoken of possesses more than one object of the kind referred to, this double form of possessive is properly used. "It was a fault of my friend to be loquacious" would signify the one particular weakness of my friend: "It was a fault of my friend's to be loquacious," that is, "of my friend's faults," would signify that this was one of various faults.
The apostrophe is not used with the possessive personal pronouns. Write "yours (not your's) truly." Compare 's.
post: A colloquialism, generally undesirable, for inform. It is derived from the bookkeeping signification of the term, where it means that the ledger is supplied, by transfer, with the information contained in the books of original entry.
pour, pore: Exercise care in using these homophones. The first is of Celtic origin and means "to cause to flow, as a liquid, in a continuous stream"; whereas pore is from the Middle English poren, and means "to gaze or ponder with close and continued application, as in reading or studying."
power: In the sense of "a great number or quantity," this word is an undesirable colloquialism that has gained ground especially in rural districts. One may say of a man "He was a power among the people," but not "A power of people heard him."