A pretty good explaination of how it all works. I just speed read over it but I don't think he is aware the original depositor is also loaned back his money and all deposits are held in reserve or of the abandonment of funds .
A Simple Example
Suppose a teenager, Bill, is rummaging in the attic and finds $1,000 in physical currency in an old chest. Bill is ecstatic and runs to the local bank, where he opens a checking account and deposits the green pieces of paper.
Under a 100-percent-reserve banking system, this would be the end of the story. In the act of making the deposit, Bill's currency holdings would fall by $1,000, while his checkbook balance would rise by $1,000. Putting the money in the bank wouldn't affect the total amount of money in the economy.
However, in our current system, Bill's bank would see a new profit opportunity. After the bank put the $1,000 of paper currency into its vault, its reserves would be that much higher, while its outstanding deposit liabilities would have risen by $1,000 as well (in the form of Bill's new checking account). But since banks in the United States are subject only to a reserve requirement of (approximately) 10 percent, the bank would have new excess reserves of $900. If it found a suitable borrower, the bank would have the legal ability to grant a new loan for this amount.
Suppose the bank found such a borrower, Sally, and charged her 5-percent interest for a 12-month loan. Assuming she paid off the loan in a timely manner, here is what the bank's balance sheet would look like at various stages in the process:
Continued..
http://mises.org/daily/4499