Shekalim 10 - Remainder and remainder of remainder
The shekels donated to the Temple were used for sacrifices. This included daily offering, Shabbat offering, wine, oil, the Bread of Vision, and other public offering. A special problem was presented by the two loafs of bread brought on Shavuot when the year was Shmita. In Shmita year one is not allowed to plow and sow, and so, at the end of the year, they would have no wheat! Therefore, the Temple would hire guardians to shew away the animals and to ask passers by not to interfere with the wheat that grew of itself and that would be used or Shavuot. These people had to be paid - and not because of the lack of volunteers, but because in guarding the wheat they could accidentally take the produce, thus acquiring it, so that it would not belong to the congregation later on. If they were paid, however, even if they took the produce, they would do so on behalf of the congregation and would not acquire it. This essential payment had to be done with the same shekalim.
Some money would remain in the chamber itself, and, being that their mitzvah was already accomplished, the money could be used for the goat of Yom Kippur, and for the city walls and towers. If any money was still left, the Temple could use it for commerce - so says Rabbi Ishmael. However, Rabbi Akiva says that it would be degrading. He also says that surplus money from donations to the poor cannot be used for commerce either - but must be held at hand for any contingency. Rabbi Akiva himself was charity administrator.
Art: The Lesson in Charity by Henri Nicolas van Gorp