The prefix centi indicates one-hundred and the prefix milli indicated one-thousand. Since one-thousand is 10 times one-hundred there ate 10 milliliters in a centiliter.
I looked up hogshead in my Oxford dictionary and was surprised by what I found. It seems that the size of a hogshead depends on what you are measuring. The first definition of hogshead was:
A measure of capacity for wine.
52.5 imperial gallons,
63 US gallons
and the second definition was:
A measure of capacity for beer.
54 imperial gallons,
64 US gallons