The farad, whose symbol is M, is the unit of capacitance and a condenser or a circuit to have a capacitance of one farad must be of such size that one coulomb, which is the unit of electrical quantity, will raise its charge to a potential of one volt.
"The Radio Amateur's Hand Book"
A. Frederick Collins
The practical unit of capacity is called the micro-farad, the real unit is the farad, and takes its name from faraday.
"Electricity and Magnetism Nature's Miracles, Vol. III."
Elisha Gray