| MadSci Network: Chemistry |
"Soap" is nothing more than the sodium salt of a long chain fatty acid:
CH3-(CH2)n-COONa
^^^^^^ ^^^
'fatty part' 'water soluble' end
The idea behind it is that the hydrocarbon ("fatty") portion dissolves
dirt and oils, while the ionic end makes it soluble in water. Thus, it
allows water to remove normally-insoluble matter.
I can't say that I am an expert on its history; however, if you are old enough to remember "The Beverley Hillbillies", Granny was always cooking "lye soap" by the ce-ment pond. She would boil lye (sodium hydroxide) and lard (animal fat) in a big pot. The mushy mass left behind, when dry, would congeal into soap which Jethro said would "take off the dirt and a little bit of skin, too." That was probably because Granny did not understand stoichiometry and put too much lye in it.