I'm sure there are some chemist that can give a better answer but years ago most lubricants were basically soaps. Any fat or oil came from lard or sperm whale oil which was outlawed causing all kinds of problems in wire drawing and automatic transmission problems. fatty acids are the various acids that make metal working lubricants work. A Google search for fatty acids in lubricants gives a lot of info. Too little fatty acids generally indicated a lubricant problem.