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Variable said
Okay, I guess what I'm going for is: is milk a solution? Or is it a mixture of stuff in suspension. Like, after a period of time, will it all settle out?
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Milk doesn't really fit the definition of a homogenous solution, it's more like a colloid or suspension than a solution. Milk straight from the cow is a mixture of water in which fats, proteins, vitamins and minerals are suspended. If you took milk straight from the cow and just let it sit there for a while, it will settle out. If you read old accounts of cheese or butter making, they would strain the fresh milk through a very fine sive or cloth to collect the fat (cream) and then beat the cream until it congealed into butter. When you make cheese you add either acids or enzymes to separate the milk protein from the water, you take the protein (cheese curds) and them do other stuff to make it into cheese.
If it were really a true homogenous solution, you wouldn't be able to separate it by such crude mechanical means. You would have to heat it, or subject to to a chemical process to make the components separate if it were a true homogenous solution.
What we think of as homoginized milk is just normal milk that has been processed to make the fat particles uniformly distributed. If you just let it sit out though, it does start to settle. Of course by the time it starts to settle, it's also starting to go bad
