Don't try to can milk with just a boiling water bath: it doesn't get hot enough to kill all microorganisms. But you CAN can (can can?) milk with a pressure canner. Be aware the milk will be just fine pressure canned but will turn slightly brownish like evaporated milk. The reason it does this is due to the high temps of pressure canning. It caramelizes the milk sugars. The milk will be fine for cooking....it's fine for drinking too...it just doesn't taste quite the same.

Pressure Canning Milk:

Fill clean jars with strained milk, leaving ½ inch headspace for expansion. Put on lids and rings and tighten down rings gently. Place in pressure canner with 2-3 inches of water and process at 15 lbs pressure for 10 minutes. Remove and let cool 24 hours undisturbed before moving into storage.