Before milk was homogenized the cream would rise to the top of the milk bottle. Consumers would want to pour the cream off but in a conventional milk bottle the milk would just mix with the cream as it was poured out. Thus there was a lot of interest in designing a milk bottle that would allow one to remove the cream without mixing it with the milk. All the bottles on this page are examples of trying to solve that problem.
There were devices to remove the cream from a regular bottle of milk. To go to the page with cream extractors.