identical with the principle of skimming, although the two processes appear so dissimilar. The milk revolving in the separator at great speed acquires immensely increased centrifugal force, which corresponds to the force of gravity. This centrifugal force acts more strongly on the heavy non-fatty portion of the milk and less strongly on the cream, and consequently the non-fatty part of the skim milk gravitates by the centrifugal force to the outside of the revolving circle, leaving the cream to flow away in the inside in an almost pure condition.
A few weeks ago I tried experiments with each of the separators at work in these dairies, and in some cases found the proportion of fat present in the skim milk reduced to even less than ·1 per cent.
These separators at the same time produced cream of high quality, and the skim that they produced is more palatable than skim milk obtained by the old process. I have known this statement to raise a smile on the faces of those who thought they knew all about milk, and have wondered how it was possible that one skim milk could be more palatable than another; but the reason is not far to seek: mechanical action in the separator thoroughly aerates the skim milk while it is fresh and has lost none of the aroma peculiar to new milk. Milk exposed to the action of air for twelve or eighteen hours in open vessels loses its aroma, and is apt to become contaminated by an impure atmosphere.
Here we have the other constituents of skim milk separated, by which you will see that we have a very small increase in the proportions of sugar, caseine, and salts, due to the proportion of fat that has been removed.
Our next array of samples shows us a further subdivision. Here we have the cream divided into its two constituents of butter and butter milk. Still the same rule holds good of the constituents of the original milk passing through, though in diminished proportions, into the finished product. Thus butter always contains milk, sugar, and caseine or curd, and even soluble albumen is not entirely
