in a tank of water, the temperature of which is raised as fast as possible to the desired point. After holding at the desired temperature for the proper length of time, the warm water in the tank is exchanged for cold water as fast as is possible without breaking the bottles. When cooled sufficiently, the bottles may be removed from the tank and packed in ice. From a sanitary standpoint this method is a good one.

No matter what method of pasteurization is used whether in the milk plant, on the farm or in the home-the milk should be heated to the proper temperature as quickly as possible. After heating, it should be cooled to 50 degrees F. or below, as rapidly as possible. Very frequently, after the heating part of the process of pasteurization is completed the vessel containing milk is removed from the water and the milk is allowed to cool without any particular pains being taken to hurry the process. The milk will cool rather rapidly for a time, until it reaches a temperature in the neighborhood of 100 degrees F. It then begins to cool more slowly and it remains for a long time at the temperature at which germs grow best. If the process of pasteurization did not kill all the germs, even though there were only a few remaining, the fact that the milk was not cooled so rapidly as it should have been would make it possible for the germs again to begin multiplying and the milk would soon be badly contaminated.

SANITARY ECONOMICAL APPLIANCES IN CLEAN

MILK PRODUCTION

H. E. Ross

Professor of Market Milk, Cornell University, Ithaca

All changes occurring in milk are due to the action of small plants called bacteria. In the case of a diseased udder, some bacteria come from the cow. Most bacteria, however, enter milk after it is drawn, the most common sources being the dust in the air, the body of the cow, the person of the milker and dirty utensils. Bacteria are carried from one place to another on particles of dust and dirt, so that by keeping dust and dirt out of milk, the entrance of bacteria is prevented.

Unfortunately, the production and handling of clean milk is associated with the idea of a large outlay of money. It costs very little more to produce reasonably clean milk than to produce dirty milk. In order to produce clean milk the dairyman must know what constitutes cleanliness and then must use common sense in applying sanitary principles.

Fresh air and sunlight are two cheap and effective agencies in the production of clean milk. Most germs do not flourish in a well-ventilated, well-lighted stable. In lighting a dairy building of any kind, attention should be paid to the distribution, as well as to the amount of light. A dairy barn should have at least four square feet of light for each cow. However, many barns containing this amount of glass, have the light so poorly distributed that a part of the building is comparatively dark. This not only makes the performance of work more difficult, but also makes extra precautions necessary in keeping the dark places in a sanitary condition.

A cloth curtain is a cheap and effective method of ventilation. The exact principle on which a cloth curtain acts as a ventilator is disputed, but its action is supposed to depend on the tendency of gases of different densities to pass through a porous membrane. The cloth curtain allows fresh air to enter a stable without producing a draft on the animals. It is well to have curtain ven

tilators on at least two sides of the barn and the openings covered by curtains should be large enough to supply fresh air at all times. If it is desirable to partially close the openings because of cold weather, a wooden slide door built in front of each curtain

will accomplish the purpose. Cloth curtains should never be installed in the place of windows. While the curtain does admit some light, it does not to any extent take the place of glass for lighting purposes. One objection to cloth-curtain ventilators is that they collect dust and dirt and in order to prevent their becoming a source of contamination they should be renewed occasionally.

In the construction of a dairy barn, special care should be taken to have as few ledges and cracks as possible. In ceiling a barn, plain matched ceiling is much cheaper than beaded matched ceiling and the former is far more sanitary than the latter, because it does not furnish cracks in which dust will lodge. It is desirable to have the ceiling over the stable dust-proof. An old barn, in which the timbers are uneven, is difficult to ceil with matched lumber. In such an instance, a good, heavy grade of building paper may be used to advantage. The strips should overlap by a good margin and the paper should be whitewashed. This makes a clean, dust-proof ceiling, and while it is not so durable as wood, all or any part of it may be replaced at small

expense.

Objectionable ledges, such as those formed by the sills of a barn, may often be partially removed by fastening a smooth board in a slanting position over such a ledge. This board forms a steep roof over the ledge and dust and dirt will not stick to it so easily.

It has already been stated that many germs enter milk from the body of the cow. Particles of dust and dirt are loosened during milking and since these particles carry almost numberless quantities of germs, they are one of the most serious sources of contamination. If the udder and the flanks are wiped with a damp cloth just before milking it will prevent much of this dirt from falling into the milk pail. The coarser particles are wiped off and the finer particles, being damp, are not so easily loosened by the process of milking. A cow should always be cleaned with a comb and brush at least an hour before milking. This will allow the dust to settle that is raised by the process of cleaning.