Milk bottles and cans should always be thoroughly washed before fresh milk is put into them. This washing cannot be done by little children; it is work for a man or woman, and careful work at that.
(5) By polluted water
I have just told you that milk vessels should be thoroughly washed. It is true, however, that disease germs may get into the milk through this very process of washing the vessels. Water sometimes contains disease germs, especially the germs that cause typhoid fever, cholera, and other diseases of the intestines. Such water is said to be polluted. When milk vessels are washed with polluted water, the germs are left in them and thus get into the milk. If the water used to wash the cans is thoroughly boiled, the germs will be killed; hence it is important to scald all milk vessels.
All water used about a dairy should be perfectly pure. If there is the least suspicion about the quality of the water, it should be examined by a chemist; and if it is not pure, the milk from such a dairy should not be used. In order to prevent the possibility of any infection, all water used to wash milk vessels should be thoroughly boiled even when the water is known to be pure, and the vessels should afterward be scalded, to kill any germs that may be left after washing.
(6) By flies falling into the milk
Flies very frequently get into the milk. Later we shall learn more about how flies carry germs, but at present it is enough to know that on every fly there are a great many germs, and whenever a fly gets into milk it plants those germs and they grow very rapidly. As soon as a cow is milked, the milk should be taken to a clean cooling house, with screens at all the windows and doors, and there strained into a vessel and cooled.
(7) By disease in the cow
The last way that we will mention by which germs get into milk is by disease in the cow herself. Cows suffer from many diseases, just as men do; and when a cow is sick, her milk is very likely to contain the germs of the disease that is making her sick. Especially is this true of tuberculosis, or consumption, as it is called. A great many children get consumption by drinking milk from consumptive cows. No milk should ever be used from a cow that is not healthy. All dairy cows should be examined at frequent intervals by a competent veterinarian to make sure that they are free from any disease.
Questions. 1. Milk forms what per cent of the food of the people of the United States? 2. Why is it important that milk should be kept clean? 3. Name some ways by which germs get into milk. 4. What is the danger from a dirty cow and barn? 5. How can this danger be prevented? 6. How does the milkman allow germs to get into the milk, and how can he avoid doing so? 7. How should milk cans and bottles be washed? 8. Why is it important that only pure water be used about the dairy? 9. How can flies be kept out of milk? 10. How should milch cows be tested to make sure that they are free from tuberculosis?