Sometimes there are sick people at the dairy farm. Often some one nurses a sick person until milking time and then goes out and milks the cows. When this is done, the milker is almost sure to plant the germs of the disease in the milk. No milk should ever be used from any dairy where there is an infectious disease; and no one who has charge of a sick person, no matter what the nature of the sickness, should ever handle milk that is to be used by others. [Illustration: FIG. 17. A model bottling establishment.] [Sidenote: (4) By dirt in cans and bottles] The cans and bottles in which the milk is placed are frequently sources of dirt and germs. Milk cans and bottles are supposed to be thoroughly washed before milk is put into them, and they should be thoroughly scalded after they are washed. This is not always done, and sometimes the bottles are not washed at all. Some dairymen will tell you that the bottles and cans are always washed and scalded just before the milk is put into them, and that this is never neglected by any dairyman. That is what a dairyman once told me. Then I asked him how he accounted for the fact that I had found a milk ticket in the bottle with the fresh milk. Of course he could not explain this, though I thought I could explain it for him. The old milk bottle was returned to the milkman with the ticket for the new milk inside it. The deliveryman left the fresh milk, but forgot to take the ticket out of the bottle; and the man who "washed" the bottles must have forgotten to take out the ticket too. Of course, the bottle was not washed at all, and if one bottle goes unwashed, it is reasonable to assume that others are neglected in the same way. 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. [Sidenote: (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.