+289. Boiler-room.+--The boiler-room should be easily accessible from the manufacturing rooms. A gauge located in the latter should tell the steam pressure. Windows or doors should be so located that the flues of the boiler can be cleaned. The coal supply should be handy. Great care should be exercised to keep the boiler-room clean for otherwise the dirt will be tracked all over the factory. +290. Whey tanks+ should be kept clean. Daily washing is absolutely necessary to prevent offensive odors. Pasteurization of whey has been found requisite to prevent the spread of disease if raw milk is used.[130] This is required by law in some states. It is sometimes accomplished by heat with steam coils; in other cases by running live steam directly into the whey. Whey tanks may be made of wood or steel. The acid of the whey seems to eat and decompose concrete. +291. Store-room.+--There should be a separate room or a place in the attic where the supplies can be kept. This saves much waste and keeps the factory cleaner and more tidy. +292. The floors.+--The floor is the most important part of the building. It should be of non-absorbent material, which can be easily cleaned, and it should not leak. Concrete makes the best floor of any material used at present. It should slope very gently to the drain. The corners between the floor and side walls should be rounding to make cleaning easy. The drain should be provided with bell traps to prevent the entrance of sewer gas into the factory. If the traps and floor about them are slightly depressed, it will help to make the floor drain more quickly. A catch-basin should be provided just outside the factory for all solid material which might clog the sewer pipe. This should be cleaned three or four times a year. [Illustration: FIG. 60.--A well arranged Cheddar cheese factory, including the equipment for the manufacture of whey butter.] +293. Arrangement of machinery and rooms.+--The rooms and machinery should be arranged so that the work will follow the natural sequence of the process with as little inconvenience as possible. Some of the points to be observed in this connection are: vats should be near the weigh-can; boiler-room near the work room; cheese presses near the vats; cheese presses near the curing-rooms and the like.