The price quoted for eggs is low, and even less could be obtained for ten cents at prevailing prices in 1913-1914. This kind of estimate is a help in making menus and dietaries. (See Chapter XVIII.) Another method of estimating economy for this purpose is by calculating the cost of 100-Calorie portions of various food materials. A table giving such a comparison will be found in the next chapter. PURCHASING FOOD In addition to the general principles of buying discussed in Chapter XXI there are some details to be studied in purchasing food. =Personal attention in buying food.=——It is absolutely necessary to visit the market and the grocery where food is purchased. The purchaser would not fail to visit a shop before deciding to patronize it regularly, but frequent calls are necessary if buying is to be economical. Select the grocery, market, and bakery with a view to their cleanliness. Notice if the doors and windows are screened, and if proper effort is made to catch flies that may have entered. Refuse to buy food that is exposed upon the sidewalk, and if it is within doors, see that it is protected from dust and flies. The best markets now have tiled walls and floors, which help to insure cleanliness. The difference in odor is marked between a market that is properly cleaned daily, and one where the proprietor uses uncleanly methods. Meat and vegetables, in particular, should be personally selected whenever this is possible. The butcher must understand that the purchaser is familiar with the different cuts of meat and that honest service is demanded in regard to the quality, trimming, and weight of the meat. One does not want to be too suspicious, but it is well for the butcher to know that the purchaser has a set of standard scales at home by which to prove the accuracy of his weighing. It is also important to inspect fruit and vegetables for quality and cost. =Quantities in which to purchase food.=——The amount that one purchases of a certain food depends on its keeping qualities, and upon the storage space available at home. A general rule may be stated: Buy perishable foods in small quantities; non-perishable foods in large. The reason for buying in larger quantity is that the cost is somewhat less, although sometimes it seems but little less. Some one has remarked that no one is a good buyer who does not consider a quarter of a cent. In a modern house or apartment where there is not room for a barrel of flour or sugar, then the quantity must be gauged by the space. The same is true of canned goods as of flour and sugar. Buying by the dozen saves a little on each can if you have shelf room for piling the cans.