The acidity of the tomato is the active principle which causes the milk to curdle. If this acidity runs 0.60% it will curdle the milk badly. If it is reduced to 0.50% it will still curdle the milk, but if it is reduced to 0.40% it will not curdle the milk, if the milk is fresh. The aim of the soup maker should therefore be to keep the acidity of the soup between 0.30 and 0.40%, not allowing it to go above or below these limits. If it is reduced below 0.30% the flavor of the tomato begins to be effected—in fact, if possible, it is best to keep the acidity between 0.35 and 0.40% to avoid any possibility of loss of tomato flavor. Now, the packer will ask—“How am I going to do this acidity testing? I’m not a chemist, and have no chemist at my factory, or any laboratory.” The acidity test on pulp and soup is a very simple one. The equipment required scarcely amounts to anything, as the sample can be taken by volume. Any chemist will be glad to show you how to make this test and to secure for you the few accessories needed. Why is there less danger of curdling if the soup is poured into the milk than if the milk is poured into the soup? The soup contains all the acid, and the milk contains none. If the soup is poured into the milk slowly, with stirring, the acid is slowly added to the milk, and is diluted, there being at the beginning of the mixing a very small volume of acid and a large amount of milk. If, however, the milk is added to the soup, a small volume of milk is at first being thrown into a large volume of acid, and naturally the danger of curdling is considerably increased. But if the acidity of the soup is not above 0.40% and the milk is fresh, there will not be an appreciable amount of curdling no matter which way the two are mixed. A statement as to the proper way of mixing with milk should be made on the label. Price and Quality That the soup, to be a success, must be popular in price and packed in convenient sizes is self evident, and there is no need of dwelling on this point. Practically all of the tomato soup on the market is packed either in the 10½ oz. or 16 oz. size, and almost all of it is cheap in comparison with other foods, but it is a mistake to cut the quality one iota in order to shade the price. The mark for quality should be set at the highest point possible and the price to correspond. The canner may book a lot of new business with a low price and mediocre quality but he is not likely to hold it. Almost anyone would rather pay a cent a can more and get better quality. Microscopical Counts