Soup. As a general rule a soup is made by boiling meat or vegetables in what is called 'stock.' To prepare the latter the cook obtains fresh meat, bones, and vegetables such as carrots or leeks, and after the addition of salt allows them to simmer for some hours in sufficient water. The stock is the infusion thus prepared, and contains small quantities of starch, if vegetables have been used, and in any case some gelatine, which will often cause it to solidify on cooling. Together with a small quantity of nourishment, the infusion has extracted from the meat and vegetables those pleasant flavoured extractives which give it taste. Taking this stock as a basis, the various soups are made by boiling with it the bones and flesh of the hare, ox-tails, &c., and vegetables such as carrots, potatoes, turnips, rice, sago, &c.
If we view the preparation of soups from the point of domestic economy, the following facts must be kept in mind. Bones, otherwise valueless to the householder, contain much nutritive gelatine, which is extracted from them in the preparation of stock; no bones should therefore be thrown away, for their use is a clear gain. It is to be remembered that meat on the other hand yields little of its nutritive matter to the stock, and if the meat be thrown away, as it generally is in England, the greater part of its value is lost. It is the greatest waste of nutritive material to prepare a stock from gravy beef, which yields hardly more to the water than its flavouring extractives; yet householders regularly buy meat for this wasteful purpose. If then it is an object to obtain the nutritive value from the food, the meat should as much as possible be retained and eaten. While the greatest extravagances may be thus committed by using meat, which might be eaten as such, in the preparation of stocks and clear soups, it is certainly the case that equal wastefulness is frequently committed by throwing away the water in which meat, fowls, fish, bacon, and pork have been boiled. These always contain some nutritive matter, and every capable cook should be able to make it the basis of an excellent soup.
From a dietetic point of view we may regard soups as gastric stimulants and as articles of nutrition. They owe their stimulating properties to their warmth, and the salt and flavoured extracts they contain, and are of value inasmuch as they cause a ready flow of digestive juice preparatory to the more substantial portions of the repast. To some persons this stimulating action is a necessary preliminary to a properly digested meal, and it is often obtained by more harmful resorts, say to sherry and bitters. Most persons after a hard day's work, and with the bodily energies below par, have experienced the difficulty of at once facing a plate of cold mutton or beef, which would however have been quite acceptable if it had been introduced by a basin of hot broth.
From the point of view of nourishment little can be said of clear soups and beef-tea, and numberless invalids are yearly starved out of existence by doctors and nurses who imagine that by stewing a pound of gravy beef the nourishment goes to the water. Soups thickened by vegetables, such as peas, potatoes, &c., are highly nutritious, and pieces of meat and thick gravy retained in the soup add greatly to its nutritive value.