The Chemistry of Cookery

by W. Mattieu Williams

Usually we have no very strong motive for removing either these or the dissolved carbonate of lime, or the atmospheric gases from water, but there is another class of impurities of serious importance. These are the organic matters dissolved in all water that has run over land covered with vegetable growth, or, more especially, that which has received contributions from sewers or any other form of house drainage. Such water supplies nutriment to those microscopic abominations, the micrococci, bacilli, bacteria, &c., which are now shown to be connected with blood poisoning. These little pests are harmless, and probably nutritious, when cooked, but in their raw and growing state are horribly prolific in the blood of people who are in certain states of what is called ‘receptivity.’ They (the bacteria, &c.) appear to be poisoned or somehow killed off by the digestive secretions of the blood of some people, and nourished luxuriantly in the blood of others. As nobody can be quite sure to which class he belongs, or may presently belong, or whether the water supplied to his household is free from blood-poisoning organisms, cooked water is a safer beverage than raw water. I should add that this germ theory of disease is disputed by some who maintain that the source of the diseases attributed to such microbia is chemical poison, the microbia (i.e. little living things) are merely accidental, or creatures fed on the disease-producing poison. In either case the boiling is effectual, as such organic poisons when cooked lose their original virulent properties.

The requirement for this simple operation of cooking increases with the density of our population, which, on reaching a certain degree, renders the pollution of all water obtained from the ordinary sources almost inevitable.

Reflecting on this subject, I have been struck with a curious fact that has hitherto escaped notice, viz. that in the country which over all others combines a very large population with a very small allowance of cleanliness, the ordinary drink of the people is boiled water, flavoured by an infusion of leaves. These people, the Chinese, seem in fact to have been the inventors of boiled-water beverages. Judging from travellers’ accounts of the state of the rivers, rivulets, and general drainage and irrigation arrangements of China, its population could scarcely have reached its present density if Chinamen were drinkers of raw instead of cooked water. This is especially remarkable in the case of such places as Canton, where large numbers are living afloat on the mouths of sewage-laden rivers or estuaries.

The ordinary everyday domestic beverage is a weak infusion of tea, made in a large teapot, kept in a padded basket to retain the heat. The whole family is supplied from this reservoir. The very poorest drink plain hot water, or water tinged by infusing the spent tea-leaves rejected by their richer neighbours.

Next to the boiling of water for its own sake, comes the boiling of water as a medium for the cooking of other things. Here, at the outset, I have to correct an error of language which, as too often happens, leads by continual suggestion to false ideas. When we speak of ‘boiled beef,’ ‘boiled mutton,’ ‘boiled eggs,’ ‘boiled potatoes,’ we talk nonsense; we are not merely using an elliptical expression, as when we say, ‘the kettle boils,’ which we all understand to mean the contents of the kettle, but we are expounding a false theory of what has happened to the beef, &c.—as false as though we should describe the material of the kettle that has held boiling water as boiled copper or boiled iron. No boiling of the food takes place in any such cases as the above-named—it is merely heated by immersion in boiling water; the changes that actually take place in the food are essentially different from those of ebullition. Even the water contained in the meat is not boiled in ordinary cases, as its boiling-point is higher than that of the surrounding water, owing to the salts it holds in solution.

Thus, as a matter of chemical fact, a ‘boiled leg of mutton’ is one that has been cooked, but not boiled; while a roasted leg of mutton is one that has been partially boiled. Much of the constituent water of flesh is boiled out, fairly driven away as vapour during roasting or baking, and the fat on its surface is also boiled, and, more or less, dissociated into its chemical elements, carbon and water, as shown by the browning, due to the separated carbon.

As I shall presently show, this verbal explanation is no mere verbal quibble, but it involves important practical applications. An enormous waste of precious fuel is perpetrated every day, throughout the whole length and breadth of Britain and other countries where English cookery prevails, on account of the almost universal ignorance of the philosophy of the so-called boiling of food.

When it is once fairly understood that the meat is not to be boiled, but is merely to be warmed by immersion in water raised to a maximum temperature of 212°, and when it is further understood that water cannot (under ordinary atmospheric pressure) be raised to a higher temperature than 212° by any amount of violent boiling, the popular distinction between ‘simmering’ and boiling, which is so obstinately maintained as a kitchen superstition, is demolished.

The experiment described on [pages 8 and 9] showed that immediately the bubbles of steam reach the surface of the water and break there—that is, when simmering commences—the thermometer reaches the boiling-point, and that however violently the boiling may afterwards occur, the thermometer rises no higher. Therefore, as a medium for heating the substances to be cooked, simmering water is just as effective as ‘walloping’ water. There are exceptional operations of cookery, wherein useful mechanical work is done by violent boiling; but in all ordinary cookery simmering is just as effective. The heat that is applied to do more than the smallest degree of simmering is simply wasted in converting water into useless steam. The amount of such waste may be easily estimated. To raise a given quantity of water from the freezing to the boiling point demands an amount of heat represented by 180° in Fahrenheit’s thermometer, or 100° Centigrade. To convert this into steam, 990° Fahr. or 550° Cent. is necessary—just five-and-a-half times as much.