2 3 2 THE POPULAR SCIENCE MONTHLY.
I dare not estimate. The celebrated bird colony on the Bass Rock is but a covey compared with this.
The inhabitants of the little human settlement in the Bay of Sver- holt derive much of their subsistence from the eggs of these birds ; but whether they could gather a few millions for oil-making, without repeating the story of the goose and the golden eggs, is questionable. The eider-ducks that inhabit some of the low mossy islands thereabout, are guarded by strict legislative regulations during their incubation period, lest they should emigrate, and the down-harvest be sacrificed.
I now come to the subject of stewing, more especially the stewing of flesh food. Some of my readers may think that I ought to have treated this in connection with the boiling of meat, as boiling and stewing are commonly regarded as mere modifications of the same pro- cess. According to my mode of regarding the subject, i. e., with ref- erence to the object to be attained, these are opposite processes.
The object in the so-called " boiling " of, say, a leg of mutton is to raise the temperature of the meat throughout just up to the cooking temperature (see Nos. 3 and 4) in such a manner that it shall as nearly as possible retain all its juices ; the hot water merely operating as a vehicle or medium for conveying the heat.
In stewing nearly all this is reversed. The juices are to be ex- tracted more or less completely, and the water is required to act as a solvent as well as a heat-conveyer. Instead of the meat itself sur- rounding and enveloping the juices as it should when boiled, roasted, grilled, or fried, we demand in a stew that the juices shall surround or envelop the meat. In some cases the separation of the juices is the sole object, as in the preparation of certain soups and gravies, of which " beef-tea " may be taken as a typical example. Extractum Carnis, or " Liebig's Extract of Meat," is beef -tea (or mutton-tea) concentrated by evaporation.
The juices of lean meat may be extracted very completely without cooking the meat at all, merely by mincing it and then placing it in cold water. Maceration is the proper name for this treatment. The philosophy of this is interesting, and so little understood in the kitchen that I must explain its rudiments.
If two liquids capable of mixing together, but of different densities, be placed in the same vessel, the denser at the bottom, they will mix together in defiance of gravitation, the heavy liquid rising and spread- ing itself throughout the lighter, and the lighter descending and diffus- ing itself through the heavier.
Thus, concentrated sulphuric acid (oil of vitriol), which has nearly double the density of water, may be placed under water by pouring water into a tall glass jar, and then carefully pouring the acid down a funnel with a long tube, the bottom end of which touches the bottom of the jar. At first the heavy liquid pushes up the lighter, and its upper surface may be distinctly seen with that of the lighter resting