1. A familiar example of the first method is afforded in common glue, which in its hard and dry state may be kept for any length of time. So also may white of egg, if prepared by pouring the white of a number of eggs into a large flat dish, and exposing this for twelve or fourteen hours to heat in front of the fire. As the water evaporates, the albumen forms into a yellow, transparent, hard, shining, brittle mass, which scales off at the least touch—a test that it is properly done. These two substances, gelatine and albumen, are two of the constituents of flesh; fibrin or fleshy fibre, which is the third, dries equally well, and is not liable to putrefaction in that state. Gelatine, after being dried, may be softened by the action of hot water. Albumen coagulated by heat cannot be softened again by water; but if dried at about 140° without being coagulated, it may be dissolved in cold water, retaining all its valuable properties. Hence, in preserving meat by drying, too high a temperature must be carefully avoided, or the albumen will become coagulated, and the meat be made insoluble.
The dried flesh of the bison, of the buffalo, and of the deer, forms pemmican, the preparation of which is thus described in Captain Back's Journal:—
"While meat remains in a thick piece, it is impossible to get the middle dried before putrefaction commences; but if the meat be cut into slices, its desiccation may be easily effected. The fleshy parts of the hind quarters are cut into very thin slices, dried in the sun, or before the fire, and pounded. Two parts of the pounded meat are then mixed with one of melted fat, and packed into a bag formed of the hide of the animal. A bag weighing ninety pounds is called a taureau by the Canadian voyageurs; and, in fact, only one bag of pemmican is generally made from each bison cow. Two pounds of this kind of food are sufficient for the daily support of a laboring man; though, when the voyageurs first commence upon pemmican, they each consume three pounds or more. In the spring, they generally boil the young shoots of Epilobium angustifolium with it, and some Scotchmen in the service of the Hudson's Bay Company add flour or oatmeal, thus rendering it more palatable. The best pemmican is made of finely-pounded meat mixed with marrow, and further improved by the addition of dried berries or currants. If kept from the air, it may be preserved sound for several years, and being very portable, it might be used with great advantage in provisioning troops that have to make forced marches. It may be eaten raw, or mixed with a little water and boiled; and although not much relished by those who taste it for the first time, the voyageur, with the single addition of the luxury of tea, requires nothing else for breakfast, dinner, and supper."
In the West Indies, and in South America, jerked beef is prepared by cutting the meat into slices, dipping them into sea-water or brine, and then drying them in the sun. The flesh of wild cattle is thus preserved at Buenos Ayres. Sometimes this dried meat is pounded in a mortar, into a uniform paste, which is pressed into jars, and if intended to supply the wants of the traveller, it is beaten up with maize meal and packed closely in leather bags. It is eaten in this state without further cooking. Drying meat in the air is said, however, to injure its flavor, and to dissipate a great portion of the nutritious juices.
Some kinds of fish are preserved by slitting them down the middle, and drying them in the air to evaporate the moisture. Small cod, haddock, and stock fish, prepared in this way, will, if kept dry, remain good for a great length of time.
Portable soup is prepared by processes similar to those used in the manufacture of glue. The gelatine of meat is dissolved by boiling water, and the water being evaporated, the gelatine is left in a solid state. Any fresh lean meat, with the fat cut away, will answer the purpose. Bones are also used for the purpose, the gelatine being extracted by means of a digester. In the French manufacture of gelatine brut fin, one hundred pounds of bones yield about twenty-five of gelatine, which is dried, cut up into dice, and used for making soup.
2. The effect of cold in the preservation of animal substances received a remarkable illustration in the discovery made by Pallas, in the year 1779, on the shores of the Frozen Ocean, near the mouth of the river Lena, of an animal of immense size, imbedded in ice, which, as it melted gradually, exposed it to the air and furnished food for the hungry wolves and other animals of those regions. It was the opinion of Cuvier that this animal differed from every known species of elephant, and was antediluvian, preserved from the remote period of the deluge in the mass of ice which enveloped it. Some of the hair of this animal may be seen in the museum of the Royal College of Surgeons, in Lincoln's Inn Fields, England.
In Russia, Canada, Hudson's Bay, and other countries where the frost is sufficiently steady, meat preserved in this way is a common article of commerce. Travellers speak with admiration of the frozen markets of Russia, supplied as they are from distant places with provisions solidified by the cold. Thus, in the market at Petersburg, Mr. Kohl noticed partridges from Saratoff, swans from Finland, heathcocks and grouse from Livonia and Esthuria, while the wide Steppes furnished the trapp-geese which flutter over their endless plains, where the Cossack hunts them on horseback, and kills them with his formidable whip. All these birds, as soon as the life-blood has flown, are apparently converted into stone by the frost, and, packed in huge chests, are sent for sale to the capital. So rapid are the effects of frost in that country, that the snow-white hares, which are brought in sledge-loads to the market, are usually frozen in the attitude of flight, with their ears pointed and their legs stretched out, just as they were at the moment of death. Another curious sight in these markets is a frozen reindeer, its knees doubled under its body, its hairy snout stretched forth upon the ground, and its antlers rising majestically in the air; or a mighty elk, disappearing piece by piece, as the action of the saw and the axe separates it for distribution among the several customers.
When provisions have been frozen, great care is required in thawing them; for, if this be done suddenly, putrefaction soon sets in, and although cooked immediately, they are hard and deficient in flavor. They must be thawed by immersion in cold water.
The London markets are supplied with salmon packed in ice from many of the northern rivers that flow to the eastern coasts of Britain. Every salmon fishery is now provided with an ice-house, and a stock of ice collected during the winter. The salmon is packed in large oblong wooden boxes, with pounded ice between, and the fish is received in London as fresh as when it was taken out of the water. It is not, however, frozen. Most fishmongers are furnished with ice-houses or cellars for the preservation of their fish in tubs of ice; and we do not see why English butchers should not be provided with larders cooled by the same means. In many parts of the United States every housekeeper has a small ice-safe, in which, through the warm season, all kinds of perishable provisions are kept. Public ice-houses are also maintained by the butchers, so that, under the burning climate of South Carolina, there is less loss in the way of butcher's meat, fish, game, &c., than in the comparatively temperate summer of London. The meat is sent to the ice-house, near the market, every evening, and is cooled down to near the freezing-point during the night; when exposed on the stalls next day, it retains its low temperature for a long time. Such a plan, adopted in London, would prevent the immense waste of meat during every summer, which is said to amount to at least two thousand tons in London alone. It is true that, when meat has been once frozen, its flavor is injured, but the reduction of meat to 32° or thereabouts, and the solidification of its juices, are very different things; and it would be easy to regulate the temperature within a range of several degrees.