英文科学读本 第六册·Lesson 51 Tallow and Offal of Animals

Lesson 51 Tallow and Offal of Animals

The fat or tallow of animals, especially of those whose flesh is used as food, forms an important article of commerce. It is obtained by boiling down the carcasses in huge boilers; the fat, of course, floats on the top, and is drawn off into coolers. Tallow is used now mostly in the manufacture of soap. Formerly large quantities were made into candles, but since the introduction of solid paraffin very few tallow candles have been made.

England's home product of tallow amounts to about 120,000 tons annually, but they import, in addition to this, from many parts of the world, the total value of imports being from 2.5 to 3 millions sterling. Most of England's imported tallow comes now from South America, the United States, Australia, and Russia. The last-named country formerly supplied by far the largest quantities, but of late years the trade in Russian tallow has declined.

Till recent years Australia reared its sheep and cattle almost solely for the sake of the wool and hides, there being little demand for the flesh. Whole carcasses were boiled, 300 or 400 at a time, in huge vats or boilers, 11 or 12 feet high. The fat was drawn off for tallow; the flesh was used for feeding pigs, or put on the land as manure. In New South Wales and Victoria the number of carcasses of sheep alone boiled down for tallow annually averaged 1.5 millions. The rise of the Australian trade in frozen carcasses as food for the home market has now caused a corresponding fall in the supply of tallow from these colonies.

Under the head of offal are included all the waste or refuse parts of the carcass, as well as certain parts which are used as food—e.g. the head, tongue, feet, heart, liver, kidneys, lungs, tripe, gut, and bladder.

The tripe-dressers of London and other large towns carry on an extensive and flourishing trade in the preparation and sale of offal as food. Some parts of it are highly esteemed as delicacies; others form cheap and wholesome food for the poor.

Calves' heads form a nutritious dish which is regarded as a luxury. Ox-tongues are also largely in demand as a delicacy. Immense quantities of salted tongues are imported from South America, Russia, and Australia.

The feet of oxen, when boiled, yield gelatine—a very wholesome food. Calves'-foot jelly is much esteemed as a delicacy for invalids. There is a large amount of fatty oil in the foot of the older animal, which must be extracted before it is fit for food. The fat extracted is the useful oil known as neat's-foot oil.

The accumulation of animal refuse in the slaughterhouses and meat markets of our large towns was formerly a source of great danger to the community, and various means were adopted to destroy it, or get rid of it in some way before it could work mischief. Now every part of it is applied to some definite purpose, and provides a remunerative source of employment and profit.

The blood of the slaughterhouses, instead of being allowed to run away into a drain as useless, is now put to various uses, either as food or in the industrial arts. The blood of pigs and sheep is used for making black puddings, and in Sweden the lower classes of the population live on a very wholesome bread made of the blood from the slaughterhouses mixed with wheaten flour.

Blood is largely used in the arts in the form of blood-albumen. One kind of blood-albumen is obtained from the clot after the blood is allowed to stand for some time; another is derived from the serum or liquid part of the blood. The first of these is used by calico-printers to produce the color of the particular kind of cotton cloth known as Turkey-red.

It is estimated that upwards of 6000 tons of blood are used annually for this purpose. That derived from the blood-serum is employed by dyers as a mordant for fixing or biting in the colors in woollen fabrics.

Dried blood is used to clarify wines and syrups, and it also forms a valuable manure for the land.

The intestines of animals are prepared for various purposes, and are thus the source of large and important branches of manufacture. The delicate membrane of the small intestine of the ox is the material from which gold-beaters skin is made. One London maker alone is said to use up the gut of no fewer than 10,000 oxen every week for this purpose. Other parts of the gut are made into strings for musical instruments, lashes, and whip-cords, and skins for sausages.

Cow-hair is used for mixing with mortar for plastering purposes, but not so much as formerly, because it can find (at least the best part of it) a better market. Large quantities of it are now made up into cheap imitations of sealskin for ladies' jackets, etc. The best of the hair for this purpose realizes from £10 to £11 per ton. The coarser, rougher hair is used for stuffing chairs and sofas, and in making felt for roofing purposes. It is also made into ropes, as well as carpets and other textile fabrics.

Glue is made from all sorts of refuse animal matter, including the fleshings (i.e. the parings of the hides from the slaughter-houses and tanneries), the refuse parts of the hoofs and ears of horses, oxen, and sheep, and the cuttings and scrapings of the horns of animals. Almost any animal offal and garbage, useless for other purposes, is available as a material for making glue. The dried sinews, the inner bony core of the horns, even old worn-out leather (if it is first deprived of its tannin) —all are made to yield glue.

Size is a weak solution of glue allowed to cool and clarify. Scraps of vellum or parchment, old kid gloves, and rabbit skins are used as materials for making gelatine and size.

The process of glue manufacture is simple. The fleshings are soaked in lime-water to cleanse them, after which they are washed, and then boiled. The impurities rise to the surface and are skimmed off during the boiling, and the clear liquid is then run away into molds and left to dry and harden.

The prices of glue in England vary, according to the quality, from £45 to £75 per ton. It is estimated that the average quantity of glue used is upwards of 10,000 tons.

Gelatine is used for stiffening straw hats and for dressing silks and other fabrics. It is also used as an article of food.

Size is chiefly used for mixing with whiting and color in whitewashing and coloring ceilings and walls.