are obtained, by methods now in vogue, from the greasy excretions which, after circulating through the animal's system, attach to the wool of sheep. These products are used as a base for ointments and toilet preparations, for dressings for leather, as a lubricant for wool and other animal fibers, and in conjunction with

lizing the fat of beef and hogs. Another important article obtained from fat is glycerin, which may be refined or distilled, or used as an ingredient in glycerin soaps and toilet preparations. Glycerin is now recovered also from tank water, which is a by-product of rendering establishments produced in cooking the scraps of meat, bones, intestines, and other nitrogenous matter containing fats.

A valuable by-product of the slaughterhouses is marrow obtained from the finer medullary substances of the rib bones of young cattle. This is extracted immediately after the animal has been killed, and is macerated or digested in pure glycerin for several days. The medullary glyceride is then strained off for use as a medicinal preparation to stimulate the production of red blood corpuscles. The manufacture of gelatin, or glue, as a by-product of the slaughterhouse is well known.

In the woolen industry there are many materials formerly regarded as wastes which are now made to serve valuable ends. Old rags are recovered into new wool, and wool-grease is used in other industries. No fewer than five products

certain lubricating oils.

At a large plant in Massachusetts, more than 200,000 pounds of wool are "degreased" every ten hours. From two million to three million dollars' worth of wool fat and potash are estimated to have been wasted during a year in the United States before the solvent process of extraction came into general use.

Mention has been made of the reconversion of woolen rags into wool. A few years ago the rags were thrown on the waste heap to become manure, or used to make a cheap grade of paper. Now each little woolen rag, regardless of its previous condition of servitude, enters again into the factory and once more emerges as clothing. The rags are used over and over again until completely worn out, when they are mixed with horns, hoofs, and the blood from slaughter-houses, and melted with scrap iron and wood ashes to form material from which Prussian blue is made.

In the industries of cotton manufacturing and cottonseed oil making, scarcely anything is allowed to go to waste. For many years the seed of the cotton plant was regarded as without value; now the cottonseed crop of the United States is worth about one-fifth of the total cotton crop of the country. Among the principal uses of cottonseed oil are its part in making lard compound and white cottolene, both valuable food products. Cottonseed oil is also used as a substitute for olive oil, by soap-makers in the making of soap, by bakers, and also in the manufacture of washing powders.

The leather industry is equally saving

in the matter of wastes. In the tanning of leather, there are developed as side products scrap and skin, from which glue is made; hair, from which cheap blankets and cloths are manufactured, and waste liquors containing lime salts. By means of a special apparatus, scraps of leather are converted into boot and shoe heels, inner soles, etc. What is called shoddy leather is made by grinding the bits of leather to a pulp, and then by maceration and pressure forming them into solid strips.

Not many years ago coal-tar or gas-tar was a waste material very hard to get rid of. When thrown into a stream the water was polluted; buried in the ground, vegetation was destroyed by it. At the present time, coal-tar products are of

Even without chemical change, many articles once profligately cast away are now being made to serve useful purposes. Broken and worn stuff from the bench, broken pieces of grindstone, old pipes, etc., are more and more being regarded as having only half performed their ser

the highest commercial value in the production of beautiful dyes and in the making of medicines and disinfectants; and from them is also produced a saccharine substance several hundred times sweeter than sugar. Among other products of gas-tar are naphtha, naphthaline, benzol, and anthracene.

The solid refuse of breweries, distilleries, and sugar factories is treated with soda lye, then mixed with various kinds of resins, dried, pressed, and used as laths, panels, wall coverings, etc. Old rubber is steamed, passed between rollers, and in a softened condition applied to a strong, coarse fabric, or used for stiffening the heels of boots.

vices, and in a hundred different forms are made still to contribute to the satisfaction of human needs. Worn-out files may make turning tools, scrapers, and burnishers, while the steel by forging down may be utilized in almost any way." When a grindstone is worn to a small diameter, it can be turned in a lathe into grooves for grinding paring gouges. A few elbows, tees, and bends, applied to iron gas-piping, which formerly was given away, will construct many thingsexcellent hand-rails to steps, or fencing for gardens, or supports for shelves or tables.

Truly the conservation of matter is of wide practical application.

HE "tallow dip" of our grandfathers is no longer made of tallow, exactly. It is made of stearic acid, which is only one ingredient of the tallow that grows in the sheep and in the steer. Neither is the "tallow dip" of today a real "dip." They used to take long wicks and dip them in hot tallow, time after time, till the candle had acquired the proper thickness. Today they run hot stearic acid into molds and make a hundred candles instantaneously.

The "tallow dip" on the market today therefore would be more accurately described if it were called a "stearic acid mold." But nevertheless it remains a tallow product. It is the direct lineal It is the direct lineal descendant of the "tallow dip" of our grandfathers. And it is still so popular that just about 130,000,000 pounds of tallow, according to the calculation of

one of the best-informed manufacturers of Chicago, is consumed every year in the candle factories of the United States.

Society has said good-bye to the tallow dip many times. When illuminating gas was brought into general use, the tallow candle was commiserated. Its long and active career was surely at an end. When Mr. Rockefeller made kerosene so cheap and so prevalent, the funeral oration of the tallow candle was again pronounced. And when Mr. Edison invented a practical filament for the incandescent electric lamp, the very last farewells were waved to the old homely illuminant of the Middle Ages. the Middle Ages. Yet, although gas and kerosene and electricity have deprived the candle of a large part of the popularity to which it might have considered itself justly entitled, it is probable that in both hemispheres today there are at least as many candles shedding their mild and humble radiance as in any previous period of the world's history.

In the first place, there are a great many more people in the world today than ever before. In the second place, there are millions of homes in which gas and electricity are not available and in which, as is natural, the kerosene lamp is not found to be so easily handled for incidental use as the tallow dip. In the third place there are thousands of metal mines in which there are no electric light plants and in which tallow dips are used night and day.

For at least these three reasons, and for a fourth which will be referred to later, there were so many candles used in the year 1906 that in London there is a candle factory covering eleven acres and in the United States there are at least fifteen tallow candle manufacturers of prominence and importance. Thus the candle, like the English House of Lords, continues to exist and to be powerful and influential in an age which looks upon it as a curious and impertinent survival of times gone by.

Any visitor to a candle factory will rapidly become convinced, however, that candlemaking, no matter how ancient a process it may be in its origin, has now become a process as completely modern as the dynamo in an electric light station. The candle factory of today is based upon the most recent developments in the science of chemistry.

This is the reason why tallow candles are no longer made of full tallow. Full tallow not only makes a poor candle but it contains ingredients which are much more profitable when they are devoted to other purposes.

The full tallow, therefore, when it arrives at the candle factory is soon split up into at least three main

products. It arrives yellowish and greasy. It may have come from the Chicago stockyards, extracted from the steers and sheep which have been made into steaks and chops, or it may have come from a remote farm in the country, or it may have come from the vast plains of the Argentine Republic. From all over the world it makes its way to the modern manufacturer of the medieval means of illumination.

Its first experience, immediately after its arrival, is to go into enormous tanks in which it gives up the glycerin which is a large part of its composition. This valuable substance was for many decades allowed to run out on the ground. It is now carefully preserved and it finds so many divergent uses that its real character is calculated to perplex the observer. It is used in making parchment paper. It is used in making the inking rollers in printing presses. Distilled and purified, it assists in composing medi

BOILED AT A HIGH TEMPERATURE.

cines which restore human beings to health. But treated with nitric acid it makes the nitroglycerin which blows. human beings into eternity. Pursuing these various routes to usefulness it separates itself from its original tallow in the tanks of the candle maker and leaves be

When it resumes its troubles it is taken, panful by panful, and wrapped in cloths. Carefully swaddled up, it is deposited in hot pressing-machines. These machines squeeze it till the observer might suppose there would be nothing Reddish streams, rich and thick,

left.

issue from the cloths, trickle into pipes and are carried off into fat, heavy barrels.

These rich, thick reddish streams are oil. Their essential part is oleic acid. They form a by-product fully as important as glycerin. They are sold by the candle maker to the maker of soaps. They are also sold to men who use them in the shrinking of wool.

The candle maker's tallow has now given up its glycerin and its oil. What is left is the stuff from which the tallow dips of today are made. It is, of course, not tallow at all. It is stearic acid. It is not yellowish but whitish. The purer it is the whiter it is. And it is

not greasy. It is dry and crumbly to the touch.

Each panful of tallow, squeezed dry of its oil, has now become a flaky slab of stearic acid. This stearic acid is used for many purposes besides the mak ing of candles. Ine candle manufacturer sells a great deal of it in its slab form without doing anything more to it.

hind it a substance which is now no longer real tallow because it has lost one of its principal ingredients.

It is still to lose another principal ingredient. It rests for some time in a vast array of shallow pans arranged on long tiers of shelves. It drips from the higher pans to the lower. It finally fills them all. It is still yellowish in color. It lies quiescent for a few days.

Stearic acid is used in the manufacture of certain kinds of metal polish. It scours our metal fixtures for us. It is used in making graphophone records. It helps to reproduce our voices. It is used even in the manufacture of plaster casts. It appears in the bodies of the little holy