Chapter 7

Many of the compositions which have been invented have been well adapted for use for certain purposes and have been used to adulterate the pure rubber, but no substance has been produced which could even approach India rubber in several of its important characteristics. There has never been a substance yet recommended as a substitute for rubber which possessed the extraordinary elasticity which makes it indispensable in the manufacture of so many articles of common use.

Great hopes were at one time placed in a product prepared from linseed oil. It was found that a material could be produced from it which would to a certain extent equal India rubber compositions in elasticity and toughness.

It was argued that linseed oil varnish, when correctly prepared, should be clear, and dry in a few hours into a transparent, glossy mass of great tenacity. By changing the mode of preparing linseed oil varnish in so far as to boil the oil until it became a very thick fluid and spun threads, when it was taken from the boiler, a mass was obtained which in drying assumed a character resembling that of a thick, congealed solution of glue.

Resin was added to the mass while hot, in a quantity depending upon the product designed to be made, and requiring a greater or less degree of elasticity.

Many other recipes have been advocated at different times to make a product resembling caoutchouc out of linseed oil in combination with other substances, but all have failed to give satisfaction, save as adulterants to pure rubber.

Among the best compounds in use in rubber factories at present is one made by boiling linseed oil to the consistency of thick glue. Unbleached shellac and a small quantity of lampblack is then stirred in. The mass is boiled and stirred until thoroughly mixed. It is then placed in flat vessels exposed to the air to congeal.

While still warm the blocks formed in the flat vessels are passed between rollers to mix it as closely as possible. This compound was asserted by its inventor to be a perfect substitute for caoutchouc. It was also stated that it could be vulcanized. This was found to be an error, however. The compound, upon the addition of from 15 to 25 per cent. of pure rubber, may be vulcanized and used as a substitute for vulcanized rubber.

Compounds of coal tar, asphalt, etc., with caoutchouc have been frequently tested, but they can only be used for very inferior goods.

The need for a substitute for gutta percha is even more acute than for artificial India rubber. A compound used in its stead for many purposes is known as French gutta percha. This possesses nearly all the properties of gutta percha. It may be frequently used for the same purposes and has the advantage of not cracking when exposed to the air.

Its inventors claimed that it was a perfect substitute for India rubber and gutta percha, fully as elastic and tough and not susceptible to injury from great pressure or high temperature.

The composition of this ambitious substance is as follows: One part, by weight, of equal parts of wood tar oil and coal tar oil, or of the latter alone, is heated for several hours at a temperature of from 252 to 270 degrees Fahrenheit, with two parts, by weight, of hemp oil, until the mass can be drawn into threads. Then one-half part, by weight, of linseed oil, thickened by boiling, is added. To each 100 parts of the compound one-twentieth to one-tenth part of ozokerite and the same quantity of spermaceti are added.

The entire mixture is then again heated to 252 degrees Fahrenheit and one-fifteenth to one-twelfth part of sulphur is added. The substance thus obtained upon cooling is worked up in a similar manner to natural India rubber. It has not been successfully used, however, without the addition of a quantity of pure rubber to give it the requisite elasticity.

A substitute for gutta percha is obtained by boiling the bark of the birch tree, especially the outer part, in water over an open fire. This produces a black fluid mass, which quickly becomes solid and compact upon exposure to air.

Each gutta percha and India rubber factory has a formula of its own for making up substances as nearly identical with the natural product as possible, which are used to adulterate the rubber and gutta percha used in the factory. No one has as yet, however, succeeded in discovering a perfect substitute for either rubber or gutta percha.

The history of chemistry contains many instances where natural products have been supplanted by artificial compounds possessing the same properties and characteristics. One of the most notable of these is the substance known as alizarine, the coloring matter extracted from the madder root. This, like India rubber, is a hydrocarbon.

Prior to 1869 all calico printing was done with the coloring matter derived from the madder root, and its cultivation was a leading industry in the eastern and southern portions of Europe.

In 1869 alizarine was successfully produced from the refuse coal tar of gas works and the calico printing business was revolutionized.

The essence of vanilla, made from the vanilla bean, and used as a flavoring extract, has been supplanted by the substance christened vanilla by chemists, which possesses the same characteristics and is made from sawdust.

Isoprene, from which Dr. Tilden produced India rubber, is comparatively a new product, as derived from oil of turpentine. It yet remains to be seen whether rubber can be synthetically produced certainly and cheaply. The result of further experiments will be awaited with interest, as the production of artificial rubber at moderate cost would be an event of enormous importance.

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DEEP AND FROSTED ETCHING ON GLASS.

The best means of producing these effects is by printing from a steel plate or lithographic stone on thin transfer paper, which, in turn, is made to give up the design to the surface of the glass, the exposed portions of the latter being then etched with acid.

In preparing the steel plate, a coating of varnish is prepared by mixing 200 parts by weight of oil of turpentine, 150 of Syrian asphaltum, 100 of beeswax, 50 of stearin, and 50 of Venice turpentine in the warm. The design is then copied in outline by tracing from the original, the shading being reproduced in a less detailed manner, but with fewer and bolder strokes, in order to adapt the picture to the process. It is then pricked through the tracing paper on to the varnish coating of the plate, and, after clearing out the lines with graving needles, the plate is etched with a mixture of 1 vol. of water and 4 to 7 vols. of nitric acid, either by application or immersion; in the latter event the back of the plate must be varnished over. When the metal is bitten by the acid to about 1-75 of an inch in depth, the operation is finished.

To transfer the design to the glass it is printed from the steel plate on to thin silk paper, the ink used being compounded from 500 parts of oil of turpentine, 1,500 of Syrian asphalt, 500 of beeswax, 400 of paraffin, and 300 of thick litho varnish. The printing is performed in the usual manner, and the transfer laid on the warmed surface of the glass sheet or ware to be decorated, rubbed over uniformly with a cloth to make the ink adhere to the glass, and then the paper is moistened and taken off again, leaving the imprinted design behind. It is well to have the ink fairly thick, and rely on warmth to impart the necessary fluidity; otherwise the design may come away with the paper in patches, and be imperfect.

For etching in the design on the glass, the edges of the latter are coated with the protective varnish, and then hydrofluoric acid is brushed over the exposed portions, which are thereby corroded, leaving the parts covered by the ink standing in relief. According as a clear or frosted etching is desired, the etching liquid is modified, being, for the latter purpose, composed of 500 parts of ammonium fluoride, 100 of common salt, 300 of fuming hydrofluoric acid and 30 of ammonia. This is brushed over the glass two or three times, and then rinsed off with lukewarm water. For deep etching, hydrofluoric acid is diluted with 1½ vols. of water and stored for twenty-four hours before use. The objects are immersed in the baths for thirty to fifty minutes, and kept quite still the while. If the etching is to be left clear, the acid is neutralized by boiling the glass in soda, but if to be frosted afterward it is coated with the first named etching liquid while still damp. Finally, the ink is washed off with turpentine, the glass rubbed over with sawdust, washed in hot lye and rinsed with water.

Grained or lined designs can be very suitably printed from a litho stone, on paper faced with a mixture of 1,500 parts of water, 250 of wheaten starch, 1,000 of glycerine and 200 of a thick solution of gum arabic, the ink for printing being prepared by melting and mixing 500 parts of pure tallow, 250 of white beeswax, 250 of liquid mastic, and 150 of pale resin, with 100 parts of lampblack, 5 of minium, and 500 of litho varnish. In transferring the design to the glass, the latter, if flat, may be passed between India rubber rollers or protected by layers of gutta percha when the pressure is applied. The impression produced by this lithographic process has to be strengthened to enable the thin coating of ink to resist the etching liquid, and this is done by dusting powdered resin over the printed surface of the glass, brushing off all that does not adhere, and causing the remainder to attach itself to the ink by means of warmth, and so form an impervious covering. The further treatment is the same as that already described. These methods are particularly suitable for reproducing landscapes, etc., on thinly flashed glass of various colors.--Diamant.

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SLATE AND ITS APPLICATIONS.

Slate is, as we know, merely a variety of argillite. Slate quarries are found in England, Switzerland and Italy, but it is in France especially that the industry has been most extensively developed by reason of the large deposits that underlie its surface, particularly in the province of Anjou, where they extend from Trelaze to Avrille, a distance of six miles, and in the department of Ardennes, at Remogne, Fumay, etc.

Normandy, Brittany, Dauphiny and Marne likewise possess quarries, although they are not so productive.

The exploitation is commonly done in open quarry. After the vegetable mould (which in this case is called "cover") has been removed, we meet with a solid slate which it is difficult to split into laminæ, and it is not until a depth of at least fifteen feet is reached that we find a material that is fit to be exploited. All the best beds of slate, in fact, improve in quality in proportion as they lie deeper under the surface, near to which they have little value. Without entering into details as to the exploitation of this product, let us say that the blocks have to be divided in the quarry, since, in the open air, they rapidly lose the property of readily splitting into thin, even laminæ.

Slate has but slight affinity for water, and, moreover, resists atmospheric influences, humidity and heat pretty well.

This property renders it valuable for a large number of domestic purposes.

There is no certain proof, it is true, that it was employed by the ancients, but it is, nevertheless, extremely probable that it was used in mass at an early period for stair heads, pillars for buildings and as a material for fencing.

The exploitation of the material became especially active at the period when the idea occurred to some one to use slate for the rooting of houses. It was employed for this purpose along with tiles as far back as the eleventh century in the majority of schistose districts. It is well known, for example, that Fumay (Ardennes) at this period had a brotherhood of slate quarrymen.

A method of getting out the material and cutting it regularly was found toward the end of the twelfth century, and it was not till then that it became of general application. Moreover, with the advent of the Gothic period slate became indispensable for castle roofs, which have a conical form.

The best slate for roofing purposes is hard, heavy and of a bluish gray color. A good slate should readily split into even laminæ; it should not be absorbent of water either on its face or endwise, a property evinced by its not increasing perceptibly in weight after immersion in water; and it should be sound, compact and not apt to disintegrate in the air.

For a long time past there have been used in schools slate tablets upon which the pupils write with a pencil made of soft gray schist. This application, which is capable of rendering services in a host of details of domestic economy, has given rise to artificial slates, which, made by a process of moulding a composition analogous to cardboard pulp, present the same advantages as ordinary slate, while being much lighter.

Along about 1834 an Englishman of the name of Magnus utilized the property that slate possesses of taking a fine polish in the invention of what are called enameled slates. These products are used especially in the manufacture of table tops, mantelpieces, altars, etc. They very closely imitate the most expensive marbles, and their properties, along with their low price, have been the cause of their introduction into the houses of all classes of the English population, as well as into those of entire Europe and America.

The ease with which slate is obtained in slabs of large dimensions has greatly contributed in recent times toward still further increasing its applications. One of the first of such applications was the substitution of it in urinals for cast iron plates, which very rapidly oxidize and become impregnated with nauseous odors that necessitate a frequent cleaning and constitute a permanent source of infection.

For a few years past, too, slate has been used, in the manufacture of vats designed for breweries. These vats, of which we show in the accompanying figure a model of the installation employed in the Ivry Brewery, are each 6½ feet square and 5 feet in depth. For leading the beer, which, upon coming from the brewing apparatus, must rest for a few days, they are connected by a system of pipes. A second system of pipes, which in our figure is seen running along the cellar vault, serves as a cooling apparatus and maintains a temperature of 5° C. above zero in the vats arranged in two rows to the right and left.

The details or even a simple enumeration of the new applications of slate would, in order to be anywhere nearly complete, necessitate a lengthy article. Let us say in conclusion that slate is substituted for wood, which is too easily attackable, and for marble, which is much more costly, in our laboratories and amphitheaters and everywhere where the manipulation and stay of easily corrupted liquids and solids require the greatest cleanliness in the material of construction.--La Science en Famille.

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BIRTHPLACE OF THE OILCLOTH INDUSTRY.

In Kennebec County, Me., is the quiet borough of East Winthrop, for more than half a century known wherever oilcloth carpeting was used as Baileyville.

Were it not for the inventive brain of one of East Winthrop's early inhabitants, says a contemporary, the village would hardly be known across the lake, but early in the present century one of the numerous family of Maine Baileys evolved a scheme to fill his purse faster than the slow process of nature was likely to do it in growing crops.

Oilcloth carpetings were not known in the long ago, when Ezekiel Bailey pictured in his mind how they might be made, and it was in the little hamlet of East Winthrop that the conceit of their manufacture was hatched and executed. Ezekiel Bailey was, in the days prior to the war of 1812, looked upon as a very likely boy. He was studious and industrious, and while other boys of the village were out in the white oak groves setting box traps for gray squirrels, and spearing pickerel by torch light in the waters of Cobosseecontee, Ezekiel was busy in his little workshop fashioning useful things to be used about the house.

Just how and when and where he was prompted to attempt the making of oilcloth carpet nobody now living at East Winthrop seems to know. Many of the burghers thought he was "a-wastin' uv his time," but they thought different some years later when great factories for the manufacture of oilcloth floor carpeting were erected in East Winthrop, Hallowell, New Jersey, and other places.

And Ezekiel? He amassed a considerable fortune and left the path of life much easier for his kin to pursue. Having met a peddler one day, he bought a table cover made of a combination of burlap and paint. Such things were a luxury in the country at that time, and Ezekiel Bailey was shrewd enough to foresee a big demand for them if the cost could be moderated a bit. While thinking, an idea came to him, and following the idea a small voice which whispered: "Make 'em yourself." He decided to try, and there is a legend to the effect that half the farmers of the village quit work to see the first table cover.

Procuring a square of burlap, or rather enough burlap from which to fashion a square of the desired size, Ezekiel Bailey framed up the fabric as the good old grandmas used to hitch up quilts at a quilting bee, the only difference being that the burlap was framed or stretched over a table made of planed boards large enough for the full spread of the burlap. With paint and brush he began his work. The first coat was a tiller; the next, a thicker one, gave body to the cloth, and when this was rubbed down to a smooth surface the last coat was prepared. This was of a different color and was spread on thick. Then, with a straight edge, a piece of board with a true, thin edge, reaching across the whole surface of painted cloth, the finishing touches were put on. Commencing at one end of the fabric, the straight edge was moved back and forth, and straight along over the fresh paint once or twice, and the whole thing left to dry.

The first table covers were great curiosities, and the homes of the Baileys were visited by all the neighboring housewives, who were anxious to see "how they worked." Of course, it was easy to keep them clean, and they saved the woodwork of the table, which was recommendation enough. To see a cloth was to covet it, and it was not long before Ezekiel Bailey had a considerable business. Employing a boy to help him, he turned out table cloths as fast as his limited facilities would permit, and, as he progressed, new ideas for decorating took shape in his mind. In less than a year he had men out on the road selling them.

The turning out to perfection of an oilcloth carpet in those days was a task that would make a person in these piping times of labor-saving machinery wish for something easier. All the smoothing or rubbing down was done by hand. Heavy, long-bladed knives, as big as the "Sword of Bunker Hill," were used to scrape down the rough body coats of paint, and a smooth surface, on which to stamp the geometrical figures in colors, was fetched after long and laborious polishing with bricks and pumice stone.

Drummers employed by Mr. Bailey traveled to Massachusetts, to New York, and away down into the South, and ere long the demand for oilcloth carpeting became so general that other factories were built and made to chatter and clank with the new industry. There was living not far from East Winthrop at this time a shrewd, wideawake Yankee farmer named Sampson, who had kept his weather eye peeled on the progress of Ezekiel Bailey, and when housewives everywhere began to yearn for the new carpeting, taking a neighbor in as a partner, Mr. Sampson built a factory, and in a very short time was in a position to be considered a formidable rival of Mr. Bailey.

But the originator of the oilcloth carpet was not to be outdone. Discerning good returns from a plant established close to a big center of consumption, Mr. Bailey entered into a deal with New Jersey capitalists, and a big factory was set a-going in that State. A trusted employe of the Bailey concern, Levi Richardson (who still lives and is the proprietor of a modest little store in East Winthrop), was sent to New Jersey to instruct the green hands there in the art of manufacture. While thus engaged, Mr. Richardson's brain was busy with the problem of labor saving, and one day a phantom device for smoothing and rubbing down the first rough coats on the burlaps took form in his mind, and for some weeks he spent his spare time in experimenting. The result was the present patent used in most factories, whereby as much rubbing down can be done in one day as could have been accomplished in four by the old hand method. --Industrial World.

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THE KOPPEL ELECTRIC LOCOMOTIVES.

The question of the design of small locomotives for use on pioneer lines has been always a difficult matter.

The needs of the railway contractor have called for such locomotives, for which several systems of power have been tried. In many ways the electric locomotive has distinct advantages over its rivals, steam and compressed air, for these narrow gage lines. Reviewing these advantages briefly, we see that the electrical equipment is more economical to work, as one good stationary engine develops power much more cheaply than several small locomotives. Again, the electric locomotive can be more readily designed for narrow gages than steam or compressed air locomotives.