Inventions in the Century

In some the pug mill is arranged horizontally to feed out the clay in the form of a long horizontal slab, which is cut up into proper lengths to form the bricks. Some machines are in the form of a large horizontal revolving wheel, having the moulds arranged in its top face, each mould charged with clay as the wheel presents it under the discharging spout of the grinding mill, and then the clay is pressed by pistons or plungers worked by a rocking beam, and adapted to descend and fit into the mould at stated intervals; or the moulds, carried in a circular direction, may have movable bottom plates, which may be pressed upwards successively by pistons attached to them and raised by inclines on which they travel, forcing the clay against a large circular top plate, and in the last part of the movement carrying the pressed brick through an aperture to the top of the plate, where it is met by and carried away on an endless apron.

In some machines two great wheels mesh together, one carrying the moulds in its face, and the other the presser plate plungers, working in the former, the bricks being finally forced out on to a moving belt by the action of cam followers, or by other means.

In others the moulds are passed, each beneath a gravity-descending or cam-forced plunger, the clay being thus stamped by impact into form; or in other forms the clay in the moulds may be subjected to successive pressure from the cam-operated pistons arranged horizontally and on a line with the discharging belt.

Third, the drying and burning of the brick. – The old methods were painfully slow and tedious. A long time was occupied in seasoning the clay, and then after the bricks were moulded, another long time was necessary to dry them, and a final lengthy period was employed to burn them in crude kilns. These old methods were too slow for modern wants. But they still are in vogue alongside of modern inventions, as in all ages the use of old arts and implements have continued along by the side of later inventions and discoveries.

No useful contrivances are suddenly or apparently ever entirely supplanted. The implements of the stone age are still found in use by some whose environment has deprived them of the knowledge of or desire to use better tools. The single ox pulling the crooked stick plough, or other similar ancient earth stirrer, and Ruth with her sickle and sheaves, may be found not far from the steam plough and the automatic binder.

But the use of antiquated machinery is not followed by those who lead the procession in this industrial age. Consequently other means than the slow processes of nature to dry brick and other ceramics, and the crude kilns are giving way to modern heat distributing structures.

Air and heat are driven by fans through chambers, in which the brick are openly piled on cars, the surplus heat and steam from an engine-room being often used for this purpose, and the cars so laden are slowly pushed on the tracks through heated chambers. Passages and pipes and chimneys for heat and air controlled by valves are provided, and the waste moisture drawn off through bottom drains or up chimneys, the draft of which is increased by a hot blast, or blasts of heated air are driven in one direction through a chamber while the brick are moved through in the opposite direction, or a series of drying chambers are separated from each other by iron folding-doors, the temperature increasing as cars are moved on tracks from one chamber to another.

Dr. Hoffmann of Berlin invented different forms of drying and burning chambers which attracted great attention. In his kiln the bricks are stacked in an annular chamber, and the fire made to progress from one section of the chamber to another, burning the brick as the heat advances; and as fast as one section of green brick is dried, or burned, it is withdrawn, and a green section presented. Austria introduced most successful and thorough systems of drying brick about 1870. In some great kilns fires are never allowed to cease. One kiln had been kept thus heated for fifteen years. Thus great quantities of green brick can at any time be pushed into the kiln on tracks, and when burned pushed out, and thus the process may go on continuously day and night.

To return to pottery: As before stated, Wedgwood of England revolutionised the art of pottery in the eighteenth century. He was aided by Flaxman. Before their time all earthenware pottery was what is now called "soft pottery." That is, it was unglazed, simply baked clay; lustrous or semi-glazed and enamelled having a harder surface. Wedgwood invented the hard porcelain surface, and very many beautiful designs. To improve such earthenware and to best decorate it, are the objects around which modern inventions have mostly clustered.

The "regenerative" principle of heating above referred to employed in some kilns, and so successfully incorporated in the regenerators invented since 1850 by Siemens, Frank, Boetius, Bicheroux, Pousard and others, consisting in using the intensely hot wasted gases from laboratories or combustion chambers to heat the incoming air, and carrying the mingled products of combustion into chambers and passages to heat, dry or burn materials placed therein, has been of great service in the production of modern pottery; not only in a great saving in the amount of fuel, but in reduction in loss of pieces of ware spoiled in the firing.

The old method of burning wood, or soft coal, or charcoal at the bottom of a small old-fashioned cylindrical fire brick kiln attended to by hand, and heating the articles of pottery arranged on shelves in the chamber above, is done away with to a great extent in large manufactories for the making of stone and earthenware – although still followed in many porcelain kilns.

Inventions in the line of pottery kilns have received the aid of woman. Susan Frackelton of the United States invented a portable kiln for firing pottery and porcelain, for which she obtained a patent in 1886.

As in drying clay for brick, so in drying clay for porcelain and pottery generally, great improvements have been made in the drying of the clay, and other materials to be mixed therewith. A great step was taken to aid drying by the invention of the filter press, in which the materials, after they are mixed and while still wet, are subjected to such pressure that all surplus water is removed and all air squeezed out, by which the inclosure of air bubbles in the clay is prevented.

Despairing of excelling the China porcelain, although French investigators having alleged their discovery of such methods, modern inventors have contented themselves in inventing new methods and compositions. Charles Aoisseau, the potter of Tours, born in 1796, rediscovered and revived the art of Palissy. About 1842, Thomas Battam of England invented the method of imitating marble and other statuary by a composition of silica, alumina, soda, and traces of lime, magnesia, and iron, reducing it to liquid form and pouring it into plaster moulds, forming the figure or group. His plaster casts soon became famous. In the use of materials the aid of chemists was had in finding the proper ingredients to fuse with sand to produce the best forms of common and fine Faience.

Porcelain Moulding, and its accompanying ornamentation and the use of apparatus for moulding by compression and by exhaustion of the air has become since that time a great industry.

Porcelain Colours.– Chemists also aided in discovering what metallic ingredients could best be used when mixed with the clay and sand to produce the desired colours. As soon as a new metal was discovered, it was tested to find, among other things, what vitrifiable colour it would produce. In the production of metallic glazes, the oxides generally are employed. The colours are usually applied to ware when it is in its unglazed or biscuit form. In the biscuit or bisque form pottery is bibulous, the prepared glaze sinks into its pores and when burned forms a vitreous coating.

The application of oil colours and designs to ware before baking by the "bat" system of printing originated in the eighteenth and was perfected in the nineteenth century. It consists of impressing oil pictures on a bat of glue and then pressing the bat on to the porous unbaked clay or porcelain which transferred the colours. This was another revolution in the art.

One manner for ages of applying colours to ware is first to reduce the mixture to a liquid form, called "slip," and then, if the Chinese method is followed, to dip the colour up on the end of a hollow bamboo rod, which end is covered with wire gauze, then by blowing through the rod the colour was sprayed or deposited on the ware. Another method is the use of a brush and comb. The brush being dipped into the coloured matter, the comb is passed over the brush in such manner as to cause the paint to spatter the object with fine drops or particles. A very recent method, by which the beautiful background and blended colours of the celebrated Rookwood pottery of Cincinnati, Ohio, have become distinguished, consists in laying the colour upon the ware in a cloud or sheet of almost imperceptible mist by the use of an air atomiser blown by the operator. By the use of this simple instrument, the laying on a single colour, or the delicate blending and shadings of two or more colours in very beautiful effects is easily produced.

This use of the atomiser commenced in 1884, and was claimed as the invention of a lady, Miss Laura Fry, who obtained a patent for thus blowing the atomised spray colouring matter on pottery in 1889; but it was held by the courts that she was anticipated by experiments of others, and by descriptions in previous patents of the spraying of paint on other objects by compressed air apparatus known as the air brush. However, this introduction of the use of the atomiser caused quite a revolution in the art of applying colours to pottery in the forming of backgrounds.

Enamelled ware is no longer confined to pottery. About 1878 Niedringhaus in the United States began to enamel sheet iron by the application of glaze and iron oxide, giving such articles a granite appearance; and since then metallic cooking vessels, bath tubs, etc., have been converted in appearance into the finest earthenware and porcelain, and far more durable, beautiful and useful than the plain metal alone for such purposes.

When we remember that for many centuries, wood and pewter, and to some extent crude earthenware, were the materials from which the dishes of the great bulk of the human family were made, as well as their table and mantel ornaments, and compare them in character and plenteousness with the table and other ware of even the poorest character of to-day, we can appreciate how much has been done in this direction to help the human family by modern inventions.

Artificial Stone.– The world as yet has not so far exhausted its supply of stone and marble as to compel a resort to artificial productions on a great scale, and yet to meet the demands of those localities wherein the natural supplies of good building stones and marble are very scarce, necessitating when used a long and expensive transportation, methods have been adopted by which, at comparatively small cost, fine imitations of the best stones and marbles have been produced, having all the durable and artistic qualities of the originals, as for the most part, they are composed of the same materials as the stone and marbles themselves.

The characteristic backgrounds, the veins and shadowings, and the soft colours of various marbles have been quite successfully imitated by treating dehydrated gypsum with various colouring solutions. Sand stones have been moulded or pressed from the same ingredients, and with either smooth or undressed faces. When necessary the mixture is coloured, to resemble precisely the original stones.

One of the improvements in the manufacture and use of modern cements and artificial stones consists in their application to the making of streets and sidewalks. Neat, smooth, hard, beautiful pavements are now taking the place everywhere of the unsatisfactory gravel, wood, and brick pavements of former days. We know that the Romans and other ancient peoples had their hydraulic cements, and the plaster on some of their walls stands to-day to attest its good quality. Modern inventors have turned their attention in recent years to the production of machines to grind, crush, mix and set the materials, and to apply them to large wall surfaces, in place of hand labour. Ready-made plaster of a fine quality is now manufactured in great quantities. It needs only the addition of a little water to reduce it to a condition for use; and a machine operated by compressed air may be had for spreading it quickly over the lath work of wood or sheet metal, slats, or over rough cement ceilings and walls.

Glass.– The Sister of Pottery is Glass. It may have been an accidental discovery, occurring when men made fire upon a sandy knoll or beach, that fire could melt and fuse sand and ashes, or sand and lime, or sand and soda or some other alkali, and with which may also have been mixed some particles of iron, or lead, or manganese, or alumina to produce that hard, lustrous, vitreous, brittle article that we call glass.

But who invented the method of blowing the viscid mass into form on the end of a hollow tube? Who invented the scissors and shears for cutting and trimming it when soft? Or the use of the diamond, or its dust, for polishing it when hard? History is silent on these points. The tablets of the most ancient days of Egypt, yet recovered, show glass blowers at work at their trade – and the names of the first and original inventors are buried in oblivion. Each age has handed down to us from many countries specimens of glass ware which will compare favourably in beauty and finish with any that can be made to-day.

Yet with the knowledge of making glass of the finest description existing for centuries, it is strange that its manufacture was not extended to supply the wants of mankind, to which its use now seems so indispensable. And yet as late as the sixteenth and seventeenth centuries glass windows were found only in the houses of the wealthy, in the churches and palaces, and glass mirrors were unknown except to the rich, as curiosities, and as aids to the scientists in the early days of telescopy. Poor people used oiled paper, isinglass, thinly shaved leather, resembling parchment, and thin sheets of soft pale crystalised stone known as talc, and soapstone.

The nineteenth century has been characterised as the scientific century of glass, and the term commercial, may well be added to that designation.

Its commercial importance and the advancement in its manufacture during the first half of the century is illustrated in the fact that the Crystal Palace of the London Industrial Exhibition of 1851, although containing nearly 900,000 square feet of glass, was furnished by a single firm, Messrs. Chance & Co. of London, without materially delaying their other orders. In addition to scientific discoveries, the manufacture of glass in England received a great impetus by the removal of onerous excise duties which had been imposed on its manufacture.

The principal improvements in the art of glass-making effected during the nineteenth century may be summarised as follows:

First, Materials. – By the investigations of chemists and practical trials it was learned what particular effect was produced by the old ingredients employed, and it was found that the colours and qualities of glass, such as clearness, strength, tenacity, purity, etc., could be greatly modified and improved by the addition to the sand of certain new ingredients. By analysis it was learned what different metallic oxides should be employed to produce different colours. This knowledge before was either preserved in secrecy, or accidentally or empirically practised, or unknown. Thus it was learned and established that lime hardens the glass and adds to its lustre; that the use of ordinary ingredients, the silicates of lime, magnesia, iron, soda and potash, in their impure form, will produce the coarser kinds of glass, such as that of which green bottles are made; that silicates of soda and lime give the common window glass and French plate; that the beautiful varieties of Bohemian glass are chiefly a silicate of potash and lime; that crystal or flint glass, so called because formerly pulverised flints were used in making it, can be made of a suitable combination of potassia plumbic silicate; that the plumbic oxide greatly increases its transparency, brilliancy, and refractive power; that paste– that form of glass from which imitations of diamonds are cut, may be produced by adding a large proportion of the oxide of lead; that by the addition of a trace of ferric oxide or uranic acid the yellow topaz can be had; that by substituting cobaltic oxide the brilliant blue sapphire is produced; that cuperic oxide will give the emerald, gold oxide the ruby, manganic oxide the royal purple, and a mixture of cobaltic and manganic oxides the rich black onyx.

Professor Faraday as early as 1824 had noticed a change in colour gradually produced in glass containing oxide of manganese by exposure to the rays of the sun. This observation induced an American gentleman, Mr. Thomas Gaffield, a merchant of Boston, to further experiment in this direction. His experiments commenced in 1863, and he subjected eighty different kinds of glass, coloured and uncoloured, and manufactured in many different countries, to this exposure of the sun's rays. He found that not only glass having manganese as an element, but nearly every species of glass, was so affected, some in shorter and some in longer times; that this discoloration was not due to the heat rays of the sun, but to its actinic rays; and that the original colour of the glass could be reproduced by reheating the same.

Mr. Gaffield also extended his experiments to ascertain the power of different coloured glasses to transmit the actinic or chemical rays, and found that blue would transmit the most and red and orange the least.

Others proceeded on lines of investigation in ascertaining the best materials to be employed in glass-making in producing the clearest and most permanent uncoloured light; the best coloured lights for desired purposes; glasses having the best effects on the growth of plants; and the best class for refracting, dispersing and transmitting both natural lights and those great modern artificial lights, gas and electricity.

Another illustration of modern scientific investigation and success in glass-making materials is seen at the celebrated German glass works at Jena under the management of Professors Ernst Abbe and Dr. Schott, commenced in 1881. They, too, found that many substances had each its own peculiar effect in the refraction and dispersion of light, and introduced no fewer than twenty-eight new substances in glass making. Their special work was the production of glass for the finest scientific and optical purposes, and the highest grades of commercial glass. They have originated over one hundred new kinds of glass. Their lenses for telescopes and microscopes and photographic cameras, and glass and prisms, and for all chemical and other scientific work, have a worldwide reputation.

So that in materials of composition the old days in which there were substantially but two varieties of glass – the old-fashioned standard crown, and flint glass – have passed away.

Methods.– The revolution in the production of glass has been greatly aided also by new methods of treatment of the old as well as the new materials. For instance, the application of the Siemens regenerative furnace, already alluded to in referring to pottery, in place of old-fashioned kilns, and by which the amount of smoke is greatly diminished, fuel saved, and the colour of the glass improved. Pots are used containing the materials to be melted and not heated in the presence of the burning fuel, but by the heated gases in separate compartments.

Another process is that of M. de la Bastie, added to by others, of toughening glass by plunging it while hot and pasty and after it has been shaped, annealed, and reheated, into a bath of grease, whereby the rapid cooling and the grease changes its molecular condition so that it is less dense, resists breaking to a greater degree, and presents no sharp edges when broken.

Another process is that of making plate glass by the cylinder process – rolling it into large sheets.

Other processes are those for producing hollow ware by pressing in moulds; for decorating; for surface enamelling of sheet glass whereby beautiful lace patterns are transferred from the woven or netted fabric itself by using it as a stencil to distribute upon the surface the pulverised enamel, which is afterwards burned on; of producing iridescent glass in which is exhibited the lights and shadows of delicate soap bubble colours by the throwing against the surface of hydrochloric acid under pressure, or the fumes of other materials volatilised in a reheating furnace.

Then there is Dode's process for platinising glass, by which a reflecting mirror is produced without silvering or otherwise coating its back, by first applying a thin coating of platinic choride mixed with an oil to the surface of the glass and heating the same, by which the mirror reflects from its front face. The platinum film is so thin that the pencil and hand of a draughtsman may be seen through it, the object to be copied being seen by reflection.

Again there is the process of making glass wool or silk– which is glass drawn out into such extremely fine threads that it may be used for all purposes of silk threads in the making of fabrics for decorative purposes and in some more useful purposes, such as the filtration of water and other liquids.

We have already had occasion to refer to Tilghman's sand blast in describing pneumatic apparatus. In glass manufacture the process is used in etching on glass designs of every kind, both simple and intricate. The sand forced by steam, or by compressed air on the exposed portions of the glass on which the design rests, will cut the same deeply, or most delicately, as the hand and eye of the operator may direct.

Machines.– In addition to the new styles of furnaces, moulds and melting, and rolling mills to which we have alluded, mention may be made of annealing and cooling ovens, by which latter the glass is greatly improved by being allowed to gradually cool. A large number of instruments have been invented for special purposes, such as for making the beautiful expensive cut glass, which is flint glass ground by wheels of iron, stone, and emery into the desired designs, while water is being applied, and then polished by wheels of wood, and pumice, or rottenstone; for grinding and polishing glass for lenses; and for polishing and finishing plate glass; for applying glass lining to metal pipes, tubes, etc.; for the delicate engraving of glass by small revolving copper disks, varying in size from the diameter of a cent down to one-fifteenth of an inch, cutting the finest blade of grass, a tiny bud, the downy wing of an insect, or the faint shadow of an exquisite eyebrow.

Cameo cutting and incrustation; porcelain electroplating and moulding apparatus, and apparatus for making porcelain plates before drying and burning, may be added to the list.

It would be a much longer list to enumerate the various objects made of glass unknown or not in common use in former generations. The reader must call to mind or imagine any article which he thinks desirable to be made from or covered with this lustrous indestructible material, or any practicable form of instrument for the transmission of light, and it is quite likely he will find it already at hand in shops or instruments in factories ready for its making.

Rubber – Goodyear

The rubber tree, whether in India with its immense trunk towering above all its fellows and wearing a lofty crown, hundreds of feet in circumference, of mixed green and yellow blossoms; or in South America, more slender and shorter but still beautiful in clustered leaves and flowers on its long, loosely pendent branches; or in Africa, still more slender and growing as a giant creeper upon the highest trees along the water courses, hiding its struggling support and festooning the whole forest with its glossy dark green leaves, sweetly scented, pure white, star-like flowers, and its orange-like fruit – yields from its veins a milk which man has converted into one of the most useful articles of the century.