Inventions in the Century

by William Henry Doolittle

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.