rollers or rolling-pins,—for the rubber is spread out like so much dough,—are passed over a steam chest, which drives off the naphtha and dries, to a certain extent, the material. In some cases the film is rolled on to a cotton fabric and adheres to it, film after film being added until it is built up to the required substance: the object of this building up being to prevent the possibility of air-holes occuring, which would be fatal to a water-proof or air-proof material. When it is not necessary for the india-rubber to be lined with cloth, the roller of that material on to which it is wound, is sized, consequently no adhesion takes place between the two materials, and the rubber is easily peeled off. The process of Vulcanisation that gives such extraordinary resiliency to the material, which we are so familiar with in the form of india-rubber bands, springs, &c., is accomplished by the application of heat. The sulphur having already been worked into the material and thoroughly incorporated with it, the articles made of this hard compound are carefully packed in sand so as not to touch one another, and then are run into steam chests, where they remain from two to six hours, according to thickness, at a heat varying from 200 to 300 degrees. This application of heat turns the soft doughy substance into the famous elastic material which, under the name of vulcanised india-rubber, is even invading the province of steel in the manufacture of springs. What is the nature of the chemical change which takes place when this final increment of heat is applied, is entirely unknown, and the discovery itself was one of those fortunate accidents which have so often produced noble fruit. The peculiarity of the elasticity produced by vulcanisation is, that its power never seems to be worn out. The bow must be unbent, if its force is to be husbanded, but an india-rubber band may be kept stretched to its utmost limit for years, and it will still retain its wonderful resiliency.
But we have yet to describe another process—that of manufacturing Hard india-rubber. To Goodyear, the American, the merit of this great discovery is due, for great we must call it, inasmuch as it has introduced into the arts and sciences a material somewhat similar to horn, but which possesses qualities far surpassing that natural product, and which can be made in any quantities and in any sizes.
In this new material a very large amount of sulphur is used; to produce mere vulcanisation two ounces to the pound of rubber is sufficient, but to make hard india-rubber or ebonite, as the Messrs. Silver term their preparation of it, as much as two of sulphur to one of rubber is used. The application of great heat, say 300 degrees, transforms the india-rubber thus treated into a material more resembling to the eye ebony than anything else—a dense black substance, which takes a high polish, is very light, and to some slight extent elastic. The uses to which hard india-rubber is put can scarcely be enumerated. In many articles it is entirely displacing horn and tortoiseshell. Hundreds of tons, for instance, are sold to the comb makers; for paper-knives, handles of all kinds, bracelets most closely imitating jet—but with this advantage over that material, that it will not break by falling on the floor—cups and troughs of all kinds, and especially those for the use of photographers, as neither acids nor metals have action upon it; in short, we scarcely know to what this beautiful hard substance is inapplicable, so multifarious are the uses to which it has already been applied. It is greatly used as an insulator in telegraphy, in consequence of its non-conducting quality; and moulded into forms before being baked, it takes the place of many articles formerly made of gutta-percha, to which material it is infinitely preferable, as it is neither affected by heat nor cold.
The little community of Silvertown is, as it were, self-contained. Situated, as it is, far away from the town, on the Essex shore of the Thames, the proprietors had, as it were, to found a little colony. When the factory was built, there were no houses near, and no market, consequently the Messrs. Silver had to provide for the wants of their work-people, and they certainly have done so with a care worthy of all praise. The rows of cottages in which many of their work-people are housed contrast very favourably with the squalid habitations one passes on the railway in going to the factory. Then there is a store in which bacon, flour, and many other necessaries of life, are obtainable at cost price, and a public-house in which the beer is pure. The Messrs. Silver found it was incumbent upon them to build a public-house, otherwise it would have been done for them by independent parties, and the consequence would have been that, a very efficient means of administering to the comfort of the work-people, and at the same time of controlling excess, would have passed out of their hands.
The great charge brought against the manufacturers, as a class, used to be that they were utterly careless with respect to their “hands,” and that they looked upon them merely as machines—or rather less than machines—for when their day’s task was done, they washed their hands of them, and cared not what became of them; a state of things which placed the free Englishman, as regards physical comfort, in a less favourable position than the negroes, whose bodily wants their masters have always had the good policy to attend to. In thus making themselves responsible to a certain extent for the domestic comfort of their work-people, the employers are doing service to the community at large, for it is to the exertions of individual manufacturers that society must look for the accomplishment of that all-important task, the elevation of the social status of the workman. The example of little communities such as Silvertown is beginning to tell upon that mass of squalor which once seemed to be so hopeless in its immensity. It is becoming a habit of large manufacturing companies, we are happy to see, to look upon their workmen as human beings, to be cared for, as well as machines, to be used up; and the formation of the two little colonies of engineers at Wolverton and Swindon has been followed on a smaller scale by thousands of private employers throughout the country, who have found out that their own interests are concerned in concerning themselves with the happiness of those in their employ. The Messrs. Silver may justly pride them-