Class XXVIII.]

“ VULCANIZED ” INDIA-RUBBER—AWARDS.

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completing by the manufacture of waterproof shoes the 1 and the means of separating the sulphur and reproducingservice which Mackintosh had begun by the invention of , the pure caoutchouc presents at the present day an im-the garments which bear his name. Since 1842, Mr. I portant problem to solve. If this action of heat which

' modifies the caoutchouc is exercised upon a mixture

Goodyear has imported into Europe shoes which possessou unlimited and permanent elasticity, and which resistcold: two of their surfaces may be pressed against eachother without the least adhesion taking place. These areprecisely the remarkable qualities which characterize thatcaoutchouc which is called in the present day vulcanizedIndia-rubber. Impressed, perhaps, with the idea, toooften moreover a just one, that the specification of apatent is sometimes nothing more than the occasion ofattracting the attention of imitators, Mr. Goodyear tookno patent for this article, but he endeavoured in Europe to take advantage of his discovery, by communicating itas a process of which he alone possessed the secret, whichmight be lost to mankind and disappear with its solepossessor, when Mr. Thomas Hancock , of Stoke Newing-ton, who had been engaged in Europe in the working ofcaoutchouc with no less perseverance and success thanMr. Goodyear in America , discovered anew the process ofthe vulcanization of India-rubber, and secured it by a

enclosed and compressed in a mould, the material thenacquires a form which the indefinite and permanentelasticity of the vulcanized India-rubber causes it toretain.

This sulphurization of the India-rubber, instead of beingproduced with free sulphur, may be obtained with sulphurin a state of combination, as with the chloride of sulphur.If articles of common caoutchouc are immersed for oneor two minutes in chloride of sulphur, diluted in 50 or 00times its weight of sulplmret of carbon, they acquire byexposure to a proper temperature, all the properties ofvulcanized India-rubber. In commerce this caoutchoucis designated by the name of converted caoutchouc.

From the moment in which the vulcanization of India-rubber was known, all the inconveniences which ordinarycaoutchouc presented having disappeared, its employmentreceived an extension which is continually increasing,and each year sees new applications of this product spring

patent, which Mr. Goodyear afterwards demanded for the into use. The enumeration of the objects exhibited by

same subject. Mr. Thomas Hancock discovered that ahand of caoutchouc dipped into melted sulphur, and im-pregnated with this substance, without losing any of itsproperties, only required to be afterwards exposed to atemperature of about 300° Fahrenheit, to acquire pro-perties entirely novel, which were precisely those pos-sessed by the material employed by Mr. Goodyear for thewaterproof shoes.

This was, as may be seen, a new discovery of a factalready known—a novel solution of a problem which wasknown to be soluble, since it had been already solved.This discovery must, however, have presented its diffi-culties, and required also the fortuitous co-operation offavourable circumstances. For though analysis mighthave pointed out to Mr. Hancock the existence of sulphurin the productions of Mr. Goodyear , and have also dis-closed the presence of the salts of lead which the latterhad deemed indispensable, it could not in any mannergive him a clue to the discovery of the essential conditionof this transformation, that is to say, the employment ofa given temperature which alone was able to impart tothe mixture of caoutchouc and sulphur, the new propertieswhich appeared to make of it an entirely new body.

'Whatever may be the share of merit assigned to Mr. Goodyear and to Mr. Hancock in this important invention,the latter has not the less exclusive merit of having dis-covered that sulphur was the sole cause of the vulcaniza-tion of India-rubber. On seeing Mr. Charles Goodyear introducing the different salts of lead into the specificationof the patent which he subsequently took out, it is felt thatlie regarded their intervention as indispensable, while it isnow demonstrated that sulphur alone is sufficient; if othersubstances are employed in certain cases, it is not so muchto aid in the vulcanization of the caoutchouc as to add toits weight and solidity.

The vulcanization of India-rubber is an easy process.The India-rubber, softened by the heat evolved when it isbeing kneaded by strong machines, is mixed with the

the two manufacturers to whom this branch of manufac-ture is the most indebted, Mr. Goodyear , in America , andthe firm of Mackintosh, in Europe , will tend to show’ howwidely spread, and how varied the use of this materialhas already become.

§ 2. Council Medals.

1. Charles Mackintosh and Co., 73 Aldermanbury(7G, pp. 782, 783). The firm of Charles Mackintosh andCo. comprises the names of the men who in Europe havemade the most useful discoveries in the art of apply-ing caoutchouc to the most varied uses:—the late Mr.Mackintosh, who gave his own name to the waterproofgarments, and Mr. Thomas Hancock , whose share of meritin the discovery of the vulcanization of India-rubber wehave already mentioned. In going through the collectionof articles exhibited by this firm, the importance of theuses to which the substance is capable of being applied,especially since the discovery of the process of vulcaniza-tion, can be readily appreciated.

The kinds of fabrics with which the garments calledMackintoshes are manufactured have always remained thesame, but the garments themselves have acquired morelightness and less smell, and the substitution of vulcanizedfor common caoutchouc insures to them at the presentday a permanent suppleness.

The other sendees which these fabrics are called uponto perform, have been greatly multiplied. Their pricehaving become less, they are capable of being applied inlieu of tarpaulings for covering waggons, carriages, &c.The property which they possess of serving to containwater, and which had at first been made available for awell-known therapeutic use, has allowed of their beingmade into portable baths, which can be rolled up like anordinary cloth when not in use. The shoes exhibited byMessrs. Mackintosh and Co. are made with much care,and with a degree of elegance which shows that in Europe these articles are but little used except by the more opu-sulphur in the masticating apparatus already alluded to. I lent classes.

This mixture retains all the solubility of the caoutchouc j It is not only in the making of shoes that India-rubberin the different menstrua,—the property of becoming hard has been called in to supersede leather; the articles ex-at a low temperature as well as that of uniting with hibited by Messrs. Mackintosh and Co. show the use thatitself: but as soon as it is exposed to a temperature of 1 can be made of it to form pistons of pumps, and how300° Fahrenheit,—a temperature which would have j conical valves of India-rubber can be advantageouslysufficed to change the pure caoutchouc,—the matter ! substituted for leather or metal ones. Sheets of caout-

acquires new properties. It is no longer soluble in themenstrua which dissolve caoutchouc, but is impregnatedwith them by contact, and swells out like an animalmembrane that is moistened with water; resuming itsprimitive properties on being dried. It no longer becomesrigid when exposed to cold, nor does it unite with itself,and it resists without any alteration a temperature whichwould have sufficed to transform the ordinary caoutchoucinto a sticky matter; it is, in short, vulcanized India-rubber. This absence of the tendency to adhesion is sodecided, that in actual manufacture no use whatever canbe made of the shavings of tlie caoutchouc thus modified,

chouc of different colours, cither smooth or worked in re-lief, are brought in to supersede moulded ornaments in themanufacture of furniture, of ottomans, and in the bindingof books.

The use of vulcanized India-rubber to form the piston-valves in steam-engines on the screw principle, has greatlycontributed to the employment of these novel motivepowers, which are destined in some degree to effect achange in navigation by allowing steam to come in solelyas an auxiliary to the wind. The exhibition of Messrs.Mackintosh and Co. comprises a valve of this description,which after six months’ use has undergone so little alter-

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