Page:The New International Encyclopædia 1st ed. v. 17.djvu/363

* RUBBER. 331 RUBEFACIENTS. ilogree. Reduced to the temporal uic of fieeziiig water (32° F. ), it hardens, and in jjreater part, if not entirely, loses its olastieity, but does not become brittle. When heated, as by placing in boiling water, it softens, and becomes very much more elastic than at ordinary temperatures, though it does not in any degree dissolve in the water. If suddenly stretclieil to seven or eight times its original length, it becomes warm; and sulphur used and heat applied, if kept in this outstretched form for several A few grner..l classes of vuleani/ weeks, it appears to lose, in great part, its elastic goods are: ( 1 dered soajjstone, talcum, or ulln'r powder it fre<'ly used. The rubber is heated in a cast-iron cylin- drical oTen with one end littc'd as a door. Goodyear invi^nted two dilferent kind* of rub- ber, the j)liable .so// nilihrr and Imril ruhhir, or ebonite, which is used for making a great variety of utensils and fancy articles. The chief dill'erence between the two ix in the nniount of properties, and in this condition is readily cut into those thin threads which are used in the elliptic ]nit in gloves, boiniets, etc., and tlic elas- ticity of which is readily renewed by the a|)])lica- tion of gentle heat. Elastic thread is now pre- pared with vulcanized rubber. Connnereial rub- ber is insoluble in water and alcohol, is not acted upon b.y alkalies or acids, except when the latter are concentrated, and heat is applied; but is soluble in ether, chloroform, bisulphide of carbon, naphtha, petroleum, benzol, and the essential oils of turpentine, lavender, and sassafras. JIany other essential and fixed oils, when heated with caoutchouc, cause it to soften, and jiroduce thick glutinous compounds, especially linseed oil. When heated to 248° F., caoutchouc fuses: and at 000° it is volatilized, at the same time undergoing decomposition, and yields a liquid called ctiout- choucine or caoiitchisiiif. possessing great solvent powers over rubber and other substances. There are some useful applications of india-rub- ber in the liquid or semi-liquid state, which it is worth while to note; thus, when melted at 308° F., and mixed with half its weight of slaked lime, it forms a useful cement, which can be easily loosened, but it will dry and harden if red lead is added. A very tenacious glue is formed by heating rubber, coal tar, and shellac together. It forms an ingredient in some special kinds of varnishes, and it also improves the lubricating qualities of mineral oils, when a small quantity is dissolved in them. Pure india-rubber is now- used only to a limited extent in the arts, but it is applied in the vulcanized state to an almost end- less variety of purposes. Process of JI.xif.^ctire. The first step in the manufacture of crude rubber is one of thor- ough cleansing. The rubber is allowed to remain in steam-heated water for about twenty-four hours, after which it is cut up and the larger impurities removed by hand. It is then washed by passing between tAvo heavy corrugated iron rollers. A stream of water flows o'er the rubber from a pipe directly at the point of contact with the rollers, and the combined action of the rollers and water removes all foreign substances adher- ing to the rubber. The rubber is next placed in drying chambers and after thorough drying is stored in a dark, dry room until needed. Methods of vulcanizing vary with the article to be ATilcanized, but in general the purilied and masticated gum is thoroughly kneaded with the requisite amount of sulphur and cut and shaped before heat is applied. In case the goods are to be made of a rubber cloth, as in the case of shoes (q.v.). the rul)ber is spread on its backing with heated iron rollers and the goods made up before they are vulcanized. The material is not sewed, but held together by some solvent, as turpentine, which makes the edges adhere. To prevent ad- hesion of the articles during the vulcanizing pro- cess, they are very carefully packed, and pow- VOL. X II.— 22. ized rubber Footwear and other wiiteriiroof clothing; (2) mechanical goods, including iim-, belting, tires, etc.; (3) electrical and <illier seientitie artdianees; (4) medical aiul surgiial apparatus and allied articles; (.".) hard rubIxT goods; ((i) licpiid or semi-liquid materials, u» varnishes and cements. This classilicution is ob- viously imperfect, but it will serve to suggest tho enormous variety of commercial products of which india-rubber is an essential eonstitnent. In eleetrical appliances rubber is almost indis- pensable as an msulating material. Ki ntly thi* field has been extended by substituting it for gutta-percha in insulating submarine cables. (.See C. i.KS. Electric.) During the last deeade of the nineteenth century the value of the crude rubl)er imported into the United States increased from .$18,020,804 in 18!)1 to $31.:-.r).-).483 in I'.KM). This increase of value was caused not only by the adilitional amount consumed, but also by the rise in price, which in 1000 was 63 cents |K'r pound. ilh the increase in cost of the raw product, olil rublier is more and more used for re-mannfacture. HlliLlocEAPiiY. Consult: Urannt. hidid-lluU ber, Guita-I'enha, and liahita (Philadelphia. 18S3) ; Pearson, Crude Rubber and Conipoumlinij inflrcdientu (New York, 180!)) ; Nissenson, India' Rubber: Its Manufacture and Use ( ib., 1801); .lohnson, article on '■-•Vmerican Rubber Manufac- tures," in Our Hundred Years of Amerieiin Com- meree (N<'W York, 180.5); and the section on '■Rubber noots and Shoes." Twelfth Census of the U)iilrd States (Washington, 1002). RUBBLE. See Masonry. RUBEFACIENTS (from Lat. ruhefacicns, ])r(s. part, of rubifncere, to nnike red. from rubcre, to be red, from ruber, red 4- faeere. to make). Substances employed in medicine for the purpose of stinuilating and reddening the skin over the part to which they are applied. Thi'se agents have the power of relieving congestion, pain, spasm, or excessive irritability of superfi- cial ])arts or deep-seated organs. All substances which after a certain period act as blisters may be made to act as rubefacients if their time of action is shortened. Anmng the most conmionly used rubefacients may be menti(mcd: Heat in the form of hot baths! cloths .soaked in very hot water, iioultices. bottles filled with hot water, and heated solids such as bricks, sanil bags, etc. Mustard, either in the shape of mustard leaves (siieets of paper coated with mustard and applieil moist) or thick poultices, comiioscd of various proportions of mustard, mixed with Hour or meal and cold water. (See Pofl-TICE.) Oil of 7'iir;«-ii- tine, applied by means of flannels wrung out of hot water and' sprinkled with the oil — the tur- pentine stupe, or as a liniment. Ammonia in the form of a liniment (volatile liniment). Cap- sicum (cayenne ))eppcr) in the form of n poul- tice or alcoholic lotion is niucli used in the We«t Indies. Cantharidin (Spanish fly) is properly