ELASTIC BANDS.) The India-rubber manufacture is one of the most important branches of art, rivalling that of some of the older textile fabrics. In this country it has made pro digious strides within a few years. The India-rubber shoes are made by women on the Amazon, by dipping the lasts, sent there from this country, into the juice of the tree, and then holding the last over a palm fire to dry it off ; the last is then dipped again in the milk, and again dried, and so repeated till it ac quires the due thickness ; this is com pleted in five minutes. Two gallons of milk suffice for ten pair of shoes. The shoes are then sun-dried, and next day stamped with pointed sticks, or the spines of the palm. The shoe is then cut from the last, and is 'ready for packing.
From its softness and impermeability it is made into boogies, catheters,. gas tubes, and bottles. Its use as a varnish is almost endless, dissolved in any of the solvents previously mentioned, or in bi sulphuret of carbon, without the use of heat. This constitutes Parker's patent solvent. Chloroform is an excellent sol vent, but it is too costly. By digesting the rubber in solution of carbonate of soda, or water of ammonia, previously, it dissolves more readily.
India-rubber is now rarely used alone in manufacture, but is previously mixed with other matters, which do not to any great extent affect its elasticity, or its waterproof properties. By mixing in sulphur when the rubber is in a semi fluid condition it is said to be vulcanized, hut as this gives en unpleasant odor to the fabric, various improvements have been made to obviate it. Patents have been taken out to use the hyposulphites, either alone or combined with sulphites and sulphurets. The sulphuret of anti mony has been used with advantage. In another patent the rubber after being steamed and dried is thionized, which consists in submitting the mass to the action of the fumes of sulphur or sul phurous acid, by which the sulphur be. comes incorporated. For manufacture the rubber is now never prepared by so lution in turpentine or other menstrunre but it is reduced into a pasty mass b3 heavy grinding, and then passed throng a succession of rollers until it is brought into sheets of uniform texture.