This spiral cut draws off the milk as completely and quickly as possible without harming the tree. The man is pulling off a strip of coagulated rubber that clogs it.] [Illustration: IN MAKING GARDEN HOSE THE RUBBER IS FORMED INTO A TUBE BY THE MACHINE ON THE RIGHT AND COILED ON THE TABLE TO THE LEFT] The Peruvian natives had used caoutchouc for water-proof clothing, shoes, bottles and syringes, but Europe was slow to take it up, for the stuff was too sticky and smelled too bad in hot weather to become fashionable in fastidious circles. In 1825 Mackintosh made his name immortal by putting a layer of rubber between two cloths. A German chemist, Ludersdorf, discovered in 1832 that the gum could be hardened by treating it with sulfur dissolved in turpentine. But it was left to a Yankee inventor, Charles Goodyear, of Connecticut, to work out a practical solution of the problem. A friend of his, Hayward, told him that it had been revealed to him in a dream that sulfur would harden rubber, but unfortunately the angel or defunct chemist who inspired the vision failed to reveal the details of the process. So Hayward sold out his dream to Goodyear, who spent all his own money and all he could borrow from his friends trying to convert it into a reality. He worked for ten years on the problem before the "lucky accident" came to him. One day in 1839 he happened to drop on the hot stove of the kitchen that he used as a laboratory a mixture of caoutchouc and sulfur. To his surprise he saw the two substances fuse together into something new. Instead of the soft, tacky gum and the yellow, brittle brimstone he had the tough, stable, elastic solid that has done so much since to make our footing and wheeling safe, swift and noiseless. The gumshoes or galoshes that he was then enabled to make still go by the name of "rubbers" in this country, although we do not use them for pencil erasers. Goodyear found that he could vary this "vulcanized rubber" at will. By adding a little more sulfur he got a hard substance which, however, could be softened by heat so as to be molded into any form wanted. Out of this "hard rubber" "vulcanite" or "ebonite" were made combs, hairpins, penholders and the like, and it has not yet been superseded for some purposes by any of its recent rivals, the synthetic resins. The new form of rubber made by the Germans, methyl rubber, is said to be a superior substitute for the hard variety but not satisfactory for the soft. The electrical resistance of the synthetic product is 20 per cent, higher than the natural, so it is excellent for insulation, but it is inferior in elasticity. In the latter part of the war the methyl rubber was manufactured at the rate of 165 tons a month.