Samuel Emmett Horne Jr. was a research scientist at B. F. Goodrich noted for first synthesizing cis-1,4-polyisoprene, the main polymer contained in natural tree rubber, using Ziegler catalysis. Earlier attempts to produce synthetic rubber from isoprene had been unsuccessful, but in 1955, Horne prepared 98 percent cis-1,4-polyisoprene via the stereospecific polymerization of isoprene. The product of this reaction differs from natural rubber only slightly. It contains a small amount of cis-1,2-polyisoprene, but it is indistinguishable from natural rubber in its physical properties.