Isoln by Brieger in 1888 from decomposing horsemeat; described as a product of putrefaction: I. Greenwald, J. Am. Chem. Soc. 41, 1109 (1919). Prepn: E. Erlenmeyer, Ber. 3, 896 (1870); E. A. Werner, J. Bell, J. Chem. Soc. 121, 1790 (1922); R. Phillips, H. T. Clarke, J. Am. Chem. Soc. 45, 1755 (1923); E. Philippi, K. Morsch, Ber. 60, 2120 (1927); T. L. Davis, E. N. Rosenquist, J. Am. Chem. Soc. 59, 2112 (1937). Toxicity data: Alles, J. Pharmacol. Exp. Ther. 28, 251 (1926); Fühner, Arch. Exp. Pathol. Pharmakol. 166, 437 (1932).