The author has extracted ptomaïnes from the urine of patients suffering from certain infectious diseases by the following method :— (a) A considerable quantity of urine was made alkaline by the addition of a solution of sodium carbonate, and then agitated with half its volume of ether, (b) The ethereal solution (after standing) was filtered, and agitated with a solution of tartaric acid. The tartaric acid combines with any ptomaïnes present, forming soluble tartrates ; and the solution of tartrates forms the lower layer of the liquid mass, (c) The tartaric acid solution (after being separated from the ether) was also made alkaline by the addition of sodium carbonate, and was once more agitated with half its volume of ether. (d) The ethereal solution (after standing) was separated, and the ether allowed to evaporate spontaneously, (e) The residue (after drying over sulphuric acid) was treated with water, an excess of pure calcium hydroxide added, and the mixture evaporated on a water-bath. The residue so obtained was treated with chloroform and filtered. The filtrate (after evaporation) yielded the ptomaïne in an isolated and a crystalline condition.