AbstractSemicarbazide is the common but incorrect name for carbamic acid hydrazide:The atom are numbered as indicated.Semicarbazide reacts readily with aldehydes and ketones, and this reaction is often used to separate those compounds from mixtures or to identify them. The purpose of the investigation here described was the preparation of several methylated semicarbazides and the investigation of the possibility of using these substances for the identification of aldehydes and ketones.The following substances are discussed:A2‐methylsemicarbazide.B4‐methylsemicarbazide.C2,4‐dimethylsemicarbazide.D4,4‐dimethylsemica