Thermomicroscopic characteristics of a wide range of narcotics were established using the Kofler block to assist in the identification of these materials. Melting behavior and nature of crystals are described, and data are presented for eutectic temperature (with suitable compounds selected from azabenzene, benzil, acetanilide phenacetin, benzanilide, ephedrine, dicyandiamide, saccharin, phenolphthalein, 4-sulfamoylbenzaic acid and UV absorption melt refractive index, for the following materials: acetyldihydrocodeinone.HCl, ethylmorphine base, ethyimorphine.HCl, allylprodine.HCl, alphaprodine.HCl. amphetamine sulfate, benzoylecgonine, benzyl-morphine base, cocaine base, cocaine HCl, cocaine nitrate, codeine base, codeine.HCl, codeine phosphate, dexamphetamine sulfate, dextromethorphan base, dextromethorphan, HBr, dextromoramide base, dextromoramide tartrate, diacetylmorphine base, diacetylmorphine.HCl, dihydrocodeine base, dihydrocodeine bitartrate, dibydrocodeine.HCl, diphenoxylate.HCl, (-)-ecgonine, fentanyl base, fentanyl citrate, hydrocodone base, hydrocodone bitartrate, hydrocodone.HCl, hydromorphonebase, hydromorphone. HCl, ketobemidone base, ketobemidone.HCl, levomethorphan base, 1evomethorphan.HBr, levorphanol tartrate, lysergide tartrate, mescaline sulfate, methadone base, methadone.HCl, methadone intermediate, rec. and (+)-L-methamphetamine.HCl, methylphenidate HCl, morphine base, morphine HCl, morphine N-oxide, morphine sulfate, nalorphine base, nalorphine.HCl, nicocodine base, nicocodine.HCl, nicomorphine base, nicomorphine.HCl, normethadone.HCl, norpipanone base, norpipanone.HCl, oxycodone base, oxycodone.HCl, pethidine,HCl, pethidine intermediates A and G. phenadoxone,HCl, phenmetrazine.HCl, phenoperidine base, phenoperidine,HCl, pholcodine, L-polamidone base, L-polamidone. HCl, psilocine, thebaine base and thebaine,HCl.