The original formula for this plaster was compiled by Tiberius Claudius Menecrates, who lived in the reign of the Emperor Tiberius, and was probably his physician. In a Greek inscription discovered at Rome he is described as Physician of the Cæsars, probably Tiberius, Caligula, and Claudius, for he died in the reign of the last named. He wrote a great work on remedies entitled “Autocrator Hologrammatos,” literally, “The Emperor, whose words are written in full.” Probably the book was dedicated to one of the Emperors, and thus got its first title. The second intimates that the recipes are written out in full so that any reader could understand them; suggesting that the other physicians who wrote such books were in the habit of employing abbreviations. The formula for diachylon and the directions for compounding it were put into iambic verses by Servilius Damocrates, who lived a little later than Menecrates, and it is in this form that they have been preserved by Galen. Briefly the composition was to incorporate 1 lb. each of the mucilages of fœnugreek, of linseed, and of marshmallow root with 3 lb. of old oil, and 1½ lb. of golden litharge. The mucilages were made by boiling the seeds and root in water. Damocrates concludes his poem with the line (I quote from the Latin translation): “Vocabat ipsum non absurde Dia Chylon.” Mesué wrote at length about this plaster, and devised a much more complicated formula which was named Diachylum Magnum. It contained, besides the mucilages already named, others made from raisins and figs, juices of orris, squill, and dill, œsypus (sheep wool fat), turpentine, rosin, and wax. Subsequent authors also devoted their talents to the further improvement of this famous preparation. Diachylon meant a preparation of juices, and this plaster received the name of plaster of the mucilages in many pharmacopœias. In 1746 the London College, having dismissed the adjuncts, altered the name of the simple plaster to Emplastrum Commune, but the old term has refused to die. An Emplastrum Commune cum Gummi was also prescribed. This contained galbanum, thus, and turpentine combined with the Emplastrum Commune.