The original of the Pulv. Rhei Co. of the British Pharmacopœia was a prescription very frequently given by Dr. James Gregory, of Edinburgh, in his time the most famous physician of that city. He died in 1822. This Dr. Gregory was Professor of Medicine in Edinburgh University, as his father was before him. His son became Professor of Chemistry in the same university. Direct ancestors of these Gregorys had been professors of history, astronomy, and mathematics at Edinburgh, Oxford, and St. Andrews. Within a century and a half the family furnished sixteen professors to British universities, and it is a curious coincidence that the Church of Rome likewise counts sixteen Gregorys among its Popes. [Illustration: DR. JAMES GREGORY. Professor of Medicine in Edinburgh University, 1790–1821. Author of _Conspectus Medicinæ Theoreticæ_ and inventor of Gregory’s Powder. (From a mezzotint, “after Raeburn,” in the British Museum.)] It does not appear that the Gregory of powder fame ever published any special recommendation of his compound. He wrote a “Conspectus Medicinæ Theoreticæ” (1788) but the formula for his powder does not appear in that book. Annexed is a facsimile of one of Dr. Gregory’s prescriptions for his powder. He gave this prescription very frequently, but occasionally varied the proportion of the ingredients. [Illustration: FACSIMILE OF DR. GREGORY’S PRESCRIPTION.] HIERA PICRA. A medicine with this familiar name can be bought in any chemist’s shop in Europe or America to-day, just as it could in Damascus a thousand, or in Rome and Alexandria two thousand years ago. Probably it is the oldest pharmaceutical compound still in existence. Through all the centuries the hiera picra known to the public has been a preparation of aloes. The adjuncts have varied but aloes has always been the essential ingredient, with one celebrated exception. The origin of this medicine is variously stated by medical historians. The common theory is that it first acquired fame as a remedy employed in one or other of the Æsculapian Temples. This may have been the case, but there is no evidence in support of the suggestion. It is possible that the name may have suggested the notion, and the drug vendors of Rome would certainly not discourage the fancy. Before the time of Julius Cæsar there were no physicians in Rome. Greek practitioners of the minor arts of medicine, such as bath-keepers, corn-cutters, tooth-drawers, and herbalists crowded into the great city as it became rich, and opened shops which were known as “medicinas,” and it is likely that most of these brought with them a more or less famous “hiera,” claiming that it had been compounded from a genuine Temple formula.