In 1745 when a new London Pharmacopœia was nearly ready for issue, a scholarly exposure of the absurdity of the compound which still occupied space in that and in all other official formularies, along with its equally egregious companion, Theriaca, was published by Dr. William Heberden, a leading physician of the day, and though it was too late to cause the deletion of the formulas in the edition of 1746, that was the last time they appeared in the Pharmacopœia, though they had been given in all the issues of that work from 1618 onwards. No better completion of the history of this preparation can be given than that which Dr. Heberden wrote 165 years ago. The King of Pontus, he assumed, like many other ancient royalties, was pleased to affect special skill in the production of medicines, and it is not surprising that his courtiers should have flattered him on this accomplishment. Thus the opinion prevailed among his enemies as well as in his own kingdom that his achievements in pharmacy approached the miraculous. His conqueror, Pompey, apparently shared the popular belief, and took uncommon care in the ransack of his effects, after Mithridates had been compelled to fly from the field, to secure for himself his medical writings. According to Quintus Serenus Samonicus, however, the Roman general was amused at his own credulity when, instead of a vast and precious arcana he found himself in possession of only a few trifling and worthless receipts. [Illustration: DR. WILLIAM HEBERDEN. 1710-1801. (From a mezzotint in the British Museum.) ] The anticipation of some marvellous secrets was so universal, and the Roman publishers so well disposed to cater for this, that it is not to be wondered at that a confection of Mithridates and stories of its miraculous power soon found their way into literature. A pompous formula, which it was professed had been discovered among the papers of Mithridates captured by Pompey came to be known under the title of Antidotum Mithridatium. It is noteworthy that Plutarch, who in his life of Pompey mentions that certain love letters and documents helping to interpret dreams were among these papers, makes no allusion to the medical recipe; while Samonicus states explicitly that, notwithstanding the many formulæ which had got into circulation pretending to be that of the genuine confection, the only one found in the cabinet of Mithridates was a trivial one for a compound of 20 leaves of rue, 1 grain of salt, 2 nuts, and 2 dried figs. So that, Dr. Heberden remarks, the King of Pontus may have been as much a stranger to the medicine to which his name was attached as many eminent physicians of this day are to medicines associated with their names.