The patent for his fever powder was taken out in 1747. It is on record that Johnson introduced him to John Newbery, a noted bookseller of the time, who had a shop at the corner of St. Paul’s Churchyard and Ludgate Hill. Newbery became the agent and part proprietor of the medicine. It is still owned and prepared by the direct descendants of John Newbery, who carry on business in Charterhouse Square. The specification of the patent directs to “Take antimony, calcine it with a continual protracted heat in a flat unglazed earthen vessel, adding to it from time to time a sufficient quantity of any animal oil and salt well dephlegmated; then boil it in melted nitre for a considerable time, and separate the powder from the nitre by dissolving it in water.” The doctor adds to his specification a process for a mercurial pill with antimony, made by amalgamating equal parts of martial regulus of antimony with “pure silver” (_sic_), adding a proportionable quantity of sal ammoniac, then distilling off the mercury and using it again. This performance was to be repeated nine or ten times, the mercury being at last dissolved in spirits of nitre (nitric acid), distilled to dryness, the caput mortuum calcined till it was of a golden colour, and this powder, after spirits of wine had been burnt upon it, was ready to be made into pills. Dr. James gave the moderate dose of the antimonial powder at 30 grains, and that of the mercurial at 1 grain. Paris says that James “usually combined his antimonial powder with some mercurial, and always followed it up with large doses of bark.” He suggests that the adjuncts largely accounted for the success of the medicine. The fever powder acquired great fame in James’s lifetime, and after his death imitations were numerous. One of these is of interest because of an advertisement against it written by Dr. Johnson. The man who ventured to imitate the genuine product was named Hawes, and he had once been in the employment of Dr. James. He professed that he had learned how to make the powder during his service, but Dr. James signed an affidavit against his pretensions a short time before his death. Later Hawes asserted that when the doctor made that affidavit he was not in the possession of his mental faculties. To this Francis Newbery replied by an advertisement quoting affidavits by many of James’s patients and acquaintances. A paragraph was appended which Newbery himself stated was written by Dr. Johnson, and as a section of literature rather foreign to the famous author, it seems worthy of reproduction. It ran thus:--