An account of an investigation of cream of tartar resulting in the isolation of tartaric acid was his first published paper. He next made an examination of fluor-spar from which resulted the separation of fluoric acid. From this on the suggestion of Bergmann he proceeded to a series of experiments on black oxide of manganese which besides showing the many important combinations of the metal led the chemist direct to his wonderful discoveries of oxygen, chlorine, and barytes. This work put him on the track of the observations set forth in his famous work on “Air and Fire.” In this he explained the composition of the atmosphere, which, he said, consisted of two gases, one of which he named “empyreal” or “fire-air,” the same as he had obtained from black oxide of manganese, and other substances. He realised and described with much acuteness the part this gas played in nature, and the rest of the book contained many remarkable observations which showed how nearly Scheele approached the new ideas which Lavoisier was to formulate only a few years later. “Air and Fire” was not issued till 1777, three years after Priestley had demonstrated the separate existence and characteristics of what he termed “dephlogisticated air.” But it is well known that the long delay of Scheele’s printer in completing his work was one of the disappointments of his life, and there is evidence that his discovery of oxygen was actually made in 1773, a year before Priestley had isolated the same element. Both of these great experimenters missed the full significance of their observations through the confusing influence of the phlogiston theory, which neither of them questioned, and which was so soon to be destroyed as the direct result of their labours. Among the other investigations which Scheele carried out were his proof that plumbago was a form of carbon, his invention of a new process for the manufacture of calomel, his discovery of lactic, malic, oxalic, citric, and gallic acids, of glycerin, and his exposition of the chemical process which yielded Prussian blue, with his incidental isolation of prussic acid, a substance which he described minutely though he gives no hint whatever to show that he knew anything of its poisonous nature. The subjects mentioned by no means exhaust the mere titles of the work which Scheele accomplished; they are only the more popular of his results. The value of his scientific accomplishments was appreciated in his lifetime, but not fully until the advance of chemistry set them out in their true perspective. Then it was realised how completely and accurately he had finished the many inquiries which he had taken in hand. A PHARMACEUTICAL PANTHEON.