Page:Chronicles of pharmacy (Volume 1).djvu/286

 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.

The School of Pharmacy of Paris, built in 1880, honours a number of pharmacists of historic fame by placing a series of medallions on the façade of the