Page:Popular Science Monthly Volume 42.djvu/708

688 Air and Fire, written in 1775, is the most remarkable one, were collected and published in 1793. His contributions to the Academy of Sciences in Stockholm have been issued in an English translation by Thomas Beddoes. Prof, von Nordenskjöld prepared for the recent celebration a complete collection of Scheele's scientific notes and of his letters to eminent contemporaries, which has just been issued in a Swedish and a German edition. This voluminous and splendidly prepared work is an important supplement to all former publications of Scheele's writings and the several historical sketches of his life and labors, and is of paramount value to every student of the history of chemistry. From among the many interesting new facts brought to light in it are: Scheele obtained and recognized oxygen (fire-air) as early as in 1765 in connection with his researches of nitrous acid. Before the year 1771 he obtained oxygen in various ways by heating silver and mercury carbonates, silver and gold oxides, alkaline nitrates, arsenic acid, and black oxide of manganese. He therefore obtained and recognized oxygen several years before Priestley's independent discovery of it. At about the same time he obtained and recognized nitrogen, hydrogen sulphide, hydrogen chloride, ammonia, and nitrogen dioxide gases. He knew before 1772 the color reaction of the blowpipe flame with potassium and sodium compounds, and made use of them, as also the methods of separating iron from manganese by means of acetic acid. He was also familiar with the transformation of insoluble silicates into soluble ones by fusing them with alkalies.

Scheele's letters and laboratory notes just published by Prof, von Nordenskjöld bear evidence of his advanced knowledge in most departments of chemistry, and of the unusually large number of his researches, observations, and exact discernment in his numberless experiments and deductions. The book abounds in novel views and facts relative to the interesting period of the transformation from the phlogiston epoch to the modern doctrines of chemical philosophy and application. It furthermore bears ample evidence of the fundamental influence and part which Scheele's labors and ingenuity have had in preparing and clearing the domain of chemistry for Lavoisier's subsequent theoretical consummation.