A HISTORY OF SCIENCE 



ments along the lines of definite theories from the be- 

 ginning, the results obtained being the logical outcome 

 of a predetermined plan. 



Scheele was the son of a merchant of Stralsund, 

 Pomerania, which then belonged to Sweden. As a boy 

 in school he showed so little aptitude for the study of 

 languages that he was apprenticed to an apothecary at 

 the age of fourteen. In this work he became at once 

 greatly interested, and, when not attending to his duties 

 in the dispensary, he was busy day and night making 

 experiments or studying books on chemistry. In 1775, 

 still employed as an apothecary, he moved to Stock- 

 holm, and soon after he sent to Bergman, the leading 

 chemist of Sweden, his first discovery that of tartaric 

 acid, which he had isolated from cream of tartar. 

 This was the beginning of his career of discovery, and 

 from that time on until his death he sent forth accounts 

 of new discoveries almost uninterruptedly. Mean- 

 while he was performing the duties of an ordinary 

 apothecary, and struggling against poverty. His 

 treatise upon Air and Fire appeared in 1777. In this 

 remarkable book he tells of his discovery of oxygen 

 "empyreal" or "fire-air," as he calls it which he 

 seems to have made independently and without ever 

 having heard of the previous discovery by Priestley. 

 In this book, also, he shows that air is composed chiefly 

 of oxygen and nitrogen gas. 



Early in his experimental career Scheele undertook 

 the solution of the composition of black oxide of man- 

 ganese, a substance that had long puzzled the chemists. 

 He not only succeeded in this, but incidentally in the 

 course of this series of experiments he discovered oxy- 



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