SKETCH OF THE LIFE OF DR. PRIESTLEY, 485 



prosecuting his experiments. Lord Shelbiirne allowed him |200 a year 

 extra to assist in this object. This arrangement continued seven years, 

 when his lordship seems to have got tired of it, and a separation re- 

 sulted, although it was entirely amicable. Some years afterward his 

 lordship proposed to renew the relation, but Priestley declined. 



Dr. Priestley then took up his residence in Birmingham, where he 

 assumed charge of a congregation, and continued for several years en- 

 gaged in his theological and scientific investigations. His apparatus, 

 by the liberality of his friends, had become excellent, and his income 

 was now so good that he could prosecute his researches with freedom. 

 lie here continued his Theological Repository, and published a variety 

 of tracts on his peculiar opinions in religion and upon the history of 

 the primitive Church. 



Dr. Priestley had commenced the investigation of gases while liv- 

 ing at Leeds, and had there prepared the first volume of his researches 

 upon air. These researches were continued during his residence with 

 Lord Shelburne, and the last three volumes of his experiments on air 

 were printed after he was settled in Birmingham ; and while here he 

 also contributed various papers to the Transactions of the Royal Society. 

 No man ever entered upon any undertaking with less apparent means 

 of success than Dr. Priestley did on the investigation of airs. He was 

 unacquainted with chemistry, excepting that he had some years before 

 attended an elementary course delivered by Mr. Turner, of Liverpool. 

 He had no apparatus, and knew nothing of chemical experimenting, 

 and was without means to carry on investigations. These adverse con- 

 ditions may, however, have been serviceable as he entered upon a new 

 field of chemistry, where apparatus had to be invented, and the ar- 

 rangement devised by him for the manipulation of gases is unsur- 

 passed in simplicity, and has been in use ever since. The first of his 

 discoveries was nitrous gas, the properties of which he ascertained 

 with much sagacity, and applied it to the analysis of air. It contrib- 

 uted very much to all subsequent investigations in pneumatic chemis- 

 try, and may be said to have led to our present knowledge of the consti- 

 tution of the atmosphere. It was while living with Lord Shelburne that 

 he made his grand discovery of oxygen gas, and established the prop- 

 erties of that remarkable body. He showed its power of supporting 

 combustion better, and animal life longer, than the same volume of com- 

 mon air. Lavoisier laid claim to the discovery, but Dr. Priestley informs 

 us that he prepared this gas in M. Lavoisier's house in Paris, and showed 

 him the method of procuring it in the year 1774, which is a consider- 

 able time before the date assigned by Lavoisier for his pretended dis- 

 covery. Scheele, however, the Swedish chemist, actually obtained 

 this gas without any previous knowledge of what Priestley had done, 

 but the book containing this discovery was not published till three 

 years after Priestley's process became known to the public. 



Dr. Priestley first made known sulphurous acid, fluosilicic acid, and 



