PROCEEDINGS OF THE REGENTS. 103 



for the year 1859, and a general statement of the finances, which 

 were read and referred to the Executive Committee. 



The Secretary read the following letter from the Duke of North- 

 umberland, and presented the books to which it refers: 



Northumberland House, July 4, 1859. 



Sir: Permit me to present to the Smithsonian Institution some 

 books which I have had privately printed as materials for the history 

 of the county of Northumberland. There is a survey of the Roman 

 wall which was built across the north of England; coins of the Roman 

 families, some of which were found in this country; and an account 

 of some ancient castles which have historical interest. 



I again beg to express my thanks to the members of the Smith- 

 sonian Institution for the valuable publications which they have had 

 the kindness to send me. 



I am, sir, your obedient servant. 



NORTHUMBERLAND. 



The Secretary exhibited a burning lens and a condensing air- 

 pump, which had been presented to the Institution by J. R. Priest- 

 ley, esq., of Northumberland, Pa., a grandson of the celebrated Dr. 

 Priestley, and made the following remarks: 



This lens is undoubtedly connected with the history of one of the 

 most important chemical discoveries of the latter part of the last 

 century. Dr. Priestley, who has been styled the father of pneumatic 

 chemistry, made a series of experiments on different kinds of air, 

 which greatly extended the science of chemistry, and has been of 

 material importance in the improvement of various practical arts. 



"At the time of my first publication," [says Dr. Priestley,]* "I 

 was not possessed of a burning lens of any considerable force, and for 

 want of one I could not possibly make many of the experiments 

 which I had projected, and which in theory appeared very promising. 

 But having afterwards procured a lens of twelve inches diameter and 

 twenty inches focal distance, I proceeded with great alacrity to ex- 

 amine by the help of it what kind of air a great variety of substances, 

 natural and factitious, would yield, putting them into glass vessels, 

 which I filled with quicksilver, and kept them inverted in a basin of 

 the same. With this apparatus, after a variety of other experi- 

 ments, on the 1st of August, 1774, I endeavored to extract air from 

 mercurius calcined us per se, and I presently found that by means of 

 this lens air was expelled from it very readily. Having got three or 

 four times as much [air] as the bulk of my materials, I admitted water 

 to it, and found that it was not imbibed by it. But what surprised 

 me more than I can well express was, that a candle burned in this 

 air with a remarkably vigorous flame." 



The gas thus discovered, to which he gave the name of " dephlo- 

 gisticated air," was what is now known as oxygen. 



a Experiments and observations on different kinds of air, &c, by Jos. Priestly : vol. ii> 

 pp. 106-112. Birmingham, 1790. 



