JOSEPH FRIES TLB Y. 175 



of the lungs; and that the florid red colour of arterial blood 

 •.vas communicated by the contact oif air through the containing 

 vessels. 



But it is impossible to enumerate here all Dr. Priestley's 

 discoveries; they are too numerous. "How many invisible 

 fluids," says one writer, "whose existence evaded the sagacity 

 of foregoing ages, has he made known to us ! The very air we 

 breathe he has taught us to analyse and examine, and to im- 

 prove a substance so little known that even the precise effect of 

 respiration was an enigma until he explained it. He first made 

 known to us the proper food of vegetables, and in what the 

 difference between these and animal substances consists. To 

 him pharmacy is indebted for the method of making artificial 

 mineral waters, as well as for a shorter method of preparing 

 other medicines ; metallurgy, for more powerful and cheap sol- 

 vents ; and chemistry for such a variety of discoveries as it 

 would be tedious to recite — discoveries which new-modelled 

 that science, and drew to it and to this country the attention of 

 Europe." 



Upon the life of Dr. Priestley, apart from science, we shall 

 not touch. He died in America, on the 6th of February, 1S04. 



When the Council of the Royal Society honoured Dr. Priest- 

 ley by the presentation to him of Sir Godfrey Copley's medal, 

 on the 30th of November, 1733, Sir John Pringle, who was 

 tlien president, delivered on the occasion an elaborate discourse 

 on the different kinds of air, in which, after expatiating upon 

 the discoveries of his predecessors, he pointed out the particular 

 merits of Priestley's investigations. In allusion to the purifica- 

 tion of a tainted atmosphere by the growth of plants, the 

 president thus eloquently and piously expressed himself: — 



" From these discoveries we are assured that no vegetable 



