386 On phlogiston. 



Wifliing the continuance of your fuccefs In the feveral 

 vahiable inquiries in which you are engaged, and which 

 has aheady gained you much deferved reputation, I am, 



Dear Sir, 



Yours fincerely, 



J. PRIESTLEY. 



Northumberlatid, Aug. 8, 1798. 



In all my computations of the quantity of pure air con- 

 tained in a portion of atmofpherical air, I have of late years 

 followed the example of others in agitating the mixture of 

 nitrous air with it. But 1 have lately obferved that this 

 agitation only promotes the abforption of part of the ni- 

 trous air by the water, and not the imion of the two kinds 

 of air, as has generally been fuppofed. Confequently, 

 my original method of mixing them "without agitation is 

 preferable to it, and this gives the proportion of pure air 

 in atmofpherical air more agreeable to the truth, viz. about 

 S7 parts in 100 ; whereas, if the computation be made af- 

 ter the agitation of equal quantities of the two kinds of 

 air, the proportion will be about 2,3 iri lOO- After agita- 

 tion, one meafure of atmofpherical air and one of nitrous 

 will generally occupy the fpace of i.oi or 1.02 meafures; 

 when without agitation, it will be about 1.25; and this 

 alfo the refult of firing together an equal quantity of in- 

 flammable and atmofpherical air. 



J. PRIESTLEY. 



