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No. III. 



Experiments relating to the Abforption of Air by Water. 

 By Dr. Joseph Priestley. 



IN my attempts to afcertain the proportion 

 between the phlogifticated and dephlogifti- 

 cated air that conftitutes the atmofphere, of which I 

 gave an account in the fourth volume of the Philo- 

 Jhphical Tranf anions of Philadelphia^ I made one of 

 my compvitations from the diminution of atmofpherical 

 air by a mixture of nitrous air, confidering one-third 

 of the quantity that difappeared to have been dephlo- 

 gifticated air ; and fince by long {landing this diminu- 

 tion proceeded much fiirthcr than at the firft, I con- 

 cluded that this farther diminution was occafioned by 

 the fame caufe as the firfl, only operating more flowly, 

 and confequently that there was in the atmofphere 

 much more dephlogifticated air than had been fuppofed. 

 Since that time, however, I have found that this fe- 

 cond abforption has fome different caufe, though 1 have 

 not been able to difcover it ; becaufe if fufficient time 

 be allowed, all kinds of air without diftindlion will 

 be wholly abforbed by the water with which they are 

 confined. 



As this obfervation was made in confequence of re- 

 fuming the experiments of which an account was given 

 before, viz. on mixtures of nitrous and common air, I 

 fhall firft recite thofe which were made with this mix- 

 ture. In the beginning of May 1798 1 fet by a mix- 

 ture of this kind, then occupying the fpace of 1.25, and 

 obferved that, without agitation, the diminution kept 

 proceeding (though it was fometimes ftationaiy) till on 

 the iSth of 0<^ober, I examined it, and found it to be 



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