K 



4 



Dr. H^lyoke's Estimde of the Excess of. Heat and' Cold. 



in ^vliich Drs. Priestley and Ingenousz conclucted tlieir's ; and 

 I constantly found air produced from the leaves of juniper and 

 pine (the only ones I have yet made trial of) in the same 

 manner, as from other leaves in sumiper.* But it 

 be observed, that this manner of experimenting cannot be 

 prosecuted, when the water is colder than 32 'Regrees by 

 Fahrenheit's thermometer, as the water would then be con- 



ought to 



verted into 



but it appears reasonable 



suppose, if as 



much air is produced in these -experiments, when the ther- 

 mometer is at 34° or 35°, as when it mounts to 70° or 80°, 

 that the weather, though much colder, would make no 

 material alteration in the result. This fact then is not 



to b 



e 



adered as 



fully established (though 



I believe 



whenever proper and deci 



periments are made 



be confirmed) but as in a good degree probabl 



This being allowed, what a fund of 



pur 



dephlogisticated 



have we here in America, beyond what Europe at pr 



possesses 



There are no doubt evergreens of various kinds 



scattered all over Europe; yet it cannot be supposed, that 

 the quantities bear any proportion to those, which once 



i; especially in the southern and middle regi- 

 ons of that continent; and as to Scandinavia, where 



;hed ther 



«? 



I sup 



pose 



'Pportunity 



greens, as I could wish, or as I promise myself I may have ; but, from Tvhat I have ex- 



? 



common 



should yield four barrels of pure dephlogistleated air in one clear fair day ; to .vhich, if 

 ^e add that as much phlogiston Is absorbed in the same time, as an equal quantity of 

 common almcpherick air contains; we may readily imagine, that, In a country abound- 

 ins with trees of this kind, the atmosphere must be much more dephlogisticated in 

 -mter, than m a country, where evergreens are rarely met with. 



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