26S EXPERIMENTS and OBSERVATIONS 



viz. in Water between Market and Arch Streets ; in 

 Spruce near Fourth Street ; in Chefnut near Fifth ; and, in 

 Market between Second and Third Streets. Each of 

 thefe airs gave nearly the fame refult, and generally agreed 

 with that of the air of the yard of my lodging : None 

 of the experiments fliew a difference of 0.02 of a meafure. 



Similar experiments I have fmce repeated and the re- 

 fult was the fame. 



Auguft 3d. 1 collected air on the top of the hill where- 

 upon Dr. Smith's Obfervatory ftands at the Falls of 

 Schuylkill, five miles from i'hiladelphia. In another 

 phial I received air from above the middle of the road 

 directly at the foot of the hill. And immediately on my 

 return home I fubmitted them and the air of the yard to 

 experiment and found them to agree exaftly as follows ; 

 Upon mixture 2.48 



After fhaking the tube 1.7B and upon adding a fecond 

 meafure of nitrous air 2.63 remained. 



Auguft 3th. 1 colledled air from above two different 

 marfhy fituations immediately below the rope-walks to 

 the fouth of this city. It is of confequence to remark 

 that thefe marfhes are overflowed by the tide. Another 

 phial I filled immediately before entering the city in Front 

 Street. Thefe airs fuffered an equal diminution from a 

 mixture of nitrous gas, viz. 2.47 upon mixture; after 

 fhaking the tube 1.79; and after adding a fecond mea- 

 fure of nitrous gas 2.64 remained. 



The air near my lodging yielded upon mixture 2.49 ; 

 after fhaking the tube 1.78 ; and upon the addition of a 

 fecond meafure of nitrous gas 2.62. 



I performed fome experiments on air colledled in other 

 fituations about the city ; but, finding the refult fo much the 

 fame as thofe above related, I did not make any note of 

 them, and remain perfedly fatisfied that Fontana's af- 

 fertion is well founded. 



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