Mndyfis of the Air. 185 



it a^ain , but could find no difference in 

 the fpecifick gravity of the two airs, and it 

 was the fame with an air of tartar which 

 was 10 days old. 



As to the other property of the air, elafti- 

 city, I found it exactly the fame in the air of 

 tartar, which was 15 days old, and common 

 air* by filling two equal tubes with thefc 

 different airs, the tubes were 10 inches long 

 and fealed at one end 5 I placed them at 

 the fame time in a cylindrical giafs condenf- 

 ing receiver, where I compreffed them with 

 two additional atmofpheres, taking care to 

 fecure myfelf from danger in cafe the glafs 

 fliould burft, by placing it in a deep wood- 

 en veffel, the water rofe to equal heights in 

 both tubes. This receiver was gently an- 

 nealed and thereby toughened, by being 

 boiled in Urine where it lay till all was 

 cold. 



I put alfo into the fame tubes fome new 

 made air of tartar, both the tubes {landing 

 in cifterns of water 5 the air of one of thefe 

 tubes I compreffed in the condenfing en- 

 gine for fome days, to try whether in that 

 compreffed ftate, more of the air's eiafticity 

 would be deftroyed by the abforbing va- 

 pours 



