OF LIQUIDS IN VAPOUR. g 



4. Of Phofphoric air. 



Phofphoric air, though confined by mercury, will 

 not always retain its property ot taking fire by the ad- 

 mifliou of atmofpheric air. A quantity of this air which 

 was made the i8th of November would not take fire on 

 the 2 2d, but burned with a lambent yellow flame on the 

 approach of a lighted candle, fmelling ftrongly of 

 phofphorus. At other times I have found this air re- 

 tain its peculiar property much longer; but it was al- 

 ways changed to a lambent inflammable air by keeping, 

 nor would heat reftore it. 



5. Of the purity or impurity of airs in various circum- 

 Jlances. 



Some experiments feem to indicate that fomething po- 

 fitive is communicated to feveral fubftances, folid and 

 fluid, in confequence of being expofed to heat. At leafl: 

 they are difpofed after this to attract pure air from the 

 atmofphere, like other fubftances during the emiflion of 

 phlogifton. The following obfervations may ferve to 

 throw fome light on this fubjedl, and perhaps deferve 

 to be profecuted farther. 



Air from v/ater frefla diftilled, from rain water, or 

 frefh fpring water, gave out air fomething worfe than 

 that which had been expofed to the atmofphere. 



Air from fnow water, from a folution of blue vitriol, 

 and from water diftilled from this folution, gave air a 

 little worfe than water long expofed to the atmofphere. 

 Such alfo was air from river water during a flood from 

 late rains. 



Putting a fmall quantity of fpirit of wine into a phial, 

 •ind covering it with a fmall glafs veflel ftanding in wa- 

 ter, I found the air within it confiderably lefs pure than 

 common air. 



Air incumbent on water impregnated with nitrous 

 vapour extinguillied a candle. 



Vol. V. B A 



